Chinook Salmon Stocking Survival Study
Written by Greg Houtteman   
Sunday, 15 January 2006 05:26

Dave Clapp of the Michigan DNR presented, at the Ludington SeaGrant meeting, the results of a CWT (Coded Wire Tag) study of the survival rates for planted chinook salmon.  The study evaluated the effects of location, rearing technique, and release location on the survival rates of return planted kings.  The study was conducted for the 2002 through 2005 seasons at 16 stocking sites for Lake Michigan.

One area of study was the survival rates of fish that are reared and released in a number of ways.  Survival was evaluated on net pen reared and released fish against direct plants from downstream and upstream locations.  The results indicated that the survival rates were (from best to worse) with the ratio of surviving fish

net pen (2.2) > downstream direct (1.3) > upstream direct (1.0)

the survival ratio for net pen chinook versus direct plants, regardless of downstream versus upstream planting location, was 1.6 : 1.0 which indicates the effectiveness of the net pen rearing projects and plays a part in how fish will be planted in the future, as the 25% stocking reduction takes place.  Some direct plant location will be converted to net pen projects for the 2006 stocking plan to improve survival rates.

The other area of research data was the survival rates of chinooks in Northern plant sites versus Southern plant sites.  And going from the most northern of the study sites to the most southern of the study sites the survival success was much better in northern sites and progressively declined the further south the fish were planted.

1.0 (North) : 0.4 (South)

It's not exactly clear why the survival rates are so different as you move south along the lakeshore becasue it was not part of the study.  The best guess is that the decreased survival rates is related to the predatation from walleye and other fish as the planted kings hold in the released waters gaining size until they make the push into the big lake.


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