The ef®ciency with which estuarine habitats produce ®sh is poorly understood due to the complexity of life cycles. Spatial dynamics of estuarine ®shes comprise retentive and dispersive behaviors which occur on seasonal and ontogenetic scales. Salinity is an important scalar in the spatial dynamics of estuarine ®shes, that may affect production and dispersal. In this paper, we review investigati...

Toothed whales emit high-powered ultrasonic clicks to echolocate a wide range of prey. It may be hypothesized that some of their prey species have evolved capabilities to detect and respond to such ultrasonic pulses in a way that reduces predation, akin to the situation for many nocturnal insects and echolocating bats. Using high-speed film recordings and controlled exposures, we obtained behav...

—We developed and applied a stable isotope turnover model to estimate how long age-0 American shad Alosa sapidissima reside within tidal freshwater and brackish-water habitats in the York River estuary, Virginia. The residence time was estimated by modeling the changing stable isotope ratio (either the carbon [dC] or sulfur [dS] stable isotope ratio) of an age-0 American shad as it migrates sea...

—The physiological responses of juvenile American shad Alosa sapidissima were evaluated during the period of downstream migration in freshwater (FW) and after seawater (SW) acclimation associated with postmigration. Fish were subjected to a standardized, acute handling and confinement stress (3 h). Changes in plasma cortisol, plasma chloride, and hematocrit were monitored for 24 h. Basal levels...

Larval and juvenile American shad (Alosa sapidissima) raised from eggs in the laboratory were subjected to biweekly 24-h seawater (35 ppt) challenges. There was no survival in seawater before 36 days post-hatch, and most mortalities occurred within 2 h of transfer. Twenty-four hour survival reached 89% in seawater at 45 days post-hatch (when larval–juvenile metamorphosis occurred), 96% at 58 da...

Otsego Lake (42o 41’N-70o’W) is the headwaters of the glacially-created Susquehanna River valley within the northern Appalachian Plateau. Historically considered oligo-mesotrophic, (Harman et al., 1997) the unauthorized introduction of alewives (Alosa pseudoharengus) in 1986 (Foster 1989) affected the lake, creating changes similar to those of eutrophy (Harman et al. 2002). Efficient planktivor...