Distribution, Growth, Selective Feeding, and Energy Transformations of Young-of-the-Year Blueback Herring, Alosa aestivalis (Mitchill), in the James River, Virginia

Abstract

A direct relationship existed between standing crops of zooplankton and distribution, growth, and feeding of young-of-the-year blueback herring, Alosa aestivalis, in the James River, Virginia. Zooplankton densities were highest upstream where food consumption and growth rates were correspondingly highest. A progressive downstream decrease and upstream increase in fish abundance occurred during the study. Condition (K) decreased after flooding from Hurricane Camille.Blueback herring fed primarily on copepods (Eurytemora a//inis, Cyclops vernalis, and Can. thocamptus robertcokeri), but cladocerans (Bosmina sp. and Diaphanosoma brachyurum) were also important. Selection (electivity) was strongest for adult copepods and weakest for copepod nauplii. Selection for copepodRes and Bosmina sp. was moderate to weak. Feeding occurred only during daylight. Predation on copepods and copepodires by blueback herring resulted in population dominance by the smaller Bosmina sp. Respiration experiments were carried out in the laboratory. The regression of oxygen consumption on temperature (routine metabolism) was expressed asLog 0 -----1.4451 q-0.0548 T, where O: oxygen consumption (rag O•/g wet weight per hr), and T= temperature (C). Energy transformations were computed from growth and respiration values converted to their calorific equivalents. Mean maintenance requirement (% of food assimilated) was 88.3%, compared to 11.7% for growth (% of food assimilated). In the present study energy transformations are computed for young-of-the-year blueback herring, Alosa aestivalis, in the James River, Virginia. Seasonal distribution, growth rates, and feeding habits are described. Application of the energetics approach to fish has been a relatively recent development. Winberg (1956) provided the theoretical basis for study of energy transformations in natural populations, but comparable studies have appeared only recently (). The anadromous blueback herring occurs from northern Florida to Nova Scotia (Bigelow and Schroeder 1953), and spawns from late March through May at water temperatures from 21 to 24 C (Bigelow and Welsh 1925). Transformation occurs at about 20 mm total length (Mansueti and Hardy 1967), and • Contribution Number 620 of the Virginia Institute of Marine Science. z Present Address: Escuela de Pesquerias y AlL mentos, Universidad Cat51ica de Valparaiso, Valparaiso, Chile. young-of-the-year remain in the estuaries until fall before migrating to sea. Juveniles remain in the Atlantic for three or four years before returning to spawn. Little has been published on young-of-theyear blueback herring. Massmann (1953) and Massmann, Ladd, and McCutcheon (1952) discussed relative abundance in Virginia estuaries. Brooks (1968) and Brooks and Dodson (1965) considered prey size selection. Chittenden (1972) described salinity tolerance experiments. STUDY AREAThe James River, the southernmost major tributary of the Chesapeake Bay, drains 26,000 km ø-and flows 560 km in a southeasterly direction from the Allegheny Mountains to the Chesapea...

Diel variation in density, length composition, and feeding activity of juvenile alewife, Alosa pseudoharengus Wilson, and blueback herring, A. aestivalis Mitchill, at near‐surface depths in a hydroelectric dam impoundment

“…The suggestion by Loesch (1987) that the juvenile blueback herring studied by Burbidge (1974) may have increased diurnal feeding activity as sky opacity increased (decreasing light) may be partly a coincidence of the observed pattern of sky opacity.…”

The diet of juvenile and adult twaite shad Alosa fallax fallax (lac�p�de) from the rivers Severn and Wye (Britain)

“…The diet of juvenile twaite shad in the Severn Estuary consisted of zooplankton species, mainly copepods, cladocerans and mysids. Copepods and cladocerans were similarly found to be utilized by the American species of alosids in tidal waters (Burbridge, 1974;Davis & Cheek, 1966;Leim, 1924;Williams & Bruger, 1972). While in heavily wooded estuaries of the rivers studied by Massman (1963), juvenile Alosa sapidissima fed mainly on insects the majority of which were of terrestial origin (mostly Hymenoptera).…”

Factors affecting migration patterns of juvenile river herring in a coastal Massachusetts stream

“…Metabolism, maintenance requirements, and oxygen consumption are all influenced by increasing water temperatures, resulting in decreased growth efficiencies of juvenile bluebacks (Burbridge 1974). As a result, high water temperatures may have had a physiological affect on the early migration strategy, magnifying fluctuations in food availability.…”