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23-07-2010, 09:07 AM #1
Salmon: To stock or not to stock that is the question?
To help answer this question and to agree procedures a workshop hosted by ASFB & RAFTS was held on 5 May 2010 at the Birnam Institute, near Dunkeld.
The meeting called: "Workshop on salmon stocking in Scotland – current practice & policy" comprised a number of excellent individual presentations which are available on the ASFB website and are extremely interesting!
The jury is still out whether or not stocking is sensible practice but clearly sensible precautions are in place in Scotland.
One thing is for sure, salmon are extremely good at breeding for themselves given the chance!
ASFB = Association of Salmon Fishery Boards.
RAFTS = Rivers and Fisheries Trusts of Scotland.
24-07-2010, 09:04 AM #2
I recommend this excellent paper on the subject too:
Development of wild Atlantic salmon stocks in the rivers of the northern Baltic Sea in response to management measures
A Romakkaniemia,*, I Peräb, L Karlssonc, E Jutilad, U Carlssone and T Pakarinend.
ICES Journal of Marine Science: Journal du Conseil 2003 60(2):329-342; doi:10.1016/S1054-3139(03)00020-1
© 2003 by ICES/CIEM International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer
27-07-2010, 06:10 AM #3
The links made interesting reading. However with more and more predation, and our fishery managers having their hands tied behind their backs can salmon continue to re-produce to maintain the current level of returning fish.
With our returning fish getting smaller, the average number of eggs each pair will produce may be around 3000. On some rivers the number of fry from these eggs is around 35%, so we now have 1050 fry/parr. Only 8% of these make it as smolts, so the number is now down to 84. If these smolts make it to sea around 3% then return as adult fish, number now 2.5. I know some of our agencies and fishery boards will not agree, but one pair on the redds may produce half a fish more than the returniing pair. Total catch and release, egg boxes, and releasing smolts may be the only way forward.
27-07-2010, 12:05 PM #4
Some good stats and observations here Loomisguide.
Three things are for certain:
1. Dead salmon don't spawn.
2. If salmon dont produce more smolts than themselves then the population declines.
3. Salmon are actually very good at reproducing themselves.
It is man that has tipped the balance of course. We are netting them, poisoning them with pollution, blocking them with dams etc, infecting them with desease and parasites via fish farms, taking their food out of the sea, destroying spawning gravels, and killing them after rod and line capture.
They dont really need us to breed them - they simply need us to stop doing the above!
The biggest single factor in most systems is over-exploitation by nets and rods. These are the biggest threats of all and that's where we should focus.
Hatcheries certainly are great (when used properly) for education, research, genetic safeguards and tourism but not for papering over the cracks. They are no substitute for the real thing.
27-07-2010, 02:28 PM #5
One word stands out for me in your reply, Tourism, i.e. visiting angler's. I am sure that our salmon stocks would be even more less favourable without angling, and those that are employed in the industry to promote and protect it.
The same could be said for game shooting, would we have any grouse left if it was not for shooting sports ?. Although I agree with most of your post I think predation is an area of most concern. It is about time the government and its various agencies look at the facts, do they want the income in millions to the rural economy from angling and game shooting, or would they be happy with the pittance from Fred Smith and his boat showing people around what was once a major salmon river estuary full of seals. Do bird watchers need to see more hand reared and then released birds of pray and even more fish eating ducks and cormorants ?. We carried out a study when I was managing a fishery, and 95% of our bird watchers were local and therefore contributed nil to the local economy. We can clean up our act, go total catch and release, clean gravel beds, make more access to spawning areas etc, but the predation of our salmon stocks is now getting out of hand.
27-07-2010, 02:51 PM #6
I am working at home today, looking at the forums and doing some work for our local rivers trust. My visiting anglers are off to Balmoral today, and then a Distillery on Saturday as four blank days are better than six. Will they come back next year ?
27-07-2010, 03:17 PM #7
I agree about predators but I did enjoy watching an Osprey attempt to fish on my pool of the Dee last year.
The thing about natural predators is that they follow a well known cycle. Their numbers increase until the prey population can't support them then they decline and the prey population increases again and the cycle goes on again. Lotka–Volterra equation I think is the mathematics behind this. Nevetheless it hurts when you are at the bottom of the prey population in the cycle but it does not normally go to far. That's where humans come in. Predators that dont rely on the prey (like us) - dont follow this cycle and cause havoc!
27-07-2010, 03:52 PM #8
Sorry that would not be fair on the river or the beat. Just pointing out we have a problem.
28-07-2010, 09:06 AM #9
Ok appreciate that - hopefully they are just running late!
11-08-2010, 06:03 PM #10
Here is an important document on the stocking subject!
Restocking of salmonids--opportunities and limitations
M. W. Aprahamian, K. Martin Smith, P. McGinnity, S. McKelvey, J. Taylor
I actually found a copy on the web here