Over-fishing is already a concerning problem, but new research indicates that not only could it mean losing fish species, it could also contribute to global warming more than we'd previously thought.
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That's because researchers from the Marine Institute and the University of Southampton have found that fish that feed on our ocean floor and do not come to the surface actually act as carbon sinks. Other examples of naturally occurring carbon sinks include forests and, indeed, the oceans themselves. What's more, the UK-based researchers have found that deep-sea fish might be capturing more than a million tons of carbon dioxide from UK and Irish waters.
The process starts with what are known as mid-level swimming fish, as well as jellyfish and certain cephalopods like squid. They will often venture close to the surface, feed and then, for a short time, dive to deeper waters. When they do this, they run the risk of becoming prey for larger bottom dwellers who never surface. When this happens, the carbon in the prey animals' system transfers to the predator fish — and there it stays. True, when one of those predator fish dies it’s likely some of that carbon is released, but even then those fish are often dined on by others at the bottom of the ocean, and so the majority stays in our deep water fish.
The researchers investigated this by collecting muscle tissue samples from fish caught in fish trawls off the west coast of Ireland, at varying degrees between 500 and 1,800 meters. To look at how much carbon was present at each stage they searched the muscle samples and looked for carbon and nitrogen isotopes. By doing this, the researchers are able to see how carbon transfers through the ecosystem and thereby determine diet and the predator/prey dynamics of that area.
This is an important finding because it tells us a number of things. Chiefly, it reveals a vital carbon sink that could help us in a small but significant way to combat adding to the global warming problem. It also tells us how dangerous unregulated fishing and overfishing practices can be. For instance, many of the bottom-feeders are not caught for food but regularly get swept up in fishing trawls regardless. They are killed in this process and then usually thrown back, thus releasing that carbon (which is just one troubling aspect of this practice).
Peacock flounder image via Shutterstock.
Read more at ENN Affiliate, Care2.