Using Commercial Fisheries Tagging Data to Assess the Status of Lake Sturgeon in Saginaw Bay, Michigan

In an effort to better understand the status of lake sturgeon in Saginaw Bay, Michigan, the U.S. Fish and Wildlife Service initiated a project in 1995 utilizing the voluntary participation of commercial fishers who encounter lake sturgeon as by-catch in their fisheries. To date, 357 individual lake sturgeon have been tagged by commercial fisherman in Saginaw Bay.  We utilized tagging information collected in 1995-2011 to make inferences on the population demographics of lake sturgeon in this system.  Individual fish capture histories were input into MARK to estimate population status and apparent survival.  Of the 357 originally tagged fish, 22 have been recaptured once in a different year and three have been recaptured in two different years.  The estimated population size of lake sturgeon is 2,881 (95% CI = 2041 – 4139).  Apparent survival estimates were much lower than what has been reported in other systems < 70%, suggesting temporary emigration out of this system.  Concurrent mark-recapture studies by the Ontario Ministry of Natural Resources in Southern Lake Huron have recaptured 11 lake sturgeon initially tagged in Saginaw Bay.  Data suggests a substantial amount of movement between these two stocks; however additional tagging is needed to better understand interactions between these stocks.