Genetic integrity

A few of you will know I recently moved to Hay on the Welsh border, and the river Wye. The salmon didn't take long to get my attention and I managed three last season, two of them on the fly whilst spey casting; best one was just over 12lb. I recommend it to you all!
Naturally I dipped a toe into the online salmon forums and entered as a rank beginner, picking up all kinds of information and finding myself in the middle of a heated 'debate' (these guys are close to killing each other sometimes ) about the 'potential' damage which can be done to the genetic integrity (I kid you not) re if any offspring of returning hatchery fish mated with wild fish.
There are two main camps: pro hatchery and anti-hatchery, with some fishery scientists in each corner. The latter camp want to shut down hatcheries and these are currently the blokes in power promoting what I see as a fashionable and money-saving view. This viewpoint is being held as the prime reason to shut down any stocking and even close hatcheries, even though the river is still on its knees decades after the last salmon crash.

The bit I don't get is how this Genetic Integrity idea is so firmly entrenched in the game-fish world but seems not to matter a button in the coarse fish world, where the EA regularly stock, from the only (?) fish farm we have at Calverton, (e.g.) Trent barbel into the Thames, Ouse, Kennet etc. Diversity used to be considered good, now its all mixed up

Perhaps TBO Phil or someone else who is qualified can comment on this - or explain the apparent dichotomy? (If thats the right word)

Do fish need to breed with fish outside their group to maintain the gene pool as in mammals? how do they know that the none stocked fish are pure? I ask because I haven't a clue.

What happens if the stockings stop and there are even less salmon in the river, seems to me that if the stockings finish it will be harder to sell salmon rods on the river.

Er...I might be being incredibly dim but where do the hatchery brood stock come from in the first place ?

S-Kippy said:

Er...I might be being incredibly dim but where do the hatchery brood stock come from in the first place ?

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Certainly from the Thames system in the 50s and the Rhine originally when the eastern flowing rivers including the Trent were tributaries of the Rhine. According to Freshwater Fish of The British Isles By Nick Giles.

But in the case of salmon at least (there's too little research on coarse fish to be sure) each river has its own genetic strain of fish - so fish swimming into the Severn estuary can be (via DNA) determined to be Wye, Usk or Severn fish, and probably can even work out which tributary of those rivers they spawned in. Clever innit?

geoffmaynard said:

But in the case of salmon at least (there's too little research on coarse fish to be sure) each river has its own genetic strain of fish - so fish swimming into the Severn estuary can be (via DNA) determined to be Wye, Usk or Severn fish, and probably can even work out which tributary of those rivers they spawned in. Clever innit?

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Nature is very clever why do you think nature has evolved in this way any ideas must be a reason there always is with nature.

the blanker said:

Do fish need to breed with fish outside their group to maintain the gene pool as in mammals? how do they know that the none stocked fish are pure? I ask because I haven't a clue.

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The current viewpoint is that wild fish are pure and breeding with hatchery fish weakens the gene pool or something. Straying visitor fish from other rivers are okay becasue they were not 'domesticated' in a hatchery.

the blanker said:

What happens if the stockings stop and there are even less salmon in the river, seems to me that if the stockings finish it will be harder to sell salmon rods on the river.

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That last bit is true but it's not about selling tickets. The anti-hatch view is that wild fish breeding with hatchery progeny produced weaker strains which depresses the run. Yes, that hatchery introduced fish produces less and weaker fish in the long-term.

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tiinker said:

Nature is very clever why do you think nature has evolved in this way any ideas must be a reason there always is with nature.

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Dont know. But personally I think there's a lot of spun-science in the rational.

Is there any scientific proof that hatchery fish being introduced produces less and weaker fish? or is it just a case of fish snobbery.

the blanker said:

Is there any scientific proof that hatchery fish being introduced produces less and weaker fish? or is it just a case of fish snobbery.

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The most successful, improved and prolific salmon fishery in the country is the Tyne. This is a "hatchery" river primarily.

Getting involved in that argument on a salmon forum is comparable to posting about Dragon Carp gear or cheap centrepins on here - incendiary stuff. mg:

jacksharp said:

The most successful, improved and prolific salmon fishery in the country is the Tyne. This is a "hatchery" river primarily.

Getting involved in that argument on a salmon forum is comparable to posting about Dragon Carp gear or cheap centrepins on here - incendiary stuff. mg:

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So that would be a good indication that the anti hatchery side are not speaking from a scientific point of view.


I think some dragon gear is ok, but then I don't care what I look like on the bank, its the bit in the water I am interested in.

I use some Dragoncarp gear and it works ok for what I want it for. It may not last as long as some other gear but I haven't paid a lot for it.

With regard to genetic integrity, has it done us any harm? :doh:

the blanker said:

So that would be a good indication that the anti hatchery side are not speaking from a scientific point of view.

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On the contrary, the recent scientific advice is that hatcheries are 'potentially' harmful and that they 'could' be damaging the recovery. Too many ifs and maybes for my liking, hence I think it's 'spun'.

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Using the Tyne as an argument river is a bit controversial. Some say the salmon had completely died out there during the pollution years, so all fish there now are a result of straying fish from other rivers and habitat improvement - and its a hard argument to refute. The words 'maybe' and 'if' and 'potential' seem only to have relevance when uttered by a fishery scientist.

geoffmaynard said:

On the contrary, the recent scientific advice is that hatcheries are 'potentially' harmful and that they 'could' be damaging the recovery. Too many ifs and maybes for my liking, hence I think it's 'spun'.

