Research First to Study the Mixed Results of Fishing and Ocean Warming on Fish Populations – Watts Up With That?

Warming and fishing affect the survival of small fish

UNIVERSITY OF MELBOURNE

Research news

PICTURE: RAPID OCEAN WARMING AND THE PRACTICE OF TARGETING LARGE FISH AFFECT THE VIABILITY OF WILD POPULATIONS AND GLOBAL FISH STOCK

The combined effect of rapid ocean warming and targeted control of large fish affects the viability of wild populations and global fish stocks, according to new research from the University of Melbourne and the University of Tasmania.

In contrast to previous studies, which traditionally looked at fisheries and the climate in isolation, the research found that ocean warming and fishing together affect fish recruitment and that it took four generations to manifest.

“We found a large drop in recruitment (the process of bringing new young fish into a population) in all populations exposed to warming, and this effect was greatest when all of the largest individuals were fished,” said the lead author and PhD candidate Henry Wootton from the University of Melbourne.

Mr. Wootton and his team set up 18 independent fish populations in their laboratory and exposed them to either control or elevated temperatures and one of three fishery harvesting systems. They then followed the fate of every population for seven generations, which corresponds to almost three years of laboratory time.

“Our study is the first to experimentally examine the joint effects of fishing and ocean warming on fish populations,” said Wootton.

The study is published today in the journal PNAS. Researchers say the solution is less selective fishing, which will help ensure gender balance and the persistence of valuable taller women.

Co-author Dr. John Morrongiello said, “Wildlife fisheries provide food for billions of people around the world, especially in our Pacific region, where fish is the main source of animal protein. Previous fishing practices have resulted in spectacular fishing crashes. It is therefore important that we adopt management approaches that ensure that our oceans continue to maintain sustainable fisheries. “

He added: “Sustainable fisheries management in the face of rapid environmental change is a real challenge. If we do it right, it will not only provide food and economic security for millions of people worldwide, but also help protect the precious biodiversity of our ocean for generations to come. “

Dr. Asta Audzijonyte, co-author of the University of Tasmania and a Pew Fellow in Marine Conservation, said it was surprising to find such strong and delayed negative effects of warming on small fish survival.

“We still don’t fully understand why this is happening, but our results clearly show that protecting fish size diversity and large fish can increase their resilience to climate change. Reversing climate change is difficult, but restoring and protecting the diversity of fish sizes is one thing that we can safely do and that we must do quickly, “she said.

Dr. Audzijonyte added, “Most of the experimental studies on the effects of climate change are conducted over relatively short periods of time, with fish being studied for two or three generations at best. We found that strong negative effects of warming only became apparent after four generations. This suggests that we may underestimate the potential impacts of climate change on some fishery stocks. “

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From EurekAlert!

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