Spatial and temporal distribution of native fish larvae in seasonal and perennial tributaries of the Sacramento River, CA, USA

Abstract

Mediterranean climates with their pattern of seasonal rainfall and predictable annual flooding produce a wide variety of seasonally inundated aquatic habitats. Many studies have shown the benefits of these temporary habitats, such as floodplains, for the early life stages of fishes but little work has examined the use of seasonal streams or the differences in the abundance and distribution of native fish larvae between seasonal and perennial stream habitats. We compared the spatial and temporal distribution of fish larvae among two seasonal and two perennial tributaries of the Sacramento River, CA, USA during the winter and spring of 2004 and conducted a detailed examination of the distribution of fish larvae in Mud Creek, a seasonal stream, in 2006 and 2007. In 2004, both seasonal streams had higher average water temperatures (19.0°C and 16.8°C) and an earlier initial appearance of fish larvae (early March) than the perennial streams (15.5°C and 13.3°C; late March and early May). One of the seasonal streams (Mud Creek) yielded significantly higher catch per unit effort (CPUE) of fish larvae (1131 larvae per 10 m3, 95.6% of total CPUE) as well as the highest diversity (0.92 compared to 0.09 or less) and species richness (seven compared to two or fewer) among the four streams sampled. Our detailed study of Mud Creek in 2006 and 2007 yielded a CPUE of 3856 and 18,626 (larvae per 10 m3), respectively. Samples in Mud Creek for all years yielded five to six native species of Cyprinidae, a family currently recognized as declining in California. Our findings suggest that seasonal streams in the Central Valley are used as spawning and rearing habitat for native fishes. The associated higher water temperatures may induce earlier spawning by adults and the increased temperatures, when coupled with high prey abundances, may increase somatic growth and survival rates.