Has not been much in the way of dialogue in this area for awhile so I thought 
I would get the ball rolling again by citing an example of the pitfalls when 
man manipulates ecosystems.
 
The following case study focuses on the kokanee fishery in the Okanagan Lake 
in Southern British Columbia. Back in 1966, a fisheries biologist introduced 
a freshwater shrimp known as mysis to the lake. It was known that adult 
kokanee feed on mysis. Further, mysis had been introduced to Kootenay Lake 
and had stimulated the growth of kokanee there. Therefore, it was hoped it 
would have the same desired effect in Okanagan Lake as kokanee are an 
important fishery.
 
The premise was that given mysis are a staple diet for trout in many lakes in 
British Columbia, it was hoped that it's introduction would stimulate the 
kokanee population in 
Okanagan Lake.
 
Initially the shrimp seemed beneficial and kokanee numbers increased in 
response to the shrimp. However, shortly thereafter in the early 1970s, 
fisheries biologists noticed a corresponding and reciprocal decline in 
kokanee as the mysis population `exploded.'
 
Recently biologists (including fisheries biologist Bruce Shepherd with the BC 
Ministry of Environment) have discovered the cause of the problem. The shrimp 
have been competing with the kokanee fry at the bottom of the food chain. 
While adult kokanee feed on the shrimp, the shrimp are better at harvesting 
the plankton at the bottom of the food chain that the emerging kokanee fry 
require for survival. The mysis are diverting the food supply from the 
kokanee fry and starving them out. 
 
The result has been the collapse of one of the Interior's great sport 
fisheries as kokanee numbers have fallen from 1.6 million to less than 
200,000 over the past 20 years. Fisheries biologists recommend that to 
increase the lake carrying capacity will require the closure of the kokanee 
fishery coupled with boosting spawning grounds along the lake shore and 
streams, and improving the water quality of the lake.
 
It will be some years before kokanee numbers are restored to the levels 
before the mysis were introduced. However, biologists now do not want to fall 
into the same trap as back in 1966 and plan to proceed more carefully; and 
thereby avoiding quick fix solutions. Whether kokanee levels will recover is 
a matter of conjecture. But clearly we must be careful when we decide to play 
god over nature.
 
 
Cheers... Daniel Abrams
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