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Suzacq, Luca de la Paz.
Changes in abundance and distribution of humpback whales Megaptera novaeangliae in Hervey Bay Marine Park, Australia, based on aerial surveys conducted in 1992 and 2004
h [electronic resource] /
by Luca de la Paz Suzacq.
[Tampa, Fla] :
b University of South Florida,
ABSTRACT: Aerial surveys were conducted throughout Hervey Bay Marine Park between August and October 1992 and 2004 to determine changes in abundance and distribution of the Eastern Australia humpback whale population in this area. Due to concerns about possible effects of boat traffic on whale distributions associated with a growing whale watching industry, the number and location of vessels were also recorded during these surveys. Throughout the 1992 season, 17 flights were conducted and a total of 41.93 surveys hours were completed, recording 186 pods, and a total of 320 animals. In addition, 392 boats were spotted in the area. During 2004, 10 flights took place with a total of 23.56 survey hours, 203 pods were sighted and a total 388 animals were recorded. In addition 216 boats were spotted in the study area.Results suggested an overall increase in the density of whale sightings from 1992 to 2004. By comparing total numbers for both years normalized to the number of survey hours, it can be seen that the total number of pods and the total number of individuals both increased. In 1992, with 7 more flights and an extra 10 hours on survey, the total number of pods and the total number of whales observed were less than in 2004. The composition of the pods showed a variation throughout both seasons consistent with a known distinctive temporal segregation of humpback whales on their annual migration. The percentage of calves was higher in 2004 than in 1992 consistent with the overall recovery of the eastern Australia population.Boat traffic did not show an effect on whale distributions in either year of the study. However this work provides a baseline for continuing to monitor boat traffic and whale distributions to help ensure that the east Australia whale population will continue to recover together with a sustainable growing whale watching industry.
Thesis (M.S.)--University of South Florida, 2007.
Includes bibliographical references.
Text (Electronic thesis) in PDF format.
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Adviser: Edward S. Van Vleet, Ph.D.
x Marine Science
t USF Electronic Theses and Dissertations.
Changes in Abundance and Distribution of Humpback W hales, Megaptera novaeangliae in Hervey Bay Marine Park, Australia, Based on Aerial Surveys Conducted in 1992 and 2004 by Luca de la Paz Suzacq A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science College of Marine Science University of South Florida Major Professor: Edward S. Van Vleet, Ph.D. Joseph J. Torres, Ph.D. Paul H. Forestell, Ph.D. Date of Approval: April 4, 2007 Keywords: migration, calves, boat traffic, whale wa tching, management Copyright 2007, Luca de la Paz Suzacq
A mi querida familia
ACKNOWLEDGMENTS This study was conducted with the guidance and enco uragement of Dr. Ted Van Vleet. His support and assistance were essential fo r the completion of this study. Thank you to Greg Kaufman and the Pacific Whale Foundatio n which funded and conducted the1992 and 2004 aerial surveys and kindly provided the data to develop this work. Thanks to all my teammates in the field including B rad Chainey, our pilot from Hervey Bay Air Adventures. My deepest gratitude to the Ly nch Family in Hervey Bay; Pete, Jodie, and Anika. Thank you for opening the doors o f your home and your hearts while completing this work. I couldnÂ’t have done it witho ut your incredible support and endless sources of kindness and chocolate. I would like to thank Paul Forestell for his assistance, for sharing his knowledge and thoughts, and togethe r with Dr. Torres, reviewing this manuscript and providing constructive comments and additional guidelines to this study. A special thanks for Jay Sprinkel at Mote Marine La boratory for all his hard work and assistance on the statistics portion of this work; thank you for your valuable time. To my dear friends in so many different places, I am so h appy to know you and grateful for your friendship. To my incredible family, an endless sou rce of love, inspiration and encouragement. Thank you for your support, for alwa ys believing in me and helping me overcome any obstacles along the way while pursuing my dreams. For my cangrejo, you deserve my very special thanks, you backed me up an d your immense love gave me the strength and motivation I often lost and I daily ne eded to keep me going. Thank you to the whales for taking me into this incredible journ ey.
i TABLE OF CONTENTS LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . iv LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . v ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . 1 Humpback Whale Migration in the Southern Ocean . . . . . . . . . 2 Effects of Commercial Whaling . . . . . . . . . . . . . . . . . 6 Whale Watching Industry . . . . . . . . . . . . . . . . . . . . 7 OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 METHODS AND MATERIALS . . . . . . . . . . . . . . . . . . . . 13 Study Area . . . . . . . . . . . . . . . . . . . . . . . . . 13 Aircraft and Flight Schedule . . . . . . . . . . . . . . . . . . 14 Personnel and Equipment . . . . . . . . . . . . . . . . . . . . 14 Aerial Survey Design . . . . . . . . . . . . . . . . . . . . . 15 Survey-Flight Procedure . . . . . . . . . . . . . . . . . . . . 18 Data Entry . . . . . . . . . . . . . . . . . . . . . . . . . 19 General Data Analysis . . . . . . . . . . . . . . . . . . . . . 20 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 1992 Season . . . . . . . . . . . . . . . . . . . . . . . . . 21
ii Whale Numbers . . . . . . . . . . . . . . . . . . . . . 21 Pod Composition . . . . . . . . . . . . . . . . . . . . 33 Boat Traffic . . . . . . . . . . . . . . . . . . . . . . 34 2004 Season . . . . . . . . . . . . . . . . . . . . . . . . . 38 Whale Numbers . . . . . . . . . . . . . . . . . . . . 38 Pod Composition . . . . . . . . . . . . . . . . . . . . 47 Boat Traffic . . . . . . . . . . . . . . . . . . . . . . 49 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Whale Distribution . . . . . . . . . . . . . . . . . . . . . . 55 1992 Season . . . . . . . . . . . . . . . . . . . . . . . 55 2004 Season . . . . . . . . . . . . . . . . . . . . . . . 59 Comparison 1992 and 2004-Whale Pod Distribution . . . . . . . 63 Comparison 1992 and 2004-Mom-Calf Distribution . . . . . . . 64 Boat Distribution . . . . . . . . . . . . . . . . . . . . . . . 68 1992 Season . . . . . . . . . . . . . . . . . . . . . . . 68 2004 Season . . . . . . . . . . . . . . . . . . . . . . . 71 Comparison 1992 and 2004-Boat Distribution . . . . . . . . . . 74 Boat-Whale Pod Interaction . . . . . . . . . . . . . . . . . . . 75 1992 Season . . . . . . . . . . . . . . . . . . . . . . . 75 2004 Season . . . . . . . . . . . . . . . . . . . . . . . 78 SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
iii Appendix A Sea State Condition described by Beaufo rt Sea State Scale . . 90 Appendix B Chi-Square Goodness of Fit Test. Whale Pod Distribution August-September-October . . . . . . . . . . . . . . . . . . . 91 Appendix C Chi-Square Goodness of Fit Test. Whale Pod Distribution 1992-2004 . . . . . . . . . . . . . . . . . . . . . . . . . . 92 Appendix D Chi-Square Goodness of Fit Test. Boat D istribution 1992-2004 93 Appendix E Chi-Square Goodness of Fit Test. Whale Pod-Boat Distribution 94
iv LIST OF TABLES Table 1 Aerial survey summary in Hervey Bay Mar ine Park during 1992 season Â… 22 Table 2 Aerial survey summary in Hervey Bay Mar ine Park during 2004 season Â… 39
v LIST OF FIGURES Figure 1. Map of study area, Hervey Bay, Queensland Australia. The enclosed area shows Hervey Bay Marine Park bo undaries. Depths are given in meters . . . . . . . . . . . . . . . . 5 Figure 2. 1992 Aerial Survey Transect. Depths are given in meters . . . . 16 Figure 3. 2004 Aerial Survey Transect. De pths are given in meters . . . . 17 Figure 4. Total number of whales recorded during 19 92 season surveys . . . 23 Figure 5. Location of all humpback whale pods sight ed during August 1992 aerial surveys . . . . . . . . . . . . . . . . . . . 24 Figure 6. Location of all humpback whale pods sight ed during September 1992 aerial surveys . . . . . . . . . . . . . . . . . . . 2 5 Figure 7. Location of all humpback whale pods sight ed during October 1992 aerial surveys . . . . . . . . . . . . . . . . . . . 2 6 Figure 8. Location of all boats recorded during Aug ust 1992 aerial surveys . 27 Figure 9. Location of all boats recorded during Sep tember 1992 aerial surveys 28 Figure 10. Location of all boats recorded during Oc tober 1992 aerial surveys . 29 Figure 11. Total number of (A) pods and (B) indivi duals during 1992 and 2004 surveys . . . . . . . . . . . . . . . . . . . . . . . . 31
vi Figure 12. Total number of (A) pods and (B) individ uals per survey hour during and 2004 surveys . . . . . . . . . . . . . . . . . 32 Figure 13. Changes in percentages of pod compositio n during 1992 season . 33 Figure 14. Total number of boats per survey hour du ring 1992 season . . . . 35 Figure 15. Total number of boats per survey hour du ring weekday and weekend surveys during 1992 season . . . . . . . . . . . . . . . . 35 Figure 16. Total number of boats per survey hour recorded during each weekday and (B) weekend surveys during 1992 season . . . . . 37 Figure 17. Total number of whales recorded during 2 004 season surveys . . . 40 Figure 18. Location of all humpback whale pods sigh ted during August 2004 aerial surveys . . . . . . . . . . . . . . . . . . . 4 1 Figure 19. Location of all humpback whale pods sigh ted during September 2004 aerial surveys . . . . . . . . . . . . . . . . . . . 42 Figure 20. Location of all humpback whale pods sigh ted during October 2004 aerial surveys . . . . . . . . . . . . . . . . . . . . . 43 Figure 21. Location of all boats recorded during Au gust 2004 aerial surveys . 44 Figure 22. Location of all boats recorded during Se ptember 2004 aerial surveys. 45 Figure 23. Location of all boats recorded during Oc tober 2004 aerial surveys . 46 Figure 24. Changes in percentages of pod compositio n during 2004 season . . 48 Figure 25. Total number of boats per survey hour du ring 2004 season . . . . 50 Figure 26. Total number of boats per survey hour re corded during weekdays and weekends during 2004 surveys . . . . . . . . . . . . . 50
vii Figure 27. Total number of boats per survey hour r ecorded during each (A) weekday and (B) weekend surveys during 2004 s eason . . . . 51 Figure 28. Location of humpback whale pods recorded during (A) August, (B) September and (C) October 1992 aerial survey s according to the five defined regions . . . . . . . . . . . . . . . . . . 57 Figure 29. Location of humpback whale pods recorded during (A) August, (B) September, and (C) October 2004 aerial surv eys according to the five defined regions . . . . . . . . . . . . . . . . . . 61 Figure 30. Location of boats recorded during (A) August, (B) September, and (C) October 1992 aerial surveys according to t he five defined regions . . . . . . . . . . . . . . . . . . . . . 69 Figure 31. Location of boats recorded during (A) Au gust, (B) September, and (C) October 2004 aerial surveys according to the five defined regions . . . . . . . . . . . . . . . . . . . . . . . . 72
viii Changes in Abundance and Distribution of Humpback W hales, Megaptera novaeangliae in Hervey Bay Marine Park, Australia, Based on Aerial Surveys Conducted in 1992 and 2004 Luca de la Paz Suzacq ABSTRACT Aerial surveys were conducted throughout Hervey Bay Marine Park between August and October 1992 and 2004 to determine changes in abund ance and distribution of the Eastern Australia humpback whale population in this area. Due to concerns about possible effects of boat traffic on whale distribut ions associated with a growing whale watching industry, the number and location of vesse ls were also recorded during these surveys. Throughout the 1992 season, 17 flights wer e conducted and a total of 41.93 surveys hours were completed, recording 186 pods, a nd a total of 320 animals. In addition, 392 boats were spotted in the area. Duri ng 2004, 10 flights took place with a total of 23.56 survey hours, 203 pods were sighted and a total 388 animals were recorded. In addition 216 boats were spotted in the study are a. Results suggested an overall increase in the densit y of whale sightings from 1992 to 2004. By comparing total numbers for both years no rmalized to the number of survey hours it can be seen that the total number of pods and t he total number of individuals both increased In 1992, with 7 more flights and an extra 10 hours on survey, the total number of pods and the total number of whales obser ved were less than in 2004 The composition of the pods showed a variation througho ut both seasons consistent with a
ix known distinctive temporal segregation of humpback whales on their annual migration. The percentage of calves was higher in 2004 than in 1992 consistent with the overall recovery of the eastern Australia population. Boat traffic did not show an effect on whale distri butions in either year of the study However this work provides a baseline for continuin g to monitor boat traffic and whale distributions to help ensure that the east Australi a whale population will continue to recover together with a sustainable growing whale w atching industry.