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Using the Tyne as an argument river is a bit controversial. Some say the salmon had completely died out there during the pollution years, so all fish there now are a result of straying fish from other rivers and habitat improvement - and its a hard argument to refute. The words 'maybe' and 'if' and 'potential' seem only to have relevance when uttered by a fishery scientist.

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Advice only then not scientific proof. I cant see the argument being decided either way unless there is proof and that could take many years, I wonder which side is paying the scientists for their advice or is that just me being cynical.

Without seeing the papers they are using (both sides) to argue their case, it's hard to come to a definitive view and assuming Science could show one. And without boring you lot ridged, that’s a 95% + confidence level.

Now are they, the anti hatchery side, arguing about stocking fish from commercial hatcheries as in the Fish Farming Industry?
Or from the EA hatchery (Calverton)?

Important point this, Industrial hatchery fish could well be hotch potch of fish as brood stock. They are not really interested in where they come from, as long as they grow fast and can be brought to market at the earliest opportunity. They will have selectively selected brood stock years ago for this purpose and continually tweaked them as the years have gone on. Commercial Salmon farming is circa 40 years old.

Those fish (escapees) breeding with wild fish would have an impact on genetic integrity and I know over the last 20 years or so, much concern has been expressed by both the scientists in the field and anglers about it.

As to EA hatchery fish (cocks and hens), they take brood stock I’m lead to believe from the rivers they enter on an annual basis, strip them, return the spent fish to river of origin, rear on to parr in dedicated river tanks, return them to the parents river in the Autumn. So the returned parr are genetic to the river. All that has happened is they were raised for 6 months in captivity in conditions as near to what they would have likely encountered in the wild.
The genetic provenience would still be the same and as if they’d been spawned in the river.

If their argument is that these fish don’t have the fighting fitness of wild river spawned fish, how do they know? Few of the parr are marked or tagged to indicate which they are. The fish go though the normal cycle of life once released, and regain any loss, assuming there was some, of fighting fitness. Loss of fighting fitness is not a genetic integrity argument at all. It’s a fitness argument, which as we all know can be corrected and would be corrected by then living out a normal cycle of life.

That all makes eminent sense to me. I can understand why people would be concerned about "mongrel" hatchery brood stock but if the hatchery fish are taken from the same river [or catchment] then they surely are as genetically pure as a "wild" fish ? I dont understand how "fighting fitness" has got anything to do with genetics.

Many of my relatives live in South Island New Zealand.
One of them worked for many years on the King Salmon hatchery which was used to increase the stocking density their rivers.
This hatchery was closed down because the numbers of returning fish were not what they expected and those that did return were "not the same" as the naturally spawned fish.

In the late 90's I fished the Rakaia river for Kings and saw deformed fish struggling to make it into the river.
These 10-20lb fish had obviously lived at sea for a few years, but they were quite horribly deformed with bent bodies, misshapen fins and tails, and crooked heads, but they had still made it back to the river of their 'birth'....!

If the NZ experience is anything to go by the Wye anglers have a good reason to object although in my experience its not genealogy that is the issue.

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A few points to clarify here.

The 'mongrel' fish from EA Calverton are the coarse fish which are stocked throughout the country with no regard to their genetic origins and nobody seems to care if they breed with the 'wild' stock in the future.

The salmon are as TBO explains; hatchery raised in tanks from native Wye eggs stripped from captured parent fish which are kept in tanks at the hatchery. The resulting baby fish are reintroduced to the native river either as fry or parr.

This hatchery stage of their lives is considered by the 'anti-hatchery' scientists to 'domesticate' them, or otherwise weaken the wild strain resulting in later weakened progeny from crossed wild/hatchery returnees. The word 'weaken' is used in regard to their future breeding abilities, not the angling/fighting qualities of the fish. These are not referred to or considered.

These Anti-hatch guys are big-gun names in the fishery science world and people like the Wye & Usk Foundation, and other river trust organisations hang on to their every word as if it is gospel and will be backing the viewpoint. Below is a recent presentation by the head-honcho - there's plenty of others there too.

But to me it's all far too fluffy. Why is this genetic origin stuff considered so important for one species and totally irrelevant to others?
I suspect political interference - it's far cheaper to close hatcheries than to run them. And the rumours are, that's exactly what is in the pipeline

IBIS AST Nov 2013 Thu 0900 - IBIS-eu dissemination site

Far to much waffle and no proof, use of words like might, could, theory heard far to often and I haven't listened to it all as the guy was doing my head in. the bit about fitness having to do with the size of the egg made me smile.

If everything was ok before hatchery fish were introduced why were the hatchery fish needed? if these hatchery fish are put back where the brood fish were from what's the difference?

the blanker said:

If everything was ok before hatchery fish were introduced why were the hatchery fish needed? if these hatchery fish are put back where the brood fish were from what's the difference?

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There was a massive decline on the Wye but a slow recovery is taking place, very slow I might add. The river needs help as Nature isn't doing too good a job of it. Chinese demand for salmon has increased 1000% and is expected to triple in the next decade so wild fish will be put under a lot more pressure. Hatcheries for salmon have historically never been very good but recent advances in rearing methods make sense and could be the future. Here's one, the SNR project, I'm a volunteer for:
stocking

From reading that it would seem to be the way to go.