Light Trap Sampling of Juvenile Northern Pike in Wetlands Affected by Water Level Regulation1
Abstract.—New approaches are needed for sampling northern pike Esox lucius in the complex habitats they use as nursery areas. We examined spatial and temporal variation in light trap catches of northern pike in potential pike nursery areas affected by water level regulation in Rainy and Na-makan Res...
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| Format: | Text |
| Language: | English |
| Published: |
2007
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.563.4768 http://files.dnr.state.mn.us/publications/fisheries/investigational_reports/550.pdf |
| Summary: | Abstract.—New approaches are needed for sampling northern pike Esox lucius in the complex habitats they use as nursery areas. We examined spatial and temporal variation in light trap catches of northern pike in potential pike nursery areas affected by water level regulation in Rainy and Na-makan Reservoirs. Light trap catches varied greatly among eight sampling locations and between years during 2004-2006. Total numbers of pike caught each year were 56, 26, and 8 fish respectively, and by far the most common individual light trap catch was 0 fish. A single sampling location ac-counted for a majority of the fish, with 64 % of all fish being caught in Dove Bay of Rainy Lake. Wa-ter level elevations coincident with the largest catches in Dove Bay were 102.85-102.90 m above sea level, surface water temperatures were 12.9-16.7 oC, and over 90 % of the pike were caught 17-31 days after ice-out on Rainy Lake. We observed a nearly three-fold difference in individual lengths of pike early in their life history. Challenges encountered in light trapping were variable spring weather patterns making it difficult to achieve a consistent sampling scheme, rising water levels influencing the efficiency of light trapping, and the large size and complex nature of the habitats we sampled. |
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