1 INTRODUCTION Humpback whales, Megaptera novaeangliae (Borowski 1781), are found in all ocean basins. They spend summer months on productive feed ing grounds and migrate to warmer breeding/calving grounds during the winter ( Chittleborough 1965, Dawbin 1966). Southern Hemisphere baleen whale stocks hav e been defined by the International Whaling Commission (IWC) in relation to their Antarctic summer feeding aggregations (Allen 1980). Humpback whales off the east coast of Australia fee d in Antarctic Area V (130 E170W) and are described as the Eastern Australia group V stock (EAGVS). A number of authors (Chittleborough 1965, Dawbin 19 66; Chaloupka and Osmond 1999, Garrigue et al. 2000) agree that the Group V population may separate into an eastern group (New Zealand and the Pacific Islands) and a western group (east Australian coast). In addition to movements within the Group V population, intermingling in the feeding grounds among Group IV (70E -130 E), west Australian, and Group V has also been recorded (Chittleborough 1965, Rock et al. 2004). In studies conducted in the South Pacific (Gaskin 1976 ) over 3,000 humpbacks were tagged. Most recaptures showed that the Western Aus tralia, Eastern Australia and New Zealand stocks are separate ones however these stocks slightly overlap at the feedi ng grounds off Antarctica.
2 Humpback Whale Migration in the Southern Ocean In the Southern hemisphere marked humpback whales have been tracked over 6,000 kilometers between tropical breeding and polar feed ing grounds, and the connections between these two areas have been established (Kato na et al. 1979, Kaufman et al. 1990). After their summer feeding in Antarctic waters, Eas tern Australia humpback whales begin their northward migration along Austra liaÂ’s eastern coast to sub-tropical waters to mate and give birth during the winter and spring months (Chittleborough 1965, Dawbin 1966). The main calving ground for Gro up V whales is hypothesized to be the warmer lagoon waters of the Great Barrier Re ef (GBR) (Chittleborough 1965, Paterson 1984, Chaloupka and Osmond 1999). Along t he northern route, the eastern Australia group tends to remain close to shore betw een Tasmania and the GBR where they disperse widely throughout its sheltered water s (Paterson 1991). The peak in abundance of the northern migration occurs during l ate June and July (Chittleborough 1965, Paterson 1984). No such distinctive peak of humpback whales during the southern migration in August, September and October has been identified (Chittleborough 1965, Paterson 1984, 1991). Day length is a cue for many seasonallybreeding m ammals and birds and it has been suggested to be one of the triggers to commence nor thern migration for humpbacks (Dawbin 1966). Prey availability (Clapham 1996), a voidance of predators (Corkeron and Connor 1999), breeding condition (Dawbin 1966) and water temperature (Nishiwaki 1959) may also influence migratory timin g. It has been suggested that not all females migrate all the way to the breeding gro unds every season. Instead Â“restingÂ”
3 females might remain in southern areas in some year s while migrating further north in other years, depending upon reproductive condition (Chittleborough 1958, 1965, Brown et al. 1995, Craig and Herman 1997, Mikhalev 2000). Movement patterns during migration indicate a disti nctive temporal segregation on the migration based on age, gender and reproductive sta tus (Dawbin 1997). Temporal segregation observed in humpback whales appears to be inextricably related to mating strategies and reproductive success (Craig et al. 2 003). During the EAGVS northward migration, lactating females, accompanied by their yearlings are among the first group to appear on the wintering areas. They are followed by immature males and females, and then mature males and females. The last whales to appear in the wintering areas include the pregnant females (Chittleborough 1965, Dawbin 1966). A distinctive temporal segregation based on age, gender and repro ductive state also occurs during their southward migration (Dawbin 1997). Whales be gin their southern journey from the GBR in late July (Forestell et al. 2003); howev er the majority leaves the region from mid-August to mid-October (Paterson 1991, Fore stell et al. 2003). During this period humpbacks begin to enter Hervey Bay (Figure 1) (Bryden et al. 1989, Forestell et al. 1993, Corkeron et al. 1994). It has been estimated that 30 to 50 percent (Bryden et al. 1989, Chaloupka et al. 1999) of the Eastern Australia population enter the calm sheltered waters of Hervey Bay every season as part of their southern migration. Humpba cks have been recorded in Hervey Bay during the months of July to November (Kaufman et al. 1993). Whales enter and
4 leave Hervey Bay through its northern mouth. Photo -identification studies in conjunction with aerial surveys conducted in 1988 a nd 1989 suggested a mean residence time of EAGVS humpbacks in Hervey Bay of 1 to 3 days (Corkeron et al. 1994), although some individuals have been observed to remain in the Bay for up to 9 days (Forestell et al. 1993). Whales entering Hervey Bay seem to follow the movem ent pattern consistent with the distinctive temporal segregation of humpback whales on their migration (Chittleborough 1965). Immature and adult humpback whales have been the first groups sighted throughout the Bay during August and September foll owed by mothers and their calves.
5 Figure 1. Map of Study Area, Hervey Bay, Queensland, Australia. The enclosed area shows Her vey Bay Marine Park boundaries. Depths are g iven in meters.
6 Mothers and calf pods reach peak levels by mid-Sept ember and have been sighted in Hervey Bay through late October. Studies along Byr on Bay (28r S), a southern location along the eastern Australia coast, recorded mothers and their calves comprising more than 50 percent of all humpbacks during the final w eeks of the EAGVS southward migration ( Chittleborough 1953). Effects of Commercial Whaling Humpbacks of the Eastern Australia Group V stock we re severely reduced by commercial whaling during the 1950s and early 1960s Chittleborough (1965) estimated that the entire EAGVS was reduced from its original status of 10,000 to only 500-800 individuals by 1960. Recent documents have suggest ed that unreported illegal Soviet catch during the late 60Â’s (Mikhalev 2000) may have exceeded population estimates derived by Chittleborough (1965). After serious de pletion of all stocks, the hunting of humpback whales in the entire Southern hemisphere w as banned in 1963 by IWC (Mackintosh 1965). Despite all, humpback numbers al ong the east coast of Australia have shown evidence of population recovery during t he last two decades (Paterson et al. 1994). Today EAGVS seasonal abundance in Hervey Bay has be en estimated to be increasing at a rate of 6-11.7 percent per year (Paterson et a l. 1994, Bryden et al. 1997, Chaloupka et al. 1999). Chittleborough (1965) estimated 36-6 3 years for Group V to recover to its pre-whaling status of 10,000.
7 1998 estimates (Paterson cited QDEH 1999), 33 years later, show the Eastern Australia Group V population to be approximately 3,5004,000 individuals. Whale Watching Industry Whale watching has grown from an activity carried o ut in few places and by few people into a USD$1 billion commercial industry, attractin g more than 9 million participants a year in 87 countries and territories world-wide (Ho yt 2001). In Australia, commercial whale watching has become one of the fastest growin g tourism sectors. The number of whale watchers increased from 335,200 in 1991 to ov er 730,000 during 1998, generating total revenues of USD$32.3 million and USD$56 million respectively (Hoyt 2001). Hervey Bay has become the main whale watch center o f the state of Queensland from July to October. Since the first whale watching ex cursions in 1987, immediate concerns of potential harassment of whales by priva te and commercial whale watching operators arose (Chaloupka 1990). By 1989, the Dep artment of Environment and Heritage (Queensland National Parks and Wildlife Se rvice) declared the eastern portion of Hervey Bay a Marine Park, in order to regulate h uman activity and ensure the protection of the whales during the early stages of a growing commercial whale watching industry.
