Project Information

Title: APEX: Abundance and Distribution of Forage Fish and Their Influence on Recovery of Injured Species 96163-A

Project Year and Number: 1996: 96163-A

Other Fiscal Years and Numbers for this Project: 2000: 00163-A, 1999: 99163-A, 1998: 98163-A, 1997: 97163-A, 1996: 96163-A1, 1995: 95163-A, 1995: 95163-A1

Principal Investigator (PI): Lew Haldorson (University of Alaska Fairbanks)

Managing Agency: NOAA

Assisting Personnel: None

Research Location: Prince William Sound

Restoration Category: Research

Injured Resources Addressed: Common Murres, Harbor Seals, Marbled Murrelets, Pacific Herring, Pigeon Guillemot, Pink Salmon

Abstract: Prince William Sound (PWS) and the nearby Gulf of Alaska (GOA) provide a foraging area for large populations of apex predators including piscivorous seabirds and marine mammals. These surface-dependent predators were severely impacted by the Exxon Valdez oil spill (EVOS); and many - especially common murres, marbled murrelets, pigeon guillemots and harbor seals - suffered population declines that have not recovered to pre-EVOS levels. Piscivorous seabirds and marine mammals in PWS are near the apex of food webs based on pelagic production of small fishes and macroinvertebrates. Recovery of apex predator populations in PWS depends on restoration of important habitats and the availability of a suitable forage base. Since the 1970's there apparently has been a decline in populations of apex predators in the pelagic plankton production system, and it is not clear if failure to recover from EVOS related reductions is due to long term changes in forage species abundance or to EVOS effects. In this proposal we describe research that will provide quantitative descriptions of the forage community in PWS. Macrozooplankton, including euphausiids, shrimp, mysids, amphipods, are a central component in the diets of herring, sand lance, capelin and pollock, as well as young salmon (Clausen 1983; Coyle and Paul 1992; Livingston et al. 1986; Straty 1972). When aggregated in sufficient densities, macrozooplankton are fed on directly by marine birds (Coyle et al. 1992, Hunt et al. 1981 Oji 1980). Swarming behavior by breeding euphausiids (Paul et al. 1990b) and physical factors (Coyle et al 1992; Coyle and Cooney 1993) may concentrate macrozooplankton and micronekton into aggregations of density suitable for efficient foraging by predators. Unfortunately, there is little information on the abundance, distribution and fluctuations of these key invertebrates in the EVOS impact region. In the GOA, zooplankton abundance has varied on a decadal time scale (Brodeur and Ware 1992); and, superimposed on longer cycles, are interannual fluctuations as high as 300% (Frost 1983; Coyle et al 1990, 1992; Paul et al 1990a, 1990b, 1991; Paul and Coyle 1993). Such variability in abundance may affect populations of apex predators in PWS.


Proposal: Not Available

Reports:
Annual Report FY96: View (8,462 KB)
Final Report: See Project 00163-A

Publications from this Project: None Available