Intensive fishing prompts much concern and debate over sustainability of fish stocks, but could it also be driving evolutionary changes that render fish of the future less catchable?
There are many examples of an evolutionary 'arms race' between predator and prey, where adaptations that help hunted animals avoid capture prompt changes in hunters that help them become more deadly.
Scientists at the University of Glasgow investigating whether commercial trawling is similarly driving evolutionary change in fish have found fitter fish are better at evading capture. They speculate that, over time, this could lead to physiological changes in future fish populations.
Dr Shaun Killen of the Institute of Biodiversity, Animal Health and Comparative Medicine, said: "There is a lot of concern on how overfishing is affecting the abundance of wild fish, consequences for the economy, employment and the ecosystem as a whole.
"But one aspect that is often overlooked is that intense fishing pressure may cause evolutionary changes to remaining the fish that are not captured."
A study led by Dr Killen, published in the journal Proceedings of the Royal Society B, used simulated trawling with schools of wild minnows to investigate two key questions around fisheries-induced evolution.
The researchers wanted to know whether some individuals within a fish shoal were consistently more susceptible to capture by trawling than others, and if so, was susceptibility related to individual differences in swimming performance and metabolism?
The researchers measured the swimming ability, metabolic rate, and indicators of aerobic and anaerobic physical fitness of 43 individual fish. They then placed them in a tank with a trawling net in a simulation that was repeated several times, enabling the identification of individuals which were more susceptible to capture.
Dr Killen said: "Fish being trawled will try to swim at a steady pace ahead of the mouth of the net for as long as possible, but a proportion will eventually tire and fall back into the net.
"Fish that escape trawling are those that can propel themselves ahead of the net or move around the outside of the net. The key question is whether those that escape are somehow physiologically or behaviourally different than those that are captured. Most trawlers travel at the about same speed as the upper limit of the swim speed of the species they are targeting.
(Score: -1, Troll) by Anonymous Coward on Sunday August 09 2015, @11:54AM
There will be 366 days next year, don't you know, as part of Obama's desperate attempt to reform the calendar and prolong his dwindling time in power before he becomes a lame duck for whom you voted.
(Score: 1, Offtopic) by janrinok on Sunday August 09 2015, @12:01PM
You are an idiot - I'm not American, I don't vote for US Presidents.
(Score: 1, Offtopic) by Runaway1956 on Sunday August 09 2015, @12:13PM
"You are an idiot - I'm not American, I don't vote for US Presidents."
Your sig? "It's always my fault..." It doesn't matter if you voted or not, it's still your fault.
(Score: 1, Offtopic) by janrinok on Sunday August 09 2015, @12:34PM
(Score: 0) by Anonymous Coward on Sunday August 09 2015, @12:20PM
Thanks for replying to the obvious troll: fact followed by insult followed by conspiracy theory supported by half truth and concluded with a personal attack. Too subtle for you, idiot?
Seriously though, 365-days-a-year is off-by-one because the calendar has 366 days to accommodate leap years. Idiot.
(Score: 2) by janrinok on Sunday August 09 2015, @12:29PM
(Score: 2) by janrinok on Sunday August 09 2015, @12:37PM
My objection, such as it was, is that you assumed that I voted for him, or any other candidate for that matter.
(Score: 0) by Anonymous Coward on Monday August 10 2015, @10:43PM
Don't blame me. I voted for Kodos.