8 To regulate interaction between the public and the whales, an official guideline to whale watching was issued by the Queensland Departm ent of Environment and Heritage (QDEH) and the Pacific Whale Foundation in 1994 ( QDEH 1997, Vang 2002). State guidelines require that commercial a nd recreational boaters approach whales no closer than 100m, approach animals slowly from the side, and avoid sudden changes in course and speed. In addition, boats a re not to place themselves in a whaleÂ’s predictable path or separate a group of wha les. Additionally, boaters are requested to abandon interaction with whales at any sign of the whale becoming disturbed (e.g. swimming evasively, diving for long periods of time). By 2004, 12 commercial whale watching operators wer e operating in Hervey Bay and the number of whale watchers visiting the area was estimated to be approximately 65,000 each season (Queensland Park and Wildlife Se rvice (QPWS) 2004). Although the number of commercial whale watching vessels ent ering the park has been limited through a permit system since the establishment of Hervey Bay Marine Park, there is no limit on the number of private vessels, an issue of concern especially taking into account the rapid growth of Hervey Bay and nearby c ities. The city of Hervey Bay, with 49,371 residents in 20 04, was the second fastest growing local government area in Queensland and the 11th fastest growing city in Australia at that time. The population is projected to reach ov er 86,675 by 2026 (QG 2005). Strong advertising, a new airport, and recent flight servi ces from Sydney and Melbourne,
9 combine to make Hervey Bay a growing business cente r and a premier tourist destination. As in other communities, with economic expansion of a whale watching industry come the concerns of its effects on whale populations. It has been recognized for many years that harassment by vessels can have both short and long term effects on humpback whales (Norris and Reeves 1978). While short-term disturbances may impact an individual or a group briefly, long-term effects ha ve been more difficult to quantify and may be more damaging to the general fitness and rep roductive success of a whale population. Cetaceans display a wide variety of re actions to human activities; they may approach a vessel, move away or not react at all. Humpback whales generally respond to whale watching boats with a stereotyped tendency to increase their swim speed (Bauer 1986, Bauer and Herman 1986, Au and Green 2001). Recent studies on responses of humpba ck whales to whale watching vessels recorded an increase in their swimming spee d by 50 percent in studies at their breeding grounds off the coast of Ecuador (Scheidat et al. 2004) and as much as 300 percent in Hawaiian Island breeding grounds (Au and Green 2001). Repeated disturbance of critical behavior such as feeding, r esting and mating can reduce the biological fitness of the population. While on the ir breeding grounds, humpback whales do not feed; they rely on their blubber rese rves obtained during the summer months at their feeding grounds, and therefore may be exceedingly vulnerable to energetic costs as consequence of repeated disturba nce. Mom-calf pairs are especially
10 vulnerable to disturbance since some of the mothers Â’ avoidance responses are to increase their swim speed and dive time, thus reduc ing the amount of feeding and resting time with their calves. In Hawaiian waters mom-calf pairs are proportionally less frequent in shallow coastal waters where recre ational boating has increased (Glockner-Ferrari and Ferrari 1985, 1990, Salden 19 88). As a result, monitoring the extent of disturbance in calving grounds by whale w atching activities is important especially in Hervey Bay when the peak number of m om-calf pairs coincides with local school spring holidays and there is a major i ncrease of vessel traffic. Boat traffic may disturb whales and possibly even l ead them to avoid an area. Gray whales in Baja California have been reported to aba ndon Guerrero Negro, a breeding lagoon, presumably as a response to the increased s hip traffic for a salt work operation (Bryant et al. 1984). When the traffic was relocate d, the whales returned to the lagoon. In recent years, observations of gray whales migrat ing further off shore in the Southern California Bight have been interpreted as either a response to increased human activity along the coast or a reoccupation (by an increasing whale population) of routes historically used (Rice and Wolman 1971, Dohl and G uess 1979). When engaged in surface behaviors (e.g. feeding, nu rsing, and mating) whales may be less attentive to their surrounding making them mor e vulnerable to ship strikes. Data suggest that younger whales may be more susceptible to collision with vessels, perhaps because they typically spend more time on the surfa ce, are less visible, are closer to shore ( Herman et al. 1980, Mobley et al. 1999, Smu ltea 1994) or due to a combination
11 of these factors. Habitats preferred by calves and juvenile whales may be areas of greater risk of vessel collision, especially if the se areas have high vessel traffic. Data also suggest that whales may learn to avoid vessels as they mature. In either case, habitats preferred by nursing humpback whales could be areas where collision risks are greater and more attention should be required from boaters. Humpback whales have been recorded to exhibit a hig h degree of site fidelity on their feeding and breeding grounds (Clapham et al. 1993). Results from long term photoidentification studies in Hervey Bay have suggested a high degree of site fidelity among whales sighted in this area (Forestell et al. 2003) While strong site fidelity in Hervey Bay can be evidence of the ability for adaptation a nd tolerance to human activity, it may equally show the biological importance of these areas for the continuation of recovery of EAGVS population. Whether or not there is a limit to such tolerance, it is important to evaluate changes in whale distribution in relation to human activities in this marine area. There is no information to suggest that commercial whale watching in the area has altered the distribution of whales in Hervey Bay. P re-whaling distribution is unknown. However by looking at distribution patterns of whal e pods during two separate seasons twelve years apart, this work intends to assess sig nificant changes in whale distribution that may have occurred as a result of Hervey BayÂ’s growing whale watching industry.
12 OBJECTIVES The present study was undertaken to evaluate changes in abundance and distribution of humpback whales in Hervey Bay during the months of August, Septembe r and October by comparing data from 1992 and 2004 aerial surveys Data collected during the surveys was used to test the following hypotheses: (1) Null Hypothesis [H]: The number of whales found i n Hervey Bay between July and October has not increased from 1992 to 2004. Alternate Hypothesis [H1]: The number of whales entering Hervey Bay from 1992 to 2004 has increased as a r esult of recovery of the Eastern Australia Group V Stock. (2) Null Hypothesis [H]: There has not been a change in the distribution of pods throughout Hervey Bay from 1992 to 2004. Alternate Hypothesis [H1]: Increases in the number of whales entering Hervey Bay from 1992 to 2004 has resulted in a shif t in distribution and habitat use throughout the Marine Park. (3) Null Hypothesis [H]: Boat traffic in Hervey Bay h as had no effect on pod distribution. Alternate Hypothesis [H1]: A shift in whale pod distribution can be related to changes in commercial and recreational boat traffic from 1992 through 2004 in Hervey Bay Marine Park.
13 METHODS AND MATERIALS Study Area Hervey Bay (24 42.0Â’ S, 152 50.7Â’ E) is a sandy shallow marine embayment of approximately 4000 square kilometers (Vang 2002) l ocated in Queensland, on the east coast of Australia (Figure 1). Most of the Bay is less than 24 m deep and is delimited on the western side by the Australian coastline and on the eastern side by Fraser Island, the world largest sand island (126 km long). Under a Hervey Bay Marine Park Permit aerial survey s were conducted in the study area from early August through late October in 1992 and 2004. This period coincides with the time of peak number of humpback whales in the area (Forestell et al. 1993), providing sufficient numbers that afford statistica l comparison of their quantity and distribution during subsequent years. Data from 19 92 surveys were collected by research colleagues and kindly provided for analysi s and further comparison with 2004 data. In order to maintain a basis of comparisons among both years, the 2004 aerial surveysÂ’ protocol was kept similar to the 1992 (For estell et al. 1993) except for slight differences in the type of aircraft used, the lengt h of transect followed, and the frequency of flights.
14 Aircraft and Flight Schedule In 1992, seventeen aerial surveys were conducted fr om August 11th through October 24th; providing a total of 41.93 survey hours while in 2004 ten surveys were conducted from August 9th through October 22nd completing 23.56 hours of survey effort. During the 1992 surveys, a single-engine, high-wing aircra ft Cessna 210 was used. In 2004 surveys were conducted using a single-engine, highwing Cessna 172. In both years, flights were at 300 m altitude, with an average airspeed of 90 knot s. 300 m survey altitude has been proved most effective for assessm ent of large cetaceans (Dohl et al. 1983) with minimal disturbance (Bauer and Herman 19 86). For both years, flights were programmed to take place twice a week, one flight d uring the week and one flight during the weekend. If flights needed to be resched uled due to poor weather conditions, surveys were always reprogrammed in order to fly eq ual number of days during the week and during the weekend. Personnel and Equipment In both years, a pilot, two observers and a data re corder accompanied each flight. The data recorder flew next to the pilot in the front r ight-hand seat and the two observers in the rear seats on each side of the aircraft. For ea ch flight, weather and sea condition data (wind speed, cloud coverage, Beaufort Sea Stat e scale, and visibility) were recorded at the beginning and end of each survey or throughout the survey if conditions changed.
15 Sea state conditions, described through a Beaufort Sea state scale (Appendix A) are known to significantly affect sighting probabilitie s (Buckland et al. 1993). Mobley et al. (2000) reported a significant drop in sightings above a Beaufort Sea State of 3. In 1992 and 2004, sea state averaged 1.75 0.21. Win d speed conditions average 7.5 0.29 knots for both survey years. Onboard the aircraft, a portable Garmin GPS (Global Positional Service) navigator was used throughout 1992 surveys to control transect fi delity and record location at each sighting. In 2004, a portable Garmin GPSMAP 176C p re-loaded with the survey track lines on a study area nautical chart by Garmin Paci fic BlueChart v. 4.01, was used to control transect fidelity and to automatically reco rd real-time track, with latitude and longitude location, altitude and speed of the aircr aft each second of the survey. Aerial Survey Design Transects were designed to minimize the effects of glare and maximize coverage within the Marine Park boundaries to assess whales on the east side of the Bay, a region named Platypus Bay, well-known to be favored by wha les (Forestell et al. 1993, Corkeron et al. 1994,). During both years, survey track lines were designed according to distance sampling theory (Burnham et al. 1980, B uckland et al. 1993). Using this approach, the surveys followed a systematic paralle l line transect design. A series of pre-determined north-south line transects of various lengths spaced 4.82 km apart were followed (Figures 2 and 3).
