Acoustic sampling will likely be an important tool in the assessment of coregonine population restoration efforts in the great lakes because no other tool can effectively sample across such a large…

The Regents of the University of Minnesota will receive $136,475 under a three-year Cooperative Agreement from the U.S. Department of the Interior Fish and Wildlife Service Region 3 to develop acoustic sampling methods for coregonine fish populations in the Great Lakes. The project will acquire data on the current distribution and depth patterns of species such as bloater, shortjaw cisco, and lake whitefish during stratified and isothermal periods in Lake Superior and northern Lake Huron. Researchers will use this information to apply acoustic dead zone corrections tailored to specific conditions. The work supports the goals of the Great Lakes Restoration Initiative to identify, protect, conserve and restore habitats and species in the region.

Acoustic sampling will likely be an important tool in the assessment of coregonine population restoration efforts in the great lakes because no other tool can effectively sample across such a large geographic range while also assessing the water column. Species such as bloater and shortjaw cisco and lake whitefish are partially to mostly demersal, which presents a challenge for acoustic enumeration due to the bottom associated acoustic dead zone (ADZ). Thus, reported acoustic estimates for these demersal species are conservative. Marine researchers have developed methods for correcting these conservative acoustic estimates of economically important demersal species including COD, haddock and walleye pollock, however, similar methods have not been attempted on the great lakes. We propose develop ADZ correction methods for locations in lake superior near grand island, michigan, which has a multispecies coregonine assemblage (round whitefish, cisco, bloater, lake whitefish, and reputed shortjaw cisco and blackfin cisco), and a northern lake huron location having round whitefish, cisco, bloater and lake whitefish. By describing how different coregonine species are distributed relative to the lakebed during ISO thermal and thermal stratification periods, we will acquire the necessary data to apply condition specific ADZ correction methods. Our objectives will be to sample areas where bentho pelagic and demersal coregonine species currently are found to 1) acquire knowledge of the current distribution of coregonines that have or are likely to be reintroduced in the lower great lakes, 2) describe season specific depth distribution coregonines, and 3) develop detailed understanding of characteristics the acoustic signatures of known coregonines using tree based models that provide corrections for fish found in the ADZ.