I think the answer is that the seal population is close to an all-time high, so it's no surprise that you are seeing them even in the wintertime, especially in the estuaries where, as you say, there may be sea trout around.
The science indicates that the growth we've seen in the stock in the last 10 years is good, and that's taking place in the presence of this large seal population.
The latest information on harp seals suggests, if I recall correctly, that the seal population seems to be levelling off. This is not grey seals now. This is harp seals. It seems to have levelled off and is perhaps a bit lower than it was a few years ago. At the moment it doesn't look as if it's going to continue to increase, whereas cod is in an upward track.