Pacific Ocean Perch Research Articles

Availability, Size Composition, Age Composition, and Growth Characteristics of Pacific Ocean Perch (Sebastes alutus) off the Northern Washington Coast During 1967–72

Cruises were conducted off the northern Washington coast each year during 1967–72 to study trends in the availability and biological characteristics of Pacific Ocean perch (Sebastes alutus).There were marked differences in catch rate between cruises, and corresponding differences in age composition and age–length structure indicated that they resulted from differential availability of an old, slow-growing segment of the population to on-bottom trawling. Females from this segment of the population were particularly available when the cruise coincided with the period of peak spawning, and both sexes were available during the 1972 summer cruise.Within cruises, adults from different portions of the bathymetric range showed similar age composition, but there was an inverse relationship between depth and size attained by age 15. Size compositions consequently contained a smaller proportion of large fish as depth increased.Juveniles were confined to the shallow portions of the bathymetric range. There were obvious between-year changes in the length and age composition of juveniles, caused by the temporal progression of a dominant 1961 year-class.Fluctuations in availability make it difficult to monitor changes in mortality and since age composition also varies with availability, the problem is compounded further. Unless all segments of the population are located and sampled in proportion to their abundance, estimates of mortality can be made only between those cruises where the old, slow-growing component of the population is equally available.

Development and Present Status of Bottomfish Resources in the Bering Sea

Fisheries for bottomfish in the Bering Sea are largely a post-second world war development, with landings having increased from 13,000 metric tons in 1954 to an estimated 2 million metric tons in 1971. Most of the harvest is off Alaska in the southeastern sector of the Bering Sea, where conditions are most favorable for development of resources and fisheries. In 1970 and 1971, Japan accounted for approximately 84% and the USSR 15% of the combined harvest by all nations. South Korea, United States, and Canada took the remaining 1% of the harvest. Initial target of the fisheries of Japan and USSR was yellowfin sole. Yields of yellowfin sole were not sustained and Japan shifted attention to Alaska pollock. Production of Alaska pollock in 1970 from the North Pacific (about half is from the Bering Sea) was tied with Atlantic cod for second place in worldwide landings of a single species.Analysis of condition of resources is handicapped by unavailability of adequate statistics for earlier years of the fishery. Even for those participants who provided detailed statistics, information is usually lacking on quantities offish discarded, and changes in fishing gear and fishing tactics that need to be corrected for in assessing the condition of stocks. There is no institutional mechanism for Bering Sea or the North Pacific that makes it mandatory for all nations to provide common and comprehensive statistics on their fisheries and to undertake joint management.Consideration of available data suggests that the pulse nature of the Bering Sea fisheries resulted in the depletion of several important resources. Yellowfin sole were overfished during the early period of the fishery. Although the picture is far from clear for other species, the Pacific Ocean perch, blackcod, and shrimp resources also appear to have been overfished at least on certain important grounds within the Bering Sea. The chronology of Japan’s fishery for herring suggests the initial exploitation of the stock in the western Bering Sea off Asia may have been intense enough to deplete that resource. Although there is yet no indication of depletion of Alaska pollock, the great increase in harvest of that species, coupled with reliance on a few year classes to support the fishery, should serve as a warning against further uncontrolled increases in fishing.

Helminths of Sebastes alutus (Pisces: Teleostei) from the northeastern Pacific.

Incidences and intensities of infection for 19 species of helminths recovered from Sebastes alutus are presented. Seven are regarded as new host records. Lecithophyllum anteroporum Margolis, 1958 is placed in synonymy with L. botryophorum (Olsson, 1868) Odhner, 1905.

