Biotic and Abiotic Factors Influencing Cisco Recruitment Dynamics in Lake Superior during 1978–2007.

Historically, the CiscoCoregonus artediwas abundant throughout the Great Lakes basin, but anthropogenic influences caused the collapse of stocks during the mid-1900s, and fishery managers are currently exploring options for restoration. To increase understanding of biotic and abiotic factors influencing Cisco recruitment dynamics throughout the Great Lakes, we used Ricker stock–recruitment models with rearing-habitat-weighted indices of recruitment and adult spawning stock size in Lake Superior to identify and quantify (1) the appropriate spatial scale for modeling age-1 recruitment dynamics and (2) the effects of biotic and abiotic factors on age-1 recruitment dynamics within the regions identified for modeling. Cisco recruitment variation in Lake Superior was best described by a regional model with separate stock–recruitment relationships for western, southern, eastern, and northern regions. The spatial scale for modeling was approximately 260 km. Age-1 recruitment was negatively correlated with adult spawning stock size in all four regions. Multifactor models suggested (1) a positive correlation between age-1 recruitment and the interaction between wind speed and air temperature on a lakewide scale and (2) a negative correlation between age-1 recruitment and the biomass of Rainbow SmeltOsmerus mordaxon a regional scale. Large-scale abiotic factors are beyond the control of fishery managers, so harvest of adult Ciscoes and potential predators and competitors should be carefully managed to achieve desired goals in Lake Superior. Although our study was limited to Cisco stocks in Lake Superior, we believe that our general findings can be more broadly applied (albeit with caution) to the restoration and management of remnant stocks throughout the Great Lakes basin. Received June 4, 2013; accepted August 16, 2013 [ABSTRACT FROM AUTHOR]