A method of determining the genetic differences or similarities between individual fish or groups of fish by using tissue samples. A measurement of egg-producing ability of a fish. Fecundity may change with the age and size of a fish. A measurement of the rate of removal of fish from a population by fishing. Fishing mortality can be reported as either annual or instantaneous.
Annual mortality is the percentage of fish dying in one year.
Instantaneous is that percentage of fish dying at any one time. The acceptable rates of fishing mortality may vary from species to species. It is used in areas of little or no water current. A passive capture gear constructed of vertical panels of netting set in a straight ine in which fish can become entangled. When fishing pressure on a smaller fish is too heavy to allow the fishery to produce its maximum poundage.