16 Figure 2. 1992 Aerial Survey Transect. Depths a re given in meters.
17 Figure 3. 2004 Aerial Survey Trans ect. Depths are given in meters.
18 Each straight line transect drawn between two endpoints, represented o ne transect leg. Each year, the same series of line transects was flown on every survey. Half of the flights were conducted in a south-north line of tra vel, where the starting point of the survey was south of the bay at Point Vernon (2513. 5Â’ S, 15254.5Â’ E). The other half were flown on a north to south direction where th e starting point of the survey was located at northern tip of Fraser Island (2432.0Â’ S, 15320.1Â’ E in 1992, and 2440.4Â’ S, 15311.7Â’ E in 2004). In 1992, flights were conducted along a series of n ine pre-determined line transects connecting eighteen endpoints along a total of 460 km. In 2004 flights were conducted along a series of seven pre-determined line transec ts connecting fourteen endpoints along 356 km, covering most of Hervey Bay Marine Pa rk boundaries including shallow near shore waters off the west and north shore of F raser Island. The survey covered an area of 600 square km SurveyFlight Procedure When a pod of whales was sighted, observers called out the data and the recorder manually noted on a preformatted data sheet the t ime of the day, group size and composition (adults, sub-adults, calves), the spott ing cue, the Â“clockÂ” pod location relative to the aircraft, the estimated right angle distance (the shortest distance from the transect line to the animalÂ’s position), and the pr esence of any vessels within 400 m to
19 the pod. In addition to humpback whales, the locati on and number of other species of whales, dugongs, dolphins and boats were also recor ded. Estimates of distance from the horizontal track lin e were categorized as 800 m, 1600m or 2400m. These estimates were made with the help o f a tape on the wing strut, which when lined up with a mark on the aircraft window pr ovided sighting lines at these three categories at any height of the aircraft ( Scott a nd Wind 1980). During turns at each endpoint and when flying over Fraser Island area, o bservers were offsurvey and spotted pods were recorded as off-survey pods and w ere not considered for the total count of pods. Data Entry Following each survey, the real-time track was down loaded from the portable GPS into Garmin MapSource v.6.5. The location for each of the pods was derived from the aircraft location at the time the pod was sighted, the Â“clockÂ” heading location to the pod, and the distance from the track line to the po d.
20 General Data Analyses Data Treatment and Statisti cs. A series of chi-square Goodness-of-Fit (Cochran 195 2) analyses were conducted to assess significance differences in the distribution of whale pods and boats throughout the study. Only sightings within Hervey Bay Marine Park boundaries were compared within the statistical analysis. In a first test, the difference between months (August, September and October) were compared for each year to investigate the changes that occurred throughout the season. A second series of chi-square Goodness-of-Fit were conducted between the three months of study (i.e. A ugust 1992 was compared to August 2004, September 1992 compared to September 2 004, and October 1992 was compared to October 2004). Finally, to examine the interaction of whale pods with boats, a series of chi-square Goodness-of-Fit tests were conducted to assess the similarity between the location of boats and whale pods during August, September and October for each survey year.
21 RESULTS 1992 Season Whale Numbers A total of 41.9 survey hours were completed during 17 flights from August 11th through October 24th during the 1992 season (Table 1). Of the 17 fligh ts, 9 were conducted during the week and 8 during a weekend. In addition 9 surveys were conducted along a southÂ–north travel direction and 8 conducted in a n orth-south direction. During the 1992 season, 186 pods were recorded with a total of 320 humpback whales; 289 were adults (90.3%), 4 were subadults (1.2%) and 27 we re calves (8.5%) (Figure 4). Due to uncertainty in differentiating adults and sub-ad ults, the two groups were combined in further figures and discussions. In addition, a to tal of 392 vessels were observed in the study area during the survey hours (Table 1). Fig ures 5, 6 and 7 show the location of whale pods observed during August, September and Oc tober 1992 surveys, and Figures 8, 9, and 10 superimpose the location of all boats sighted during those same times.
22 Table 1: Aerial Survey Summary in Hervey Bay Mari ne Park During 1992 Season Date Obs. Cond. Survey Hours No. of Pods Total No.of ind No. of Adults No.of SubAdults No. of Calf Pods per Hour Ind. per Hour No. of Boats Boats per Hour 8/11 EX 2.85 11 22 20 2 0 3.86 7.71 9 3.16 8/14 GD 2.38 13 17 16 1 0 5.46 7.14 11 4.62 8/23 GD 2.59 8 18 18 0 0 3.09 6.95 26 10.04 Â† 8/26 EX 2.37 8 13 13 0 0 3.38 5.49 18 7.59 AUG 10.19 40 70 67 3 0 3.93 6.86 64 6.28 9/1 EX 2.59 9 10 10 0 0 3.47 3.86 23 8.88 *Â† 9/5 EX 2.5 13 21 19 1 1 5.2 8.4 21 8.4 9/10 EX 2.58 20 31 30 0 1 7.75 12.01 37 14.34 9/12 EX 2.39 8 12 12 0 0 3.35 5.02 30 12.55 *Â† 9/19 EX 2.59 12 16 15 0 1 4.63 6.17 21 8.11 Â† 9/22 EX 2.58 14 26 23 0 3 5.43 10.07 28 10.85 9/26 EX 2.49 19 34 31 0 3 7.63 13.6 27 10.84 SEPT 17.72 95 150 140 1 9 5.36 8.46 187 10.55 10/1 EX 2.52 17 34 29 0 5 6.75 13.49 37 14.68 *Â† 10/3 EX 2.45 15 33 30 0 3 6.12 13.46 47 19.18 10/6 EX 2.62 8 11 9 0 2 3.05 4.19 29 11.07 *Â† 10/10 EX 2.49 6 11 8 0 3 2.41 4.41 19 7.63 Â† 10/16 GD 2.59 5 11 6 0 5 1.93 4.24 6 2.32 *Â† 10/24 GD 1.35 0 0 0 0 0 0 0 3 2.22 OCT 14.02 51 100 82 0 18 3.64 7.13 141 10.06 Total 41.93 186 320 289 4 27 4.44 7.6 392 9.35 *Weekend Flight Â† Reverse Flight Track EX= Excellent Observation Conditions GD= Good Observation Conditions
23 70 150 100 320 0 100 200 300 400 500Total No. of Whales AugustSeptemberOctoberTOTAL Total Number of Whales 1992 Season No. of Adults No. of Calves Figure 4. Total number of whales recorded during 1992 season surveys.
24 Figure 5. Location of all humpba ck whale pods sighted during August 1992 aerial sur veys.
25 Figure 6. Location of all humpba ck whale pods sighted during September 1992 aerial surveys.
26 Figure 7. Location of all humpba ck whale pods sighted during October 1992 aerial su rveys
27 Figure 8. Location of all boats recorded during August 1992 aerial surveys.
28 Figure 9. Location of all boats recorded during September 1992 aerial surveys.
29 Figure 10. Location of all boats recorded during October 1992 aerial surveys.
30 The total number of pods and individuals vary throu ghout the season in 1992, with the highest number of pods and individuals recorded dur ing the month of September with 96 pods and a total of 150 whales (Figures 11A and 11B). The lowest number of pods and individuals were recorded in August with 40 pod s and 70 whales, whereas in October 52 pods and a total of 100 individuals were sighted. For further comparison, the number of pods and indi viduals were calculated as pods and individuals per survey hour (Table 1, Figures 1 2A and 12B). September, having the highest values for total pods and individuals also presented the highest values of pods and individuals per hour (5.36 pods per hour, 8.46 individuals per hour). Meanwhile, August and October with lower total number of pods and individuals represented the lowest number of pods per hour (3.93 pods per hour, 3.64 pods per hour) and individuals per hour (6.86 individuals per hour, 7. 13 individuals per hour respectively).
31 (A) 0 20 40 60 80 100No. Pods AugustSeptemberOctober No. of Pods 1992 vs. 2004 Season 1992 Season 2004 (B) 0 50 100 150 200No. Ind AugustSeptemberOctober No. of Individuals 1992 vs. 2004 Season 1992 Season 2004 Figure 11. Total number of (A) pods and (B) indiv iduals during 1992 and 2004 surveys.
32 (A) 0 2 4 6 8 10 12No. Pods per Hr AugustSeptemberOctober Pods per Hr 1992 vs. 2004 Season 1992 Season 2004 (B) 0 5 10 15 20 25No. Ind per Hr AugustSeptemberOctober Individuals per Hr 1992 vs. 2004 Season 1992 Season 2004 Figure 12. Total number of (A) pods and (B) indiv iduals per survey hour during 1992 and 2004 surveys.
33 Pod Composition Composition of the pods showed a variation througho ut 1992 season (Figure 13). In the total number of whales, the highest percentage of adults was recorded in August (95.7%), and decreased as the season progressed to values of 93.3% by September and 82% by October. Meanwhile, monthly calf sightings increased from 0% in August, to 6% in September and 18% in October (Figure 13). Th e first mom and calf pair of the 1992 season was sighted on September 5th (during survey number 6). 0% 20% 40% 60% 80% 100% Individuals AugustSeptemberOctoberTOTAL 1992 Season Changes in Pod Composition % Adults % Calves Figure 13. Changes in percentages of pod composi tion during 1992 season.
34 Boat Traffic To evaluate the amount of boat traffic in Hervey Ba y Marine Park during whale season and eventually assess probabilities of their impact s on the whales, data on the number of boats was recorded during week and weekend surve ys. Since the total number of survey hours for each month was different, boat tra ffic was compared using values of boats per survey hour (Bts/hr) only (Table 1). Dur ing 1992, September showed the highest number of recorded boats (10.55 Bts/hr), wh ile August showed the lowest number of recorded boats for the entire season (6.2 8 Bts/hr, Figure 14). Although September represented the highest number of boats d uring the entire season, it only represented the highest number of sightings du ring weekday hours (11.35 Bts/hr), while October and August represented the highest nu mber of boats during weekend hours (10.97 Bts/hr and 10.30 Bts/hr respectively) (Figure 15). Therefore, with the exception of September when the number of boats per hour was generally higher during weekday than during weekend surveys, August and Oct ober presented higher values of boat traffic during weekends than during weekdays.
35 0 5 10 15No.Boats per Hr AugustSeptemberOctober 1992 Season Boats per Hour Figure 14. Total number of boats per survey hou r during 1992 season. 0 5 10 15No. Boats per Hr AugustSeptember October Boats per Hour 1992 Season Weekday vs. Weekends Weekday Surveys Weekend Surveys Figure 15. Total number of boats per survey hou r during weekday and weekend surveys during 1992 season.
36 Figures 16A and 16B show the number of boats per ho ur recorded for each weekday and weekend survey during 1992. The highest numbers of boats recorded in a single day during the entire season were during a weekend day on October 3rd (survey number 13) where a total of 19.18 Bts/hr were sighted, and during a weekday survey on October 1st (survey number 12) where 14.68 Bts/hr were recorde d. These high numbers of boats in the area are likely due to an increased flow of tourists that travel to the region during Australian schoolsÂ’ holidays. These data will be compared to 2004 below, and further compared with peak numbers of mo m-calf pods that generally occur by the end of the season.
37 (A) 8-Aug 14-Aug 26-Aug 1-Sep 10-Sep 22-Sep 1-Oct 6-Oct 16-Oct 0 5 10 15 20 25 30No. Boats per Hr1992 Boats per Hour Weekday Surveys (B) 23-Aug 5-Sep 12-Sep 19-Sep 26-Sep 3-Oct 10-Oct 24-Oct 0 5 10 15 20 25 30No. Boats per Hr 1992 Boats per Hour Weekend Surveys Figure 16. Total number of boats per survey hour r ecorded during each (A) weekday and (B) weekend surveys during 1992 season.
