Signal Crayfish Extermination?

[Liamsm]

Hi Lee,

I doubt if there are any white claws left on the Kennet now mate and I think that I would go along with Newt on the fact that they probably don’t have a great deal of chance anywhere else either, unless something drastic is done on the Southern waters where they have already taken over the natural eco system of the rivers.

I honestly don't think that anyone that can be bothered enough to want to make a difference, would not know the difference between the white claw and the signals anyway.

I have a lot more faith in anglers as a whole, than to think that most of them are not capable of doing ‘their bit’ without a problem.

OK! these kind of laws are made for the few numpties that are about, but I still think that it is at the determent of using the many more caring and capable anglers out there, that just might make enough of a difference.

The ones that would not bother and are probably the same ones that leave their litter on the bank, would not be part of the equation anyway.

Most of the projections of the full effect that the signals are having on our eco system, are coming from past experience of them in a totally different one. I think that in this there are mistakes being made and things being taken for granted that may not apply the same.

It is not just a case that these things are having an effect on the native crayfish. They are changing the whole balance of the systems that they taking over.

Half of what they are effecting is not even known yet, because of the false premise that they effect each environment in the same way.

There are too many people arguing about what should be done, while in the meantime doing nothing.

Even a brief halt in their progress may give enough time for those that need to, to see the full picture.

It’s a bit like religion!. There is a finger pointing the way to heaven, but everyone is so busy arguing about whose finger it is, that they never get there.

It is not hard to see that the laws in effect at the moment are very contradictory and need changing quickly.

As it is at the moment, any angler having contact with them is breaking the law no matter what they do with it. Do we go with the law, or use common sense?.

 

……………Liam

 

P.S. 'Save up for a rainy day' Lee!.

On this one mate it has been pouring it down for a long time!.

 

[ 14. May 2005, 11:53 PM: Message edited by: Liamsm ]

[ayjay]

Liamsm:

unless something drastic is done on the Southern waters where they have already taken over the natural eco system of the rivers.

I've never seen one on the H.Avon or D.Stour.

 

Certainly heard about them from time to time but never come across anyone who's had a problem with them whilst fishing.

[Liamsm]

Hi John,

Thank you!.I think that you have helped to make my point very well.

The kennet is infested with them and the true effects of such an infestation are only just being realised on there. Some longer term effects have probably not even shown up yet.

When you do know of a problem on your water it will probably be too late.

There is no doubt that they will spread quite easily throughout the south to the same proportion that they have infested the kennet with.

The trick is to see the bus coming before it hits you.

 

...........Liam.

 

P.S. Your quote would have read as it was writen if it had been in full and not half of a sentence of what was said.

 

[ 15. May 2005, 06:24 PM: Message edited by: Liamsm ]

[Cyranne 12]

If I may add two bits more ---- the Basingstoke Canal is crawling with the things ---- and they all wave bright red claws at your disgorger

[Will Wilkinson]

We have loads of them round Milton Keynes. The Ouse is full of them, can be a major bother on some stretches but the chub, barbel and perch have been gorging themselves on them for a few years now and are getting rather large

 

They're in the majority of the stillwaters and are now beginning to be found in the canal (grand union) as well.

 

Will

 

[ 15. May 2005, 08:34 PM: Message edited by: Will Wilkinson ]

[Leon Roskilly]

Discussed at today's SAA Meeting.

 

Apparently, when signals first colonise a water, there is plenty of food and there are literally thousands of the buggers in front of you, a few anglers taking a few crays for the pot are not going to make a dent in their numbers.

 

Then the population falls off as it matures, and many of the remaining signals become bigger.

 

If you now remove a number of the big crays, you get a mini-exlosion of new small crays, so a mature population is best not interfered with.

(A bit like removing large pike only causes an explosion of ravenous jacks)

 

 

If anglers were allowed to take them, there is a fear that when they are transported alive, escapees (there will always be escapees) will colonise new waters in other areas not yet affected.

 

(Surprisingly, so long as it is damp, signals will live three months out of water!)

