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Acoustical Assessment of Squid ( Loligo opalescens ) off the Central Oregon Coast

1987; Canadian Science Publishing; Volume: 44; Issue: 6 Linguagem: Inglês

10.1139/f87-149

1205-7533

Katharine Jefferts, Janusz Burczyñski, William G. Pearcy,

Marine animal studies overview

Squid (Loligo opalescens) were surveyed acoustically in an area off the Oregon coast using dual-beam and echo integrator techniques. The method developed is shown to be feasible for in situ estimation of target strength, distribution, and abundance of midwater squids. Average target strength was estimated both while drifting with a squid school and cruising over one. The values derived, −58.6 to −58.7 dB, are much lower than previous estimates, but more realistic in relation to the target strength of fishes. Schools judged to be fish or squid showed little difference in depth or size, but varied significantly in geographic distribution. Density estimates ranged from 9.9 t/km 2 in a known spawning area to 0.93 t/km 2 in an adjacent area.