Here is an excerpt about Kamloops trout and survival rates.

In the world of fish, it's an event as impressive as the return of red-backed sockeye salmon to Interior rivers.In fact, the return of more than 20,000 wild rainbow trout each spring to spawning beds in Pennask Creek in the central interior of B.C. is the biggest run of naturally spawning rainbows in the world, says fisheries biologist Brian Chan. 

PennaskLake is a sprawling body of water found about 40 kilometres southeast of Merritt. Surrounded by pines, the lake sits almost at the crest of the region's high country. The lake is home to the original population of Interior red-band trout, commonly known as Kamloops trout. Rainbow trout have occupied PennaskLake since post-glacial days. It's believed the PennaskLake trout are descendants of ancient steelhead that were trapped in large inland lakes by receding glacial water flows.Every spring, about half of the lake's fish head for inlet and outlet creeks to reproduce. It's on Pennask Creek, about five kilometres up from the lake, that the Freshwater Fisheries Society of B.C. collects eggs and milt from spawning trout. The fry that eventually hatch are stocked in lakes across B.C.'s southern Interior.

 

PennaskLake trout have evolved into insect eaters and can reach weights over 10 pounds feeding only on bugs. There are other strains of rainbow trout collected and hatched in B.C. that feed on fish the blackwater strain for example, but they are put mostly in lakes with populations of illegally introduced forage fish, like shiners.

Siemens says 85 to 90 per cent of the eggs collected will hatch and grow into releasable fish. By comparison, only 10 per cent of eggs deposited naturally by trout in the Pennask Creek gravel will survive and reach the lake as fry.

It's estimated that only two of every 500 eggs laid naturally in Pennask Creek will hatch, grow and survive the required three to four years to return as spawning adults, Siemens says.B.C. is the only jurisdiction in North America to operate a hatchery/stocking program based on the collection of eggs from wild fish.http://www.gofishbc.com/tips_articles/pennask.htm