Saturday, December 18, 2010

Officials: Sea Lamprey Control Seeing Success

The Lake Champlain Fish and Wildlife Management Cooperative is reporting unprecedented success resulting from the on-going sea lamprey control program. The Vermont Department of Fish and Wildlife, New York State Department of Environmental Conservation, and the U.S. Fish and Wildlife Service are working together to improve and manage the fisheries of Lake Champlain.

As a result of the program, the number and size of lake trout and salmon in the lake are increasing according to a press release issued this week. This is expected to translate into better fishing on Lake Champlain in the coming year. The wounding rate reductions observed this fall on lake trout and salmon are a good indication that lamprey are having less of an impact on other fish in Lake Champlain. Species such as walleye and the lake sturgeon, which is listed as endangered in Vermont, also benefit.

Personnel from the Cooperative treated five rivers in the Lake Champlain Basin with the lampricide (TFM) in September. Observation of larval lamprey mortality and other data indicate treatments on all five rivers were considered by officials to be “highly successful.” A final assessment of the treatments’ effectiveness will be completed next summer employing a systematic search of these rivers to determine how many sea lamprey survived the treatments. Officials said that although positive effects are already being seen in response to prior treatments, further improvements to the fisheries are expected over the next four years as more larval lamprey fail to become parasites.

Data collected this fall indicate that the number of sea lamprey wounds on lake trout and landlocked Atlantic salmon continue to decline. The sea lamprey wounding rate is measured as the number of wounds per 100 fish examined. Sampling this fall found 15 wounds per 100 salmon. This is down from 30 wounds per 100 salmon last year. This marks the first time that the management goal of 15 wounds per 100 salmon has been met since the inception of the control program.

The wounding rate on lake trout is also down from last year with 40 lamprey wounds per 100 lake trout being found this fall, down from 55 last year. Although the lake trout wounding rate goal for Lake Champlain is 25 wounds per 100 fish, 40 wounds per 100 fish represents a significant improvement from the 2006 wounding rate of 99 wounds per 100 fish. With fewer sea lampreys in Lake Champlain, more trout and salmon are now surviving to older ages and larger sizes. Continuation of current sea lamprey control efforts and ongoing innovations are expected to lead to further improvements in the trout and salmon fishery of Lake Champlain as well as the entire aquatic community.

The overall effectiveness of the sea lamprey control program is measured by fish biologists from all three agencies who collect hundreds of lake trout and salmon each fall. The fish are weighed, measured, examined for sea lamprey wounds, and then released. This information is used to assess the health of the fish populations and the relative degree of lamprey parasitism in the lake. As data analysis has progressed this fall, improvements in the condition of Lake Champlain fisheries have surpassed anything seen since the 1990s:

* Greater numbers of salmon, steelhead, and brown trout were collected.

* Greater numbers of smaller lake trout were found entering the spawning population, indicating increased survival of younger age classes.

* Greater numbers of older fish were collected, with salmon exceeding 5 lbs and lake trout exceeding 12 lbs increasing in frequency.

* A few salmon exceeding 9 lbs were collected. Salmon of this size haven’t been seen for over ten years.

* Record returns of salmon and steelhead to the Winooski River fish lift and a substantial increase in returns of salmon to the Boquet River fishway are further indications of improvements.

* For the first time in many years, multiple age classes of steelhead were found.

U. S. Senator Patrick Leahy has annually secured the funds enabling a now successful and effective sea lamprey control program. With these necessary funds, the three agencies have worked to address the sea lamprey problem in Lake Champlain.


Photo: Sea lampreys on a lake trout. Courtesy Wikipedia.

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