Salmon Genetics

[salmoseeker]

I wonder if anyone might be able to put me right on something I've often wondered about.

I think I know that springers run early, spawn and their progeny also become springers.

Similarly back end fish breed and produce offspring which also run the river late.

What I don't understand is how clear cut is this; ie do fish that run the river in November never spawn with springers? They must do and if so what do the resulting fish become? Springers or autumn runners?

I'm not going to even mention grilse.

Would appreciate any comments. Thanks

[betanut]

In general, the springers spawn at the same time as fish that run at the back end and equally any grilse/summer fish that have run a river - although often fish from the same or similar run will "pair up" to spawn this by no means assures the subsequent offspring will be springers etc etc.
In other words, 2 springers may spawn together and (in theory at least) their progeny could return as a grilse - remember that a grilse is a single sea winter fish and whilst common perception is that these fish are smaller this is not always the case.
A hen spring fish may spawn with back end run cock - there's little evidence to suggest which way their progeny will go. They could equally return as multi sea winter fish, as a grilse, in the spring or in the autumn.
It's not an exact science but where salmon farming has proved useful is defining strains of fish - showing a genetic trait or disposition towards grilsing for example.
So artificially it's very possible to create a fish from selective breeding that you know is likely to do x and not y. In the wild however, nothing is certain so I'd be inclined to suggest that it's plausible to suggest that progeny from a springer are likely to return as springers because of a genetic disposition or because of where they were 'bred'. Certain tributaries on rivers have been shown to have larger numbers of spring fish than autumn for example.
I hope that answers the question.....

[tynespeycaster]

Willie Gunn has some excellent info on genetics,springers etc from the Spey Board research guys. I think they are convinced springers breed springers and where they spawn is important also, I think.

W.G. is your man!

[charlieh]

On the whole, the early running fish tend to run furthest. So springers will spawn in the highest tributaries, whereas the later running fish tend to spawn further down the river. On the Spey, for example, the lower beats will still catch fresh fish at the end of the season, but these fish don't go all that far upstream.

There are also instances where a class of fish will tend to favour a particular tributary - on the Tweed, the large majority of the spring fish spawn in the Ettrick, and the main river beats above the junction tend not to catch many fish until the autumn run arrives. Of course it's not an absolute science, and obviously there will be interbreeding, but it seems to me that, just as neighbouring rivers have different strains of fish with different run patterns, so there's no reason why there shouldn't be different strains of fish in different areas of a single large river system.

Also, the length of time from spawning to hatching is to some extent regulated by temperature, and I think there is research that indicates that the longer it takes for an egg to hatch, the longer it will take a fish to mature. Thus, spring fish will tend to spawn in the highest tributaries and burns, which will usually have colder water. The offspring will therefore tend to be MSW fish rather than grilse.

[williegunn]

Nurture or nature?
Some highland rivers which were spoilt by building Hydro dams used to have prolific spring runs, Shin Beauly Conon, now these rivers are predominantly grilse rivers. I'm sure the genetics remain the same.

[salmoseeker]

Thanks for your replies boys, I'm a wee bit wiser for them.

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