Assessment of the sustainability of Solomon Islands live dolphin captures
There is a long history in the Solomon Islands of drive-hunts targeting dolphins. Recently, the Indo-Pacific bottlenose dolphin (Tursiops aduncus), a species not previously targeted by drive-hunters, has been subject to live-captures and export for display in dolphinariums and other facilities. The current quota of dolphins that can be exported each year is 50. Since 2003, 108 T. aduncus have been exported, however the actual number of dolphins removed from local populations is probably much larger given unaccounted-for deaths during capture and local captivity.
In 2009, a collaborative project was initiated by the Solomon Islands Government and the South Pacific Whale Research Consortium to assess the impacts of live-captures on the dolphin populations and improve management and conservation. The final report of that investigation, which summarises T. aduncus population status and assesses the sustainability of live-captures, was completed in March 2013. It is available here. The results of the study are summarised briefly below:
From November 2009 to July 2011, three sets of boat surveys were conducted at four study sites in the Solomon Islands, including the areas where all captures have occurred so far, i.e. north-western Guadalcanal and, to a lesser extent, western Malaita. The other two sites were the Florida Islands and southern Santa Isabel. Nine species of marine mammals were observed, including 45 groups of T. aduncus. The T. aduncus were always observed near shore (<2 nautical miles from the coast) and in shallow waters (<100 m deep). Of 225 photo-identified individuals, 46 were re-sighted in different years. All but one of the resightings were within one of the study sites, suggesting a high degree of site fidelity.
Abundance estimates from closed-population capture-recapture models suggest that each study site has a population in the low hundreds (about 100 to 300 individuals) but estimates were not precise for Malaita. Calculations of Potential Biological Removal (PBR) levels suggest that removals should be limited to one dolphin every five years for north-western Guadalcanal and the Florida Islands and one dolphin every two and a half years for southern Santa Isabel and western Malaita. On the basis of the PBR, the authorized export quota of 50 dolphins/year appears to be unsustainable for local populations. A new management procedure taking these findings into account is necessary. If any, future quotas should be species-specific and based on captures, rather than number of exports, which does not account for mortality during the capture process or local holding prior to shipment. The report suggests a complete capture ban in Guadalcanal until future monitoring shows an increase in abundance.