38 2004 Season Whale Numbers A total of 23.56 survey hours were completed during 10 flights from August 4th through October 22nd during the 2004 season (Table 2). Of the 10 flight s, 5 were conducted during the week and 5 conducted during the weekend. 5 flew on a south-north line of direction, while 5 were conducted in the opposite d irection. 203 pods were observed with a total of 388 whales, of which 342 were adult s (88%), 7 were sub-adults (2%) and 39 (10%) were calves (Figure 17). Due to uncertaint y in differentiating adults and subadults, the two groups were combined in further fig ures and discussion. In addition, 216 vessels were recorded in the study area during the surveys. Table 2 summarizes humpback whales and boat sightings observed during 2004 aerial surveys. Figures 18, 19, and 20 show the locations of the whale pods obs erved during August, September and October 2004 respectively. Figures 21, 22, and 23 superimpose the location of all boats observed during each survey. As in 1992, the total number of pods and individual s changed throughout the 2004 season. Contrary to 1992, in 2004 the highest numbe r of total pods and individuals were sighted during the month of August with 98 pods and a total of 179 individuals. Values gradually decreased through September and October w ith 73 pods and 142 whales and 32 pods and a total of 67 individuals corresponding ly (Figures 11A and 11B).
39 Table 2. Aerial Survey Summary in Hervey Bay Marin e Park During 2004 Season Date Obs. Cond. Survey Hours No. of Pods Total No.of ind No. of Adults No.of SubAdults No. of Calf Pods per Hour Ind. per Hour No. of Boats Boats per Hour 8/4 EX 2.37 14 35 34 1 0 5.91 14.76 2 0.84 Â†8/13 EX 2.35 25 44 43 0 1 10.63 18.72 3 1.27 *Â†8/21 EX 2.34 34 52 52 0 0 14.52 22.22 66 28.2 8/26 GD 2.34 25 48 44 3 1 10.68 20.51 13 5.55 AUG 9.4 98 179 173 4 2 10.42 19.04 84 8.93 9/11 EX 2.35 22 44 44 0 0 9.36 18.72 31 13.19 Â†9/17 EX 2.33 13 27 23 0 4 5.57 11.58 14 6 *Â†9/25 GD 2.36 38 71 58 2 11 16.1 30.08 31 13.13 SEPT 7.04 73 142 125 2 15 10.37 20.17 76 10.8 10/5 GD 2.38 18 38 25 1 12 7.56 15.96 19 7.98 *10/16 GD 2.38 9 20 14 0 6 3.78 8.4 22 9.24 Â†10/26 GD 2.36 5 9 5 0 4 2.11 3.81 15 6.35 OCT 7.12 32 67 44 1 22 4.5 9.4 56 7.86 Total 23.56 203 388 342 7 39 8.61 16.46 216 9.16 *Weekend Flight Â† Reverse Flight Track EX= Excellent Observation Conditions GD= Good Observation Conditions
40 179 142 67 388 0 100 200 300 400 500Total No. of Whales AugustSeptemberOctoberTOTAL Total Number of Whales 2004 Season No. of Adults No. of Calves Figure 17. Total number of whales recorded durin g 2004 season surveys.
41 Figure 18. Location of all hump back whale pods sighted during August 2004 aerial s urveys.
42 Figure 19. Location of all humpba ck whale pods sighted during September 2004 aerial surveys.
43 Figure 20. Location of all humpback whale pods sig hted during October 2004 aerial surveys.
44 Figure 21. Location of all boat s recorded during August 2004 aerial surveys.
45 Figure 22. Location of all boat s recorded during September 2004 aerial surveys.
46 Figure 23. Location of all boat s recorded during October 2004 aerial surveys.
47 Calculating the values for the total number of pods in pods per survey hour (Table 2), the same correlation was seen. August and September with the higher sightings of pods, represented the highest number of pods per hour (10 .42 pods and 10.37 pods per hour respectively), while October represented the lowest number of pods per hour (4.5). When calculating the number of individuals per hour August and September showed the highest values (19.04 and 20.17 individuals per hour), while October with the lowest number of pods per hour also represented the lower number of individuals per survey hour of the season (9.4) (Figures 12A and 12 B). Pod Composition As the number of the pods changed throughout the se ason, the composition of the pods also changed. While the percentage of adults decrea sed from August to October, the percentage of calves increased. During the beginnin g of the season, the percentage of adults was 96.6% of the total number of individuals and decreased to 88% in September and to 65.7% in October (Figure 24). Meanwhile the first mom-calf pods were spotted during our second and fourth survey of the season, on August 3rd and August 26th, and the percentage of calves in August ( 1.2%) increase d to 10.6% in September and 32.8% in October.
48 0% 20% 40% 60% 80% 100% Individuals AugustSeptemberOctoberTOTAL2004 Season Change in Pod Composition % Adults % Calves Figure 24. Changes in percentages of pod composit ion during 2004 season.
49 Boat Traffic September showed the highest number of total boats per survey hour (10.8), while October represented the lowest number of total boat s per hour (7.86) (Table 2, Figure 25). Weekend flights represented higher number of b oats per hour than weekday flights, with the exception of the first two flights of the season when boat numbers were very low (Figure 26 and Figure 27). The two highest number of boats recorded on any sin gle day were during weekend surveys on August 21st (28.2 Bts/hr; survey number 3) and September 11th (13.13 Bts/hr; survey number 5). The highest numbers of b oats per hour in any single week day survey were on October 5th (7.98 Bts/hr; survey number 8) and October 26th (6.35 Bts/hr; survey number 10) (Figures 27A and 27B). T hese high numbers of boats during a weekday survey were likely due to the presence of tourists that arrive during spring break to the area.
50 0 5 10 15No.Boats per Hr AugustSeptemberOctober 2004 Season Boats per Hour Figure 25. Total number of boats per survey hour during 2004 season. Figure 26. Total number of boats per survey ho ur during weekdays and weekend during 2004 surveys. 0 5 10 15No. Boats per Hr AugustSeptemberOctober Boats per Hour 2004 Season Weekdays vs. Weekends Weekday Surveys Weekend Surveys
51 (A) 13-Aug 26-Aug 17-Sep 5-Oct26-Oct 0 5 10 15 20 25 30No. Boats per Hr 2004 Boats per Hour Weekday Survey (B) 4-Aug 21-Aug 11-Sep 25-Sep 16-Oct 0 5 10 15 20 25 30No. Boats per Hr 2004 Boats per Hour Weekend Survey Figure 27. Total number of boats per survey hour r ecorded during each (A) weekday and (B) weekend surveys during 2004 s eason.
52 DISCUSSION The density of whale sightings increased from 1992 to 2004. By comparing totals for both years (Tables 1 and Table 2) it show that the total number of individuals both increased. In 1992, even with 7 more flights and a n extra 18 hours on survey, the total number of pods and total number of whales observed were less than in 2004. In 1992, the total number of individuals was 320 while in 2004 t he total number was 388. In 1992 a total of 186 pods were spotted while in 2004, 203 p ods were spotted. By comparing August, September and October separately for both y ears (Figures 11A and 11B) it can be seen that 2004 presents the highest values of both total number of pods and total number of individuals during the month of August (F igures 11A and 11B). For September and October, higher numbers of pods and i ndividuals were spotted during 1992. As the number of survey hours were different in bot h years, it is more appropriate to compare the data from both years in terms of pods/h r and ind/hr. In this way, it is seen that in 2004 more pods and more individuals were ob served during all three months of the season: August, September and October (Tables 1 and Table 2, Figures 12A and 12B). Comparing changes in pod composition, it can be see n that for both years as we move through the season from August to October, there is a decrease in the percentage of adults and a concurrent increase in the percentage of calv es. In 1992, the percentage of adults
53 decreased from 95.7% in August to 93.3% and 82% in September and October respectively (Figure 13), and in 2004 from 96.6% in August to 88% and 65.7% in September and October respectively (Figure 24). Th e number of calves in 1992 increased from 0% in August to 6% and 18% in Septem ber and October. In 2004, the first mom-calf pod was spotted early in the season on Aug ust 13th, whereas in 1992, the first mom-calf pair was not sighted until September 5th. In 2004, calves already constituted 1.2% of the total pod composition by the end of Aug ust and increased to 10.6% in September and to 32.8% in October. The results of a higher percentage of mothers and c alves in Hervey Bay waters during the latter stages of migration both years are consi stent with the findings of Chittleborough (1953) who analyzed groups of whales throughout Byron Bay, a southern location (28S) along the eastern Australi an coast. Chittleborough reported that mothers accompanied by their calves comprised more than 50% of all humpbacks during the final weeks of EAGVS southward migration These changes in pod composition throughout the m igratory season during 1992 and 2004 in Hervey Bay are consistent with the distinct ive migration timing presented by humpbacks based on their age, sex and reproductive status (Dawbin 1997). Newly pregnant females are the first group to leave the G reat Barrier Reef (GBR) followed by young males and females (sub-adults), and then matu re adults. Mothers with their new born calves are the last group to leave GBR waters and start the slow southern journey to their Antarctic feeding grounds. The disparity in departure times of the different
54 groups from the lagoons of the GBR result in a diff erence in their arrival times in Hervey Bay. These differences result in the tempor al distribution of whales observed in Hervey Bay during the present study. Although the same pattern of change in pod composit ion was observed for both years, the degree of change in pod composition during 2004 sur veys through August, September and October was greater than in 1992. This results show a higher proportion of calves (0.33 in 2004, 0.18 in 1992) sighted in Hervey Bay by the end of the 2004 than in 1992 season. With recent estimates of EAGVS to be incre asing at a rate of 6-11.4 per cent per year (Paterson et al. 1994, Bryden et al. 1997, Cha loupka et al. 1999), the observed increase in the percentage of new calves sighed fro m 1992 to 2004 are reflections of a population in growth and consistent with the overal l recovery trend undergo by the EAGVS.
