Cormorants: how much fish does one need?

fatfifer

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On a couple of occasions recently I've seen a cormorant at a pond in the park. So I guess there must be some fish there. I was just idly wondering how much fish would be needed to feed a cormorant for several days and what minimum size they would have to be. The pond is small and shallow (nowhere deeper than 4 feet) with a very small trickle inflow and out. I've seen fry up to 2inches long in the margins from time to time but nothing else. I've never seen anyone fishing there. There is a lot of weed and algae in the summer. TBH I was surprised to see the cormorant the first time and even more so when he was there again 3 days later. What is he feeding on, I wonder?
 
G

guest54

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Two weeks ago I caught a 20" rainbow with an obvious cormorant scar, puncture on one side and a long scrape on the other, another angler showed me a rainbow he had caught with similar scars, I'm pretty sure they'll have a go at anything, whether they can swallow it or not and they can swallow a pretty big fish.
 

black knight

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Adults eat an average of one pound of fish per day, which is typically comprised of small (less than 6 inch) size. They are opportunistic and generalist feeders, preying on many species of fish, but concentrating on those that are easiest to catch. I have run a fishery with cormorants on and seen them swallow a 1.5lb fish with ease. Some of the birds are riddled with worms and eat twice as much as a healthy bird.
 

mol

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I've been lead to believe a cormorant will eat around 500g of food per day.

I've also been told they're pretty good at only striking at what they can eat, after all why waste energy chasing what you can't eat however not all hunts are sucessful hence marked fish. Now herons and such like are more prone to striking at what they can't eat as they're an ambush predator.

They can eat pretty big fish
https://www.youtube.com/watch?v=nEUPTIiDgKs
 

22lbbrown

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Having studied comorants for a long time lol they can swallow trout up to 2lbs if a big bird but 1.5lb the easiest to go down whole, i have witnessed the biggest grandparent cleverer comorants 1 time catch 4 of 1lb to 1.5lb rainbows and drop 1 in each corner of my lake then decide which 1 was safest to swallow...another time seen 3 big birds work together from each corner of lake to middle of lake like herding the fish then together they shared a fish about 4to 5lbs...this i know as i witnessed the splashing in distance and rolling of water then a swim bladder and guts floated up and i waited to recover and see so i know the amount of fatty guts roughly, the next day i found a flank of rainbow trout skin virtually whole apart from stab puncture marks -nicely cleaned overnight by the snails!! so their range of size can be bigger than what an individual can swallow -but they also eat a lot of my golden rudd and prefer these when have young to feed as easier to swallow and maybe catch? One time on a local canal i see a bird dive a few time then come up and in 2 mins of fishing he had 3 perch and 4 roach as the perch got stuck in his throat so ended up spitting them all out..as for the parastic worms when you see them the first time they scared me as so horrible!!!hard to think something can live in a comorants acidic stomach i never want to see again them...
 
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Adults eat an average of one pound of fish per day, which is typically comprised of small (less than 6 inch) size. They are opportunistic and generalist feeders, preying on many species of fish, but concentrating on those that are easiest to catch. I have run a fishery with cormorants on and seen them swallow a 1.5lb fish with ease. Some of the birds are riddled with worms and eat twice as much as a healthy bird.

Sorry Alban,but that reply is right out of a typical RSPB or SNH handbook.

Cormorants will eat as much fish as they can get down its neck.It starts to dissolve as soon as its in its throat and everyone of them are full of worms.I have observed them at great length and seen them eat 6 fish in one day,all over 2lbs in weight.
So multiply that by 10 birds that's 60 fish gone in a day and over a week 420 fish gone.Not many waters could survive that sort of predation.They are eating machines and the ones they miss they leave damaged.
They will try and get any size of fish down even to they extent they choke on them.You have seen the pictures on here plenty of times.
 

sewinbasher

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Sorry Alban,but that reply is right out of a typical RSPB or SNH handbook.

Cormorants will eat as much fish as they can get down its neck.It starts to dissolve as soon as its in its throat and everyone of them are full of worms.I have observed them at great length and seen them eat 6 fish in one day,all over 2lbs in weight.
So multiply that by 10 birds that's 60 fish gone in a day and over a week 420 fish gone.Not many waters could survive that sort of predation.They are eating machines and the ones they miss they leave damaged.
They will try and get any size of fish down even to they extent they choke on them.You have seen the pictures on here plenty of times.
A week ago we counted 517 cormorants come in to roost on the lower Clwyd! The mind boggles at the amount of fish that lot would eat, admittedly not solely on that stretch, but they clearly eat somewhere!
 
