Fisheries Glossary D-E
Demersal - Describes fish and animals that live near water bottoms. Examples are flounder and croaker.
Directed Fishery - Fishing that is directed at a certain species or group of species. This applies to both sport fishing and commercial fishing.
Disappearance (Z’) - Measures the rate of decline in numbers of fish caught as fish become less numerous or less available. Disappearance is most often calculated from catch curves.
EEZ - See exclusive economic zone.
EIS - See environmental impact statement.
ESO - See economics and statistics office.
Economic Efficiency - In commercial fishing, the point at which the added cost of producing a unit of fish is equal to what buyers pay. Producing fewer fish would bring the cost lower than what buyers are paying. Producing more fish would raise the cost higher than what buyers are paying. Harvesting at the point of economic efficiency produces the maximum economic yield. See maximum economic yield and economic rent.
Economic Overfishing - A level of fish harvesting that is higher than that of economic efficiency; harvesting more fish than necessary to have maximum profits for the fishery.
Economic Rent - The total amount of profit that could be earned from a fishery owned by an individual. Individual ownership maximizes profit, but an open entry policy usually results in so many fishermen that profit higher than opportunity cost is zero. See maximum economic yield.
Economics and Statistics Office (ESO) - A unit of the National Marine Fisheries Service (NMFS) found in the regional director’s office. This unit does some of the analysis required for developing fishery policy and management plans
Effort - The amount of time and fishing power used to harvest fish. Fishing power includes gear size, boat size, and horsepower.
Elasmobranch - Describes a group of fish without a hard bony skeleton, including sharks, skates, and rays.
Electrophoresis - A method of determining the genetic differences or similarities between individual fish or groups of fish by using tissue samples.
Environmental Impact Statement (EIS) - An analysis of the expected impacts of a fisheries management plan (or some other proposed action) on the environment.
Escapement - The percentage of fish in a particular fishery that escape from an inshore habitat and move offshore, where they eventually spawn.
Euryhaline - Fish that live in a wide range of salinities.
Ex-vessel - Refers to activities that occur when a commercial fishing boat lands or unloads a catch. For example, the price received by a captain for the catch is an ex-vessel price.
Exclusive Economic Zone (EEZ) - All waters from the seaward boundary of coastal states out to 200 natural miles. This was formerly called the Fishery Conservation Zone.
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