Strandings, mortality and morbidity of Indo-Pacific humpback dolphins in Hong Kong, with emphasis on the role of organochlorine contaminants

Factors related to mortality and disease in Indo-Pacific humpback dolphins (Sousa chinensis) from Hong Kong waters were investigated by detailed examination of dolphin specimens found stranded 1995-2004. In total, 86 necropsied, but many these too badly decomposed provide much information. Skin blubber biopsies also collected six identified living individuals concentrations organochlorines (DDTs, PCBs HCHs) determined samples biopsied dolphins. A large proportion the strandings (53.2%) young-of-the-year. The most commonly diagnosed causes death net entanglement vessel collision. pesticide DDT showed highest ratio its breakdown products (and other information) suggests that there may be a recent or nearby source into dolphins’ ecosystem. Concentrations both DDTs pattern increasing with age males. females, they increased until sexual maturity, then decreased, finally again late life. This is consistent hypothesised transfer pollutants mother offspring during gestation lactation. Inter-laboratory differences effects decomposition are two potential biases significantly affect quality present data. order resolve problems associated issues, long-term biopsy collection programme has recently been initiated.