Thesis

Spatial and Temporal Ecology of Fish Larvae in Seasonal and Perennial Tributaries of The Sacramento River, Calfiornia

ABSTRACT
 SPATIAL AND TEMPORAL ECOLOGY OF FISH LARVAE IN
 SEASONAL AND PERENNIAL TRIBUTARIES OF THE
 SACRAMENTO RIVER, CALIFORNIA
 by
 Rebecca C. Walther
 Master of Science in Biological Sciences
 California State University, Chico
 Spring 2009
 Many studies have shown the benefits of off-channel habitats, such as floodplains,
 for the early life stages of fishes, but little work has examined the differences in
 the abundance and distribution of fish larvae between seasonal and perennial stream
 habitats. To examine this, drift nets were used to compare the spatial and temporal distribution
 of fish larvae among two seasonal and two perennial tributaries of the Sacramento
 River, California, during the winter and spring of 2004. Additionally, a detailed
 examination of the distribution of fish larvae in Mud Creek, a seasonal stream, was conducted
 in 2006 and 2007. Higher temperatures and an earlier date of first occurrence of
 fish larvae in the seasonal streams were observed. In addition, Mud Creek produced extremely
 high numbers of fish larvae and had the greatest diversity and species richness
 xii
 among the four sample streams. Taken together, the findings suggest that seasonal
 streams in the Central Valley are used as spawning and rearing habitat, and the associated
 warmer water temperatures may elicit earlier adult spawning. These same factors
 may also contribute to increased fitness and survival of fish larvae, which in turn can
 enhance recruitment success and year class strength for native fishes, many of which
 are in decline.

ABSTRACT SPATIAL AND TEMPORAL ECOLOGY OF FISH LARVAE IN SEASONAL AND PERENNIAL TRIBUTARIES OF THE SACRAMENTO RIVER, CALIFORNIA by Rebecca C. Walther Master of Science in Biological Sciences California State University, Chico Spring 2009 Many studies have shown the benefits of off-channel habitats, such as floodplains, for the early life stages of fishes, but little work has examined the differences in the abundance and distribution of fish larvae between seasonal and perennial stream habitats. To examine this, drift nets were used to compare the spatial and temporal distribution of fish larvae among two seasonal and two perennial tributaries of the Sacramento River, California, during the winter and spring of 2004. Additionally, a detailed examination of the distribution of fish larvae in Mud Creek, a seasonal stream, was conducted in 2006 and 2007. Higher temperatures and an earlier date of first occurrence of fish larvae in the seasonal streams were observed. In addition, Mud Creek produced extremely high numbers of fish larvae and had the greatest diversity and species richness xii among the four sample streams. Taken together, the findings suggest that seasonal streams in the Central Valley are used as spawning and rearing habitat, and the associated warmer water temperatures may elicit earlier adult spawning. These same factors may also contribute to increased fitness and survival of fish larvae, which in turn can enhance recruitment success and year class strength for native fishes, many of which are in decline.

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