Bridging the Energy Gap: Anadromous Blueback Herring Feeding in the Hudson and Mohawk Rivers, New York

Abstract

Adult blueback herring Alosa aestivalis (N ¼ 116) were collected during the 1999, 2000, and 2002-2004 spawning runs from sites on the Hudson and Mohawk rivers, and gut contents were analyzed. Thirty-four fish (33% of those examined) were found to contain food material. Food items were present in 41% of Mohawk River samples and 11% of Hudson River samples; all Hudson River fish containing food were captured in small tributaries above the head of tide. Hudson River fish predominantly consumed zooplankton, while Mohawk River fish consumed benthic aquatic insects in large quantities, including Baetidae, Ephemeridae, and Chironomidae. Using stable isotope analysis and a mixing model, we found that fish collected later in the season had significantly decreased marine-derived C. Condition indices of later-season fish were equal to or greater than those of fish collected earlier in the season. Blueback herring in this system may face increased energy requirements as they migrate farther upstream during spawning runs, and feeding may provide energy subsidies needed to maintain fitness over their expanded migratory range.

Ovarian dynamics and fecundity regulation in blueback herring, Alosa aestivalis , from the Connecticut River, US

“…Tapering in SG recruitment and fecundity modulates energy allocated to oocyte production, perhaps to better meet the high energetic demands of the riverine phase of its reproductive cycle, which involves upstream migration, spawning and potentially prolonged residence on the spawning ground or repeated rounds of migratory return to the spawning ground. Other populations of BBH (McBride et al., 2010; Simonin et al., 2007) incur substantial energetic losses during long upstream migrations up to ~400 km. The impact of such long migrations on energy available for reproduction has not yet been assessed.…”

A New Paradigm in Alewife Migration: Oscillations between Spawning Grounds and Estuarine Habitats

“…The cessation of feeding while spawning is widely observed in many diadromous fish (Bernatchez and Dodson ); however, recent studies show evidence negating this behavior in several alosine species (Walter and Olney ; Simonin et al. ; Harris and McBride ; McBride et al. ; Nachón et al.…”

American Shad Feeding on Spawning Grounds in the St. Johns River, Florida

“…One unexpected finding was the suggestion that American shad in the St. Johns River consume eggs of their own species. Various species of clupeids are thought to feed on eggs from unrelated conspecifics (Smith and Reay 1991) and blueback herring A. aestivalis have specifically been observed to feed on fish eggs in rivers (Simonin et al 2007). Savoy and FIGURE 5.-Average weight of the stomach contents of male and female American shad combined found to differ significantly by diel time period (see Table 2) and average stomach fullness index (SFI), by diel time period.…”