Quote:
Originally Posted by GaryF
8. Mortality rates of easy to catch smaller fish could potentially increase due to fish trauma associated with catch and release requirements. Where can I find the study on these facts?
|
http://www.acuteangling.com/Reference/C&RMortality.html
Key Mortality Factors
Two factors predominate when considering the causes of angled fish mortality: the hooking location, and the degree of physiological stress suffered by the fish.
Hooking location - This factor demonstrates the largest source of variation in mortality observed in the studies and experiments reviewed. It is consistently shown that deep-hooking (hooking in the gills or gullet) causes relatively high mortality, up to 35% when accompanied by bleeding, whereas normal hooking (lips or jaw area) consistently causes minimal mortality, which is consistently less than 5% and often less than 1%. The Maryland Department of Natural Resources, in its Recreational Catch and Release Mortality research program concludes that the location of the hook wound is the single most important factor influencing catch and release mortality (4). If the hook wound affects a vital organ, mortality, is high. The location of the wound site has been demonstrated to be a function of hook size, type, the use of natural bait versus artificial lures and additional situational factors. Studies show that when fish are hooked in the lips or jaw area (shallow hooked), mortality is negligible, typically less than 1% (4,5). Conversely, mortality is at its highest when fish are hooked in the esophagus or gills (deep hooked) (5,11). Necropsies performed on gut hooked fish in a study by (5) Grover, et al, found that the majority had sustained major internal damage to the heart, stomach or liver. Grover demonstrates that hooking location effectively correlates to mortality rate.
Physiological Stress - Exercise performed by fish during a catch event, or caused by angler handling methods and air exposure all create measurable physiological responses. Physiological stress in fish has been measured by experimenters using cortisol, lactate and respiratory gas concentrations.
Although the catch and release mortality studies reviewed do not show statistical results directly correlating the degree of physiological stress to mortality, an experiment by Ferguson and Tufts examined the effects of artificially induced stress on rainbow trout. They concluded that various forms of physiological stress contribute to fish mortality (12). It is reasonable to infer that such stress also contributes to mortality in angled fish and therefore, that minimization of stress assists in reduction of catch and release mortality.