Dry season survival of juvenile salmonids in an intermittent coastal stream
Résumé
We estimated dry season survival of imperiled salmonids in an intermittent coastal stream in California across four years (2009-2012). Our study encompassed two dry and two wet winters allowing us to explore patterns of survival across and within dry seasons with different antecedent precipitation. Apparent survival of age-0+ steelhead trout (Oncorhynchus mykiss) was higher following wet winters compared to dry winters. Moreover, antecedent precipitation was positively correlated with cumulative survival of age-0+ steelhead. Within years, apparent survival of steelhead varied among weeks with a tendency to decrease in the late summer indicating that fish exhibited some resistance to seasonal drought. Additionally, we found a slight but significant survival advantage for age-0+ coho salmon (O. kisutch) compared to equal34 aged steelhead. Our results emphasize the influence of antecedent precipitation in driving the survival of imperiled salmonids and highlight that these fishes are somewhat resistant to seasonal drought, at least to a point.
