Shark lines
Branch lines that run directly off a longline’s floats or floatlines. Avoiding the use of shark lines can help to reduce shark bycatch in longline tuna fisheries.
See http://issfguidebooks.squarespace.com/s/Shark-Lines-Illustration.pdf
Circle hooks
Wide circle hooks appear to reduce the capture of turtles if the hooks are wider at their narrowest point than J-shaped hooks, tuna hooks, and teracima hooks, making it difficult for the circle hook to fit inside a turtle’s mouth. Furthermore, circle hooks are circular, with the point turned perpendicularly back toward the shank, less exposed in comparison to J or tuna hooks. Thus, if a turtle does bite a circle hook, they are less likely to be deeply hooked (where the hook is swallowed down the throat or pierces the roof of the mouth), making dehooking easier.
Shark catch rates are higher on circle hooks relative to J-shaped hooks, but at-vessel mortality rates are lower. This is because animals caught using circle hooks are not hooked as deeply, are less likely to suffer internal injury, and therefore have a higher likelihood of survival.
In fisheries where sharks are not retained, there will be a higher shark fishing mortality on circle hooks. However, the benefit of very large reductions in marine turtle catch rates on wide circle hooks may outweigh the tradeoff of increased shark mortality.
“Fins naturally attached (FNA)” is a requirement that retained sharks are to be landed with their fins still attached to the carcass by prohibiting the removal of shark fins on board vessels as well as the prohibition of retaining onboard, transshipping or landing removed shark fins.
Source: the MSC-MSCI Vocabulary
Target species
Those species that are the main subject of fishing effort in a fishery. The tropical‑tuna fisheries, depending on their fishing strategy, target skipjack, yellowfin and/or bigeye tuna; while the fisheries that cover temperate waters also target bluefin and albacore species. Considerations such as size also matter since tunas that are undesirably small for processing are also sometimes called bycatch.
See also ALB, BET, BFT, SKJ, YFT.
Shark finning
A fishing practice that consists in removing the fins from sharks and discarding the bodies back to the ocean. This practice has been banned in some countries, where it is mandatory to land the whole sharks with their fins naturally attached, as a way to monitor compliance with finning bans and to collect more accurate data on shark catches.
Non‑target species
Species that are incidentally captured while fishing for a target species. In tropical tuna fishing, these generally include minor tuna species (bullet and frigate tunas, Pacific black skipjack, little tunny), other bony fishes (mahi‑mahi, rainbow runner, billfishes), sharks, rays, turtles, etc. Some of these species can be targeted opportunistically during a fishing trip.
See also Bycatch, Byproduct and Discard.
https://www.iss-foundation.org/tuna-stocks-and-management/our-media-library/infographics/download-info/non-target-species-caught-in-tuna-fisheries/
Finfish
Term used to describe the strictly classified biological group of fishes, sometimes called true fishes to distinguish them from other aquatic life whose common names also end in “fish”, including mollusks (e.g., cuttlefish), crustaceans (e.g., crayfish), echinoderms (e.g., starfish), and other animals (e.g., jellyfish); or any other aquatic life harvested in fisheries or aquaculture (e.g. shellfish).
Bycatch mitigation
Mitigation measures for tuna fisheries intended to reduce catches of non‑target species including seabirds, sea turtles, marine mammals, sharks, and rays. They include changes in gear designs and fishing methods to avoid catching bycatch, along with techniques to release bycatch species when caught.
Bycatch
Any fish or other marine species — such as sharks, dolphins, marine turtles, and seabirds — that is not the main objective or the target of a fishing fleet and are caught unintentionally while fishing, whether retained or discarded.
See also Byproduct and Discard.
