The proportion of a population alive at the beginning of the year that is caught during the year. That is, if 1 million fish were alive on January 1 and 200,000 were caught during the year, the exploitation rate is 0.20 (200,000 ΒΈ 1,000,000) or 20%.
The percentage of a fish population that are caught by all fisheries combined. For example, if 650,000 fish were caught out of a population of 1 million fish, the exploitation rate would be 0.65 or 65 per cent.
Applied on a fish stock, it is the proportion of the numbers or biomass removed by fishing. A 10% exploitation rate means that 10% of the available stock is being harvested within the time frame considered (per year, per month, etc.). As a measure of fishing pressure, it is proportional to fishing mortality
The proportion of a returning run or total population of salmonids that is taken by fisheries.
The proportion of fish in a population, at a given time and place, which dies by fishing mortality. For example, in three separate sequential fisheries, the exploitation rate could be 50% in each; of 1,000 fish available to the first fishery, 500 would be harvested and 500 escape. In the second fishery, 250 would be harvested and 250 escape. In the third fishery, 125 would be harvested and 125 escape. This calculation does not account for fish dying of natural causes between or during fisheries.
the fraction of total animal (usually fish) deaths caused by fishing, usually expressed as an annual value. Exploitation rate can also be defined as the proportion of a population caught during a year.
The probability that a given fish will die during the year because of fishing.
The proportion of a population at the beginning of a given time period that is caught during that time period (usually expressed on a yearly basis). For example, if 720,000 fish were caught during the year from a population of 1 million fish alive at the beginning of the year, the annual exploitation rate would be 0.72.