ROB HUGHES ‘Do the maths on predation’

IWAS pretty good at maths in school. Top set, good grades, and in my subsequent life as a lawyer and a small businessman, I have to make sure that the numbers add up. If they don’t there’s gonna be trouble somewhere down the line… which leads me on to fish stocking and, more importantly, predation.

According to a recent Environment Agency press release, those fantastic chaps at Calverton Fish Farm, bred, hatched and released a whopping 520,000 fish into our rivers and lakes.

Now that’s more than half a million fish – an enormous number, and one to be applauded.

But let me look at another important calculation that hasn’t been announced with such vigour.

Official estimates say there are 62,000 overwintering cormorants in this country. Let’s say the winter starts in November and runs until the end of February, that’s 120 days. Each cormorant eats about 2lb of fish, or 20 individual fish, every day.

Time to do some more maths: 62,000 x 120 x 20 = 148,800,000.

Now that’s a fairly big number with lots of zeros, so let’s say it. One hundred and forty eight million, eight hundred thousand fish. Remember, this is just cormorants, and I’m talking about the non-native invasive Carbo sinensis version, not our own indigenous cormorant. Add in ruthless sawbills like goosanders and mergansers, and we’ve got a big problem. Don’t even get me started on signal crayfish. And then we can add otters, just for good measure.

At first glance half a million looks really good, but the reality is that the EA fish farm was set up to restock after pollution.

Predation is at an incredible level, and this winter’s floods and habitat destruction only add to the mounting impact on fish stocks.

More protection is needed before our already threatened stocks reach a point that is beyond repair.

Rob