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122 results on '"Pearcy, William G"'

9. Ocean distribution of the American shad (Alosa sapidissima) along the Pacific coast of North America

Author

Pearcy, William G. and Fisher, Joseph P.

Subjects
Shad -- Distribution -- Observations, Invasive species -- Observations -- Management -- Distribution, Company business management, Company distribution practices, Zoology and wildlife conservation
Abstract

Abstract--We examined the incidental catches of American shad (Alosa sapidissima) taken during research cruises and in commercial and recreational landings along the Pacific coast of North America during over 30 [...]

Published
2011

10. Seasonal changes in growth of coho salmon (Oncorhynchus kisutch) off Oregon and Washington and concurrent changes in the spacing of scale circuli

Author

Fisher, Joseph P. and Pearcy, William G.

Subjects
Silver salmon, Animal development, Zoology and wildlife conservation
Abstract

Abstract--In this study we present new information on seasonal variation in absolute growth rate in length of coho salmon (Oncorhynchus kisutch) in the ocean off Oregon and Washington, and relate [...]

Published
2005

19. Deep-water octopods (Mollusca: Cephalopoda) of the northeastern Pacific

Author

Voss, Gilbert L. and Pearcy, William G.

Abstract

Descriptions and illustrations are given of nine species of Octopoda from depths of 1,000 m to 4,000 m off the coast of Oregon. Eight are new: Grimpoteuthis bathynectes, G. tuftsi, Benthoctopus robustus, B. canthylus, B. oregonensis. B. yaquinae, B. macrophallus, and Graneledone pacifica. Four genera are treated: Cirroteuthis and Grimpoteuthis of the Cirrata and Benthoctopus and Graneledone of the lncirrata. Cirroteuthis muelleri is first recorded from the Pacific Ocean and is redescribed. The genus Benthoctopus in the North Pacific is discussed and a provisional key for the nine recognized species is provided. The variability and form of the radula of Graneledone are considered to be due to degeneracy and not primitiveness, and to lack of selective feeding pressure.

Published
1990

21. Species associations of epipelagic nekton of the North Pacific Ocean, 1978-1993

Author

Pearcy, William G., Fisher, Joseph P., Anma, Gen, Meguro, Toshimi, Pearcy, William G., Fisher, Joseph P., Anma, Gen, and Meguro, Toshimi

Abstract

Strong latitudinal gradients in species composition were revealed by two-way indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA) of 41 species of epipelagic fishes and squids in 513 gillnet collections by research vessels of Hokkaido University over a huge area of the northern North Pacific during the summers of 1978-1993. Salmonids inhabited northern subarctic water and skipjack tuna (Euthynnus pelamis) and flying squid (Ommastrephes bartrami) inhabited the regon of the Subarctic Boundary, but distinct boundaries between species groups and sample groups were lacking, largely because abundant species, such as Pacific saury (Cololabis saira) and Pacific pomfret (Brama japonica), migrated across most of this region during the summer. Longitudinal differences were not pronounced, but some species, including Japanese sardine (Sardinops melanosticus) and Japanese anchovy (Engraulis japonicus), were only found in the western pacific. Pacific saury was more common in the western Pacific, whereas sockeye samlon (Oncorhynchus nerka) was concentrated in the eastern Pacific. Interannual flucuations in the latitude of species groups were most closely correlated with changes in sea surface temperatures. In the western Pacific, 1982, 1983, 1985, 1987-88, and 1992-93 were cool years when subarctic and transitional assemblages were found farther to the south than other years. Temperature and silinity at various depths were highly correlatied with each other with first-axis DCA ordinations scores. Long-term trends in community structure were not apparent during the 1.6 decades.

Published
1996

30. Food habits of deep-sea macrourid fishes off the Oregon coast

Author

Pearcy, William G. and Ambler, Julie W.

