Seals blamed for jeopardising cod recovery plan eating 40% of stock
Grey seals are believed to consume nearly 7000 tonnes of cod each year off the west coast.
The recovery of cod stocks in Scottish West coast waters is being jeopardised by seals, researchers have found.
Seals have, historically, been anecdotally blamed for the reduction of Atlantic cod stocks.
Grey seals are believed to consume nearly 7000 tonnes of cod each year off the west coast, where landed catches now amount to only a few hundred tonnes.
The study found that, although fishing has now halved, predation by seals has rapidly increased to compensate, eating up more than 40% of the total stock.
Dr Robin Cook, a senior research fellow in Strathclyde’s Department of Mathematics and Statistics, led the study.
He said: "In recent years, cod stocks off the west coast of Scotland had declined to barely 5% of the value they had in 1981. The European Union has introduced a recovery plan to try to curb cod fishing and help the stock recover but there are few signs of improvement off the west of Scotland.
"It appears that fishing played a major part in the decline of the cod but increasing predation by seals is preventing the stock from recovering, even though the amount of fishing has reduced."
In an effort to protect the stock, the EU Cod Recovery Plan places strict regulations on the amount of time spent at sea by fishermen and the quantity of cod they can land.
However, the plan does not take into account the amount of cod eaten by seals, which researchers say could be a major reason why the strategy in the west of Scotland has had little success.
Dr Cook said: "Fishery managers face striking a difficult balance. With high predation by seals, the cod stock will struggle to improve and the Recovery Plan may not deliver the expected results. We may have to live with smaller cod stocks if we want to protect our seals."
Grey seal populations increased significantly around the British Isles after the passing of UK conservation laws in the 1970s but, more recently, their numbers in the west of Scotland have levelled off at around 30,000-40,000.
The research paper has been published in the Journal of Applied Ecology.