A report in the Journal of Applied Ecology has been summarized by the BBC.

Grey seals are compromising the recovery of cod stocks off the west coast of Scotland, research has suggested. The cod population has been in long-term decline for many years, largely due to fishing.
The EU introduced a recovery plan to try and curb cod fishing, but this appears to have had a limited effect. The study found that although cod fishing has now halved, predation by seals has rapidly increased.
Grey seal populations increased significantly after the passing of conservation laws in the 1970s but, more recently, their numbers in the west of Scotland have leveled off at around 30,000 to 40,000.
The seals are believed to consume nearly 7,000 tonnes of cod each year off the west of Scotland, where landed catches now amount to only a few hundred tonnes.

Following links supplied thanks to Rhys Toogood: