How many lbs of fish do Cormorants need to eat per day to survive?

[Steve Spiller]

The Somerset levels.

A typical roosting pylon on the levels.

How much do they eat per day?
How fast do they breed?
How many are allowed to be culled per year? Two per licence?

This is just one pylon of hundreds!

---------- Post added at 00:15 ---------- Previous post was Yesterday at 23:55 ----------

The light was fading and I couldn't get any more pics, but the cormorants kept coming!

How much do they take?

365 days a year! 25 cormorants in the pic, 2lb each per day? 4lb each per day? I've seen one cormorant take a 5lb chub!

Work it out and work out why our rivers, lakes, ponds, canals are in decline! 365*25*2lb=18250lbs per year!

And that's just one pylon on the Somerset Levels.

R.I.P. Coarse angling!

 

[geoffmaynard]

Clipped from an article dated 2002:

"Maths: On average, a cormorant eats a pound of fish each day of it's life - that's about 10,000lbs of fish eaten over it's 25 year life-span, not including the fish it damages but doesn't eat, though those damaged fish may die later.

Two cormorants however do not destroy 20,000lbs of fish. Oh no, that's just the tip of the iceberg. A breeding pair lays a hell of a lot of eggs in 25 years. Each successful hatchling will soon consume it's own daily pound of fish and begin to lay it's own eggs. The damage is compounded with every egg that hatches. Over the span of a cormorant's lifetime, given perfect conditions and assuming that just two birds will successfully hatch each year, shooting a pair of cormorants today will save approx 21,870,302.1818 tons of fish. No, the decimal point is not in the wrong place. Even allowing for a huge degree of leeway, this amount of fish damage is from a starting point of just TWO birds! "

 

[cg74]

Come on Geoff, get a grip.... While I am in total agreement that control measures need implementing the crux of it is few people actually bother to pursue this avenue.
How many licences were actually applied for last year or the years before hand because Cormorants are now officially classified as conservation status least concern and as such do not get the full protection of the law that say otters enjoy.


Just think, if every feral cat bred to its maximum potential, they'd produce 150 kittens per year and if their progeny was to be as equally successful at reproducing, bearing in mind that reach sexual maturity at 3-6 months of age. All can live for upto 10 years; well I'll leave you to do the maths....
Then if you were to compound this with the rabbit, mink, rat and otter populations and they all had maximum breeding success....

Needn't worry about coarse fishing, cos this island will be under the sea. Sunk by the sheer weight of all the verminous predators, eh there's a thought.



:j :j

 

[Steve Spiller]

Yeah get a grip Geoff......one pound of fish per day is ridiculous, a very conservative estimate if you ask me.

But as cg74 says, it's not a problem so we don't need to worry about it.....do we.

 

[Day Breamer]

What about if it was 2lbs of fish per day and each of those fish were all Roach?

 

[geoffmaynard]

Then nothing. But if they were salmon...

---------- Post added at 12:50 ---------- Previous post was at 12:41 ----------

How many licences were actually applied for last year or the years before hand because Cormorants are now officially classified as conservation status least concern and as such do not get the full protection of the law that say otters enjoy.

Well I don't know anything other than what people tell me. But what they tell me is, there are a lot of paperwork hoops one has to jump through to gain permission to shoot these predators. It takes a lot of time and aggro and after ages and ages a permit finally comes through - to shoot 5 of them in an entire year!
I don't know for certain of course but... this red-tape is most easily dealt with in the time-honoured fashion; so fishery keepers who should have gone to specsavers end up aiming at pigeons and miss. It's a lot easier than applying for pieces of paper. Just a theory of course.

 

[cg74]

Yeah get a grip Geoff......one pound of fish per day is ridiculous, a very conservative estimate if you ask me.

But as cg74 says, it's not a problem so we don't need to worry about it.....do we.

Steve if you care to read what my post actually says, rather than your own interpretation of what I wrote. You'll clearly see that I am in fact agreeing with the need for control of Cormorant numbers.
Though the cynicism I display is purely as a result of to many moaners and to few doers.
Within current legislation Cormorants are controllable and do not have conservation status as otters.

Sorry Steve you need to take your concerns up with the controlling body and land owner of the affected water and they then need to go to DEFRA and the EA, simple really, I'd say....

I should go on to point out that for high levels of breeding success it is essential for any/all species to have optimal conditions, to their criteria, do you think our inland waters offer such conditions?
(plus these optimal conditions need to be maintained for the full 25 years of the intial breeding pairs life span, as I said, "get a grip")

 

[geoffmaynard]

You are of course correct cg. But never let a shortage of facts get in the way of a good scare-story is what they teach in reporters-acadamy these days. Or so it seems to me.

I remember once reading that if we didn't have ants we would be knee deep in greenfly!

 

[cg74]

I don't know for certain of course but... this red-tape is most easily dealt with in the time-honoured fashion; so fishery keepers who should have gone to specsavers end up aiming at pigeons and miss. It's a lot easier than applying for pieces of paper. Just a theory of course.

Your therory is in this case a very accurate one, though usually said holder of the gun fires a shot over the head of the Cormorant and sadly he predicts the birds flight path incorrectly and shame on him he hits said bird....

Using a gun shot as a deterrent for Cormorants is of course fully legal and as I stated earlier if shot by innocent mistake no law is broken, because the level of protection afforded to Cormorants is greatly reduced from that of otters.

 

[geoffmaynard]

So why would any fishery keeper apply for these time consuming pieces of paper when they can just reload?

And that's why so few applications are made. You answer your own question!

 

[Dave Burr]

I've seen an autopsy report on a few cormorants (don't ask how ) and they showed that each fish had the remains if between 50 and 70 fish in their guts.

Given that these were probably consumed over a couple of days thats 25 to 35 fish each day with each fish weighing what - average 1 maybe 2 ounces? Do the math, its scary. Even if that was three days worth of food it still works out at about 1.5 to 2 pounds of fish per day.



So my choice of caption for the photograph is as follows.
"PULL!"

 

[the indifferent crucian]

I've seen an autopsy report on a few cormorants (don't ask how ) and they showed that each fish had the remains if between 50 and 70 fish in their guts.

Given that these were probably consumed over a couple of days thats 25 to 35 fish each day with each fish weighing what - average 1 maybe 2 ounces? Do the math, its scary. Even if that was three days worth of food it still works out at about 1.5 to 2 pounds of fish per day.



So my choice of caption for the photograph is as follows.
"PULL!"

By co-incidence I have been watching the repeat run of Nick Fisher's Screaming Reels TV programmes on Discovery ( Sky+ is SO useful!) and I watched an episode yesterday which spoke of them taking 2lb. of fish per day, per head, as food.


Now seeing the odd one or two is bad enough, .... whilst no one was watching they manged to empty one of the lakes by club owns.

The sight of so many in Somerset is positively chilling.

 

[geoffmaynard]

I live near Penton Hook on the Thames where, on the island, there was an EA fish breeding environment constructed, at huge cost to us the license buyers, some ten or fifteen years ago. Just a couple of hundred yards away on the lake is now a massive colony of cormorants.

I haven't noticed any increase in small fish in the area in the past decade.

 

[Tee-Cee]

...so where do I stand with the bl**dy grey squirrels eating the peanuts in my garden feeders....do I,(a)buy a gun(b)stop feeding the birds(c)learn to love them...?

I fancy a gun but I'm not a very good shot and the neighbours would probably report me .......

No,its not Cormarants or Otters but still a major problem-ask anyone who tries growing veg!!

 

[cg74]

...so where do I stand with the bl**dy grey squirrels eating the peanuts in my garden feeders....do I,(a)buy a gun(b)stop feeding the birds(c)learn to love them...?

I fancy a gun but I'm not a very good shot and the neighbours would probably report me .......

No,its not Cormarants or Otters but still a major problem-ask anyone who tries growing veg!!

Assuming your neighbours are in close proximity to yourself, it might not be a good idea going down the gun route.
For good advice on laws governing guns, best speak to your local police firearms officer.

Other possibilities include trapping and baiting, or consult your local council pest control officer (grey squirrels are vermin, no debate, love em hate em, whatever, they're a invasive alien species).

 

[geoffmaynard]

At what point do we stop calling these species 'alien' and 'invasive'? Most people in this country have never seen a red squirrel and probably never will - so the greys are here to stay.
Why are catfish still considered alien after the many decades they have been here? Why are carp accepted and catfish not - how many decades does it take before these species are considered 'native'?

And still on the 'alien' bit. I was flipping channels on the TV earlier and there was an old episode of the Saint showing with Roger Moore. His co-actors included a heavily made-up (white English) Jeremy Wassisname who was playing the part of Mr Gupta, a Pakistani. So just 50 years ago they couldn't find an Asian actor to play a Pakistani! Then an hour later, Michael Portillo was doing a documentary on Birmingham "a city where there are now as many Asians as (white English)"

(This is just an observation on how the times have changed - it's not an invitation for racist comments.)

 

[Steve Spiller]

cg74 please accept my apology, I obviously misread your post.

I don't know how many peolple know the levels, but the collony of cormorants have a free run to eat as much as they can. I think Dave B knows the levels. It really is chilling IC to see such a collony of fish killing machines roosting up for the night and as I said, there are hundreds more pylons which attract the black death at night.

I think the AT ran a piece a few years ago about how much they eat per day and it was measured in kilos....2.5kg if I remember correctly?

I know of two other roosts on the Bristol Avon which hold the same amount of birds

 

[S-Kippy]

But if they are eating so much and have been for so long then what are they going to eat when the fish run out ? I'm not being obtuse but there are a lot round my way and they've largely cleaned the rivers,canals and lakes out of silvers...so what are they eating and what will they do when there is no food left ? Eventually they must surely become a victim of their own efficiency ?

Or is that too simplistic ? Personally I'd shoot the lot of them and the hell with a licence.They do look a lot like crows to me .

 

[Steve Spiller]

I think they'll just move on when it's empty Skippy?

Didn't Sywell get devastated by the black death? The roach are no more!

I watched two cormorants recently 'working' a small lake, the estimate of 1lb of fish per day is ridiculous. They were diving and coming up with roach and skimmers all day long, at one point one of them came up with a skimmer that must have been a pound and a half. It couldn't get it down it's neck and slung it away!

The bailiff was made aware of it, he thought they were crows too......

 

[Tee-Cee]

I didn't know crows could swim........

cg74....I thought at one time it would be easy to trap the grey squirrels,pop them in the car and take them to a wood for release.Not so,as moving them around is not allowed by law(apparently).....and whats more they never stop coming back-I could move six in a week and within ten days a new mob had arrived!

Gave it up as a bad job in the end.....I just get the wife to rush into the garden now making scary noises....its very funny to see and sort of effective!!

...its staggering how many peanuts they can consume in an hour if left alone and this is the same problem with cormorants-left alone and they will systematically strip a lake......Canada geese;on my local stretch of river we have dozens of them and increasing every year and no natural predator......fifteen chicks a year minimum...how many can a river support?

How much fish does an otter need per day to survive (roughly)??(Just out of interest as we have lots now!)