Age Determination and Growth of Pacific Ocean Perch (Sebastes alutus) in the Northeast Pacific Ocean

Age was determined by means of otoliths of juvenile and adult Pacific ocean perch (Sebastes alutus) collected during 1963–69 in the northeast Pacific Ocean, from Oregon to Unalaska Island, Alaska. Consistency of otolith readings between two readers varied inversely with numbers of translucent (or opaque) zones — from 100% agreement for 0-zone otoliths to 23% for 19-zone otoliths. Variability in zone counts between two readers was not great — 85% ± 1 zone for 3- to 24-zone otoliths — and the dispersion was near-normal about zero. Validity of otolith readings was established by demonstrating the annual formation of the translucent zone for juvenile fish, and by detecting the temporal passage of dominant year-classes among juveniles and adults.Age–length relationship varied inversely with depth off British Columbia, and inversely with latitude (or longitude) in the study region. Off Vancouver Island (48°48′N lat), two partially mixed stocks with near-opposite seasonal availability maxima were delineated, from bathymetric age–length and catch-rate data. Latitudinally, there was a sharp discontinuity in the age–length relationship at Dixon Entrance (54°40′N lat).Ranges of von Bertalanffy growth parameters were as follows: L∞, 37.2–48.2; K, 0.078–0.169; and to, − 0.4 to − 1.8. No geographical trend was evident for any parameter. Values of L∞ were larger for females, while values of K were smaller. Considerable variation in parameter values exists among studies on Pacific ocean perch from the western Gulf of Alaska.Age-weight relationship was generally sigmoid in shape. Values of W∞ ranged from 791 to 1686 g. Annual weight increments were maximal at ages 7–11.

Estimate of genetic polymorphism and heterozygosity in three species of rockfish (Genus Sebastes)

1. 1. An estimate of the genetic polymorphism and average hetorozygosity in three species of rockfish, Sebastes alutus, S. caurinus, and S. elongatus' was made using differences in electrophoretic mobility of proteins on starch gel. 2. 2. In S. alutus two of twenty-five loci; in S. caurinus, one of twenty-five loci; and in S. elongatus, two of twenty-four loci were polymorphic. 3. 3. This yields estimates of 8,4 and 8 per cent of all polymorphic for the average species population and values of 3·8, 1·8 and 3·3 per cent for the proportion of the genome heterozygous per individual in the average population.

Evidence that Pacific Ocean Perch (Sebastes alutus) in Queen Charlotte Sound Form Aggregations that Have Different Biological Characteristics

Pacific ocean perch (Sebastes alutus) in market samples from Queen Charlotte Sound showed considerable variation in mean length, even when narrowly defined month-depth strata were considered. Available evidence indicated that there was also considerable between-sample variability in growth. Both phenomena were attributed to a tendency for commercially exploited Pacific ocean perch to form distinct aggregations, each with different biological characteristics. The relevance of aggregating behavior to age and growth analyses is discussed.

Reduction in Stocks of the Pacific Ocean Perch, an Important Demersal Fish off Alaska

Abstract The Pacific ocean perch (Sebastes alutus) is an important commercial fish of the North Pacific Ocean and Bering Sea. Commercially exploitable populations extend from Kamchatka through the Bering Sea and along the Aleutian Islands to California. Heavy exploitation of the stocks off North America began around 1963, principally by stern-ramp trawlers of the Soviet Union and Japan. The original catchable biomass of the species off North America seems to have been about 3.5 billion pounds, and the stocks as of 1968 appeared to be about 39% of the original biomass. Fishermen of all nations that have participated in the fishery complain of stock depletion. Because the fishery has significantly reduced the proportion of large fish in the populations and fecundity increases at a much faster rate than length or weight in the species, a severe drop in fecundity of the populations is hypothesized. If the prerecruit populations do not compensate for the lower fecundity through increased survival and growth, a...

