| Summary: | Restricted Item. Print thesis available in the University of Auckland Library or may be available through Inter-Library Loan. Southern right whales (Eubalaena australis) were once widely distributed in New Zealand waters. The population was driven to commercial extinction following extensive exploitation during the early 19th century. This thesis investigates the status of the remnant population of southern right whales in the New Zealand sub-Antarctic Auckland Islands using photo-identification and molecular methods. The distribution of southern right whales at the Auckland Is was restricted to waters surrounding Port Ross where up to 165 whales could be found on a single day. The yearly winter presence of a large number of whales, the presence of mothers and calves, and the frequency of social groups confirm that the Auckland Islands are a primary wintering habitat and calving ground for southern right whales in New Zealand waters. Of 30 southern right whales photo-identified at Campbell Is., four showed within- and/or between-year movements with the Auckland Islands suggesting that right whales from both island groups are part of one intermingling sub-Antarctic population. The Auckland Islands may represent the limit of range expansion of this remnant sub-Antarctic stock. The New Zealand sub-Antarctic stock was estimated at 936 whales (95% C.I. 740-1140), including 330 reproductive females, based on capture-recapture analysis using natural markings. By evaluating the extent and effects of each violation of assumptions on model estimates, the most appropriate estimate was found to be Chapman's Petersen pooled model. Significant mitochondrial DNA differentiation (FST=0.14150; ΦST=0.23701; p<0.001) among four wintering southern right populations (South Africa, Argentina, Western Australia and sub-Antarctic New Zealand) suggested low levels of interchange, limited largely to adjacent populations within ocean basins. The population structure may partly be the result of restrictions to female movement between adjacent regions following the reduction in the species abundance. The phylogenetic reconstruction showed two highly divergent clades with distributions that were partly concordant at the oceanic level. The historical abundance of New Zealand southern right whales was estimated at between 15,000 and 17,000 using historical catch records and a deterministic density-dependent demographic model. Genetic modeling of the impact of past whaling suggested that the current low mtDNA diversity of the New Zealand southern right whale is likely the outcome of a severe and prolonged bottleneck. The recent illegal Soviet whaling, although brief, hindered the demographic and genetic recovery of this population. The Auckland Islands are a critical habitat for southern right whales. The population is genetically distinct from other grounds, it has low diversity, and it remains at less than 5% of its pre-exploitation abundance. Restricted Item. Print thesis available in the University of Auckland Library or may be available through Inter-Library Loan.
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