Size-Selective Fishing Can Ruin Chance Of Catching Big Fish In The Future | University of Oslo

Medaka female (Oryzias latipes) carrying eggs. Credit: Eric Edeline/INRAE

Jan. 21, 2022 (Phys.org) -- Fishermen have always competed to get the biggest fish. New research show that this has a negative, long term impact on the whole ecosystem.

Who hasn´t heard an old uncle or grandfather boast about how big fish were in the old days? They often claim that things were better before. In the case of fish it seems to be true.

Several scientific reports state that overall, the size of the fish, both in freshwater and in seawater is smaller, sometimes much smaller, than what they used to be. Nevertheless, recreational, and commercial fisheries go on, just like before. The goal is still to catch the biggest fish.

Over the years fisheries have simply removed the bigger catch from the gene pool. Smaller fish with slow growth and early maturity get to reproduce and transmit their genes. This means that fishing-induced selection toward small body size is genetic. The situation is thus hard to reverse, now that we start to understand how we have affected evolution.

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