Taxonomy, Distribution, and Biology of the Northern Rockflsh, Sebastes polyspinis

Available information is summarized on the taxonomy, distribution, abundance, and biology of the northern rockfish, Sebastes polyspinis (Taranetz and Moiseev 1933). Morphological and biochemical descriptions of the taxon are provided. Geographic range is east Kamchatka (USSR) to Yakutat, Alaska (USA). Maximum depth of capture in the Gulf of Alaska is 196 fath (358 m). Absolute abundance appears to be low, and centered in shallow water with juvenile Pacific ocean perch (Sebastes alutus). Von Bertalanffy growth constants, for combined sexes, are: K = 0.18, and L∞ = 31.4 cm. All females larger (older) than 21 cm (7 years) were mature, and all smaller (younger) than 18 cm (5 years) were immature.

Studies of Populations of Sea Urchins, "Strongylocentrotus" sp., in Relation to Underground Nuclear Testing at Amchitka Island, Alaska

primarily by fleets from the Soviet Union and Japan, although U.S. fishermen are extending their operations westward to this area. The Soviets harvest Pacific ocean perch and whales; the Japanese, Pacific ocean perch, whales, and salmon. U.S. fishermen catch mostly king crabs, but some Dungeness and snow crabs and halibut are also caught. The salmon resource in the western Aleutians is of the greatest value and concern to commercial fisheries. Japan sends fleets of several hundred salmonfishing vessels each spring and summer to the western Aleutians, and, as long as international agreements are effective in maintaining the productivity of the resource, this high seas fishery will continue at a high level. U.S. and Soviet coastal salmon fisheries also have a large stake in the resource because salmon from Asian and Alaskan streams migrate through the western Aleutians before returning to parent streams as mature adults.

Phosphoglucomutase polymorphism in Pacific ocean perch, Sebastodes alutus

1.1. Three phenotypes of phosphoglucomutase were found in muscle extracts of Pacific ocean perch (Sebastodes alutus) by starch gel electrophoresis.2.2. Evidence for nonrandom distribution of phenotypes with regard to depth at which samples were taken, sex and alleles of α-glycerophosphate dehydrogenase is presented.

Reproductive Patterns of Pacific Ocean Perch (Sebastodes alutus) off Washington and British Columbia and their Relation to Bathymetric Distribution and Seasonal Abundance

Females of the ovoviviparous species Sebastodes alutus release their larvae in March in the Washington–British Columbia area. Male maturity data from Queen Charlotte Sound indicated that males probably inseminate females in September or October. Examination of the annual bathymetric cycle in three major commercial trawling areas showed that mating and insemination occur while Pacific ocean perch are moving to deep water from the shallow-water regions inhabited in summer and that females release their larvae while in the deepest part of their bathymetric range.Total 1955 through 1965 catch by month, and 11-year mean monthly catch rates were used to indicate relative seasonal abundance on major fishing grounds. Where deepwater regions were trawled, these indices showed a spring maximum associated with the March spawning period. In all areas studied there was a midsummer slump in catch and catch rate, and an October maximum occurring during the suggested mating period.

Parasitic Copepods of Sebastodes alutus Including Chondracanthus triventricosus sp.nov. and Colobomatus kyphosus sp.nov.

Sixty-six specimens of Sebastodes alutus, the Pacific ocean perch, collected from the coast of Oregon and British Columbia were examined for parasitic copepods. The six species identified are Chondracanthus pinguis Wilson, 1912, Chondracanthus triventricosus sp.nov., Clavella parva Wilson, 1912, Brachiella robusta (Wilson 1912) Kabata, 1970, Colobomatus kyphosus sp.nov., and Sarcotaces arcticus Collett 1874. Colobomatus kyphosus is the second species of the genus to be described from the eastern Pacific and Ch. triventricosus is the second chondracanthid to be found in nasal cavities. Sarcotaces arcticus is reported as a parasite of S. alutus for the first time. Details of the appendages of each new species are described and illustrated.