 

Then there is the problem of some anglers not knowing the difference between signals and native crays, and there will always be the risk that some people will be tempted to spread crays from waters that they visit, back to their home waters, because they like to take a few home with them to eat. (The same people who leave litter, and line etc!).

 

It was felt that given all of these circumstances, the EA would not give consideration to allowing all rod licence holders to remove crays.

 

Oh! and where crays are taken from polluted water, downstream of sewage discharges etc, they can be contaminated with bacteria and heavy metals and not at all healthy to eat!

 

So be careful!

 

Tight Lines - leon

 

[ 15. May 2005, 08:58 PM: Message edited by: Leon Roskilly ]

[Liamsm]

Hi Leon,

Much as expected from a limited viewpoint and understanding.

The point of a population explosion due to removing the lager crays may sound like a sound argument from past experience and mistakes made with pike, but the considerations are not the same.

Such comparisons only result in more false premises, drawn from not considering other factors that may be in play also.

Small pike are largely prayed on by bigger pike and not much else.

Although large crays feed on the smaller ones, so does every other fish in the river. Size consumed dependant only on size of fish. Not just predator fish either. (small crays are very much like fresh water shrimp etc.)

The ones that the fish do not feed on predominantly, are the larger ones. The ones that we all see and catch on our lines and to a large extent in traps.

If any trapping is to be done at all, a new design in traps is called for, to get more of the intermediate sized ones also. (Those not fit for eating) A large portion of what is left will fall pray to the fish population anyway.

That is as long as there is an up and coming fish population after the crays have gorged themselves on the spawn. ( OK! a little sarcasm, but not that far out )

It is nice that the larger fish are getting bigger for us to catch on them, but what happens to the natural balance of new stock coming through?.

I think that it has gone beyond catching them to eat. We should be catching them in large numbers and destroying them on the banks that they are caught on.

As the law is at the moment this opportunity is not there, but the other concerns that you have mentioned that may cause a spread of them still is.

The law takes away the power for the concerned angler to do anything , but the other concerns that you have expressed will be infringed by those less concerned, that will carry on regardless anyway.

We all know that eco systems depend on balance, as is the case with the pike that belong to and are a natural part of our own eco system, but the Signal Cray is not a natural part of our eco system.

It was introduced here as a mistake by man and remains a mistake to be put right by man.

Natural balance with the crays firmly embedded in it, may well be a different eco system that we now know.

I am not convinced that anyone knows for sure what that future naturally balanced eco system will be like either, as comparisons to other systems in the world are not the same.

Too many things are being taken for granted with this problem that evolve around what we know.

There is not enough consideration being made for what we don’t know and can’t know.

When this is done we will stop making comparisons with the behaviour of crays within a totally different environment, or other spices that belong here and start concentrating on the unique effects of the signal crays on our own environment.

 

……………Liam.

 

[ 15. May 2005, 11:40 PM: Message edited by: Liamsm ]

[Will Wilkinson]

I'm still catching plenty of smaller fish in the ouse, certainly doesn't look like the large crayfish population is adversely affecting spawning success here. Even seeing a welcome appearance of Barbel in the 1-2lb bracket in areas that rarey produced fish under 5lb a couple of years ago.

 

I'd still love to see the signal crays exterminated and naitve white claws replace them. Unfortunately this is probably just a pipe dream now they're established.

 

Will

[Leon Roskilly]

Liam, my understanding was that the scenarios discussed were the result of research rather than supposition.

 

It's true that no one has an idea with what to do about a population that has been established other than leave it alone, as messing with it only worsens the situation.

 

The article posted that kicked off this thread is an attempt to see if they can be eradicated from a water with a determined effort.

 

See also society.guardian.co.uk/societyguard...,769967,00.html

 

note: "They have caught 3,091 signals in a 250-metre long stretch of the Stour, and as netting accounts for only a third or less of the total, they have been tackling a total signal population of perhaps 10,000 crayfish in 250 metres of narrow river."

 

With mind-boggling densities like that, anglers removing a few fish are hardly going to scratch the surface of the problem, let alone fish eating the smaller crays.

 

Tight Lines - leon

[Leon Roskilly]

[ 16. May 2005, 08:15 AM: Message edited by: Leon Roskilly ]