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JKissane
Starting Member
22 Posts |
 Posted - 07/10/2009 : 13:05:09
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Much has been written on the perils of non-native strains or even species of salmon and trout excaping from fish farms and further adding to the threats on native salmon and sea trout stocks. Bruce Sandison had a brief note in the September FF&FT issue on the invasion of waters by the American crayfish. How it got over there, I don't know, but his solution was far different than what I'd propose. Lobster stocks have declined in recent years, probably due to overfishing, decline in their food supply and habitat degradation. The freshwater crayfish is a delightful substitute, cooked in a sauce of butter and bourbon, and served with a shot of tobasco, there are few things tastier. They also are responsible for the size of the enormous brown trout caught in Missouri and Arkansas.
But invasion of non-native species is a dangerous thing to the overall ecology, and is costly. The relase from the 1993 Flood on the Mississippi River - a fish farm on the floodplain was inundated, and its stock dispersed, has caused havock with Asian jumping crarp (Google it and watch the film clips in amazement). They have migrated upstream into the Illinois River, and are threatening to invade the Great Lakes. The consequences would be disasterous to the salmon and lake trout populations - but neither of them are native, either. Lake Trout and salmon were introduced to control the alewives in the 1950s and 60s - another non native intruder, whose origins appear to be the shipping industry. At least the lake trout and salmon that were introduced were North American natives, but they've also introduced German and Scottish strains of brown trout (ecent world record 41 lb 2 oz. brown trout taken in Manistee River, Michigan was likely a lake-run.)
So we're all mixed up in the non-native fish wars. Maybe we need an aquatic United Nations - or at least NATO to figure things out, eh?
Although prequalified by virtue of their brain size, trout have no politics.
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Bob Morgan
New Member
43 Posts |
Posted - 17/10/2009 : 19:08:43
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Hi Joe,
Interesting topic you've started here.Isn't there an electronic deterent being built on that river to stop migration into the Great Lakes? Some kind of fish zapper or something  . With regard to non native species, I think the spread or introduction of species is a problem.What I dont have a problem with is interbreeding within the various genus,something that causes a lot of arguements here in Ireland, arguements which in my opinion are pointless.On the rivers controlled by The Shannon Region Fisheries Board for example, stocking is close to impossible as those in "the know" do not want to alter the genetic composition of the native trout.There is even a great deal of money being spent on taxonomic research of the native trout along the Shannon/Erne waterway.As I see it, trout will evolve and adapt,they seem to be good at it! This evolution will involve interbreeding,so why should we stand in the way.At the end of the day,trout are trout.They came from the same place and adapted to they're environment.I read recently that trout in New Zealand were traceable back to Loch Leven through genetics.Would these trout be classed as non native if re-introduced back into Scotland?
And the can of worms is opened 
All the best,
Bob |
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JKissane
Starting Member
22 Posts |
Posted - 19/10/2009 : 09:25:24
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There is, indeed a great deal of money and effort being applied to an electro-shock fish barrier to try to prevent the Asian Carp from making it into the Great Lakes. Whether or not it succeeds is another story. It just goes to show how a specied that is relative check in one place and become a rampant invader in another, absent the factors (predation, disease, seasonal water level changes) that might lead to its containment. Much like invasive plants that take over, or land mammals in places like New Zealand, the Asian Carp seems determined to stay here, and the country is so vast and teh rivers so long it is difficult, if not impossible to plug all the leaks.
The trout interbreeding issues seem more of a hot topic in the UK and Ireland than here in the States. Fly fishermen are a minority here - and most American fishermen fish with bait, and fish to fill their freezers with their catch. I'm afraid the American "must have it, and must have lots of it - and NOW!" attitude has in part led to breeding the fast-growing triploid rainbows that cannot reproduce, but go through the motions at the expense of fish that can reproduce, so there's a bit of a problem there. There are also deliberate hybrids - "cutbows" and so-called "tiger trout" that are crosses that are usually sterile, stocked in waters where they can't migrate much of anywhere and are a novelty.
