We have sharks and other predators that pass through British waters -some moving into the area due to the sea warming up. One would expect that sick, weak seals would therefore provide easy food sources since predators do take fit and healthy ones so a weak seal is less effort. So how long before sharks begin to go hungry? Possibly a very long time since sharks tend to have a wide variety of prey.
As I pointed out in two of my books, however, Man has been fishing on an industrial scale for a very long time and in most cases had no interest in what fish populations were, or how young the fish were -they were simply interested in money. We saw nets being brought in so that was supposed to stop fishermen taking young fish that were too small and so of no modern (real) commercial value. Fishermen have also dredged up the sea floor to make catches causing any amount of damage to the environment and species of flora and fauna there.
As two fishermen I had a conversation with about ten years told me loudly: "We don't give a **** -this is our living and that puts food on the table". Long term effects of over fishing was of no real concern to them.
We know that in certain areas fishermen will lure in seals and kill them. Illegal but no one catches them -so what? We know certain fishermen put devices in and alongside lobster pots to kill seals. Again, if not caught they just keep doing this.
I have seen photographs of seals that have been shot -now, how on earth did that happen? I have seen the evidence of seals that were bludgeoned by fishermen. So we can call this Explanation 1.
I have also seen photographs of seals killed by what could only be a spiral device -a propeller. The wounds seem quite obvious. However, why did the seal hearing and seeing the craft coming towards it not swim away? Because it was weak and unable to? There is also the speedboat used by sporty types for fun and I have heard reports of these being steered at seals and even dolphins. So Propellor driven craft could be seen as Explanation 2.
We then have unknown or known diseases that affect seals could this be a major problem if they are weaker due to hunger? Older seals cannibalising younger ones is a possibility but not in high numbers so we'll class this as Explanation 3.
I have not seen any signs of "mysterious" deaths. Deaths that do not fit into 1-3 above. Does it exist?
Smaller prey or vegetation are eaten by fish and these fall prey to other aquatic dwellers including seals (themselves prey). Now, if we suppose that there are any large and unknown sea dwelling species out there and they survive the pollution and man-made hazards at sea, how would they cope if another chunk of the sea food chain goes?
So in looking at any seal deaths the "mystery" deaths if they exist, are just part of an overall problem. Just how many seals are recorded dying around the British and Irish coast -and are other aquatic species also being found -there are large numbers of whale strandings each year.
This is why I am interested in finding out just what is going on.
Image title: Male gray seal marine mammal animal halichoerus grypus Image from Public domain images website, http://www.public-domain-image.com/full-image/fauna-animals-public-domain-images-pictures/seals-and-sea-lions-public-domain-images-pictures/gray-seal-pictures/male-gray-seal-marine-mammal-animal-halichoerus-grypus.jpg.html