Distribution, abundance and biology of Group V humpback whales ...

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6.1.2 Sloughed skin sampling Sloughed skin sampling is a technique used for collecting genetic material from samples such as skin, hair and faeces from an individual at the surface (Palsbøll 1997). Sloughed whale skin contains enough DNA for genetic analysis, and offers a non-intrusive method for collecting tissue (Valsecchi et al.1998). A study undertaken by Valsecchi (1998) demonstrated that sloughed skin sampling is a viable alternative to genetic sampling and is particularly effective when applied to active groups. The sloughed skin sampling technique offers a viable alternative to biopsy darting in regions where darting is either not permitted or otherwise undesirable. Amos and Hoelzel (1992) described a method for preserving skin tissue for DNA-based analysis. The collection of skin tissue for genetic analysis is preferable because skin is easily accessible and is rich in DNA. Skin from stranded whales can remain usable for at least a week, and probably longer depending upon ambient conditions (Amos and Hoelzel 1992). 6.1.3 Acoustic tracking Male humpbacks sing while migrating to and from their wintering grounds and while they are present at the wintering grounds. However, it is uncertain whether or not song functions to maintain a space between pods or to attract females (Tyack 1981). All males in a population produce the same song, which changes over time and with increasing distance (Cato 1991). Noad et al.(1998) undertook an acoustic and visual tracking study in south-east Queensland and concluded that acoustic tracking may be especially useful for the study or survey of whale movements beyond visual range of shore-based observation points. The information gathered is dependent upon the number of hydrophones used. Three hydrophones provided positional information on singing humpbacks and the paths they took. Three hydrophones are required to make a direct comparison between visual and acoustic tracking methods. The study has implications for the interactions between singers and non-singing humpbacks; interactions between individual singers; migratory behaviour and travel rates; pod composition; habitat use; song function and boat-whale interactions. Although acoustic tracking gathers information from singing individuals, it cannot be used as a technique to identify individuals for long-term studies. For other innovations in monitoring humpbacks out of visible range of ships, acoustics have been used with other species and may eventually prove feasible for monitoring humpback occurrence at remote areas such as outer reef complexes (Clark et al.1996 and 2002; Clark and Fristup 1997; Clark and Ellison 2000; Frankel et al.1995). 6.2 Manipulative sampling techniques A close approach to a whale is required for the attachment of a conventional tag, the taking of samples for genetic analysis and the taking of identifying photographs. The attachment of tags and biopsy sampling are considered as manipulative research (Queensland Department of Environment 1997). However, the certainty with which a sample is taken and the information provided is considerable, especially when combined with photoidentifi cation data. In general biopsy samples have not been taken from calves due to cultural sensitivities and the perceived impacts of the technique. In 1992, a study undertaken by Valsecchi et al.(2002) targeted mother and calves pairs for genetic analysis; biopsy samples were taken from the mothers and when conditions were favourable sloughed skin samples were taken from the accompanying calf. The study supports the notion that mothers travel with their offspring for the fi rst year of the calf’s life. 6.2.1 “Discovery tags” Chittleborough (1959a) and Dawbin (1959) used “discovery tags” to provide distributional information on the group IV and V populations during the commercial whaling period. Discovery tags were conventional metal tags inserted sub-dermally into the humpback. The tags were retrieved when the harvested whale carcass was processed. The discovery tags were successfully used to reveal that some intermingling was occurring on the feeding grounds between the group IV and V populations; and the migratory routes, either side of the Australian continent, to the wintering grounds of the group IV and V populations (Chittleborough 1965). 6.3 Biopsy sampling Biopsy sampling is a technique that involves the taking of a core of skin using a dart fi red from a crossbow. The biopsy dart is a cylindrical punch measuring approximately 10mm in diameter and 30mm long. A metal fl ange at the base controls the depth of penetration by the dart. The dart has a collar of fl otation behind the tip, and may or may not be tethered to assist retrieval (Brown et al.1994). The combination of genetic and photo-identifi cation data provides a powerful tool for identifying individual humpbacks (Stevick et al.2001). The reactions of several cetacean species to biopsy sampling have been investigated (Patenaude and White 1995; Gauthier and Sears 1999; Weinrich et al.1992). Clapham and Mattila 1993b and Brown et al.(1994) undertook studies on humpbacks and concluded there was no signifi cant change in behaviour to the biopsy sampling. However, Weinrich et al.(1992) and other authors have noted that there is a greater reaction to the human disturbance caused by the boat and its occupants than to the sampling technique itself. Brown et al.(1994) investigated the behavioural responses of east Australian humpbacks to biopsy sampling and suggests that female humpback whales maybe particularly responsive to human disturbances. They concluded that biopsy sampling has minimal impact on humpbacks. Hooker et al.(2001) compared the reactions of biopsy sampling with tag attachment on northern bottlenose whales Hyperoodon ampullatus. They found the reactions of various species to biopsy darting is generally mild, the most common response is a “startle” reaction, although the level of reaction varies slightly between species, and also between populations and individuals. In contrast, the reaction of cetaceans to tagging with suction-cups-attached tags has been found to vary dramatically. Biopsy sampling is described as a manipulative research technique. The technique is neither encouraged nor excluded by the management approach adopted in Queensland. 6.4 Telemetry Telemetry tags methods include the use of satellite-linked time-depth recorders, satellite-linked position beacons, time-depth recorders and VHF radio tags. This technique is a powerful took for investigating aspects of baleen whales’ ranging behaviour, and are likely to become a powerful tool in the future. Mate et al.(1997, 1999 and 2000) illustrates the use and application of the tagging techniques on other baleen species. 12 • Distribution, abundance and biology of Group V humpback whales Megaptera novaeangliae: A review • August 2002