Abstract

The abyssal macrourid fishes off Oregon are generalized feeders, as theory predicts for large searchers in an unproductive environment. Analysis of stomach contents revealed that fish feed on a wide variety of foods, but the proportions of different taxa of food vary among and within species, indicating some food selectivity. Broad feeding overlaps occurred between large Coryphaenoides armatusand C. filifer, which fed mainly on squid and fish, and between small C. armatusand C. leptolepis, which fed largely on epifaunal crustaceans. Pelagic crustaceans were numerous in the stomachs of large C. leptolepis. Overlap among the food of these macrourids was more than the overlap among shallow-water, demersal fishes.

Published
1974
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31. Vertical migration and distribution of mesopelagic fishes off Oregon

Author

Pearcy, William G. and Laurs, R.M.

Abstract

Using an Isaacs-Kidd midwater trawl with an opening and closing cod-end device, we collected samples of mesopelagic fishes from depths of 0–150 m, 150–500 m and 500–1000 m during periods of daylight and darkness. The observed day catches per unit volume of all mesopelagic fishes, as well as those of each of the four dominant species, were larger than the night catches at intermediate depths (150–500 m), whereas the opposite was true in the surface layer (0–150 m). These reversed trends in the upper 500 m indicated daily vertical migration, but in all cases the night-time increase in surface waters exceeded the daytime increase at mid-depths. Moreover, the number of fishes in a column of water 1000-m deep was always higher for night than day tows. There was no evidence for day-night differences in catches from the 500–1000 m stratum where catches were uniformly low.

Published
1966
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32. Distribution and relative abundance of pelagic nonsalmonid nekton Off Oregon and Washington, 1979-84

Author

Brodeur, Richard D. and Pearcy, William G.

Subjects
Ecology, Fisheries, Biology
Abstract

Fifteen fine-mesh (32-mm mesh) pelagic purse seine surveys were conducted between 1979 and 1984 off the Oregon and Washington coasts. Environmental conditions varied greatly among the years sampled, and even within years, due to variability in upwelling conditions and productivity and the effects of a strong El Nino from late 1982 to the middle of 1984. In the 843 sets made, a total of 115,891 specimens from 69 taxa was collected. Most individuals collected belonged to nine dominant taxa. Seasonal and interannual variations in the abundance and distribution patterns of these dominant taxa are presented in detail. A recurrent group analysis delineated four major groupings of nekton. (PDF file contains 91 pages.)

Published
1986

33. Food habits and dietary variability of pelagic nekton off Oregon and Washington, 1979-1984

Author

Brodeur, Richard D., Lorz, Harriet V., and Pearcy, William G.

Subjects
Ecology, Fisheries, Management
Abstract

The food habits of 20 species of pelagic nekton were investigated from collections made with small-mesh purse seines from 1979-84 off Washington and Oregon. Four species (spiny dogfish, Squalus acanthias; soupfin shark, Galeorhinus zyopterus; blue shark, Prionace glauca; and cutthroat trout, Salmo clarki) were mainly piscivorous. Six species (coho salmon, Oncorhynchus kisutch; chinooksalmon, O. tshawytscha; black rockfish, Sebastes melanops; yellowtail rockfish, S. f1avidus; sablefish, Anoplopoma fimbria; and jack mackerel, Trachurus symmetricus)consumed both nektonic and planktonic organisms. The remaining species (market squid, Loligo opalescens; American shad, Alosa sapidissima; Pacific herring, Clupea harengus pallasi; northern anchovy, Engraulis mordax; pinksalmon, O. gorbuscha; surf smelt, Hypomesus pretiosus; Pacific hake, Merluccius productus; Pacific saury, Cololabis saira; Pacific mackerel, Scomber japonicus;and medusafish, Icichthys lockingtom) were primarily planktonic feeders. There were substantial interannual, seasonal, and geographic variations in the diets ofseveral species due primarily to changes in prey availability. Juvenile salmonids were not commonly consumed by this assemblage of fishes (PDF file contains 36 pages.)

Published
1987

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

Author

Jefferts, Katharine, Burczynski, Janusz, Pearcy, William G., Jefferts, Katharine, Burczynski, Janusz, and Pearcy, William G.

Abstract

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/km2 in a known spawning area to 0.93 t/km2 in an adjacent area.

Published
1987
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