55 Whale Distribution 1992 Season Whale pods location showed a change in their spatia l distribution throughout the season (Figures 5, 6 and 7). During August, most whale po ds were observed in the northern portion of the study area, north of Rooney Point, a longside the north and northeast ends of Fraser Island. By September, when the peak numb ers of pods were recorded, a clear shift of location was observed. Most of the pods w ere sighted south of Rooney Point, particularly along the western shore of Fraser Isla nd throughout the area known as Platypus Bay. This same distribution pattern persis ted during October with the arrival of high numbers of mom and calf pairs which resided particularly in the northeastern portion of this area. These results are consistent with previous work fr om aerial and boat-based studies (Forestell et al. 1993, Corkeron et al. 1994) which found that humpback whales entering the Bay prefer the shallow waters off the western shores of Fraser Island, particularly waters off Wathumba Creek. Though the reason for the preference for the waters off Wathumba Creek remains unclear, it has b een suggested that it could be due to the occurrence of freshwater from the creek (Van g 2001). 1992 surveys covered a broader area (than the 2004 surveys) along the north and northeast shores of Fraser Island (Figure 2) which allowed us to observe the distribution
56 of whales outside Hervey Bay Marine Park boundaries During August 1992, a high proportion of pods were sighted outside the Bay (Fi gure 5). However as the season progressed, whales coming to the area later in the season, were more likely to enter and be distributed throughout the Bay. These observati ons are consistent with the hypothesis (Forestell et al. 1993) of a high number of whales passing by Hervey Bay along the east coast of Fraser Island during the fi rst stages of their southward migration, while later in the season, whale pods, mostly consi sting of moms and their recently born calves, arrive to the area and are more likely to enter and reside in the Bay for a few days before continuing traveling south. To better determine changes in pod distribution thr oughout the three months of the study and for further comparison to changes in dist ribution between 1992 and 2004, the study area was divided into five regions (Figures 2 8). The five different regions were defined in order to include a northÂ–south and a nea r-shore-offshore component. The near-shore-offshore component was defined with a 6. 5 km distance-to-shore line that followed the Fraser Island shore outline. Region 1 (R1) includes the area north of Rooney Point off the north shore of Fraser Island. Region 2 (R2) comprises the northwest section of Hervey Bay. Region 3 (R3) cont ains the near shore northern portion of the Bay between Wathumba Creek and Roone y Point, including Bikini Cliff (see Figure 1). Region 4 (R4) includes the southern offshore area and Region 5 (R5) compromises the southern near shore portion, an are a that extends from Wathumba Creek to Moon Point and includes Triangle Cliff and Arch Cliff (see Figure 1).
57 (A) (B) (C) Figure 28. Location of humpback whale pods rec orded during (A) August, (B) September and (C) Octo ber 1992 aerial surveys according to the fiv e defined regions.
58 During August, 58.1% of the total number of pods we re sighted in R1 (Figure 28A). Within the four regions between Rooney Point and Mo on Point, the highest number of pods was sighted in the offshore regions (R2 = 13%; R4 = 19.3%), while fewer number of pods were recorded in the near shore regi ons (R3 = 3.2%, R5 = 6.4%) (Figure 28A). By September (Figure 28B) these distributions chang ed as a greater number of whales were moving south of Rooney Point into the Bay. R 1 showed a lower number of sighted pods (17.5%) than in August, while a higher number of whales (82.5%) were sighted within the remaining four regions of the Ba y. Within these four regions, the whales appeared fairly uniformly distributed (R2 = 17.5%, R5 = 20%, R3 = 22.5%, R4 = 22.5%) (Figure 28B). During October (Figure 28C), 22.2% of the whale pod s were recorded in the northern region of the study area (R1) while 77.8% of the si ghted pods were located in the southern regions of the Bay (R2, R3, R4 and R5). Ho wever, within these four regions of Hervey Bay, the distribution of whale pods did n ot remain evenly distributed as was observed during September. In October, the highest number of animals was recorded in R3, the northeastern portion of the Bay, with 31.3% of the total sighted pods. The lowest number of whales was observed in the southea stern portion of the study area in R5, which contained 11.1% of the total number of an imals. R2 and R4 presented the remaining 15.6 % and 20% of the recorded pods. Dur ing the later part of the season
59 (October), whales appeared to move out of the south ern regions of Hervey Bay into the more northern areas (Figure 28C). In order to statistically evaluate changes in whale pod distributions throughout the five regions during August, September and October, a chi -square test was conducted. Chisquare results showed that whale pods were found to be distributed proportionally differently across the five regions during the thre e months of the study (Appendix B). The proportion of number pods found on each of the defined five regions throughout August, September, and October was different. These results showed whale pod distributions did not remain constant throughout th e season. Instead, pods made use of the different sections of the study area differentl y during each month of the study. 2004 Season Pod locations in 2004 (Figures 18, 19 and 20) showed a similar change in spatial distribution throughout the season as was seen duri ng 1992 surveys, especially during October when mom and calf pairs entered the Bay and located preferentially throughout the protected northwestern shores of Fraser Island. To better quantify changes in the distribution of w hale pods throughout the season, the same approach to data analysis was followed, and th e 2004 study area was divided into the same five regions as in 1992 (Figures 29A, 29B and 29C). The number of whale pods observed during August 2004 (n=98, 10.42 pods per hr) was much higher than in
60 August 1992 (n= 40, 3.93 pods per hr). In addition during August 2004, the total percentage of animals within the southern regions o f the Bay was significantly higher (72.1%) than in August 1992 (41.9%). Pods were un iformly distributed within the four Regions south of Rooney Point with slightly higher numbers of animals in R3 (21.6%) and R4 (20.6%). This indicates that pods were fou nd spread out throughout southern regions of the Bay much earlier than in 1992. Ani mals were sighted in higher numbers from the northern shores of Fraser Island (Rooney P oint) to southern points of the Bay (Figure 29A). Throughout September (Figure 29B), the distribution of whale pods remained fairly similar to that seen in August. 73.6% of all whale pods remained located south of Rooney Point especially throughout the proximities of Wathumba Creek between Arch Cliff and Bikini Cliff. The southeastern portions o f the Bay (R4 and R5) presented the highest number of pods (22.2 % and 23.6% respective ly) while R3, which had the highest number in August, contained the lowest numb er during September (11.1%). This might suggest either a small southward migrati on of the whales in September, or the animals in the northern region of Platypus Bay were leaving the region in greater numbers.
61 (A) (B) (C) Figure 29. Location of humpback whale pods rec orded during (A) August, (B) September and (C) Octo ber 2004 aerial surveys according to the fiv e defined regions.
62 By October most of the animals had departed Hervey Bay, and the total number of whale pods had decreased substantially from August and September. Of those remaining in the area (Figure 29C), 81.2% were loca ted south of Rooney Point. Within the regions of the southern portions of Hervey Bay, near shore R3 showed the highest number of whale pods (34.4%), with R2 having 18.7%, R4 having 18.7% and R5 having 9.4%. Most animals were located north of Tri angle Cliff in the area between Wathumba Creek and Rooney Point (see Figure 1). Wit h the exception of one pod, no whales were recorded south of Triangle Cliff. Conv ersely in 1992, six pods were recorded in the southern area between Triangle Clif f and Arch Cliff. It therefore appears that during October 2004, whale pods were s hifted slightly northward along the west shores of Fraser Island compared to 1992. Is important to emphasize, of the six pods sighted south of Triangle Cliff in October 199 2, three of them were mother and calf pairs, while during 2004 the only pod sighted south of Triangle consisted only of adult whales. No mother and calf pairs were sighted south of Triangle Cliff during October 2004. Consistent with the distribution of whales during 1 992 and also with earlier work in Hervey Bay (Forestell et al. 1993), the 2004 data c onfirm the preference of mom and calf pairs for the shallow near shore waters off th e west coast of Fraser Island, especially the area off Wathumba Creek in Platypus Bay. Further research (i.e. Geographic Information System (GIS) studies) in the area off Wathumba Creek, assessing whale distribution related to water salin ity, could provide evidence of a
63 correlation between the podsÂ’ location and the occu rrence of fresh water inputs from Wathumba Creek. To statistically evaluate changes in the distributi on of whale pods in 2004 throughout the five regions during August, September and Octob er, a chi-square test was applied to these distribution data. Results indicated that the re was no significant difference in the proportion of pods recorded in each of the five reg ions during these three months of 2004 (Appendix B). Contrary to the 1992 chi-square results, the 2004 distribution of pods throughout the five regions remained fairly co nstant, indicating that whale pods in 2004 used the study area in similar proportions thr ough the migration season. Comparison of 1992 and 2004 Changes in Whale Pod Distribution A series of chi-square Goodness-of-Fit tests were c onducted to evaluate changes in whale distribution patterns between 1992 and 2004. In order to keep the same area dimensions for both years of the study, pods sighte d on the northeast section during the 1992 survey were not considered in the calculations Three separate chi-square tests were conducted in order to determine changes throug h August, September and October across the five defined regions in the study area f or 1992 and 2004. A fourth test was conducted combining the three months to test for ov erall changes in distribution between the two years.
