I can appreciate your concern on this issue. Seal conservation is a devolved matter so I can only respond with respect to England. Approximately 85 per cent of the UK seal population is in Scotland, where there is separate legislation for seal protection.
As you will probably know, under the Conservation of Seals Act 1970 it is lawful to kill a seal if it is deemed to pose a threat to fishing operations. Before this is considered measures must be taken to prevent damage occurring, and the seal must be in the vicinity of the equipment. Legislation therefore only allows limited, local action to be taken against individual problem seals.
I believe this strikes the right balance between the conservation and welfare of seals, and the needs of the fishing industry. Common and grey seal populations in England have increased over the last ten years and there is no evidence to suggest that limited local control is having any adverse effect on the conservation status of the UK seal population as a whole.
I was especially pleased to see news that the seal colony on Blakeney Point in Norfolk has seen record growth in recent years, and is thriving. Apparently there was some concern that the population growth there might lead to calls for a cull, but the National Trust, which controls the property, has confirmed that there would be no need for this to be considered.
