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Fish Online - Glossary of marine conservation
Category: Animals and Nature > Fishing
Date & country: 11/12/2007, UK
Words: 115

the behaviour of a group of individuals of a species to form a cluster (ie. in a non-random distribution).

juvenile fish with the yolk-sac still present

Algal bloom
an abundant growth of phytoplankton, typically triggered by sudden favourable environmental conditions e.g. excess nutrients. Typically seen in the spring in UK waters.

the general term given to the cultivation of any aquatic (fresh and marine) species (plant or animal).

term used to describe small-scale, traditional fisheries.

Beam trawl
in this type of trawl the mouth of the net is kept open by a beam which is mounted at each end on guides or skids which travel along the seabed.

living on or in the seabed.

those organisms attached to, living on, or in the seabed.

egg-bearing lobster or crab.

the accumulation of a substance (contaminant) within the tissues of an organism.

the variability among living organisms from all sources, including, among other things, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part.

the process whereby concentrations of certain substances increase with each step up the food chain.

the total weight of living organisms or total weight of a resource or stock.

having two shells or valves which open and shut.

living near the north; sub Arctic.

Bottom trawl
a large cone-shaped net, which is towed across the seabed. Also called an otter or demersal trawl.

a fish, which is kept for the purpose of reproduction and supply of juveniles.

non-target organisms caught in fishing gear.

the salted roe (eggs) of the sturgeon. The roe from other species, e.g. salmon, is used to make mock caviar.

a mollusc having a distinct head with prehensile and locomotive organs attached, e.g. octopus, squid and cuttlefish.

the rear end of a trawl net where the catch accumulates.

Common Fisheries Policy (CFP)
The European Union's instrument for the management of fisheries and aquaculture.

Conservation measure
term applied to legislative methods within the framework of the CFP which regulate fishing activity.

Conservative contaminants
contaminants that are permanent additions to the environment and not subject to decay.

Copepods- small (0.5
2mm long) crustacea that form part of the zooplankton community.

a group of marine invertebrate animals that live in colonies, characterized by a calcareous skeleton; appears in a variety of shapes often forming reefs. Coral is also a term for crab roe or eggs.

a group of animals with two pairs of antennae and a calcium carbonate exoskeleton e.g. crab, lobster.

any substrate laid on the seabed with the purpose of encouraging mollusc larvae (spat) settlement. Examples are shell waste, ropes and tiles.

term used to describe the process by which fishing boats are taken out of service or ‘scrapped`.

Deep-water species
those species living in water beyond the continental slope in depths of more than 400 metres.

refers to fish such as cod, haddock and plaice which live primarily on or near the seabed.

The process of removing pathogens from shellfish by keeping them in clean water for a period of time prior to sale.

fish that move during their life cycle between fresh and marine waters e.g. salmon and eels.

a group of chemical compounds that share certain characteristics. Dioxins are formed as a result of combustion processes such as waste incineration and burning fuels such as wood and coal.

fish and other organisms caught by fishing gear and then thrown back into the sea for legal, economic or other reasons.

a method used for harvesting bivalve molluscs such as oysters, clams and scallops from the seabed.

a community of organisms and their physio-chemical environment interacting as an ecological unit.

Ecosystem approach
the ecosystem approach to fisheries management involves a consideration of all the physical, chemical and biological variables within an ecosystem, taking account of their complex interactions.

A parasite that attaches itself to and lives off the external surface of an animal (fish).

fish with a cartilaginous, non-bony skeleton (sharks, skates and rays).

the process whereby receiving waters become hyper-enriched by nutrient inputs, resulting in excessive plant growth and oxygen depletion.

Exclusive Economic Zone (EEZ)
an area in which a coastal state has sovereign rights over all the economic resources of the sea, seabed and subsoil.

the loss of a local population as distinct from an entire species (extinction).

potential reproductive capacity of an organism or population expressed in number of eggs (fertile or not) produced during each reproductive cycle.

A fish with fins as opposed to shellfish.

collective term (includes molluscs and crustaceans) for any aquatic animal that is harvested.

the sum of all fishing activities on a given resource e.g. shrimp fishery, or activity of catching fish from one or more stocks e.g. North Sea cod fishery, or it may also refer to a single type or style of fishing e.g. trawl fishery.

any activity that involves the catching, taking or harvesting of fish.

Fishing capacity
the quantity of fish that can be taken by a fishing unit, i.e. individual, community, vessel or fleet.

Fishing effort
the amount of fishing gear of a specific type used over a given unit of time, e.g. hours trawled per day; the overall amount of fishing expressed in units of time e.g. number of hauls per boat per day.

Food chain
representation of the passage of energy (food) from producers to the organisms that feed on them.

