Overinflation of the gas bladder following rapid depressurization is relatively common in fishes caught in deep water and brought to the surface. Currently, the most commonly used method to reduce mortality caused by overinflation is to puncture the gas bladder with a hypodermic needle. Although the method is widely used, few studies have been conducted to determine its effectiveness. We conducted a series of experiments on yellow perch Perca flavescens collected at 10 and 15 m depths in Lake Michigan. Fish were either measured for length (control), measured and tagged, or measured, tagged, and punctured. The fish were then taken to an enclosed hatchery facility. Fish brought to the surface in stages (decompressed) had higher survival than nondecompressed fish; this effect was greater for fish caught at 10 than 15 m. Unpunctured fish floated for up to 72 h before regaining neutral buoyancy; less than 2% of the punctured fish floated on the first day. Puncturing the swim bladder had a significant, positive effect on 3-d survival. Tag returns from fish released after the experiment indicated that puncturing did not decrease longterm survival. This study demonstrates the effectiveness of puncturing the gas bladder in reducing direct mortality caused by bladder overinflation, and indirect mortality of the stricken fish which are vulnerable to predation and adverse environmental conditions at the surface. Decompression positively affected survival and, because of its ease of use, warrants further investigation.
No takes yet. Share an insight, caveat, or question.
Keniry et al. (1996) studied this question.