The stocking of one species to fill a gap left by the near-extinction of another is also part of the problem. In the 1800s, the brook trout were fished out of most Great Lakes tributaries and that void has been laregely filled by brown trout, steelhead (migratory rainbow trout) and smallmouth bass (which are quite a sporting fish on a flyrod).
The waters of the U.S. are so varied, and the original drainages where various species were native are no longer the exclusive domains of single species, let alone strains of trout.
The Rainbow trout here were originally native to Pacific drainages, and they have been introduced all over (even Hawaii) at various times. The brook trout (actually a char) was originally native to the Atlantic drainages, but was nearly fished to extinction in the U.S., and you have to go to eastern Canada or Patagonia to find large ones anymore. The cutthroat are the only American trout that inhabitted both Atlantic and Pacific drainages originally, but was only native to western waters. There are strains identified in the species of American trout, just as there are in the European brown and sea trout. And there are introduced brown trout here that have established reporducing populations, as well - although probably mixtures of Lock Levin and German seeforellen. This summer a man in Michgan caught a 41+ pound brown trout that was probably a seeforellen strain or some monstrous variation thereof - on a spoon/lure.
Although prequalified by virtue of their brain size, trout have no politics. |
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Bob Morgan
New Member
43 Posts |
Posted - 20/10/2009 : 13:47:24
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41 pounds of angry trout!!! Man I'd be running in the opposite direction! Theres a lot of effort being put into establishing accurate Pollan numbers on Lough Derg at the moment.I cant remember the last time I saw one.They are breed in the North for the commercial use.Arctic Charr have all but disappeared also. While fishing for salmon 2 years ago I caught what I belive to be a charr but light levels were very low.(Great banter in the pub afterwards though!)It could have been a cock trout in full spawning colours but it was very charr like.The spread of carp is becoming an issue here too.Escape from stocked waters is not the problem, rather people releasing them and trying to establish breeding populations.The most recent case was of two Dutch men who wanted to introduce them as an alternative for Pike. As if the population of Rudd, Roach and Bream was not healthy?? Something similar happened a few years back with barbel on a system in Co.Galway.The law is pretty lax over here so the most of us feel that a major invasion is on the cards sooner rather than later.As well as the obvious threat, there is also the risk of alien parasites infesting waterways. |
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JKissane
Starting Member
22 Posts |
Posted - 21/10/2009 : 08:30:40
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The guy that caught the 41 pound trout said he thought he had a salmon on at first, but it really doesn't matter after 20-minutes of wrestling with a beast like that. I know he was using spinning tackle, but don't know what the line strength was, and from the article I read, he was a long-time fisherman in the area - people seemed to think he really deserved this one.
My brother in Iceland fishes for charr probably more than "trout" per se - their population seems healthy enough, but I don't know if they're transplantable or if that would cause more problems (probably would). Char are present in waters that a working man can afford to fish - from what I've heard, Icelandic salmon fishing is a bit pricey for most commoners.
Among the remarkable things with these "jumping" Asian carp (Google it and watch the videos, they are astounding), is their migration. I've been told they are not particularly migratory in Asia, but the population here escaped from ponds that were flooded during the '93 Mississippi River floods - and came upstream about 500 river miles toward the canal connection into Lake Michigan, through at least 4 navigation locks and dams. So on the west coast of the U.S. we are faced with locks and dams on the Columbia River contributing to the extinction of native salmon strains, in spite of fish ladders and efforts to assist their migration, but in the Midwest, we have an invading species that overcomes all obstacles to threaten the ecosystem of the Great Lakes, navigating through the locks and dams. I guess the Asian carp are better at river navigation than salmon - or maybe they've got a little more Ghengis Khan DNA than our salmon.
Although prequalified by virtue of their brain size, trout have no politics. |
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Non-native species invasions
