Bycatch, Why We Should All Be Concerned

So, this is another topic that a short book could easily be written about, but don’t worry, I’ll keep it brief! Put simply, bycatch is the unwanted fish and other marine creatures trapped by commercial fishing nets during fishing for a different species. It is quite literally one of the largest threats to maintaining healthy commercial fish stocks, as although we do not eat the bycatch animals, they all play a role in the food web and/or ecosystem which will affect commercially caught fish populations. In fact, bycatch will often include huge numbers of commercial fish that are discarded either because they are too small, or because the boat has reached its quota!

Millions of sea turtles, rays, sharks, cetaceans, pinnipeds, and seabirds are lost every year to bycatch

As there are quite literally hundreds of facts that I find incredibly shocking about fisheries, I have again restricted myself! So, these are the top 3 I think everyone should be aware of, and which I hope will persuade you to take action against bycatch:

  1. The largest supertrawler nets have openings the size of 4 football fields and are large enough to contain 13 jumbo jets!
  2. Shrimp trawlers have recorded bycatch levels as high as 95%!
  3. Only 1 in every 3 fish caught makes it to the plate!

Considering that approximately 40% of the world’s population rely on fish and seafood as their main source of protein, we must make changes to ensure the future of healthy commercial and non-commercial marine life populations. And luckily, these changes are already happening!

Left: Turtle Exclusion Device, Right: Acoustic Pinger Cetacean Deterrent

There are many small changes being made to fishing gear which allow animals to quite simply escape being caught. The turtle exclusion device above shows how a simple barrier and hatch allows turtles, and other large air-breathing animals to escape. Acoustic pingers may only be deterrents to marine mammals, but in certain areas, it is marine mammals that represent the highest biomass of bycatch. More simple measures such as changing the mesh size of the net to allow smaller species to escape or changing the shape of the long-line hook from a J hook to a C hook, also greatly reduce bycatch. There are even some rather technical advances being made, such as ropeless pots and traps. The vertical lines between the pots on the seafloor and the buoys at the surface are particularly hazardous to large marine life, leading to both the entanglement of the animal and the loss of the pot for the fishermen. Ropeless pots have a small buoy attached, but at depth, which is only released via a signal from the returning vessel.

Many of these bycatch reduction methods are yet to be widespread, often due to the extra expense they incur. Of course, there are also a number of fishing methods which naturally result in lower bycatch too, such as pole and line fishing. So, how can we make a difference?

Consumer power!

It may increase the time you spend choosing which fish to buy, as many suppliers do not clearly label the fishing methods used, let alone whether alterations have been made to them! However, sustainable certifications will help you out; keep a look out for these, but also check online to find out what each guarantees. We can also encourage local, national, and international changes to be made to the industry as a whole, but as it often comes back to economics, remember: if we don’t buy it, they will have to make a change!

If you are able to support our team at the Marine Education Centre in creating awareness materials which will help to protect marine life, please visit You can also follow our work and learn more about marine life and what we can do to safeguard future generations at

Jenni Choma is a marine biologist based at the Marine Education Centre since its opening. Her main aim is to use marine education and research to bring about conservation of the marine environment.

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