64 Chi-square results for August data (1992 vs. 2004) were unreliable due to the low number of pod sightings recorded in some of the reg ions during August 1992. No significant differences in pod distributions were o bserved between 1992 and 2004 for any of the five regions during September or October or when the entire season was taken as a whole (Appendix C). These results show that even though the recorded number of whales was different between 1992 and 200 4, whale pods were generally found to be distributed in the same proportion thro ughout the five regions of the study area. Comparison of 1992 and 2004 Mom-Calf Pair Distrib utions Based on previous work that suggested Hervey Bay to be an important calving ground for the EAGVS population (Bryden et al. 1989, Fores tell et al. 1993), the distribution patterns of mom-calf pairs during the 1992 and 2004 seasons was assessed to examine their preferred locations as they entered the shelt ered waters of Hervey Bay. During 1992 surveys, no momÂ–calf pairs were recorded until September, whereas during 2004 the first two mom and calf pairs were sighted on Au gust 3rd and August 26th. Both of these mom-calf pairs were spotted south of Rooney P oint (Figure 18), one off the northwest shores of Fraser Island (R3) and one in t he southwestern portion of the Bay (R4). During September 1992 (Figure 6), 11.4% of the tota l numbers of pods were mom and calf pairs. These mom-calf pairs were distributed primarily within the regions south of
65 Rooney Point (66.6%) while about a third (33.3%) we re sighted in the northern portion of the Bay, north of Rooney Point. Within southern Hervey Bay waters, moms and their calves were approximately equally distributed between the north (33.3%; R2 and R3) and south regions (33.3%; R4 and R5). Mom and calf pairs located in the southern region were all recorded in the southeastern secti on of Platypus Bay (south of Arch Cliff; see Figures 1 and 6), a busy area known for its heavy boat traffic of commercial whale watching and private vessels (due to its prox imity to Hervey BayÂ’s main harbor, Urangan Boat Harbor). By October 1992 (Figure 7), the number of mom and calf pairs increased to 40% of the total number of pods. 83% of these mom-calf pairs were found within the sheltered southern waters of Hervey Bay while only 17% were sighted north of Fraser Island (Figure 7). Of the pairs found wi thin the Bay, most of the moms and calves were observed along Platypus Bay off the coa st of Wathumba Creek and Triangle Cliff, showing a slight northern shift fro m the September distribution and the importance of this area for moms and their calves. During September 2004, mom-calf pairs comprised 20. 8% of the total number of pods (n=72). This was almost double the percentage of m om-calf pairs seen during September 1992 (11.4%). The 2004 mom-calf pairs w ere located primarily within the Bay (73.4%), with 40% of the pods being sighted in the southern portion of the Bay between Wathumba Creek and Arch Cliff (R4 and R5). 33.4% were recorded north of Wathumba Creek but still near shore (R3) with the h ighest concentration found between Bikini Cliff and Wathumba Creek (Figures 19). Duri ng October, 77.2% of the pairs were located within Hervey Bay (Figure 20) with alm ost 60% distributed in
66 the northern portion of the Bay (Figure 20) off Bik ini Cliff in the area between Wathumba Creek and Rooney Point. This again suggest ed a slightly northward shift from the September distribution and was similar to the trend seen in 1992. Based on the above results for the distribution of mothers and their calves, it seems clear that moms and their calves have a preference for the sheltered near shore waters of Platypus Bay, especially the northeastern portio n between Triangle Cliff and Bikini Cliff. The preference for these waters by mothers and their calves becomes clearer as the season progresses, with more pairs arriving in the Bay and distributing themselves between Wathumba Creek and Rooney Point. Bryden et al. (1989) have suggested that the reside nce time of whales in Hervey Bay is quite brief, averaging one to three days before lea ving the Bay and continuing their southern journey. Therefore, the high number of m om-calf pods sightings off Rooney Point north of Fraser Island may be due to a contin uous movement of animals into and out of the Bay through the northern portion of Herv ey Bay (R1). Previous studies (Forestell et al. 1993) have suggested that mothers and calves spend most of this time resting within Platypus Bay, and when they leave th e area they do it relatively quickly. Data from the current study confirm that Platypus B ay is the preferred resting area for mothers and their calves (R3 and R5) while the adja cent northern area (R1) is more of a transit area use by whales to enter and leave the B ay.
67 One notable observation on the October 5th 2004 aerial survey was the unusual sighting of a pod with multiple mom and calf pairs recorded off the coast of Rooney Point north of Fraser Island (Figure 20). Although this occurr ence was the only one recorded during the aerial surveys, pods with multiple mom a nd calf pairs were recorded on fifteen different occasions during the vessel surve ys in 2004. These atypical affiliations between a mother and her calf with another mother a nd calf, while unusual for the northern Pacific humpback whale population, have be en reported for Gray whale females in their breeding lagoons of Mexico and als o on previous occasions in Hervey Bay (Pacific Whale Foundation 2000). In 2000 durin g their vessel surveys, the Pacific Whale Foundation reported the first observation of multiple mom-calf humpback whale pairs in Hervey Bay after recording on six differen t occasions unescorted mom-calf pairs affiliating with another mother and calf pair During 2004 vessel surveys, the Pacific Whale Found ation sighted 15 multiple mother and calf pods (Pacific Whale Foundation 2004). Eig ht of these were escorted by one to three escort animals. Escort whales are generally assumed to be sexually active males seeking an opportunity to mate with one of the moth ers that even though lactating may undergo postpartum ovulation and become impregnated (Kaufman and Forestell 1986). Further research in assessing multiple mother-calf associations could provide possible explanations for this notable, but still uncertain behavior in Hervey Bay females. This behavior may be conducted by females to collectivel y take care of their young as a response to the presence of boats in the area or in an attempt to avoid harassment by
68 escorts. Observations of the distribution of vessel s in this study did not show elevated numbers of boats in the proximities to where multip le mom-calf pairs were recorded. These observations provide further evidence of the importance of Hervey Bay Marine Park as a critical resting and nursing area for mot hers and their new born calves, and demonstrate the importance of this area for the con tinuing recovery of the EAGVS population. Boat Distribution 1992 Season In order to evaluate the amount of boat traffic in Hervey Bay Marine Park during whale season and assess probabilities of their impacts on the whales, data on the distribution of boats were analyzed according to the same five r egions whale pod distribution data were evaluated (Figure 30). During August 1992, the majority of boats (92%, n=5 8, 6.28 Bts/hr) were found within the southern regions of Hervey Bay Marine Park (Fig ure 30A), with boats primarily distributed in R2 (30.1%), R4 (27%) and R5 (31.7%). In R5, most of the boats were sighted offshore Moon Point (Figure 30), an area kn own for high boat traffic due to the proximity to Hervey BayÂ’s Harbor, Urangan Harbor. O nly 3.2% of the recorded boats were sighted in the northeast region of the Bay (R3 ).
69 (A) (B) (C) Figure 30. Location of boats recorded during (A) August, (B) September and (C) October 1992 aerial s urveys according to the five defined r egions.
70 This percentage increased throughout the season as more whale pods, especially mothers and their calves entered that area during t heir southern migration. By September, when the peak number of boats (n=187, 10.55 Bts/hr) and whales (n=92, 5.36 Pods/hr) occurred (Figures 30B), only 5.7% of the total number of boats were sighted in the northern region of the Bay (Region 1 ). 94% of the boats were observed south of Rooney Point in the southern regions of th e Bay (R2 = 25.4%, R3 = 8.7%, R4 = 19, 8%, and R5 = 40.1%. As was recorded in Au gust, the southeast region (R5) had the highest number of sighted boats, and the no rtheast region (R3) had the lowest number of boats. By October, the high number of recorded boats conti nued (n = 141, 10.06 Bts/hr). The highest number of boats recorded in a single day du ring the entire season was observed during a weekend day on October 3rd, where a total of 19.18 Boats/hr were recorded. As was recorded in September, 94% of the boats reco rded during October (Figure 30C) were sighted south of Rooney Point and only 6% were found off the northern shores of Fraser Island (R1) Within the southern regions of the Bay, boats conti nued to be distributed throughout the entire Bay (15.7% in R2, 26.1% in R3 25.4% in R4, and 26.8% in R5). However a higher percentage of boats were recorded in R3 during October. In fact, the highest number of boats reco rded during the entire season in the northeast region of the Bay (R3) coincided with the time that the highest number of pods was recorded in that area as well (31.3%) (Fig ure 30C). Overall we saw that in R3 the number of boats increased from 3.1% in Augus t to 9% in September to 26.1%
71 by October while the number of pods also increased from 3.2% in August to 21.5% in September and 31.3% in October. R5 presented the highest percentage of the total nu mber of boats throughout the entire season; in August 31.7%, September 40.1% and Octobe r 26.8%. Heavy boat traffic in the southern portion of Hervey Bay (R5) is not surp rising due to its proximity to Urangan Harbor and being the main route used by wha le watching fleets to enter and leave Platypus Bay. One recommendation for future studies would be to identify sighted boats as private or commercial boats to determine if the density of tra ffic is based on an increase in the frequency of trips by commercial whale watching ves sels or due to an increase of private boats in the area. 2004 Season During the 2004 survey, the number of boats sighted during August was higher than the number recorded during August 1992 (8.93 Bts/hr in 2004, 6.28 Bts/hr in 1992). The number of boats observed during September was simil ar for both years (10.5 Bts/hr in 1992 and 10.8 Bts/hr in 2004)) while during October lower number of boats were sighted during October 2004 than in 1992 (10.06 Bts/hr in 1 992 and 7.86 Bts/hr in 2004) (Figure 31).
72 (A) (B) (C) Figure 31. Location of boats recorded during (A) August, (B) September and (C) October 2004 aerial s urveys according to the five defined r egions.
73 During August 2004 (Figure 31A) the highest number of boats was sighted in the four southern regions within Hervey Bay (81.3%) while th e number of boats sighted on the northern portion of the study area was only 18.7% ( R1). Comparing boats and whale pod locations in R1, we can observe that most of the bo ats sighted were found offshore while the whale pods were located near shore along Fraser IslandÂ’s coast. Within the Bay, the highest number of boats was recorded within R5 (42. 7%), while the lowest number was observed in the northeastern R3 (10.6%). The remain ing sightings were distributed offshore between R2 (12%) and R4 (16%). By September (Figure 31B) the number of boats withi n the southern regions in the Bay increased to almost 86%, while about 14% were still sighted in R1 offshore the north Fraser Island coast. In R1, boats were observed cl oser to shore where a number of whale pods were also observed. South of Rooney Point, bo ats were sighted in all four regions with the highest numbers in R5 (33.8%). The number of boats observed in R3 increased (from 10.6% in August) to 20.7% in September. Most of these boats were found in the southern portion of R3 close to Wathumba Creek wher e most of the whale pods were sighted. By October, when the lowest number of whale pods we re recorded (n= 32, 4.5 Pods/hr) and most animals were observed in the north eastern region of Hervey Bay (R3 = 34.4%), only 13.5% of the boats were sighted in that region (Figure 31C). The rest of the boats appeared uniformly distributed in the remaining reg ions.
