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Abstract: Between the 1940s and 1970s Southern Hemisphere populations of humpback whales (including eastern Australia and Oceania populations) were hunted to near extinction by extensive commercial whaling activities in Antarctica, with fewer whales taken in shore whaling operations in New Zealand, Australia (including Norfolk Island) and Tonga. Variable rates of recovery of these populations have been documented, ranging from recovery to prewhaling numbers in eastern Australian humpbacks to very little sign of recovery in many Oceania populations. Here we analyze recent sighting data collected over 12 yr, from annual surveys in Cook Strait, New Zealand. The data show an increase in sightings, at an estimated rate of 13% (95% CI of 4.9% and 21.7%) in 2015, of humpback whales migrating through Cook Strait. The wide confidence intervals preclude substantive conclusions about the rate of increase but suggest humpback whales are returning to this region in increasing numbers, indicating an influx of immigrants from neighboring areas, namely eastern Australia. [ABSTRACT FROM AUTHOR]

Humpback whales wintering in tropical waters along the Atlantic and Pacific coasts of the South American continent are thought to represent distinct populations or 'stocks.' Here we present the first analysis of genetic differentiation and estimates of gene flow between these breeding stocks, based on both mitochondrial DNA (mt DNA) control region sequences (465 bp) and 16 microsatellite loci from samples collected off Brazil ( n = 277) and Colombia ( n = 148), as well as feeding areas near the western Antarctic Peninsula ( n = 86). We found significant differentiation between Brazilian and Colombian breeding grounds at both mt DNA ( F ST = 0.058) and microsatellite ( F ST = 0.011) markers and corroborated previous studies showing genetic similarity between humpbacks from Colombia and those from Antarctic Peninsula feeding areas. Estimates of long-term gene flow between Brazil and Colombia were low to moderate, asymmetrical, and mostly mediated by males. Assignment procedures detected some cases of interchange and individuals of admixed ancestry between breeding grounds, indicating limited mixing of individuals between these stocks. Overall, results highlight the differentiation of humpback whale breeding populations with adjacent feeding grounds. This appears to be a remarkable example of fidelity to seasonal habitat in the absence of any contemporary barriers. [ABSTRACT FROM AUTHOR]

Recent photo-identification and genetic studies have identified at least five discrete breeding populations in Australia and Oceania: western Australia (D), eastern Australia (E (i)), New Caledonia (E (ii)), Tonga (E (iii)), French Polynesia and the Cook Islands (F). Also evident are low levels of intermingling among breeding populations consistent with the degree of genetic differentiation. Photo-identification has confirmed linkages between Area V feeding areas and eastern Australia breeding grounds and one genotype match has been reported between Area V feeding areas and Oceania breeding grounds. Recent abundance estimates show strong increases in the eastern Australian population, and some recovery in the New Caledonia and Tonga populations, but with little evidence of recovery at other known Oceania breeding grounds or New Zealand. Studies to date have provided no conclusive evidence of the migratory destination of humpback whales passing through New Zealand waters en route between Antarctic feeding areas and tropical breeding grounds. Photo-identification comparisons were undertaken between humpback whale fluke catalogues from eastern Australia (EA, 1315), Oceania east (OE, 513), Oceania west (OW, 166) and New Zealand (NZ, 13). Five matches were found between OE/OW, four matches between OW/EA and three matches between NZ/EA. The data are used to investigate and discuss the migratory destination and breeding ground migratory interchange of humpback whales travelling through New Zealand waters. The data confirm that humpback whales with site fidelity to eastern Australia migrate past New Zealand including through the Cook Strait and Foveaux Strait. [ABSTRACT FROM AUTHOR]

In understanding the impact of commercial whaling, it is important to estimate the mixing of low latitude breeding populations on Antarctic feeding grounds, particularly the endangered humpback whale populations of Oceania. This paper estimates the degree of genetic differentiation among the putative populations of Oceania (New Caledonia, Tonga, the Cook Islands and French Polynesia) and Australia (western Australia and eastern Australia) using ten microsatellite loci and mtDNA, assesses the power of the data for a mixed-stock analysis, determines ways to improve statistical power for future studies and estimates the population composition of Antarctic samples collected in 2010 south of New Zealand and eastern Australia. A large proportion of individuals could not be assigned to a population of origin (> 52%) using a posterior probability threshold of > 0.90. The mixed-stock analysis simulations however, produced accurate results with humpback whales reapportioned to their population of origin above the 90% threshold for western Australia, New Caledonia and Oceania grouped using a combined mtDNA and microsatellite dataset. Removing the Cook Islands, considered a transient region for humpback whales, from the simulation analysis increased the ability to reapportion Tonga from 86% to 89% and French Polynesia from 89% to 92%. Breeding ground sample size was found to be a factor influencing the accuracy of population reapportionment whereas increasing the mixture or feeding ground sample size improved the precision of results. The mixed-stock analysis of our Antarctic samples revealed substantial contributions from both eastern Australia (53.2%, 6.8% SE) and New Caledonia (43.7%, 5.5% SE) [with Oceania contributing 46.8% (5.9% SE)] but not western Australia. Despite the need for more samples to improve estimates of population allocation, our study strengthens the emerging genetic and non-genetic evidence that Antarctic waters south of New Zealand and eastern Australia are used by humpback whales from both eastern Australia and the more vulnerable breeding population of New Caledonia, representing Oceania. [ABSTRACT FROM AUTHOR]