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Fish fatalities a controllable concern

Lingering ice cover and fishery conditions at the Salmon River Hatchery -- in Atlmar, north of Syracuse -- led to the recent loss of fish stocks this past winter.

Pond owners in DEC Region 9 areas have reported a high loss of fish as ice coatings melted off this season. "Many of these fish kills reported may likely be the result of a natural phenomenon know as 'winterkill' -- it is not an unusual occurrence," said regional fisheries manager Paul McKeown.

Oxygen depletion, especially in shallow water bodies during winters with heavy ice formation, results in winterkill events. It is rare that all fish in a pond will be killed. Species vary in their tolerance to oxygen loss. Carp and catfish may endure low oxygen levels better than sunfish species and trout, McKeown noted.

To help reduce winterkills, pond owners and caretakers should consider removing decayed plant materials that reduce oxygen content. Also oxygen levels remain high and winter survival has been higher in ponds with depths of at least 12 feet. A check on silt buildup for actual pond depth might call for dredging that could improve future wintering conditions in older ponds.

Early in March, reports came of a loss of about 200,000 Chinook salmon at the Salmon River Hatchery. A check with Phil Hulbert, hatchery supervisor at the DEC Albany office, confirmed that the hatchery has sustained a mortality rate of close to 200,000 salmon, the result of what Hulbert described as "mortality thiamine syndrome," a condition that affects the young as they progress from the egg to begin feeding.

"It occurs in females that feed heavily on alewives [bait fish], a food source that tends to break down thiamine in salmonid fish species," Hulbert explained.

"The syndrome was especially high this year; we saw a chronic loss of Chinooks through January and February despite our thiamine treatments."

The planned 1.75 million salmon projected for stocking this year could drop to 1.56 million.

He added, "DEC officials are connecting with an Ontario Province fish culture station and may obtain stock to augment the salmon numbers reduction for the Niagara River."

Available numbers of Ontario-reared salmon have yet to be determined.

e-mail: willodrs@gmail.com

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