Search

Swimbladder puncture occurs frequently during fishing operations employed in capture-based aquaculture (CBA). The function, survival and welfare of cod Gadus morhua following controlled swimbladder puncture in the laboratory was investigated. Anaesthetised cod (n=30) were exposed to reduced pressure using a vacuum chamber and their swimbladders were punctured. The pressure reduction before puncture (~70%), location of the swimbladder puncture sites near the pin bones, intraperitoneal gas evacuation path leading to the anal area and rapid repair mechanism, among other puncture characteristics, were consistent with previous findings. The mortality was low (~6%) during the procedure and did not differ from that of the control group. The experimentally punctured cod were challenged by swimbladder reinflation in a flow-through pressure chamber supplied with a surveillance camera and remote pressure regulation. The punctured fish were capable of swimbladder inflation shortly after puncture and their bu...

During rapid decompression in the course of fish capture, cod (Gadus morhua L.) is unable to reabsorb excess gas in the swimbladder sufficiently rapidly, and the bladder ruptures as the gas expands. In capture-based aquaculture (CBA), knowledge of the severity of the rupture stress is required. The objective of this study was to describe the swimbladder rupture and healing processes. Cod captured by Danish seine at depths of between 130 and 200 m were stored in a netpen. At 0, 24, 72 and 384 h post-capture, randomly selected fish (n = 20) were dissected. All fish had ruptured the swimbladder, most close to the dorsal point of pinbones; these holes were sealed and the bladders were inflated. On testing, all the bladders withstood a minimum of 20 mmHg above atmospheric pressure, a strength that increased with time and inversely with the size of holes. As the overinflated bladder deflates after rupture, the two layers of the bladder wall slide relative to each other, closing the open gas passage in ...