Pennask Lake 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 Pennask Lake since post-glacial days. It's

believed the Pennask Lake 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.

The majority of prime fishing lakes in the Kamloops area are stocked with trout hatched from Pennask Lake parents, says Chan. The government has maintained an egg collection site on the creek since 1928. Each year, staff collect up to a million eggs from a few thousand trout.

Trout begin the annual ascent up the stream as soon as the ice leaves the lake, but its not until water temperatures reach 10 C or so does the real push begin.

Three- and four-year-old trout, most in the one- to two-pound range, travel up the stream and encounter a steel barrier. Eventually, they find their way through two small openings in the barrier, each no more than 30 centimetres across. The small openings bring the fish to a holding tank, where they remain until workers pass them one at time over another barrier into a large holding pond.

The process allows biologists to count how many trout are arriving to spawn, as egg collection does not begin until at least 13,000 fish show up. At least that many fish are needed to ensure that Pennask Lake's natural stocks continue to exist.

Mark Siemens, the manager of the Summerland Trout Hatchery, says there's not yet been a year when less than 20,000 trout arrived at the collection facility. Only 10 to 15 per cent of the fish passing through the collection site are milked for their eggs and milt, he says. The rest are allowed to continue their journey upstream, to spawn naturally.

If the day ever comes that fewer than 13,000 trout show up at the egg collection site, no eggs will be taken, he says.

Eggs and milt are extracted from fish by hand. Technicians use large nets to scoop trout from the holding ponds. The fish are stroked lengthwise along their bellies, producing a stream of orange roe from females and a shot of white milt from the males.

Once milked, the fish are released alive into the creek. They return to the lake to live out their lives and perhaps return to spawn again. (While trout don't die after spawning, Siemens says few return to spawn a second time. Angling pressure, other predators and natural life cycles means few Pennask Lake fish live long enough to reach a second spawning cycle).

Half the collected eggs are fertilized on site, while the other half are kept dry until they reach a hatchery. There, the unfertilized eggs are treated to produce sterile versions of rainbow trout better suited to release in certain lakes.

Siemens says all collected eggs must be transported to a hatchery within 24 hours. Ideally, eggs are on the road within an hour or two of being collected and arrive at their destination the same day.

The Pennask Lake eggs are taken mostly to the Summerland Trout Hatchery, where they are hatched and raised for several months. There are five hatcheries in B.C.  Much of the stock collected this spring will be released as fry in lakes later this fall. The remainders will be held over the winter and released in the spring. The larger fingerlings often have a better chance of survival in some lakes.

Roughly 40 per cent of the lakes in southern B.C. receive Pennask Lake stock, Siemens says. The trout are ideal for the kind of lakes found through the Interior, typically landlocked lakes with a rich and varied insect life.

Pennask Lake 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.

Other provinces and states maintain “brood stocks” of breeding trout, says Chan. But B.C.'s approach is better, as other programs invariably produce inbred trout vulnerable to hosts of problems, including disease. In fact, B.C. fish eggs are desired the world over and are often used to start new hatchery programs in other places.

It costs more money to harvest eggs from wild fish, but the benefits are worth it, he says. Every released fish has wild parents, meaning every fish is a wild fish. As a result, the genetic pool is more diversified and the fish display the same behavioural traits as their wild parents.

Chan says without a stocking program, the sport fishery in B.C. would look much different. Most of the lakes in the Interior had no fish until they were stocked several decades ago. If stocking levels are not maintained, the fish would quickly die out, as few lakes have proper streams and creeks to allow natural reproduction.

Chan says it costs between $100 and $1,000 to stock a lake, depending on its size and how many fish are released. Popular lakes like Tunkwa and Roche lakes get more trout than small, out-of-the-way lakes like Community or Dairy.

But the cost of stocking a lake is retrieved many times over. Anglers spend an average of $45 for every day they fish, on everything from fishing licences and gear to gas, meals and lodging. By comparison, it costs about $2 per angler day to support B.C.'s hatchery program.

Popular lakes like Tunkwa generate hundreds of thousands of dollars a year in economic activity, Chan says. The province's 400,000 anglers spend an estimated $400 to $500 million a year.

“Without a stocking program, there would be a lot of fishless lakes,” Chan says. “There would be great fishing in some areas, but it would be much more isolated.“And there would be a lot more restrictions.”