Evaluating the effectiveness of rehabilitation actions in creating fish habitat in the Trinity River

Darcy Pickard successfully defended her M.Sc. project entitled "Evaluating the effectiveness of rehabilitation actions in creating fish habitat in the Trinity River" on 10 April 2006.

Fry-rearing habitat is believed to be the limiting type of habitat for Chinook (Oncorhynchus tshawytscha) in the Trinity River. This habitat is lost as growth of riparian vegetation forms permanent berms along the river edge. Evaluating the effectiveness of different river habitat rehabilitation actions on salmonid populations is very difficult due to lack of replication, lack of independence of neighbouring areas of the river, and external effects that cannot be controlled.

A simulation model of the Trinity River was first developed that models the impacts of different habitat creation actions and flow regimes upon future changes to the habitat. We then evaluate several experimental designs to determine which designs are most likely to detect a difference in habitat creation resulting from different mechanical rehabilitation actions. We model the formation of berms using transition state matrices derived from expert opinions. The model creates different transition matrices for various rehabilitation actions, flow volumes and dependence on upstream conditions.

Finally, the performance of alternative designs under different model conditions is compared and presented.

This model will be useful in helping the Trinity River Recovery Plan assess which actions will lead to the creating and maintenance of future fry habitat.

This type of interdisciplinary work is a hallmark of our program in Applied Statistics at Simon Fraser University. For more information, please contact Darcy Pickard (dcp@sfu.ca) or her supervisor Carl Schwarz (cschwarz@stat.sfu.ca), Department of Statistics and Actuarial Science.

10 April 2006