STORRS, Conn., June 4 (UPI) -- Researchers have found that wild fish are adapting to recreational and sport fishermen's catch-and-release practice by being less aggressive, and this is affecting which fish are among the fittest to survive.
Fish that opt not to take the bait and grab a line are surviving better in bodies of water where fishermen are permitted because over-aggressive males are being pulled out of the water and females are suffering from the trauma of catch-and-release, especially if they've been caught more than once.
"This scenario genetically favors the fish with lower metabolisms, the fish that are less likely to be caught by anglers," said Jason Vokoun of the Department of Natural Resources and the Environment at the University of Connecticut in a press release. "It suggests that we may be permanently changing exploited fish populations over the long term."
Baby largemouth bass were taken from four lakes by researchers, two where fishing is permitted and two where it is not, tagged for identification, and raised for a year in the same conditions -- no fishermen and no predators. They found that the fish who'd come from lakes where fishing is permitted had lower metabolic rates than those taken from protected waters with no fishing.
Vokoun said male largemouth bass aggressively protect the nest and their permanent removal has an affect on baby survival. More aggressive female fish who are caught and thrown back may experience physiological stress that results in fewer offspring and, if they are caught more than once, their energy levels and typical behavior can be altered permanently.
"People affect the genetics of plant and animal populations just by the way we interact with them, and this study contributes to a body of knowledge that will help us truly understand how traditional management strategies may become less relevant over time," he says. "The findings in this study may be a strong signal that we need to be much more creative in the ways we manage our inland fisheries."
The study was published in PLOS One.