Decompression Bubbles in Bycaught Seals and Dolphins: Gas Chromatographic Discrimination from Decomposition
Abstract
Gas bubbles were described in marine mammals entangled and drowned in gillnets by computed tomography, gross examinations and histopathology.6 The absence of bacteria and autolytic changes in the tissues of these animals suggests that the gas was peri- or postmortem produced by a fast decompression, probably by hauling animals entangled in the net.6 Gas composition analysis and gas scoring are two new diagnostic tools available to distinguish gas embolisms from putrefaction gases.1,2 These methods have been successfully applied with this goal to pathological studies of marine mammals.3-5 In this study, we characterized the flux and composition of the gas bubbles from bycaught marine mammals in anchored sink gillnets and bottom otter trawls. We compared these data with marine mammals stranded on Cape Cod. Animals with decomposition scores of 2 and 3 were prioritized. Results showed that bycaught animals presented higher gas scores than stranded animals. Gas composition analyses indicate that gas was formed by decompression, corroborating the hypothesis stated by Moore.6
Acknowledgements
The authors would like thank the fishermen and NOAA Fisheries Observers and Observer Program staff as well as to the International Fund for Animal Welfare (IFAW) for providing access and information about the animals. This study was funded by The Woods Hole Oceanographic Institution Marine Mammal Centre and Wick and Sloan Simmons.
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Literature Cited
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