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

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 these changes in growth rate to concurrent changes in the spacing of scale circuli. Average spacing of scale circuli and average rate of circulus formation were significantly and positively correlated with average growth rate among groups of juvenile and maturing coho salmon and thus could provide estimates of growth between age groups and seasons. Regression analyses indicated that the spacing of circuli was proportional to the scale growth rate raised to the 0.4−0.6 power. Seasonal changes in the spacing of scale circuli reflected seasonal changes in apparent growth rates of fish. Spacing of circuli at the scale margin was greatest during the spring and early summer, decreased during the summer, and was lowest in winter or early spring. Changes over time in length of fish caught during research cruises indicated that the average growth rate of juvenile coho salmon between June and September was about 1.3 mm/d and then decreased during the fall and winter to about 0.6 mm/d. Average growth rate of maturing fish was about 2 mm/d between May and June, then decreased to about 1 mm/d between June and September. Average apparent growth rates of groups of maturing coded-wire−tagged coho salmon caught in the ocean hook-and-line fisheries also decreased between June and September. Our results indicate that seasonal change in the spacing of scale circuli is a useful indicator of seasonal change in growth rate of coho salmon in the ocean

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

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 years of sampling. Shad, an introduced species, was mainly found over the shallow continental shelf, and largest catches and highest frequency of occurrences were found north of central Oregon, along the coasts of Washington and Vancouver Island, and in California around San Francisco Bay. Migrations to the north off Washington and Vancouver were seen during spring to fall, but we found no evidence for large-scale seasonal migrations to the south during the fall or winter. The average weight of shad increased in deeper water. Sizes were also larger in early years of the study. Most were caught over a wide range of sea surface temperatures (11–17°C) and bottom temperatures (6.4–8.0°C). Abundance of shad on the continental shelf north of 44°N was highly correlated with counts of shad at Bonneville Dam on the Columbia River in the same year. Counts were negatively related to average weights and also negatively correlated with the survival of hatchery coho salmon (Oncorhynchus kisutch), indicating that survival of shad is favored by warm ocean conditions. Examining the catch during research cruises and commercial and recreational landings, we concluded that American shad along the Pacific coast have adapted to the prevailing environmental conditions and undertake only moderate seasonal migrations compared with the long seasonal migrations of shad along the Atlantic coast of North America. We suggest that the large spawning populations in the Columbia River and San Francisco Bay areas explain most of the distributional features along the Pacific coast

Species Composition and Distribution of Pelagic Cephalopods from the Pacific Ocean off Oregon

Much of our present knowledge about the species composition and distribution of cephalopods of the Pacific Ocean is derived from collections made on cruises of the "Albatross," steamer of the U.S. Fish Commission, during the late nineteenth and early twentieth centuries. "Albatross" collections along the west coast of North America were taken mainly off California and Central America or Alaska, and comparatively few collections were made off Oregon (Townsend, 1901). Neither Berry (1912) nor Hoyle (1904) lists any cephalopods taken off Oregon. A description of a new species of squid (Pearcy and Voss, 1963) and an abstract (Pearcy, 1963) are the only reports of pelagic cephalopods off Oregon. Clearly, more data are needed before comparisons of fauna and generalization on zoogeographic distribution can be made

Some distributional features of mesopelagic fishes off Oregon

Over 200 collections made between June 1961 and August 1962 with a six-foot Isaacs-Kidd midwater trawl at various depths down to 1000 m (mostly down to 200 m) along three latitudes off Oregon have provided preliminary data on species composition, sampling variability, diurnal vertical migrations, depth distribution, and seasonal and geographic variations of adult and large juvenile mesopelagic fishes...

Volume 18. Article 1. Ecology of an estuarine population of winter flounder, Pseudopleuronectes americanus (Walbaum). Parts I-IV.

https://elischolar.library.yale.edu/bulletin_yale_bingham_oceanographic_collection/1162/thumbnail.jp

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

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; chinook salmon, 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; pink salmon, 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 of several species due primarily to changes in prey availability. Juvenile salmonids were not commonly consumed by this assemblage of fishes (PDF file contains 36 pages.

Acoustical patchiness of mesopelagic micronekton

Patterns of acoustical scattering in both depth and horizontal extent were analyzed to estimate the spatial and temporal scales of variability in biomass of mesopelagic sound scatterers, principally micronekton. The patterns observed included extensive layers of low and nearly uniform scattering strength and distinct three-dimensional patches of stronger scattering. These patches dispersed vertically at night after diel migration of a portion of the scatterers, but reassembled quite accurately the following day. Analysis of variance spectra for average acoustical scattering profiles within a patch suggest that micro-patches, with dimensions on the order of 15 m vertically by 1 km horizontally, are present both day and night. Horizontal variance spectra suggest the possibility of different horizontal aggregation mechanisms at scales above and below approximately 8.9 km

Radioactivity and its relationship to oceanic food chains

Gamma-ray spectra of some primary producers (single-cell plants), filter-feeding herbivores, and carnivores, assigned to trophic levels I, II, and III–V, respectively, were prepared from marine samples taken in the Pacific off Oregon during 1961–1962. These organisms had been exposed in their natural environment to both fission produ cts from fallout and neutron-induced radionuclides from reactors on the Columbia River...

Remote sensing and the pelagic fisheries environment off Oregon

One of the biggest advantages of remote sensing is that large areas of the earth's surface can be surveyed in short periods of time, providing nearsynoptic "pictures." Repeated surveys of one area, like time-lapse photography, can be interpreted as a movie to illustrate the dynamics of detectable features. These attributes of remote sensing from aircraft or spacecraft are especially important in coastal and upwelling regions of the oceans, where oceanographic conditions change rapidly. The world's largest fisheries are also located in these dynamic areas.Keywords: remote sensing, pelagic fisherie

A large, opening-closing midwater trawl for sampling oceanic nekton, and comparison of catches with an Isaacs-Kidd midwater trawl

A new midwater trawl for sampling deepsea nekton from discrete depths is described. Its mouth area is about 50 m2. The trawl body is lined with small mesh netting and terminates in a 5-net opening-closing codend device. Problems of delayed flushing of animals into the codend and of entanglement of animals in the netting were not acute. Compared to a 5.4 m2 Isaacs-Kidd midwater trawl, this trawl catches many more individuals and species of fishes and larger sizes of some fishes and cephalopods. This net will be most useful in sampling sparsely populated mesopelagic and bathypelagic waters