Food web
network of food chains in an ecosystem.

a term that can be used to describe fish that have been kept chilled on ice but not deep frozen. The term should not be used to describe previously frozen, thawed fish (FSA advice).

The term used to describe juvenile fish in the next stage of development after Alevins.

the taxonomic Order which includes cod, pollack, whiting, coley and haddock

a cod like fish, see Gadiformes.

any tools used to catch fish, such as hook and line, trawls, traps etc.

Genetic dilution
The process occurring when domestic farmed fish with low variation between individuals interbred with wild fish of the same species, leading to the subsequent offspring having lower variability when compared to the pure wild strain.

Ghost fishing
the phenomenon whereby lost nets or traps continue to fish.

Gill net
a loosely set and near invisible wall of fine netting (mono or multi-filament nylon) that traps fish by the gill cover.s

reproductive organs i.e. testis (male) and ovaries (female).

The term used to describe the process of sorting fish into similar sizes. This is done to minimise aggression and cannibalism as well as ensuring that fish of a similar size are grown on together and can be harvested at the same time. Grading occurs either manually, by sweep net or on a grading machine.

Ground fish
American term for demersal fish.

(or hook and line fishing) a highly selective method of fishing, producing high quality catch.

The place where fertilised eggs are grow on to fry before being transferred to freshwater tanks.

a condition in which male sexual characteristics, such as the development of a penis, is superimposed on female gastropods. An example is the effect of tributytin on the common dogwhelk.

Industrial fisheries
fisheries which do not target species for direct human consumption, i.e the capture of fish for reduction into fish meal and fish oil.

a generic term used to describe pole (or rod) & line; handline or longline fisheries.

uses both vertical and horizontal lines, often a number of miles long, to which short lengths of line (snoods) carrying baited hooks are attached at intervals.

The farming a species in sea (marine) water.

false or incorrect reporting of details pertaining to quantity and area of capture of protected species, i.e. those species regulated by quota.

Mixed fishery
comprising more than one species, e.g. North European demersal fisheries typically comprise cod, haddock, whiting, pollack and saithe.

Mobile gear
towed or encircling active fishing gears e.g. trawl, dredges or seine.

OSPAR (Oslo and Paris) Convention
replaced by the Convention for the Protection of the Marine Environment of the North East Atlantic which came into force on 25 March 1998. For more information see

Otter board
(or otter door) a paired device used to spread the trawl mouth laterally, when towed by one vessel.

Otter trawl
a large cone-shaped net, which is towed across the seabed. Also called a bottom trawl./td>

a state of saturation or an excess of catching capability, i.e. deployed fishing effort.

fishing with a sufficiently high intensity to reduce the breeding stock levels to such an extent that they will no longer suppport a sufficient quantity of fish for sport or commercial harvest.

the upper layers of the ocean where food is plentiful. Pelagic fish include herring, sardine and pilchard.

major taxonomic division of animals and plants that contains one or more classes.

the microscopic plant component of plankton.

acoustic device designed to deter marine mammals from entanglement in fishing nets.

Pole and line
hand held or mechanically operated rod with baited hook or lure.

the introduction by man, directly or indirectly, of substances or energy to the marine environment resulting in deleterious effects.

a biological unit representing the individuals of a species living in a specific area.

a trap used to capture fish, especially crustaceans.

The organic waste produced by filter feeding molluscs such as mussels.

Purse seining
the general name given to the method of encircling a school of pelagic fish with a large wall of net.

a share of the Total Allowable Catch (TAC) allocated to a country, vessel, company or individual fishermen.

a straight-sided artificial channel (usually concrete) in which fish are raised

the process by which juvenile fish enter the exploitable stock and become susceptible to fishing.

Round fish
demersal fish that are rounded in transverse section, e.g. cod, haddock and whiting (as opposed to flat fish e.g. plaice or flounder).

Safe Biological Limits
limits (reference points) for fishing mortality rates and spawning stock biomass, beyond which the fishery is unsustainable. Other criteria that indicate when a stock is outside safe biological limits include age structure,distribution of the stock and exploitation rates. A fishery that maintains stock size within a precautionary range (a range within which the probability of reaching any limits is very small) would be expected to be sustainable.

an isolated mountain situated on the sea floor.

ability to target and capture fish by size and species, allowing by-catch of juvenile and non-target species to escape unharmed.

As opposed to finfish. A collective term used to describe molluscs and crustacea.

The physiological process undergone by salmonid (salmon and trout) fish to allow them to migrate from freshwater to seawater as part of their lifecycle.

Juvenile fish that have undergone smoltification.

The stage in a mollusc`s lifecycle in which it goes from being free swimming to attaching itself to a substrate.

release of ova (eggs) fertilized or to be fertilized.