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that is just uncontrollable amount of birds and as you say how much fish are lodt to that even at 1 fish a day.Yet protected they are which is a joke.Bit like seagulls being protected,like they are really under pressure and eat anything including other birds and their young, which do need protecting.
 

fatfifer

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Thanks for all the replies. this has been very interesting. I guess at the back of my mind was the question: does the presence of a cormorant indicate that there might be fish big enough for me to consider trying to catch them. Although now hooked on fly fishing I'd happily have a brief return to coarse fishing as the pond is only 5 minutes from the house. Any thoughts?
 

sewinbasher

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that is just uncontrollable amount of birds and as you say how much fish are lodt to that even at 1 fish a day.Yet protected they are which is a joke.Bit like seagulls being protected,like they are really under pressure and eat anything including other birds and their young, which do need protecting.

We can get a licence to cull but because of pressure from RSPB it's limited to 10% of an approved count with a requirement to scare before using lethal force ..... ridiculous!
 

jeffhirst

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Angling Trust are a joke when it comes to cormorant control. It is a really serious problem on all lakes and rivers whether it is coarse or salmon family they predate on. I fish most days on Bristol reservoirs and never fail to see cormorants actively taking fish... there were 76 on Blagdon over the weekend.....I approached one at the waters edge that couldn't fly...it regurgitated a 3lb rainbow and flew off. The problem has been brushed under the carpet by UK gov and RSPB lobby. Angling Trust need to bring the problem to the fore yet again as what they got last time was p!ssing into the wind. Cormorants are a really serious threat to fish stocks(whether natural/stocked) everywhere and should concern everybody not just anglers. Eggs need pricking as well as birds being culled...there are no natural predators.
 

soldierpmr

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We can get a licence to cull but because of pressure from RSPB it's limited to 10% of an approved count with a requirement to scare before using lethal force ..... ridiculous!

There is nothing to stop the use of a shotgun on private land and with bad eye site they could be mistaken as winter fowl.

Though I would never condone such actions.
 

sewinbasher

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Angling Trust are a joke when it comes to cormorant control. It is a really serious problem on all lakes and rivers whether it is coarse or salmon family they predate on. I fish most days on Bristol reservoirs and never fail to see cormorants actively taking fish... there were 76 on Blagdon over the weekend.....I approached one at the waters edge that couldn't fly...it regurgitated a 3lb rainbow and flew off. The problem has been brushed under the carpet by UK gov and RSPB lobby. Angling Trust need to bring the problem to the fore yet again as what they got last time was p!ssing into the wind. Cormorants are a really serious threat to fish stocks(whether natural/stocked) everywhere and should concern everybody not just anglers. Eggs need pricking as well as birds being culled...there are no natural predators.
The irony is that the RSPB cull avian predators and are pricking eggs on their own reserves to protect vulnerable species but apparently salmon and sea trout aren't vulnerable enough despite the likelihood that no salmon can be kept by anglers in Wales in 2018. :confused:
 

dgp

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Now I see them frequently in the high mountain lakes of Snowdonia (unheard of a few years ago) where they must be having a huge impact on the population of wild brownies that have enough of a struggle over the long winter months anyway. RSPB advice is to employ scare tactics - what a joke !
 

Mrtrout

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A week ago we counted 517 cormorants come in to roost on the lower Clwyd! The mind boggles at the amount of fish that lot would eat, admittedly not solely on that stretch, but they clearly eat somewhere!

Similar problem up here Paul, devastating the rivers, flocks of 100 seen regularly.
We are licensed to cull a few, but it's very limited, I've seen them on the banks a dozen at a time, their bellies so full they can't take off.
They just dive under the water to hide, and as for fish, a 2lb trout or grayling is easily swallowed.
If Gove spent less time worrying about gorillas or whatever and more time on his home patch we might stand a chance.
S.
 

dave b

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The problem with cormorants is that they will often roost on good feeding grounds for the winter. The other problem is that they also feed in packs as already highlighted. Years ago on the Tees at Yarm the vast shoals of dace and roach used to gather on the Alphabet length just above the town bridge and sport for the coarse anglers was prolific however after a few years of cormorant predation the fish moved and the length never recovered.

In coloured water when the river was 4ft up the cormorants hunted in packs, it was unbelievable to watch however they are very effective hunters.

For me if they're in-land they should be shot because it's not only the fish stocks that suffer but also the other birds and wildlife that depend on having a balanced river eco-system.
 

mgj

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Is what they can eat the whole story?

No trout likes shadows over the top of them, and the fact that one has a predator hassling them that is almost/as bad as physical losses.

I would think that a reasonable number of cormorants will tend to keep the fish off the surface, and deeper down amongst the weed.

I have heard of people using lasers to move them on from their roosts - some good effect is claimed, but I have no personal experience. There is a Youtube video showing a big high powered laser to move geese, but these ones are the hand held laser pointer type things - or so I'm told. Unfortunately, because they don't sit on the water, the little electric speed boats which are so good for shifting swans and geese in the close season don't work for cormorants.
 

skyeman1

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West coast of the Highlands has always had more than enough cormorants. Sadly their saltwater food sources have been so depleted by over-fishing that they have to look elsewhere to survive and they are predating rivers and lochs. As always, sticking plasters are advocated without addressing the root cause. A bit like using chemicals to control sea lice on farmed salmon when at the root open sea farming is the problem.
 

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