An anomalous increase in the New Caledonia humpback whales breeding sub-stock E2

Sixteen years of fluke photo identifications have been used to create datasets of the New Caledonia humpback whale breeding ground (IWC sub-stock E2). Estimates of abundance have been calculated using both closed (CAPTURE 3-4 year intervals) and open models (POPAN and CJS). An abundance estimate using photo-identification that was done previously for this population (1996-2005) indicated a very small population (N=344 CI 208-480 CV=0.72). Then, beginning in 2006 through our current estimate to 2011 all models we examined show a trend of increasing abundance with a large “pulse” after 2008. This pattern of abundance is similar over all survey areas. Whether these whales represent part of the New Caledonia sub-stock or permanent or temporary immigration from different regions is currently unclear. We hypothesize that this anomalous increase could be an overspill of the East Australia population, which is currently increasing at a high growth rate. Further analysis in future years will help to track the origin of these whales and to decipher if this is indeed an anomalous “pulse” of visitors or the beginning of a trend in population growth. For the purpose of the IWC Comprehensive Assessment of Southern Hemisphere Humpback whales for the IWC breeding sub-stock E2 we recommend the use of the yearly POPAN 2008 estimates for current abundance of the breeding sub-stock E2 N=562 (CV=0.19; CI 351-772) until the anomalous increase is more documented.

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