HR: 13:45h
AN: NB23F-02    [Abstracts]
TI: Contrasting Patterns of Juvenile Chinook Salmon (Oncorhynchus tshawytscha) Growth, Diet, and Prey Densities in Off-channel and Main Channel Habitats on the Sacramento River.
AU: * Limm, M P
EM: mlimm@socrates.berkeley.edu
AF: University of California, Berkeley, 3060 Valley Life Science Building, Berkeley, CA 94901 United States
AU: Marchetti, M P
EM: mpmarchetti@csuchico.edu
AF: California State University, Chico, 400 West First Street, Chico, CA 95929 United States
AU: Power, M E
EM: mepower@socrates.berkeley.edu
AF: University of California, Berkeley, 3060 Valley Life Science Building, Berkeley, CA 94901 United States
AB: Few studies have quantified juvenile salmon growth in or between different habitats or evaluated the mechanisms by which salmon growth and survival might be enhanced. We used otolith microstructure to compare daily relative growth rates among main channel areas, off-channel ponds, and non-natal seasonal tributaries of the Sacramento River in 2001 and 2002. To examine possible mechanisms leading to growth differences, prey availability, prey preference, and stomach fullness were estimated at each site. Stable isotope ratios (δ¹³C and δ¹⁵N) in salmon tissue and their predominant prey were measured in 2002. We observed wider daily increment widths, higher prey densities, and warmer temperatures in off-channel ponds and non-natal seasonal tributaries in both 2001 and 2002. Off-channel pond salmon and chironomidae pupae had significantly different δ¹³C and δ¹⁵N than those captured in the main channel and non-natal seasonal tributaries. In 2001, all habitats had higher temperatures, wider daily increment widths, higher prey densities, and higher stomach fullness than in 2002. Our findings suggest warmer temperatures and abundant prey in off-channel habitats lead to higher growth rates. Increased access to off-channel habitats during wetter years may account for the stronger year classes and higher survival rates reported in other studies.
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly