Peter Lapsley, a well-respected fly fisherman and conservationist in the UK, writes in the January edition of "Flyfishing and FlyTying" that the Environmental Agency should allow the continued stocking of both diploid and triploid trout into our rivers. He ends.."we should insist on change only if and when there is real evidence of harm, actual or impending".

 This view is dangerous and irresponsible. In an article (see here), I argue that:

• The EA should provide greater incentives and money to habitat improvements to clubs in the form of grants with a responsibility for each wild habitat angling club to demonstrate what work it is doing to improve and preserve the habitat.
  
• Supplemental stocking should only be with broodstock grown each year from the wild trout population.
• More research to be done on the effects of  triploid trout on wild trout success rates before a decision is made over triploids.

The problem with Lapsley's article is that it ignores a lot of research from the US, it oversimplifies and incorrectly extrapolates from research in Europe and the UK and it takes the defeatist view - "why bother?" if the damage has already been done i.e. wild populations have already been contaminated by less fit trout.

 Interestingly, the damage has probably not been done. Although there seems to be an ever-increasing level of hybridisation across the world's Salmonids,  there are several studies that show local resilience. The Apache and Gila trout of lower Colorado are still distinct despite heavy stocking with Rainbows and Cutthroat Trout, as shown by mitochondrial DNA analysis. There appears to have been a recovery of Greenback Cutthroat Trout in Colorado. Westslopes seem to be holding out against Rainbows and Yellowstone Cutthroats across NW USA. Local cutthroat populations (there are over 16 distinct sub-species) seem to have been remarkably resilient given the 818 million yellowstone cutts eggs that were re-stocked from Yellowstone Lake between 1899 and 1957. That is not to say that genetic introgression is not a major issue; It is. But we should not give up without a fight.

 Trout are very difficult to study. They live in water (!); they have a huge taxonomic diversity; there is a huge variation in phenotype; there are very poorly understood relationships between genotype and phenotypic and behavioural diversity; they are very susceptible to metabolic and environmental changes; they have diverse reproductive systems. Any research that is quoted has to be put into the context that we actually know very little.

It must therefore be right to take a precautionary approach to policy.  We should preserve our wild trout populations by ensuring that stocking is only through the culture of one generation removed wild trout. We should not stock with triploids.

Here is a beautiful Westslope Cutthroat trout that I was privileged to catch and release In BC, Canada: