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The Great Lakes Science Center (GLSC) has conducted lake-wide surveys of the fish community in Lake Michigan each fall since 1973 using standard 12-m bottom trawls towed along contour at depths of 9 to 110 m at each of seven index transects. The resulting data on relative abundance, size structure,...
| Main Authors: | , , , , |
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| Other Authors: | |
| Format: | Text |
| Language: | English |
| Published: |
2008
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| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.569.7782 http://www.csu.edu/cerc/researchreports/documents/StatusAndTrendsPreyFishPopulationsLakeMichigan2007.pdf |
| Summary: | The Great Lakes Science Center (GLSC) has conducted lake-wide surveys of the fish community in Lake Michigan each fall since 1973 using standard 12-m bottom trawls towed along contour at depths of 9 to 110 m at each of seven index transects. The resulting data on relative abundance, size structure, and condition of individual fishes are used to estimate various population parameters that are in turn used by state and tribal agencies in managing Lake Michigan fish stocks. All seven established index transects of the survey were completed in 2007. The survey provides relative abundance and biomass estimates between the 5-m and 114-m depth contours of the lake (herein, lake-wide) for prey fish populations, as well as burbot, yellow perch, and the introduced dreissenid mussels and round gobies. Lake-wide biomass of alewives in 2007 was estimated at 11.67 kilotonnes (kt) (1 kt = 1000 metric tons), which was 18 % higher than in 2006. Lake-wide biomass estimates of bloater (5.39 kt) and rainbow smelt (0.88 kt) in 2007 were 59 % and 63%, respectively, lower than in 2006. Bloater biomass has declined drastically |
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