A large hyperbaric trap-respirometer for the capture and maintenance of live deep sea organisms

Summary form only given. The capture and maintenance of live deep-sea fishes is difficult due to the rapid decompression and expansion of the gas-filled bladders of some species upon ascent to the surface, and potentially to the intolerance of many species to surface pressure (1 atm). Overcoming these problems would enable an enormous diversity of studies concerning the biology and physiology of deep-sea animals. We have constructed a pressurized trap-respirometer to capture fishes and other large organisms at the depths to 4000 m and bring them to the surface under pressure. The system consists of a 90 litre stainless steel pressure cylinder (1.2 m long, 30 cm internal diameter) that is captured at depth a pressure-retaining door is sealed and the trap is brought to the surface. Upon the recovery and transfer of the system to the laboratory, high pressure pumps maintain a flow of seawater and a pressure accumulator and regulator system, controls pressure within the trap. Internal instrumentation includes a circulation pump, oxygen optode, and low light camera. Experiments are planned to investigate metabolic rates and the pressure tolerance of the captured animals.