Fish stocks

Your story, “Seals to blame for low cod stocks not over-fishing” (18 May), and the University of Strathclyde research it was based on may be oversimplifying a very complex situation.

It should be noted that seal numbers are not growing but are recovering from long-term exploitation by humans.

Indeed, seal populations may now have peaked and will drop and level off at naturally sustainable numbers. It should also be remembered that seals and fish stocks have co-existed for millions of years with neither fish nor seals becoming extinct.

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The biggest predators of fish are other fish and, as seals eat more adult fish, more fry will survive to adulthood. Seals may be eating more cod because other species of fish are even scarcer than cod.

After greatly reducing numbers of cod and several other fish species through a combination of legal fishing and many years of large scale illegal landings, our trawler fleet now lands a greater tonnage of mackerel than any other species. As mackerel numbers fall seals will have to increase their predation on other species.

Scottish trawlers landed 31 per cent more fish in 2014 than in 2013. That cannot continue. Quotas for commercial fish landings must take into account the fish stock levels required to sustain seals, otters, seabirds and other wildlife which catch fish to survive and not for profit or sport.

Only once that figure is calculated should commercial fisheries be permitted to take a sustainable amount of what remains.

John F Robins

Animal Concern