Spatial And Temporal Distribution Of Larval Alewives And Gizzard Shad in a Virginia Reservoir

Compatibility and complementarity of age-O alewife and gizzard shad as coexistent forage fishes were evaluated through analysis of their distribution, spawning periods, and growth rates in Smith Mountain Lake, Virginia, in 1983. Gizzard shad larvae appeared to be confined to the upper reservoir and alewife larvae to the down-lake region. Spatial segregation prevents direct trophic competition while increasing potential feeding encounters for juvenile piscivores. Gizzard shad spawning peaked in June; alewife spawning peaked in July. Age-O gizzard shad became too large for age-O and age-l piscivorous game fishes by mid-summer, but later spawning and slower growth of the alewife assured its morphological availability to these predators for the remainder of the year. The alewife appears to be compatible with gizzard shad, and the species are complementary in providing spatial and temporal feeding opportunities for juvenile piscivores in Smith Mountain Lake.

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