Aggregating – the behaviour of a group of individuals of a species to form a cluster (ie. in a non-random distribution).
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.
Alevins – juvenile fish with the yolk-sac still present
Aquaculture – the general term given to the cultivation of any aquatic (fresh and marine) species (plant or animal).
Artisanal – 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.
Benthic – living on or in the seabed.
Benthos – those organisms attached to, living on, or in the seabed.
Berried – egg-bearing lobster or crab.
Bioaccumulation – the accumulation of a substance (contaminant) within the tissues of an organism.
Biodiversity – 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.
Biomagnification – the process whereby concentrations of certain substances increase with each step up the food chain.
Biomass – the total weight of living organisms or total weight of a resource or stock.
Bivalve – having two shells or valves which open and shut.
Boreal – 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.
Broodstock – a fish, which is kept for the purpose of reproduction and supply of juveniles.
By-catch – non-target organisms caught in fishing gear.
Caviar – the salted roe (eggs) of the sturgeon. The roe from other species, e.g. salmon, is used to make mock caviar.
Cephalopod – a mollusc having a distinct head with prehensile and locomotive organs attached, e.g. octopus, squid and cuttlefish.
Cod-end – 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.
Coral – 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.
Crustacea – a group of animals with two pairs of antennae and a calcium carbonate exoskeleton e.g. crab, lobster.
Cultch – any substrate laid on the seabed with the purpose of encouraging mollusc larvae (spat) settlement. Examples are shell waste, ropes and tiles.
Decommission – 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.
Demersal – refers to fish such as cod, haddock and plaice which live primarily on or near the seabed.
Depuration – The process of removing pathogens from shellfish by keeping them in clean water for a period of time prior to sale.
Diadromous – fish that move during their life cycle between fresh and marine waters e.g. salmon and eels.
Dioxin – 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.
Discards – fish and other organisms caught by fishing gear and then thrown back into the sea for legal, economic or other reasons.
Dredging – a method used for harvesting bivalve molluscs such as oysters, clams and scallops from the seabed.
Ecosystem – 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.
Ectoparasite – A parasite that attaches itself to and lives off the external surface of an animal (fish).
Elasmobranch – fish with a cartilaginous, non-bony skeleton (sharks, skates and rays).
Ephemeral- Being present only briefly, as in naturally occurring mussel beds.
Eutrophication – 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.
Extirpation – the loss of a local population as distinct from an entire species (extinction).
Fecundity – potential reproductive capacity of an organism or population expressed in number of eggs (fertile or not) produced during each reproductive cycle.
Fresh – 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).
Finfish – A fish with fins as opposed to shellfish.
Fish – collective term (includes molluscs and crustaceans) for any aquatic animal that is harvested.
Fishery – 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.
Fishing – 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 and Agriculture Organisation (FAO) – Founded in 1945 it has 183 member countries and one member organisation, the European Community. FAO is one of the largest specialised agencies in the United Nations and its programme on fisheries aims to promote their sustainable development through implementation of its Code of Conduct for Responsible Fisheries. See www.fao.org for more information
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.
Fry – The term used to describe juvenile fish in the next stage of development after Alevins.
Gadiformes – the taxonomic Order which includes cod, pollack, whiting, coley and haddock
Gadoid – a cod like fish, see Gadiformes.
Gear – 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
Gonad – reproductive organs i.e. testis (male) and ovaries (female).
Grading – 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.
Handlining – (or hook and line fishing) a highly selective method of fishing, producing high quality catch.
Hatchery – The place where fertilised eggs are grow on to fry before being transferred to freshwater tanks.
Imposex – 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.
International Council for the Exploration of the Sea (ICES) – an international organisation comprising 19 Member countries around the border of the North Atlantic. Established by international convention in 1902, ICES is the oldest intergovernmental marine science organisation in the world. See www.ices.dk for more information.
Line-caught – a generic term used to describe pole (or rod) & line; handline or longline fisheries.
Long-lining – 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.
Mariculture – The farming a species in sea (marine) water.
Misreporting – 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 www.ospar.org.
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>
Overcapacity – a state of saturation or an excess of catching capability, i.e. deployed fishing effort.
Overfishing – 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.
Pelagic – the upper layers of the ocean where food is plentiful. Pelagic fish include herring, sardine and pilchard.
Phylum – major taxonomic division of animals and plants that contains one or more classes.
Phytoplankton – the microscopic plant component of plankton.
Pinger – 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.
Pollution – the introduction by man, directly or indirectly, of substances or energy to the marine environment resulting in deleterious effects.
Population – a biological unit representing the individuals of a species living in a specific area.
Pot – a trap used to capture fish, especially crustaceans.
Pseudofaeces – 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.
Quota – a share of the Total Allowable Catch (TAC) allocated to a country, vessel, company or individual fishermen.
Raceway – a straight-sided artificial channel (usually concrete) in which fish are raised
Recruitment – 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.
Seamount – an isolated mountain situated on the sea floor.
Selectivity – ability to target and capture fish by size and species, allowing by-catch of juvenile and non-target species to escape unharmed.
Shellfish – As opposed to finfish. A collective term used to describe molluscs and crustacea.
Smoltification – The physiological process undergone by salmonid (salmon and trout) fish to allow them to migrate from freshwater to seawater as part of their lifecycle.
Smolts – Juvenile fish that have undergone smoltification.
Spat – The stage in a mollusc’s lifecycle in which it goes from being free swimming to attaching itself to a substrate.
Spawn – release of ova (eggs) fertilized or to be fertilized.
Spawning stock – mature part of a stock responsible for reproduction.
Spawning Stock Biomass (SSB) – the total weight of all sexually mature fish in a population.
Static – or fixed gears refers to fishing gears that are fixed to or on the seabed e.g pots, traps or nets. These types of gears are passive as opposed to mobile gears, e.g. trawl nets, which are referred to as active gears.
Stock – term given to a group of individuals or populations in a species occupying a well-defined spatial range independent of other stocks of the same species. A stock will form the basis of a distinct fishery defined management unit in terms of season and area.
Stocking density – Usually expressed at the weight of fish per volume of water, for example 15kg/m3.
Straddling stocks – fish stocks that migrate through more than one Exclusive Economic Zone (EEZ).
Sweep – the rope (usually wire) between the otter board and trawl net.
Tangle net – a type of bottom set gill net used to capture flatfish, crustaceans and other species.
Target species – species or assemblage of species which are primarily sought in a fishery.
Teleost – fish with a bony skeleton as opposed to cartilaginous fish (elasmobranchs).
Total Allowable Catch (TAC) – maximum tonnage, set each year, that may be taken of a fish species within an area.
Trophic – pertaining to levels in a food chain
Turtle Excluding Device (TED) – turtles can be excluded from trawl nets by fitting solid grids of various kinds into the net. The TED consists of a metal frame, or hinged door system, which deflects turtles out of a webbing flap or 'trap door' in the bottom of the net. The target species, usually shrimp or prawn, pass through the grid into the cod-end.
World Conservation Union (IUCN) – founded in 1948. Every 4 years IUCN publishes a 'Red List' - an inventory of the current global status of plant and animal species - to raise awareness of species threatened with extinction and promote their conservation. Of the total number (284) of marine fish assessed by IUCN, 57% are assessed as threatened i.e. Critically Endangered, Endangered or Vulnerable. For more information see www.iucn.org
Zooplankton – the animal component of plankton; animals suspended or drifting in the water column including larvae of many fish and benthic invertebrates.
Produced by Juniper Blue