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Undersized fish are usually treated as bycatch and thrown back to sea - usually once they are dead.
Enlarge imageSome of these untargeted victims of bycatch are already endangered species.
Of all the fish caught in the world, about one quarter is unwanted bycatch, which is tossed back into the ocean dead. This wasteful practise must be stopped.
Sometimes bycatch fish are kept for market but most often they are thrown back dead because they are the wrong species, the wrong size (usually too small but sometimes too big), of inferior quality or surplus to the fishing operation's quotas.
Bycatch in longlines (horizontal lines fitted with hooks and held by floats) and purse seiners (huge bag-like nets) means death for juvenile tunas and other marine life like marlin, wahoo, swordfish, mahi mahi, sharks and turtles. More fishing vessels means more bycatch as there is no move to promote gear that lessens the destruction.
Every year, fishing nets kill up to 300,000 whales, dolphins and porpoises (collectively known as cetaceans). Most of these become entangled in the large nets then drown, die of exhaustion or are attacked by sharks.
Around Pacific Island countries each year approximately one million sharks and thousands of turtles are caught and killed as bycatch. The figure is probably higher because few fishing boats have observers on board to record these statistics.
Many die an excruciating and prolonged death, injured and sliced by the synthetic netting or hacked out of nets by fishers and thrown back into the water to die. Experts believe entanglement in nets is the cause of most cetaceans’ death and the greatest threat to the survival of many species.
Bycatch removes fish that would be better left in the sea alive as part of the intricate food web. This includes young, immature fish of commercially valuable species, which could replenish the stocks if allowed to mature.
Other bycatch includes non-commercial species of fish, which are important food for other commercially targeted fish, endangered species of fish or other marine wildlife such as seabirds.
The vast numbers of marine life killed as bycatch affect the whole marine ecosystem.
In the Gulf of Alaska, it has contributed to changes in the abundance and relationships of species.
These effects are so complex and the data often so inadequate that scientists can only highlight how enormous the problem is becoming.
Develop better gear
Better gear can help select target species more efficiently. Various technical fixes have already been developed to reduce bycatch. These fixes include:
Reduce fishing
While developing more selective gear will help, the only long term solution is to reduce global commercial fishing.
Sustainable fishing practices must also be employed. This can be done by managing targeted and non-targeted species properly.
Of all the fish caught in the world, about one quarter is unwanted bycatch, which is tossed back into the ocean dead. This wasteful practise must be stopped.
Sometimes bycatch fish are kept for market but most often they are thrown back dead because they are the wrong species, the wrong size (usually too small but sometimes too big), of inferior quality or surplus to the fishing operation's quotas.
And this is just the bycatch we know about. Added to this are the marine animals killed or harmed in fishing operations without ever being brought on board. Tangled in nets or hooked on longlines, even those that escape are sometimes too injured or weak to survive the ordeal.Every year, fishing nets kill up to 300,000 whales, dolphins and porpoises. Most of these become entangled in the large nets then drown, die of exhaustion or are attacked by sharks.
Bycatch means dwindling fish stocks
Bycatch in longlines (horizontal lines fitted with hooks and held by floats) and purse seiners (huge bag-like nets) means death for juvenile tunas and other marine life like marlin, wahoo, swordfish, mahi mahi, sharks and turtles. More fishing vessels means more bycatch as there is no move to promote gear that lessens the destruction.
Every year, fishing nets kill up to 300,000 whales, dolphins and porpoises (collectively known as cetaceans). Most of these become entangled in the large nets then drown, die of exhaustion or are attacked by sharks.
Around Pacific Island countries each year approximately one million sharks and thousands of turtles are caught and killed as bycatch. The figure is probably higher because few fishing boats have observers on board to record these statistics.
Many die an excruciating and prolonged death, injured and sliced by the synthetic netting or hacked out of nets by fishers and thrown back into the water to die. Experts believe entanglement in nets is the cause of most cetaceans’ death and the greatest threat to the survival of many species.
Bycatch removes fish that would be better left in the sea alive as part of the intricate food web. This includes young, immature fish of commercially valuable species, which could replenish the stocks if allowed to mature.
Other bycatch includes non-commercial species of fish, which are important food for other commercially targeted fish, endangered species of fish or other marine wildlife such as seabirds.
The vast numbers of marine life killed as bycatch affect the whole marine ecosystem.
In the Gulf of Alaska, it has contributed to changes in the abundance and relationships of species.
These effects are so complex and the data often so inadequate that scientists can only highlight how enormous the problem is becoming.
Bycatch solutions
There are a few ways to lessen the number of species killed as bycatch.Develop better gear
Better gear can help select target species more efficiently. Various technical fixes have already been developed to reduce bycatch. These fixes include:
- Pingers - small sound-emitting and dolphin-deterring devices that are attached to fishing nets
- Escape hatches - a widely spaced metal grid that forces the cetacean up and out of the net.
Reduce fishing
While developing more selective gear will help, the only long term solution is to reduce global commercial fishing.
Sustainable fishing practices must also be employed. This can be done by managing targeted and non-targeted species properly.
