Monday, August 7, 2017

Speaking of Diamond Lake....

If you've been in Oregon for very long you are ware of the various efforts to eliminate Tui Chubs and shiners [released from 'trophy' bait fisherman's bait wells/buckets] including the last rotenone poisoning. Similar to other battles with mother nature this one continues to thrive - and here is the latest effort to thwart the invasives....

Tui chub (bottom) and a golden shiner (top).  Both fish are present in Diamond Lake, but ODFW says the shiners don't proliferate and affect water quality nearly as intensely as the chub.
Oregon Department of Fish and Wildlife
Sterile trout will prey on invasive Diamond Lake shiners


By Bill Monroe
For The Oregonian/OregonLive

The battle for Diamond Lake has been joined.

A second sterile, cannibal of a trout has been added to its school of predators.

Biologists for the Oregon Department of Fish and Wildlife say while tui chubs and golden shiners have returned....
to the lake after it's poisoning in 2006, their numbers haven't risen to cataclysmic levels as they did twice before. And the state wants to keep it that way.

Sterile tiger trout (a brown-brook trout hybrid), 15,000 strong, were stocked in the jewel of Cascade lakes in 2016 and another 15,000 will be planted this year.

But Greg Huchko, the department's Umpqua district fish biologist, said he'll also deposit 9,000 sterile "triploid" brown trout just for extra insurance. Triploid trout are only produced in hatcheries and are physically incapable of reproduction. Both GMO-trout species are voracious predators of chub and shiner-sized fish.

The state stocks 300,000 rainbow trout fry every year for anglers in Diamond Lake. They grow quickly in the lake's fertile water, often reaching catchable size by the fall. Carryover trout become trophies. But the rainbows are mostly insect-eaters.

Tiger hybrids and brown trout, on the other hand, not only target the smaller shiners, but also tolerate warm, shallow water; and while the rainbows migrate safely to cooler deep water during the summer, browns and tigers will hopefully prowl the shallows, stalking tuis and golden shiners.

Huchko said several thousand golden shiners were physically removed by nets last year and again this year, but "their population seems to max out at a level that does not impact (other fish)," he said, adding the golden shiner numbers have fallen from last year and may even have become static over the past few years since their discovery.

Huchko said about 50 tui chubs were caught in nets in 2016 and the same level of capture has continued this season, a far cry from the estimated millions of tui chubs in the lake before they were poisoned in 2006. Tuis, unlike the golden shiners, reproduce in high enough numbers the lake historically supported up to 23-plus million adults per year before the 2006 treatment.

Tiger and brown trout will hopefully prevent a recurrence of those difficult years when even eight-inch trout were a challenge to find.

Both the tiger and brown trout must be released by anglers.

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