Scientists have unraveled genetic adjustments that cause rapid fish evolution attributable to intense harvesting—changes that previously had been invisible to researchers.
Over recent years, many commercially harvested fish have grown slower and matured earlier, which might translate into lower yields and a lowered resilience to overexploitation. Scientists have long suspected fast evolutionary change in fish is caused by intense harvest pressure.
“Most individuals consider evolution as a very gradual process that unfolds over millennial time scales. However, evolution can, actually, happen in a short time,” stated lead author Nina Overgaard Therkildsen, professor of conservation genomics at Cornell University.
The paper, “Contrasting Genomic Shifts Underlie Parallel Phenotypic Evolution in Response to Fishing,” was printed in Science.
In heavily exploited fish stocks, fishing nearly all the time targets the biggest individuals.
“Slower-growing fish might be smaller and escape the nets better, thereby having a higher probability of passing their genes on to the following generations. This fashion, fishing could cause a fast evolutionary change in development rates and other traits,” Therkildsen mentioned. “We see many indications of this impact in wild fish stocks. However, no one has identified what the underlying genetic changes have been.”
Therkildsen and her colleagues took benefit of an influential experiment printed in 2002. Six populations of Atlantic silversides, a fish that grows no greater than 6 inches in length, had been subjected to intense harvesting within the lab. In two populations, the largest people have been removed; in another two populations, the smallest people have been eliminated; and within the last two populations, the fishing was random with respect to size.