Couch Potato Fish on the Rise:
Overfishing may lead to lethargic and slow growing fish, which are harder to catch in nets and produce less offspring, according to a study out of Deakin University in Australia.
After experimenting with fish stocks in lakes in Canada where fish were harvested in gillnets unselective to size, ecologist Peter Biro found that faster growing fish fell prey to the nets at twice the rate of slower growing fish. He hypothesizes that the faster growing fish are bolder and more exploratory. "Essentially to maintain a fast growth trajectory individuals have got to get out and about, they can't be fast growing if they sit underneath a log cowering. The fast-growers are likely swimming around more, searching out food to a greater extent than slow-growers and are therefore more likely to encounter the fishing nets," he said.
As humans continue to put evolutionary pressure on fish, those with the genetics to grow slowly may be more likely to survive and reproduce — making couch potatoes out of many species.