74 The highest numbers of boat sightings within the f our regions of the Bay were observed in R5 (25%) while the lower number of whal es were recorded in same region (R5 =9.5%). The other regions contained slightly l owest number of boats (R2 = 23.1%, and R4 = 23.0%) with 18.7% of the pods sighted in b oth regions (R2 and R4). Comparison of 1992 and 2004 Boat Distribution To further evaluate changes in boat distribution pa tterns from 1992 to 2004, a series of chi-square Goodness-of-Fit tests were conducted. I n order to keep the same area dimensions for both years of the study, boats sight ed off the northeast coast of Fraser Island during the 1992 survey were not considered i n the calculations. Three separate chi-square tests were conducted in o rder to determine changes through August, September and October across the five defin ed regions in the study area between 1992 and 2004. An additional test was condu cted combining data from August, September and October. Results showed tha t the proportion of observations of boat distributions at each of the five regions betw een 1992 and 2004 was significantly different during each of the three months of the st udy. Results of the three months combined for each year also showed that overall boa t distributions were different between 1992 and 2004. (Appendix D). These results are consistent with changes in whale watching operations between the survey years. Changes in whale watching fleets into bigger and faster boats, have allowed whale wa tching operators to travel further and cover broader areas within the Bay. Upgrading to mo dern whale watching vessels have
75 allowed operators during 2004 to maximize their wha le watching trips, reach different areas than in 1992 and as a result observe changes in boat distribution between the survey years. Boat-Whale Pod Interactions 1992 Season To look at possible levels of disturbance to whale pods by boats, a further examination of the location of boats and whale pods during Augu st, September and October in 1992 and 2004 was conducted. The same approach was foll owed and the study area of Hervey Bay was considered in five defined regions t o discuss distribution of whales, boats and their interaction. In August 1992, while most whale pods (58.1%) were sighted in the northern portion of Hervey Bay (R1) most boats (92%) were recorded with in the southern areas of the Bay predominantly south of Wathumba Creek (58.7%). As a result only the pods located in these southern areas (25.7%) were exposed to signif icant boat traffic. By September when the peak number of whale pods was recorded, the highest number of boats for the entire 1992 season was also record ed due to a high influx of tourists to the area as a result of national holidays. While w hale pods during September were found fairly uniformly distributed throughout the f our regions south of Rooney Point (R2=17.5%, R3, R4 and R5 = 22.5% each), boats were sighted mostly in the southern
76 portions of the Bay in R4 and R5 (60 %), especially in the near shore waters between Wathumba Creek and Moon Point R5 (40%). 45.8% of the total number of whale pods were exposed to the highest level of boat traffic o f the season. In addition to the highest levels of traffic, the f irst mom and calf pods were sighted during September in the Bay. Of the nine mom-calf pairs sighted, six were observed in the northern portions of the study area (R1, R2, an d R3) while three pairs were observed in the busy southern region (R4 and R5) be tween Wathumba Creek and Moon Point. Of the six pairs recorded in the area north of Wathumba Creek only two were recorded with boats in their proximity. Of the thr ee pairs in the southern regions (R4 and R5), two were sighted with boats in their proxi mities. Both of these pairs were sighted in R5. After examining the distribution of mothers and their calves, it is evident that they prefer near shore waters along th e western coast of Fraser Island and also that they migrate further south and closer to Urangan Harbor, where they interact with more vessels in the area. Because this study did not differentiate between pr ivate and commercial vessels, we could not evaluate the proportion of commercial ver sus private boaters interacting with the whale pods. This is an important factor to cons ider for future studies especially taking into consideration the high number of pods t hroughout the Bay at the same time there is a peak in the number of boats in the area. The high level of traffic is of significant importance especially considering the a rrival of private boaters to the area during the holidays. Contrary to commercial operat ors, private boaters may be more
77 inexperienced or uninformed of Hervey Bay Marine Pa rk regulations and whale watching guidelines and could become potential thre at for whales while they congregate in Hervey Bay. Previous reports from w hale watching boat surveys have recorded incidents in which private boaters were se en behaving inappropriately in the proximities of whale pods, breaking whale watching regulations and disrupting the pods. By October, when pods sighted within the Bay are co mposed largely of mothers and their calves, 31.3% of all pods were found in the n ortheastern portion of the Bay (R3). R3 represented the highest number of recorded pods of any single region in the Bay. At the same time, there was an increase in boat sighti ngs in this portion of the Bay (R3) as well. The percentage of boats increased from 9% in September to 26.1% in October in this portion of the Bay while R5 south of Wathumba decreased from 40.1% in September to 26.8% in October showing a northern sh ift of the location of boats. Looking specifically at mom and calf pairs entering the Bay, of a total of 18 pairs sighted, twelve were sighted north of Wathumba, of which only four of these pairs were sighted with a vessel in their proximity. Of the re maining six pairs sighted south of Wathumba, only two pairs were sighted close to a ve ssel. At the same time, seven of the pods were comprised only of adult whales (no ca lves), and five of them were observed with vessels in their proximity. Overall i t seems mothers and their calves sighted in southern portions of the Bay may not nec essarily be the main target for boats in the area.
78 To further assess the distribution pattern of all w hale pods and boats and evaluate potential interaction between them, a series of chi -square Goodness-of-Fit tests were conducted for the 1992 data. Results showed that th e distribution of pods and boats observed within each of the five regions was signif icantly different during August, September and October of 1992 (Appendix E). These results suggest that there is not an overlap between whale pods and boat locations, prov iding evidence of no major disturbances by boats while whales enter Hervey Bay Marine Park waters. 2004 Season During August 2004, pods recorded within the four s outhern regions of the study area were found to be fairly uniformly distributed throu gh out the Bay. However boats were mainly recorded in the southeastern region of the B ay (R5=42.7%) between Triangle Cliff and Moon Point in the proximity of Urangan Ha rbor. As a result, pods sighted in the southern portions of the Bay (R5= 15.5%) are ex posed to heavy boat traffic due to its proximities to the harbor. Moreover, the first mother and her calf were spotted this early in the season, however they were located far off shore in the Bay with no boats recorded in their proximity. During September, the peak boat traffic was recorde d. The two highest numbers of sighted boats for the entire 2004 season were recor ded during two September surveys. 58% of recorded boats were sighted along the southe rn sections of the Bay throughout R4 and R5. At the same time 45.8% of the recorded p ods were sighted in these southern
79 waters as well. As a result almost half of the pods distributed throughout this area were exposed to interactions with boats. By the end of the season (October), boat traffic wa s still very high. This resulted in high levels of boat traffic overlapping with the pr esence of a high number of mothers and their calves in the area. This overlap is of s pecial concern. As suggested by previous studies, younger whales may be more vulner able to collision with boats especially because they spend longer periods of tim e on the surface, are less visible, and are less experienced avoiding boats. A combin ation of inexperienced boaters with inexperienced calves around boats could increase th e chances for collisions to new borns. Unfortunately, no differentiation was done between commercial and private vessels in this study, so we could not determine the degree of commercial versus private boat traffic in the Bay. For further studies it would be important to consider this factor in order to help with management decisions with respec t to boat traffic in the area. While the southern portions of the Bay (R4 and R5) recorded 48% of the total number of sighted boats in October, the highest number of pods was recorded in the northern regions (R1, R2, and R3). 71.8% of the total number of pods sighted during October was distributed along the northern portions of the Bay, 82% of which were mothers and calf pairs. Only 18.2% of the mom and calve pairs w ere located south of Wathumba where almost half of the boats were sighted. These results indicate no overlap in the
80 distribution of high numbers of pairs of mom-calf p airs with the high number of vessels, as most boats locate further south in the Bay while most pods locate in the northern portions which provide sheltered, shallow, and calm waters, an ideal location for mothers and their young to rest before proceedi ng on their southern return to their Antarctic feeding grounds. A series of chi-square Goodness-of-Fit tests were c onducted for the 2004 data. Results showed that the distribution of boats and pods was significantly different in each of the five regions during August and September, but it wa s not significantly different during the surveys in October (Appendix E). These results show there is an equivalent amount of boats and whale pods sharing the same region. These outcomes are worth considering as a baseline for future studies since October is the time when most mothers and their calves arrive in Hervey Bay.
81 SUMMARY In summary, the following main conclusions were rea ched in this study: 1. The total number of humpback whale sightings in He rvey Bay increased from 1992 to 2004. Sightings during 2004 surveys were higher thr oughout the three months of study, particularly during August and September when the n umber of whales in 2004 was more than double the number during 1992. The increased sightings in Hervey Bay are consistent with the overall increase of the Eastern Australia Group V Stock. 2. Although the number of whales entering Hervey Bay increased in 2004, the same pattern of seasonal change in the overall compositi on of the pods was observed in 1992 and 2004. Throughout the season from August to Oct ober, a decrease was observed in the percentage of adults composing the pods, with a concurrent increase in the percentage of calves. This trend was observed in both 1992 an d 2004 consistent with a known distinctive temporal segregation of humpback whales on their migration. 3. The overall distribution of whale pods in Hervey B ay did not change significantly when comparing 1992 to 2004. Although the number of whal es was different between years, their pattern of distribution was not statistically different throughout the months of this study.
82 4. The total number of boats recorded in Hervey Bay during the three months of the study did not increase from 1992 to 2004. During both years, the highest number of boats was observed in Hervey Bay at the same time w hen the peak number of humpback whales was sighted in the study area. 5. The distribution of boats throughout Hervey Bay was found to be different between 1992 and 2004 reflecting changes in whale watching operations between survey years. The distribution of boats was not related to the lo cation of whale sightings during August, September or October 1992. However during 2004, wh ile the distribution of boats and whales were different during August and September, it was the same during October, indicating a direct interaction of boats and whales at that time. This is significant in that it is during October that mothers and calves arrive in the area to rest, and the chances for interaction with boats are highest during this time 6. Although there has not been an increase in the to tal number of boat in the area, there has been an increase in the number of boats arrivin g every weekend to the area. This is an important consideration so that Marine Park auth orities can make sure visitors in the area learn about park regulations and guidelines fo r conducting their vessels in case of an encounter with whale pods during the season.
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90 Appendix A Sea state condition described by the Beaufort Sea S tate Scale Beaufort number Wind Speed (knots) Wind description 0 < 1 Calm 1 1 3 Light air 2 4 6 Light breeze 3 7 10 Gentle breeze 4 11 16 Moderate breeze 5 17 21 Fresh breeze 6 22 27 Strong breeze 7 28 33 Near gale 8 34 40 Gale 9 41 47 Strong gale 10 48 55 Storm 11 56 63 Violent storm
91 Appendix B Chi-square Goodness of Fit Test Whale Pod Distribution August-SeptemberOctober X 2 df 1992 Whale Pod Distribution 16.09 8 P= 0.041 2004 Whale Pod Distribution 10.53 8 P= 0.229 In 1992, proportions of observations did vary signi ficantly from month to month. In 2004, proportions of observations did not vary s ignificantly from month to month.
92 Appendix C Chi-square Goodness of Fit Test Whale Pod Distribution 1992-2004 X 2 df August 1992-2004 6.1 4 Unreliable test September 1992-2004 4.9 4 P= 0.292 October 1992-2004 0.26 4 P= 0.992 Overall 1.3 4 P= 0.848
93 Appendix D Chi-square Goodness of Fit Test Boat Distribution 1992-2004 X 2 df August 1992-2004 20.4 4 P= <0.001 September 1992-2004 24.7 4 P= <0.001 October 1992-2004 9.7 4 P= 0.044 Overall 31.9 4 P= <0.001
94 Appendix E Chi-square Goodness of Fit Test Whale PodBoat Distribution 1992 X 2 df August 57.2 4 P= <0.001 September 5.1 4 P= <0.001 October 28.01 4 P= <0.001 2004 X 2 df August 16.6 4 P= 0.002 September 9.6 4 P= 0.046 October 7.06 4 P= 0.133