The Chronicle-Journal/The Times News
May 2, 1998
Big Specs Don't Have Sex
Northwestern Ontario is famous for trophy brook trout. You only have to say the name Nipigon to conjure up beautiful visions of over-sized, wild, speckled beauties.
But can domestic brook trout be altered to grow as large or larger than their wild brothers and sisters? Judging from the results of an experimental program in the Thunder Bay district, the answer is yes.
A company called DAMSA, which is owned by John and Lauri Parks, of Nolalu, has stocked sexually sterile, or triploid trout in several Crown lakes in Adrian, Horne and Conmee townships.
Triploid fish are rendered sterile by treating them with hot water when they are fry or eggs. Sexually sterile adult trout don't use up energy on egg or milt production, so they can theoretically put all energy into growth.
The program received some public opposition when it was first floated in the late 1980s, but the Parks have weathered the storm, and are now seeing their work pay off.
A number of scientific assessments have been undertaken since 1992, when the first trout were stocked, and there have been some remarkable findings in that time period.
Lakes in the study area that were initially without sport fish are becoming good trophy brook trout fisheries. The four main lakes are protected under sanctuary status.
Chemically sterilized, triploid and non-sterile brook trout have all been grown in excess of five pounds, the minimum deemed necessary for a brook trout to be called a trophy in Northwestern Ontario.
A large variation in growth rates is evident depending on the lakes, the amount of fish in each stocking and the kind of brook trout stocked. Growth rated of up to three pounds per year have been obtained for brook trout; and up to five pounds per year for rainbows.
DAMSA has achieved 100 per cent sterility and monosexing of brook trout and rainbow trout. These capabilities could have important implications in fisheries management. In theory, sterile trout can be stocked without risk to the gene pool of indigenous fish. The same holds true for monosexed trout, which can be stocked with no threats to the integrity of the ecosystem. In either case, the effects are limited to the life of the fish as they can not reproduce.
Additional studies undertaken by the company suggest that technology for growing very large brook trout is more valuable than any possible tourism application at the study site. With this in mind, the proposed tourism resort once planned for the lake has been shelved.
And how big could these triploid brook trout get? In the fall of fall 1996, I joined Parks for an afternoon of data collection on three of the lakes in the study. During the course of the day we sampled a half dozen specs; the smallest of these fish weighed two pounds, the largest pulled the scale to eight and one half pounds.
Parks is confident that his triploid brook trout have the potential to better ten pounds.
Parks has put up a Web site with information on the DAMSA project. The address is http://www.damsa.ca
Contact him at:
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