Survey of Rockfishes, Especially Pacific Ocean Perch, in the Northeast Pacific Ocean, 1963–66

During 1963–66, a trawl and echo-sounder survey was conducted in the northeast Pacific Ocean to investigate the distribution and abundance of rockfish (Scorpaenidae) species, particularly Pacific ocean perch (Sebastodes alutus), inhabiting the outer continental shelf and upper continental slope from Cape Blanco, Oregon, to Unalaska Island, Alaska. Rockfish predominated in most trawl catches. Among areas, numbers of rockfish species declined northward, from 19–21 in the Oregon–Vancouver Island region to 5 off Unalaska Island. Within areas, maximum numbers of species were caught at intermediate depths — usually 80–139 fath (146–254 m). With rare exceptions, Pacific ocean perch was the predominant rockfish species in the trawl catches throughout the study area, although its relative abundance declined from north to south.Within areas, ocean perch catch rates were usually maximal at intermediate depths — 120–139 fath (220–254 m) in summer and substantially deeper in winter. Juvenile fish usually occupied shallower depths than adults, but were often in the company of large adults. Among areas, summer catch rates were relatively high off southwest Vancouver Island and southeastern Alaska and in the western Gulf of Alaska. Off Vancouver Island, summer catch rates were higher than winter catch rates, particularly for large adults of both sexes. Echo-sounder records indicated schools were frequently unavailable to the on-bottom trawl used in this survey.Ocean perch in the northeast Pacific Ocean were categorized, tentatively, into B.C.- and Gulf-types, whose mutual boundary is Dixon Entrance. Separation was based on differential size distributions and year-class strengths.Survival rates among year-classes were evidently quite variable, particularly for the Gulf stock west of Cape Spencer.Qualitatively, ocean perch abundance generally increased from south to north in the study area.Bottom-water temperatures varied inversely with depth and latitude. Among areas, temperature range at depths of maximal ocean perch catch rate was 4.5–7.7 C, but in high-abundance areas the temperatures did not exceed 6.0 C. Seasonally, temperature at depths of maximal catch rate varied approximately 1.5 C.

IRRADIATION OF PACIFIC COAST FISH AT SEA

An experimental shipboard irradiator was installed aboard the Bureau Of Commercial Fisheries research vessel Miller Freeman and utilized to irradiate West Coast fish at sea. The optimum dose range for irradiating whole English sole (Parophrys vetulus), Dover sole (Microstomus pacificus), Pacific cod (Gadus macrocephalus), Pacific ocean perch (Sebastodes alutus), and black rockfish (Sebastodes melanops) is in the range of 50 to 100 kilorads. The shelf life (at a high level of quality) of the irradiated products was extended by one and one-half to two times that of the nonirradiated samples. Among the five species irradiated at various states of rigor, prerigor-rigor fish generally had better storage characteristics than postrigor fish.

Electrophoretic Variants of L-Alpha-Glycerophosphate Dehydrogenase in Pacific Ocean Perch (Sebastodes alutus)

Three phenotypes of L-alpha-glycerophosphate dehydrogenase (α-GPDH) were found in muscle extracts of Pacific ocean perch by starch-gel electrophoresis. No association was obvious between alpha-glycerophosphate phenotype and sex or stage of maturity. The observed phenotypes were presumed to be under the control of two allelic genes, F and S. This assumption was supported by the distribution of phenotypes of fish collected off the coasts of Washington and Oregon. This report is the first on genetic variants of an enzyme in Pacific ocean perch and suggests that isozymes of α-GPDH may be useful in population studies of this species.

ベーリング海におけるアラスカメヌケの鱗相-II

ベーリング海におけるアラスカメヌケの鱗相-II

ベーリング海におけるアラスカメヌケの鱗相-I

The scale characters of Pacific Ocean Perch, Sebastodes alutus, and its variations by body regions were investigated for two specimens caught in the Bering Sea in 1965 (Table 1 and Fig. 1). The scale is of a ctenoid type by many characters recognized on the surface of scale (Fig. 2). There are many ridges concentrically around the central plate on the covered portion. The widely spaced ridge zone and the close one appear alternately, and they are considered to be the growth zone and the resting zone respectively (Figs. 2 and 3). The radius of the resting zone, measured from the converged point of grooves to the each outer edge, shows a smooth curve (Fig. 4), but the cumulative number of ridges indicates a inflective line (Fig. 7). The resting zones are supposed to be formed periodically from the Walford's graphic method for their radii (Fig. 6). These characters aforementioned were observed similarly on every scale of the same fish irrespectively of samlping region, and of the shape and the size of scale (Fig. 4, 5, 6 and 7). Therefore, there is a good possibility for determining the age of S. alutus by the scale character, and so far as age determination is concerned, there is no need of strictly defining of scale sampling region.

