Blueback herring (Alosa aestivalis) were first detected near the mouth of the Connecticut River on April 13, 1966, April 18, 1967, and April 19, 1968, when water temperatures were 7.8, 4.7, and 9.4 C, respectively. Spawning was first observed when stream temperature was 14 C. Abundance in the river was greatest from mid‐May to mid‐July, but smaller spawning groups were observed in late April and mid‐September. Blueback herring preferred a swift stream flow and hard substrates for spawning sites, and to a great degree were spatially isolated from spawning alewives. Both sexes were present in age classes III through VII; age V was the modal class for each sex. In the spawning areas there was a 2:1 sex ratio of males to females. Males were more abundant in age classes III, IV, and V; there was equal abundance in age class VI, but females dominated age class VII. Fecundity was related to total fish length up to about 300 mm, but declined in larger females.

Trawl catches indicated diel migratory activities by young-of-the-year alewife Alosa pseudoharengus, American shad A. sapidissima, and blueback herring A. aestivalis in Virginia rivers. Bottom catches were significantly greater during day than at night; conversely, surface catches were significantly greater at night than during day. Spatial separation of alewife and blueback herring stocks, which could reduce feeding competition, also was indicated. Surface pushnet catches of blueback herring were associated with a sky-opacity index, suggesting that this species (or its prey) is negatively phototropic. The influence of light on distributions of juvenile Alosa should be taken into account when sampling location, time, and gear are chosen for stock-assessment programs. The purpose of our study was to compare the availability of juvenile anadromous Alosa to surface and bottom sampling gear, and to relate our catches to light intensities and diel movemerits by the species. The anadromous clupeids, alewife Alosa pseudoharengus, American shad A. sapidissima, and blueback herring A. aestivalis, are important commercial species in the Atlantic coastal United States. In Virginia, American shad are taken mainly by gill nets selective for larger females. Alewives and blueback herring, collec-

No abstract

No abstract

No abstract