Cormorants - European Studies into Fishery Conflicts Published

[FishingMagic]

This is a dedicated thread for discussing article: Cormorants - European Studies into Fishery Conflicts Published

 

[MarkTheSpark]

Read down to section 4.4 in the 'Toolbox' section of the report and you find this, in explanation of how effective providing fish refuge areas are: 'The results indicated that cormorant dive duration in the refuge pond was significantly higher and the foraging efficiency of the birds (prey capture rate and the proportion of successful foraging bouts) significantly lower. In effect, the birds were working harder for fewer captured prey. There were 77% fewer cormorant visits to the refuge pond than the control pond, on average. There was also a 67% fall in the mean mass of fish consumed per cormorant visit and 79% less fish mass lost in the refuge pond.'
In other words, if you make stillwaters good for fish, they will be less good for cormorants - something I've been saying for ages.
If stillwater fishery managers would get their heads out of their collective arses, quit banging on about shooting cormorants, and get on with the job of fishery management, they wouldn't have the predation problems they have.

 

[Paul Boote]

Yes, Mark, but, like some spin-it-away Utilities PR person today and for the forseeable future, they'll be trotting out "But our customers don't like snags ... they lose tackle in them...".

Ducks, barrels, or in this case cormorants.

 

[richiekelly]

And just how do we do this for rivers?

 

[Paul Boote]

Plenty of fish-holding structure and snags, plus some pretty heavy shooting.

 

[MarkTheSpark]

And just how do we do this for rivers?

What he said. We need to create far more refuges on rivers, anyway. On my local Nene, the EA project dug out the tail of an old oxbow (which faces downstream) and encouraged more weed to grow in it. It was lifting with fry all summer.

 

[chub_on_the_block]

Many rivers are in a more overgrown state now than in previous decades. I can think of places on the Thames, Wensum and Yare that i have revisited after about 25 years - and they were barely recognisable with all the new overhanging trees and dense bushes.

Those heavily fished little club puddles where they remove all the snags and overhanging trees so that numpties can cast more easily can avoid cormorants because there is nearly always an angler or several on the bank - 24/7.

 

[sam vimes]

I've been fishing a fairly big deep pit for a few years now. We had a problem with cormorants and a lack of small silver fish. It wasn't all down to cormorants, but they certainly weren't helping. We put fish refuges in first and a few years later we got a limited licence to cull cormorants. As far as I'm aware we've not come close to our limit. However, they have got sick of the big bangs and buggered off elsewhere. We still see cormorants but the black horde just fly over now. We've seen a huge upturn in silver numbers and fry recruitment is looking very good.
I hate to think of what's happening wherever the damned things are going in preference. I suspect that the local bird sanctuary gravel pit is being steadily denuded of fish.

 

[richiekelly]

What he said. We need to create far more refuges on rivers, anyway. On my local Nene, the EA project dug out the tail of an old oxbow (which faces downstream) and encouraged more weed to grow in it. It was lifting with fry all summer.

Snags weed and overhanging trees are all present on the small river I fish as are cormorants, what are not present are small/medium sized fish.

 

[bennygesserit]

I've been fishing a fairly big deep pit for a few years now. We had a problem with cormorants and a lack of small silver fish. It wasn't all down to cormorants, but they certainly weren't helping. We put fish refuges in first and a few years later we got a limited licence to cull cormorants. As far as I'm aware we've not come close to our limit. However, they have got sick of the big bangs and buggered off elsewhere. We still see cormorants but the black horde just fly over now. We've seen a huge upturn in silver numbers and fry recruitment is looking very good.
I hate to think of what's happening wherever the damned things are going in preference. I suspect that the local bird sanctuary gravel pit is being steadily denuded of fish.

I am confused I thought the limit was two ?

 

[peter crabtree]

Those heavily fished little club puddles where they remove all the snags and overhanging trees so that numpties can cast more easily can avoid cormorants because there is nearly always an angler or several on the bank - 24/7.

I'm both surprised and disappointed you feel the need to refer to fellow anglers and their choice of venue as numpties? What's it got to do with cormorants?

 

[sam vimes]

I am confused I thought the limit was two ?

Cull limits vary from water to water. As far as I'm aware the powers that be set the limit depending on the size of the water and their assessment of the problem by region. I'm not aware of any actually being shot on our water (I don't do the shooting though). I suspect that a combination of a close by water being a duck shoot, plenty of pheasant shooting, a clay club not a million miles away and the odd attempted shot has persuaded them they are better off elsewhere.

 

[nicepix]

Out here the equivalent of the fisheries officers are deployed to shoot cormorants whenever they become a problem. I regularly see two or three officers going down to the local stretch of the river to thin the birds out.

 

[bennygesserit]

I read an article recently about the badger cull the gap left by that cull gets filled in by the badgers that surround the cull area. A cull certainly decreases the number of badgers but the surrounding population grow faster than they might have done because of the "gap".

Not that this is an otter thread but they are certainly a predator locked into the Lotka-Volterra predator prey relationship in that if you had a close system with just fish and just otters eventually the numbers would stabilise as the otters thin each other out.

[ame="http://en.wikipedia.org/wiki/Lotka%E2%80%93Volterra_equation"]Lotka–Volterra equation - Wikipedia, the free encyclopedia[/ame]

But its not a closed system you might shoot cormorants and the resultant increase in the biomass might in the ability to sustain more predators so you might increase the numbers of kingfishers , pike , perch or heron.

Kingfishers eat 5000 fry per family per year - apparantley cleaner water has enabled them to increase in numbers but again its not a closed system there are all sorts of cycles going on not least the weather temperature and flooding.

So my mind is kind of changing , particularly on otter culls ( though I understand the PR disaster that might be ) wasn't it common to hunt otters with hounds ? Isn't the increase of cormorants partly blamed ( even by the RSPB I think ) on the fact they are not controlled by shooting, same with Magpies very rare when I was a kid, Buzzards too.

Its a rambling post the point I am making is that you cannot treat one thing in isolation , no point shooting cormorants if the water isn't clean or even if the water isn't there in sufficient quantity.

My vote is there appear to be so many of them ( cormorants ) ( Do you see them everytime you fish ? My brother saw a lot down south recently ) is that a cull is long overdue.