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Fish might be shrinking!

To all the seafood lovers, you are being warned here first! The tiny piece of tuna on your plate will soon become even smaller due to climate change. Fish in the ocean will struggle to breathe due to the increasing water temperature, and many species of fish will likely shrink. According to a study published in Global Change Biology, the author predicts a decrease in sizes of the fish by as much as 30 percent. As Nexus Media explains, fish are cold-blooded animals, which means that they cannot regulate their own body temperature. Daniel Pauly, the study’s lead author and a University of British Columbia research initiative, say that due to the increase in ocean temperature, fish will have a higher metabolic rate and have to consume more oxygen. The whole metabolisms in the fish’s body, all the chemical reactions, are accelerated.

Credit:  Attribution license: Taras Kalapun,


So if the fish need to have more oxygen intake, why not just grow bigger gills? In Pauly’s research, he suggests that growing bigger gills won’t help. According to the article, the gills being mostly two-dimensional, just cannot keep up with the three-dimensional growth in the rest of the fish’s body. When a fish grows 100 percent larger, its gill could only grow about 80 percent or less, according to the study. When a gill can no longer supply enough oxygen for a fish’s larger body, the fish will just stop growing larger all together, according to William Cheung, a director of science for the Nippon Foundation. In order to match the decreased supply of oxygen, fish will have to lower their demand, which means that fish of all kinds will shrink as a result of climate change.

There is already evidence to the phenomena of fish shrinking due to climate change, researchers in the North Sea have found that fish stocks like haddock and sole had decreased in body size over the past couple decades, and it is primarily due to climate change since commercial fishing and other factors have been corrected. Furthermore, the entire ecosystem will be affected since the larger fish eat the smaller ones, and a change in body size would alter food web interactions and structure.

To read more about other impacts of climate change on marine species.


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  1. chromison

    Nice article YUROGENITAL, the effects of climate change on different species of animals is a tragic and real byproduct of the most pressing environmental issue of our time. The enormous and inevitable challenge that climate change poses is something we need to tackle as a global community and problems like these arising among fish are only further incentive to take action. Another article I found that discusses this subject is below, I highly recommend reading it as it further elaborates on climate change as a whole and on the effects that fish in a wide range of geographic locations are feeling.

  2. celliswallier

    Hi Yurogential,
    There’s also a additional risk to many humans caused by the shrinking fish. There are many parts of the world where the fish trade is a massive part of the economy, and the shrinking fish as you mentioned here throw these communities into turmoil, as well as endangering the food web of the area.
    Here’s an article which goes more in depth on that. It mentions that the total value of harvested Menhaden (a type of fish affected by these size changes) was $129 million in 2013, and that number falling will cause massive problems for many areas that rely on fishing to support their economy

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