Lake Sturgeon from Ruffe Reduction Experiment. - FWS photo

- FWS graphic

The Ashland Fishery Resources Office and the Upper Great Lakes Management Unit of the Ontario Ministry of Natural Resources (OMNR) continue to investigate bottom trawling in reducing an abundant invasive ruffe colony in the Kaministiquia (Kam) River, Ontario, a tributary of Lake Superior. 

Biologists believe that an abundance of chironomids (midge fly larvae) and oligochaetes (tubifex worms) in this site might be attracting ruffe and lake sturgeon.  A total of 4.7 hours trawling in 2005 and 2006 combined has netted a total of 6,837 adult ruffe and 14 juvenile lake sturgeon. 

OMNR is coordinating with Ontario Hydroelectric in a water flow project that allows adult sturgeon to access a known spawning site upriver from the ruffe reduction site.  OMNR reported that 9 out of the 11 sturgeon captured during the 2005 ruffe reduction were likely spawned in this upriver site in 2004. 

If ruffe reduction in the Kam River proves feasible, the juvenile sturgeon bycatch from future ruffe reductions would aid OMNR in establishing an index of juvenile sturgeon abundance. 

This index would be a useful monitoring tool during years in which a water drawdown prevents sturgeon access to their spawning site.  At least one 5-day continuous trawling effort is required to assess the feasibility of an effective long term ruffe reduction in this Kam River site.  Ashland FRO and OMNR are coordinating this trawling effort.