Lethal sampling of stingrays (Dasyatidae) for research

For some species certain biological and ecological data, such as diet and age and growth estimates can only be obtained through lethal sampling of study animals. Traditionally, commercial fishermen have provided samples of rays caught in nets for use by biologists; however, by-catch exclusion devices now prevent medium and larger-bodied rays (>100 cm disk width) from being collected in trawl nets. This means that other methods must be used for lethal sampling. We obtained a large suite of biological and ecological data from 170 wild-caught stingrays collected from Ningaloo Reef, Western Australia over two years. Our sampling program was designed to minimize or eradicate any pain and suffering to the animals, while ensuring the safety of researchers undertaking the sampling process. Small rays (< 100 cm disc width; WD) were caught in beach seines and euthanized immediately by destruction of the brain and severance of the spinal cord with a reinforced, serrated steel knife. Larger rays were euthanized by firing high-powered spears directly into their brains from close range while free diving. Of 170 rays sampled in this manner, 94 % (159) were killed instantly or within an estimated 10 - 30 seconds of capture. The design and application of this lethal sampling program was deemed successful in terms of reducing distress and suffering to the rays caught, as well as ensuring the safety of researchers. The work has provided critical data on the biology and life history of stingrays that could not be obtained by any other means.