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

Figure 4. Group IV and V distribution and migratory routes (Anderson et al.1995)
The southern Great Barrier Reef has shallow (15–60m)
warm waters characteristic of humpback wintering areas
in Hawaii (Herman and Antionoji 1977) and the West
Indies (Whitehead and Moore 1982). Simmons and Marsh
(1985) concluded from their observations that sea surface
temperature is not a determining factor for the distribution of
humpbacks.
Two factors indicate that the humpback calving grounds
are dispersed throughout Queensland waters, and that
parturition occurs along the migratory route. Paterson and
Paterson (1989) reported a number of sightings of females
with new calves migrating north past North Stradbroke
Island; and newly-born calves have been recorded stranded
at sites such as Moreton Island (Paterson et al.1993; Haines
et al.2000) and Fraser Island (Paterson and Van Dyke 1991;
Haines et al.2000). Parturition has been observed at a few
locations within the Great Barrier Reef at Little Trunk Reef,
Charity Reef and Little Broadhurst Reef (Paterson and
Paterson 1989).
Chaloupka and Osmond (1999) concluded that humpbacks
are present in all months of the year throughout the Great
Barrier Reef Marine Park (GBRMP). This study, and
earlier study by Simmons and Marsh (1985) supported
the hypothesis that humpbacks are resident year round in
the northern Great Barrier Reef. However Chaloupka and
Osmond (1999) found that most pods (75 percent) were
sighted in southern GBR waters below 19ºS (Townsville)
and mainly during winter and spring (July to September).
Humpbacks migrating north are sighted in Queensland
waters from late May. Paterson (1984) recorded a distinct
peak in the abundance of humpbacks migrating north
during late June and July at North Stradbroke Island.
However, there is no corresponding distinct peak that occurs
during the southern migration that occurs during August,
September and October (Paterson 1984).
Winter breeding grounds
(presumed)
Summer feeding grounds
6 • Distribution, abundance and biology of Group V humpback whales Megaptera novaeangliae: A review • August 2002
During August and September, Chaloupka and Osmond
(1999) reported low sightings of mother-calf pairs in most
areas below 21ºS for the period 1982–1999. They suggested
that the main calving grounds for the east Australian Group
V population occur in the extensive southern GBR lagoonal
waters defi ned in the north by the Whitsunday Group of
islands and reefs and in the east by the Pompey/Swain
Reefs complex. In recent years, anecdotal information
suggests that humpbacks are abundant further north
in areas offshore of Cairns and as late in the year as
November.
4.4.1 Moreton Bay region
Historically, a whaling station was based on Moreton Island.
Paterson and Paterson (1984) summarised the history of
exploitation in relation to a discussion of the patterns of
migration. They concluded that the migratory patterns had
not altered as a result of the commercial exploitation.
The Moreton Bay region is best described as a migratory
corridor for humpbacks although other components of their
biology may also occur here. Paterson (1994) observed
parturition on one occasion and, stranded newly-born calves
have been recorded on several occasions (Paterson et
al.1993; Haines et al.2000; 2001).
For the past 20 years, two independent land-based
censuses have been conducted from Point Lookout,
North Stradbroke Island, or Moreton Island, Queensland
(Bryden et al.1996 and Paterson, Paterson and Cato 1994).
In 1998, a brief overview of the population estimates and
rates of population increase were presented at a workshop
(Department of Environment and Heritage 1999).