Whale Poaching Detection Based on Microscopic Characteristics of Bottlenose Dolphins’ (Tursiops truncatus) Bone Fragments

Abstract

Although many countries prohibit whaling, it remains a significant cause of whale population decline. The meal of whales, likely killed during illegal whaling or caught accidentally, can ap-pear in a fish meal as a contaminant detectable by microscopic examination of bone fragments. In order to provide a rigorous basis for such a detection, microscopic characterization of bone fragments of 10 female and 10 male, less than a year to 21 years old bottlenose dolphins (Tur-siops truncatus), a widespread cetacean species herein used as a whale model, was performed and compared to the reference bone fragments of fish, ruminant, poultry and pig. The processing of bones mimicked that used in the production of meat and bone meals, while their description was based on qualitative characteristics, i.e. the shape of a bone fragment ; the shape, density and distribution of osteocyte lacunae, and the distribution and density of canaliculae. Bottlenose dol-phin bone fragments are smoothly contoured ; their elliptical osteocyte lacunae are clearly visible, while the canaliculae radiate from the lacunae in all directions. The comparison of these qualita-tive bone characteristics with that of other vertebrata under study revealed that bottlenose dol-phin bone fragments can definitely be differentiated from that of fish, may be differentiated from that of poultry and pig, but cannot be differentiated from that of ruminants. Measurements of the osteocyte lacunae showed the lacunar length to be strongly associated with animal’s age and lacunar shape, while their width was strongly associated with animal’s gender lacunar shape. The results indicate the possibility of detecting a whale meal admixture in a fish meal using light microscopy, which should be followed by PCR to enable the identification of the admixture source.