Sea warming threat to fish stocks

Eggs from Thornback Rays were used in the study

Global warming could pose a serious threat to fish stocks around Scotland's coast, according to a new study.

Researchers at Loch Lomond Aquarium, near Balloch, studied the breeding of rays at different water temperatures.

They found that in warmer water, the rays' eggs hatched earlier and their offspring were less capable of producing healthy young of their own.

The 15-month study examined the effects of three different temperatures on 400 ray eggs.

The eggs, from Thornback and Smalleye Rays, were placed in special quarantine tanks at the aquarium by zoologist, John Hume.

He said: "We incubated eggs at current sea temperature and others at two degrees cooler and at two degrees warmer.

"The eggs incubated at the warmest temperatures hatched earliest by some weeks and were smaller than we would usually expect. They suffered from accelerated gestation.

If global warming continues it will have an impact on different species of fish   John Hume, Zoologist

"It shows that even a small difference of one or two degrees can have a significant difference in the size of the young fish."

Mr Hume said this had "strong implications" for all marine life in British waters.

"The sea temperature around the coast of Britain has risen by more than one-and-a-half degrees in just a few generations," he said.

"If global warming continues it will have an impact on different species of fish.

"These rays, in common with different species of shark, come in to shallow water to lay their eggs.

"If these shallow waters are heating up the rays and sharks will hatch out smaller and produce fewer and poorer quality young. This will clearly affect the wild population."

Mr Hume said his results explained why Scots fishermen had already reported a smaller average size of rays in recent years.

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