7 Reproduction Humpback whales are a long-lived, slow breeding species and are believed to have a life expectancy of about 50 years. Clapham and Mead (1999) is an excellent review of the humpback. The following is an extract from their paper. The average and maximum life expectancies in this species are unclear, partly because whaling probably removed most of the oldest animals from the populations in which this question has been studies. The oldest whale observed by Chittleborough (1965) out of many thousands examined in the Australian catches) was one aged 48 years old. This estimate is dependent upon acceptance of the age determination technique employed which assumes that four layers are laid down each year in the laminar ear plug found in the auditory meatus. 7.1 Age and length The species exhibits sexual dimorphism with females usually being larger than males of the same age. Females from the Group IV and Group V populations appear to reach sexual maturity at an average age of 5 or 6 years old (Chittleborough 1955b and Clapham 1992) or a length of 39·5ft (12 m) and 39·66ft respectively (Dawbin 1960 and Chittleborough 1955b). Males attain sexually maturity within a simular range to females, 6–7 years, although they may not be able to successfully engage in intrasexual competition until later in life (Clapham 1992). A calf is defi ned as being approximately 63 percent of the size of its mother while on wintering grounds and is considered to be independent when it is weaned which is usually about 11 months old (Clapham et al.1999a). An immature female whale is one that has not produced a calf (Chittleborough 1965) whereas a sexually mature female is one that has produced a calf (Chittleborough 1955b). Both males and females reach a maximum size at about 20 years of age (Chittleborough 1965). However, there does not appear to be any real difference between the growth rate of humpbacks in the northern and southern hemispheres (Chittleborough 1965). 7.2 Female reproduction and behaviour Mature females are believed to conceive during the winter season en route to or from the winter grounds and return to give birth the following winter after a gestation period of 10–12 months (Chittleborough 1965). Pregnant females are the last age class to leave Antarctica on migration and usually the last to return with their new calves (Dawbin 1966). A female usually produces one young every two or three years, although annual calving has been reported for a number of individual whales by several authors (Chittleborough 1965; Straley et al.1994; Weinrich et al.1993; Clapham & Mayo 1987. Since 1992, The Oceania Project has conducted a research and education program in Hervey Bay, Queensland. Their program has positively photo-identifi ed several female humpbacks that have successfully demonstrated annual calving (pers. comm. Wally Franklin 2001). Corkeron and Connor (1999) argue the reasons for which baleen whales migrate. The paper references the physiological aspect of thermoregulation in calves and suggests that pregnant females spend the greatest time away from Antarctica to enable calves to build up fat layers. Paterson (1994) describes probable parturition by a humpback at Moreton Island. A solitary humpback remained stationary for at least 45 minutes before rising horizontally (out of the water) as if being infl ated. Approximately onethird of its body was above the water and its head and fl ukes were visible. The whale then “subsided” and was soon accompanied by a small grey-coloured calf that remained close to the adult’s pectoral region. 7.3 Maternal condition and sex ratio Feeding is a rare occurrence for humpback whales on migration (Dall and Dunstan 1957), which is probably due to the lack of preferred prey. However, there is evidence that, as in some other taxa, offspring sex ratio is related to maternal condition (Clapham 1996). In the northern hemisphere, occasional feeding of humpback whales on two known wintering grounds has been reported in Samana Bay and Maui, Hawaii (Salden 1989). Feeding has been observed on the winter grounds in Queensland (by the author 1997) and reported off Fraser Island by The Oceania Project (pers. comm. Wally Franklin 1997). Age class Size Estimated age Mean Min. Max. Calf: 4.35 m (14 ·27ft) 3 3.96m (13ft) 3 4.57 m (15ft) 3 0-3 months 3 Independent/weaned 3 : Male Female Immature (Puberty) 1 : Male Female 29.92ft 2 9.70m (31 82ft) 3 9.89m (32 44ft) 3 (36.75 ft) 1 11.73m (38 50ft) 1 Sexually mature (Upon 1 st pregnancy) 1 : Male Female 12.39m (39.66ft) 1 8.00m (26.25ft) 3 10.00m (30.48ft) 3 more than 1 year 2 separation from mother (33ft 4in) 1 11m (35ft 3in) 1 (40ft 10in) 1 13.6m (43ft 6in) 1 less than 5 years more than 5 years Figure 7. Summary of age class, length and age in years of humpbacks (Chittleborough 1955b1 and 19652 and 19652 and 1965 ; Clapham et al.1999a3 ) 3 3) 13 • Distribution, abundance and biology of Group V humpback whales Megaptera novaeangliae: A review • August 2002
Page 1 and 2: Distribution, abundance and biology
Page 3 and 4: Contents 1 Introduction............
Page 5: Figure 1. Queensland marine parks a
Page 8 and 9: Figure 4. Group IV and V distributi
Page 10 and 11: The main calving ground of the east
Page 12 and 13: During the northern migration there
Page 16 and 17: Variations in the abundance of prey
Page 18 and 19: Appendix 1. Summary of population e
Page 20 and 21: Craig, A.S. & Herman, L.M. 1997. Se
Page 22: 20 • Distribution, abundance and

Distribution, abundance and biology of Group V humpback whales ...

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