Abundance and spatial distribution of Mysis diluviana in Lake Ontario in 2008 estimated with 120 kHz hydroacoustic surveys and net tows

作者：Watkins James M^*; Rudstam Lars G; Connerton Michael J; Schaner Ted; Rudstam Per G; Bowen Kelly L

来源：Aquatic Ecosystem Health and Management, 2015, 18(1): 63-75.

DOI：10.1080/14634988.2014.965646

• hydroacoustics
• mysis
• vertical migration
• patchiness
• invertebrate ecology

Mysids are an important component of Great Lakes foodwebs, both as a prey for fish and as a predator on zooplankton. We monitored mysid abundance in Lake Ontario using lake-wide hydroacoustics data and vertical net hauls collected 1-5 August 2008 during the Ontario Ministry of Natural Resources and New York State Department of Conservation forage fish survey. Acoustic volume backscattering strength was highly correlated with both density and biomass of mysids although the correlation with biomass was stronger. The slopes of these relationships were not significantly different from theory (0.10) indicating a linear relationship between abundance and backscattering strength. Size structure significantly affected the relationship between backscattering strength and density but not between backscattering strength and biomass. Average target strength for areas with small mysids was -91.9 dB per mysid, and in areas with both small and large mysids it was -88.2 dB per animal. Acoustic estimates for Lake Ontario calculated with these regressions provided a lake-wide estimate weighted by lake area within depth intervals, of 228 mysids m(-2) (CV 17.6%) and 0.93 g dw m(-2) (CV 12.9%). Density and biomass in 14 net hauls averaged 316 mysids m(-2) (range 0 to 1113) and 1.35 g dw m(-2) (range 0 to 3.89). Mysid biomass was 33% of the biomass of other crustacean zooplankton in the summer of 2008. As in 2005, areas of low mysid abundance were detected in the middle of the transects and along the north shore. Lakewide mysid abundance in the summer of 2008 was higher than in a similar acoustic survey in the summer of 2005 and in whole-lake autumn 2000-2007 net surveys, suggesting that mysids are persisting in Lake Ontario and abundant relative to other Great Lakes.

• 出版日期2015