Ecology and demographics of Pacific sand lance in Lower Cook Inlet, Alaska: 1997 - 1999

Study History: The purpose of this study was to characterize the basic ecology, distribution, and demographics of sand lance in lower Cook Inlet. Recent declines of upper trophic level species in the northern Gulf of Alaska have been linked to decreasing availability of forage fishes. Sand lance is the most important forage fish in most nearshore areas of the northern Gulf. Despite its importance to commercial fish, seabirds, and marine mammals, little is known or published on the basic biology of this key prey species. Therefore, restoration project /306 was established to work in coordination with restoration APEX project /163M to help characterize the relationship between seabird population dynamics and forage fish abundance.

Abstract: Distinct sand lance populations occur within the relatively small geographic area of Lower Cook Inlet, Alaska. Marked meso-scale differences in abundance, growth, and mortality exist as a consequence of differing oceanographic regimes. Growth rate within populations (between years) was positively correlated with temperature. However, this did not extend to inter-population comparisons where differing growth rates were better correlated to marine productivity. Most sand lance reached maturity in their second year. Field observations and indices of maturity, gonad development, and ova-size distribution all indicated that sand lance spawn once each year. Sand lance spawned intertidally in late September and October on fine gravel/sandy beaches. Embryos developed over 67 days through periods of intertidal exposure and sub-freezing air temperatures. Mean dry-weight energy value of sand lance cycles seasonally, peaking in spring and early summer, and subsequently declining by about 25% during late summer and fall. Sand lance enter the winter with close to their minimum whole body energy content.

Publications:
Robards, M.D. and J.F. Piatt. 2000. Ecology and demographics of Pacific Sand Lance, Ammodytes hexapterus Pallas, in lower Cook Inlet, Alaska. Exxon Valdez Oil Spill Restoration Project Final Report (Restoration Project 99306), U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska.

Robards, M.D., J.F. Piatt, and G.A. Rose. 1999. Maturation, Fecundity, and Intertidal Spawning of Pacific Sand Lance (Ammodytes hexapterus) in the Northern Gulf of Alaska. Journal of Fish Biology 54: 1050-1068.

Robards, M.D., J.A. Anthony, G.A. Rose, and J.F. Piatt. 1999. Changes in proximate composition and somatic energy content for Pacific sand lance (Ammodytes hexapterus) relative to maturity, season, and location. Journal of Experimental Marine Biology and Ecology 242: 245-258.

Robards, M.D. G.A. Rose, and J.F. Piatt. 1999. Somatic growth and otolith development of Pacific sand lance (Ammodytes hexapterus) under different oceanographic regimes. (Submitted to Fisheries Oceanography).

Robards, M.R., J.F. Piatt, A.B. Kettle, and A.A. Abookire. 1999. Temporal and geographic variation in fish communities of Lower Cook Inlet, Alaska. Fishery Bulletin 97, 962-977.

Robards, M.R., M.F. Willson, R.H. Armstrong, and J.F. Piatt. 1999. Sand Lance: A Review of Biology and Predator Relations and Annotated Bibliography. U.S. Forest Service, Pacific Northwest Research Station, Research Paper PNW-RP 521, September, 1999.

Robards, M.D. and J.F. Piatt. 1999. Biology of the Genus Ammodytes – The Sand Lances. In: Robards, M.R., M.F. Willson, R.H. Armstrong, and J.F. Piatt (editors). Sand Lance: A Review of Biology and Predator Relations and Annotated Bibliography. U.S. Forest Service, Pacific Northwest Research Station, Research Paper PNW-RP 521, September, 1999.

Willson, M.F., R.H. Armstrong, M.D. Robards, and J.F. Piatt. 1999. Sand lance as cornerstone species for predator populations. In: Robards, M.R., M.F. Willson, R.H. Armstrong, and J.F. Piatt (editors). Sand Lance: A Review of Biology and Predator Relations and Annotated Bibliography. U.S. Forest Service, Pacific Northwest Research Station, Research Paper PNW-RP 521, September, 1999.

Willson, M.F., R.H. Armstrong, M.D. Robards, and J.F. Piatt. 1999. An annotated bibliography of sand lance. In: Robards M.R., M.F. Willson, R.H. Armstrong, and J.F. Piatt (editors). Sand Lance: A Review of Biology and Predator Relations and Annotated Bibliography. U.S. Forest Service, Pacific Northwest Research Station, Research Paper PNW-RP 521, September, 1999.