Understanding why fish grow the way they do and getting serious about it

Understanding why fish grow the way they do and getting serious about it

Understanding why fish grow the way they do and getting serious about it

Fish gills. Image by 2427999, Pixabay.

The distribution and concentration of dissolved oxygen and water temperature in the oceans and freshwaters are usually far more influential in shaping the growth and reproduction of fish than the distribution of their prey.

In a new paper in Science Advances, Daniel Pauly, principal investigator of the Sea Around Us initiative at UBC’s Institute for the Oceans and Fisheries, argues that scientists need to avoid attaching human attributes to fish and start looking at their unique biology and constraints through a different lens.

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Daniel Pauly publishes second edition of his book on how fish breathe and grow

Daniel Pauly publishes second edition of his book on how fish breathe and grow

Daniel Pauly publishes second edition of his book on how fish breathe and grow

For more than 40 years, Dr Daniel Pauly, principal investigator of the Sea Around Us initiative at the University of British Columbia’s Institute for the Oceans and Fisheries, has been collecting evidence to further develop his Gill-Oxygen Limitation Theory, also known as GOLT.

Back in 2010, he presented his findings in a slim book titled Gasping Fish and Panting Squids: Oxygen Temperature and the Growth of Water Breathing Animals, whose second edition has just been released; a Chinese edition will soon follow.

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Most female fish grow bigger than the males: deal with it!

A pair of One-spot Pullers (Chromis hypsilepis) preparing to spawn. Home Bommie, Ulladulla, NSW. Photo by Richard Ling, Flickr, CC BY-NC-ND 2.0.

A pair of One-spot Pullers (Chromis hypsilepis) preparing to spawn. Home Bommie, Ulladulla, NSW. Photo by Richard Ling, Flickr, CC BY-NC-ND 2.0.

In over 80 per cent of fish species, the females, including those known as ‘big old fecund females,’ or BOFFS, grow bigger than the males. This long-established fact is difficult to explain with the conventional view of fish spawning being a drain on the ‘energy’ available for growth. If this view were correct, females, which are defined by their larger reproductive effort, would always remain smaller than males.

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