Discussion in 'Conservation, Fishery Politics and Management.' started by Derby, Feb 7, 2018.
It wasn't clear to me just exactly what technique(s) they used for supplementation during the period of research.
Anyone know if it was similar to what was called the "Living Gene Bank" technique tried here?
This caught my interest from one of the referenced papers: . Supplementation alone is not a panacea because it does not correct limiting factors, which must be addressed to achieve population levels capable of sustaining ecological function...
Gets back to poor habitat = poor runs. Simplistic.. but noteworthy.
This is a pretty labour intensive way to supplement the runs. They did "Hydraulic embryo collections" in the Hamma Hamma, meaning they surveyed reds and extracted some of the eggs from the redds after they had been deposited. The embryos were selected after natural and sexual selection had occurred in the natural environment, and small portions of a larger number of families were brought into captivity than would have been possible by collecting and spawning adults in a regular hatchery operation. Fish were reared at low densities, on a restricted ration, and were released at a natural smolt age (age-2). This doesn't seem very practical for most hatchery operations, which operate on an industrial scale, but perhaps its a technique that could be used for some of the most severely endangered runs, particularly of steelhead. The result showing the increase in returning spawners ( 10 vs 26 redds) after the program was terminated is encouraging however.
Its a little different than the living gene bank, but trying to do something similar in that the LGB captured outgoing steelhead smolts in the Quinsam, Little Q and Keogh Rivers, raised them to maturity, then spawned them in the hatchery, and released the resulting smolts into the river after hatching. It didn't seem to have much effect however.
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