Our Work

Coho Salmon Turbidity Study

Statistical analysis of relationship between growth and turbidity exposure

Washington Forest Protection Association (WFPA) needed to investigate Coho Salmon growth and survival in natural turbidity regimes to assess the reasonableness of laboratory-based regulations. Rules in Washington State setting allowable turbidity levels in streams supporting juvenile salmonid rearing were based on laboratory studies.

Kleinschmidt statisticians assisted with study design and conducted statistical analysis studying the relationship between turbidity exposure and the bioenergetics-based growth and survival of juvenile Coho Salmon in Pudding Creek, CA. The movement of fish before smolt was monitored using implanted passive integrated transponder (PIT) tags and antennas placed between study reaches in proximity to turbidity and stream temperature gages. Our team reconstructed turbidity/temperature exposure histories that were compared to the growth of fish recaptured at a downstream rotary screw trap. A Kleinschmidt scientist co-authored the manuscript of study results suggesting methods for determining impactful turbidity levels, which was published in a peer-reviewed journal.

Statistically robust peer-reviewed evidence that the effects of turbidity may vary between laboratory and field studies monitoring natural turbidity regimes provides a sound baseline for future negotiations on turbidity regulations.