Preliminary Study On The Trawl Fishing Induced Phenotypic Traits Selection Differential Of Fish

Large changes are taking place in the phenotypic traits of commercially fish due to the strong selection generated by fishing gear in heavily exploited fish stocks. There is a wealth of information demonstrating changes in growth and maturation in major commercial fish stocks over time. The cause of these phenotypic changes is often not understood, and genetic change arising from the selective effects of fishing may be a contributory factor. The selection differential on a phenotypic trait is a necessary condition for fish to cause evolution, and also the evolutionary change caused by fishing are likely to be hard to reverse. It is very important to study the selection differentials of phenotypic traits induced by the fish selection.The simulated model described in this paper is based on a lot of real fishery data and matured view in the world. By estimate the fishing phenotypic differentials, preliminary study on the trawl fishing induced phenotypic traits selection differential of fish.this study makes up the absence of the study on the fish evolution induced by fishing, also provide some useful advice to the fishery government to make fishery rules.A simulation model is used to analyze the selection differentials of phenotypic traits (growth rate parameter K, asymptotic length L∞, age at first maturity Am), which induced by selection of trawl net. In the beginning of the model, simulated fishery is duplicated, one is fished called B, while the other called A has not experienced fishing effect. In the end of the simulated year, two fishery's mean growth traits are compared with each other, then the selection differential induced by fishing gear selectivity can be figured out. Fishery data on different simulated scenarios with changing biological and fishing characteristic is used in the model. The change of selection differential with the increased maximum fishing mortality (Fmax) was estimated under different...