Sampling Research Trawl Catches at Sea

During 1963 and 1964, studies were conducted aboard the research vessel G. B. Reed to test schemes for sampling individual trawl catches of groundfish, principally Pacific ocean perch (Sebastodes alutus), for size composition, weight and numbers caught, and sex ratio. A species sort into tub lots preceded sampling. Empirical tests were used to evaluate sampling methods for all parameters except sex ratio. Size composition and sex ratio samples were evaluated with chi-square tests. Estimates of weight and numbers caught were arbitrarily evaluated on the basis of their percentage deviations from actual values.For ocean perch the size composition, weight caught, numbers caught, and sex ratio were best estimated from a stratified sample consisting of the first 2, middle 2, and last 2 full tubs weighed. For 21 test hauls, the error range for weight estimates was −6 to +5%; for estimated numbers caught, −5 to +4%. Sex ratio was homogeneous among tubs within hauls.For six other groundfish species, weight caught was satisfactorily estimated from a serial sample consisting of the first 6 full tubs weighed, providing the tubs within hauls were filled uniformly. For 13 tests, the error range was −3 to +1%.

Distribution pattern of groundfishes hooked along a row of setline in the shallower part of the continental slope in the Bering Sea 2 bathymetric difference in relative abundance in relation to distribution pattern

Summary and Conclusion This report demonstrates the well‐defined bathymetric distribution of relative abundance of groundfishes in relation to the distribution pattern conjectured from the records of catch along a row of setline with remarkably large variation in the settled depth (from shallower than 350 m to deeper than 700 m) observed around 580 18′ N and 1750 28′ W on Aug. 24, 1962. The results of the analyses are depicted in Fig. 1. It is found that halibut, true cod and Sebastodes sp. (or Menuke in Japanese) show sharp or abrupt decrease in the relative abundance in accordance with depth whereas sablefish and rattail increase sharply. Arrow toothed halibut and ray do not show any clear bathymetric change in relative abundance and Pacific ocean perch shows decrease in the density in accordance with the disparity in the depth from the 500 m isobath. The patterns conjectured from this example are compared with either those shown in other reports, the results of the observations on other examples or general view of our fishermen. And many proofs to the high reliability and wide universality of the conjectured pattern of the first four species are found out. But, for the last three species, the present results differ more or less from the general view of our fishermen and the observations on other examples. For the distribution pattern, most of groundfishes incline to show chance distribution in the shallower part of the continental slope (350 m to 700 m deep) and only the species showing sharp decrease in density with increase in the depth are distributed contagiously on the shallower bottom (not deeper than 450 m).

Proximate Composition and Sodium and Potassium Contents of Four Species of Commercial Bottom Fish

SUMMARYThe proximate composition and sodium and potassium contents of four species of bottom fish from Pacific Coast waters were investigated. Pacific Ocean perch, Pacific cod, and lingcod were quite uniform in composition regardless of species, size, season and area of capture, and method of preservation on board the fishing vessel. The averages were 79‐81% moisture, 18‐19% protein, 0.5‐1.5% oil, 1.1‐1.3% ash, 60‐70 mg% sodium, and 390‐440 mg% potassium. Sablefish varied greatly in oil content, with a range of 3‐23% and an average of 15%. Variations in the other constituents were rather large; averages were 71% moisture, 13% protein, 1% ash, 56 mg% sodium, and 348 mg% potassium.