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Post by beachball on Feb 6, 2012 12:23:19 GMT
OK here is one to kick us off. I do believe that the E.A are doing great work conservation wise for our rivers with improving the bio diversity of the said environments, encouraging the invertebrates etc etc, and they do great work with the re-stocking of rivers with all the species of fish that we as Anglers love to fish for, and i understand they have to have large fish farms to do this, but my question is why when they have these resources do they not use them to also breed on the small fish that make up the micro ecology of a river like stone loach and millers thumbs, perhaps some of these small, some would say insignificant fish might help with the foreign invaders such as those killer shrimp things and the eggs of the American crayfish. surely the best way to improve an eco system is to start at the bottom of the food chain and work up, best regards Malc
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Post by envagencyyorkshire on Mar 7, 2012 13:01:37 GMT
Hi Malc.
I agree that the so-called "micro species" such as minnows, millers thumb, stone loach etc all play an extremely important role in the general ecosystem. However, they are very difficult to produce in any meaningful numbers due to their small size, limited fecundity (egg production), short life-span and their delicate nature. Any stocking scheme would have to use larvae or advanced fry which have a very low survival rate when stocked into the wild. To produce the numbers needed we would also have to use high numbers of adults. As an example, a female Millers Thumb will produce approx 300 eggs whereas a 20cm female Dace will give between 8,000 and 12,000 eggs. Numbers of adults needed to produce significant amount of stocking material would be in the hundreds. These micro-species also tend to re-populate a stretch of water fairly quickly after an adverse event so allowing them to re-colonise naturally is probably the best strategy. With regard to Crayfish eggs, some of those watercourses that suffer from the alien invasion also have good numbers of micro-species present. If loach, minnows etc were an effective way of controlling their spread we would see this in population densities. There is no evidence to support this.
Alan Henshaw Calverton Fish Farm
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