Mom, I have shrunk the fish. Intensive fishing and climate change are decreasing the size of fish. This makes some species more vulnerable to predators. This is the alarm raised by a study published in the Royal Society Biology Letters journal by marine biologist Asta Audzijonyte, of the Wealth from Oceans Flagship, belonging to one of the largest research institutions in the world, the Australian Commonwealth Scientific and Industrial Research Organization (Csiro ).
He is about to end up run over, his mother saves him
"Honey, I have shrunk the fish". Intensive fishing and climate change are decreasing the size of fish. This makes some species more vulnerable to predators. This is the alarm raised by a study published in the Royal Society Biology Letters journal by marine biologist Asta Audzijonyte, of the Wealth from Oceans Flagship, belonging to one of the largest research institutions in the world, the Australian Commonwealth Scientific and Industrial Research Organization (Csiro ).
“We found that the decrease in size leads to a large increase in fish mortality due to predation. When fishing there are nets that select the largest and fastest growing fish. Smaller fish manage to escape and only the larger ones get caught in the nets, ”explains Dr Audzijonyte.
This continues pressure on fish stocks it is causing fish to evolve towards ever smaller sizes, as documented by fisheries data in Europe in recent decades. “If the fish mature too late, they get caught in the nets without them being able to reproduce, that's why there is an evolutionary pressure that leads them to mature earlier ”, continues the biologist. Until now, however, no one had studied the impact of the decrease in size on interactions between predatory fish and prey fish in the marine ecosystem.
To figure this out, the team used a gigantic one computer model, able to simulate the interaction between 56 groups of organisms, including algae, shrimp, fish and whales. The results suggested that in five species analyzed, the decrease in size would have been just 4% in more than 50 years, but the mortality rate from predation would have increased by between 20 and 50%. This means that, regardless of the type of fishing, even a small reduction in size can result in a strong increase in predation.
Climate change is also expected to have an effect similar to that of intensive fishing on fish size. “As the temperature rises, the amount of oxygen in the water decreases and consequently the fish also receive less oxygen. This means that they cannot grow fast, "says the researcher, stressing the need to consider the new data for a more sustainable management of fishing activities. Because, concludes Audzijonyte, “the impact of fishing could be much greater than we expected“.
Roberta Ragni
READ also:
Paint a fish against the exploitation of the seas and intensive fishing
