Ocean Perch Research Articles

Summer Diet of the Harbour Porpoise (Phocoena phocoena) in the Estuary and the Northern Gulf of St. Lawrence

Stomach contents (n = 138) were examined in harbour porpoise (Phocoena phocoena) caught incidently by commercial fishermen in the estuary and the Gulf of St. Lawrence; 111 stomachs contained food. A total of 4423 otoliths and 11 upper beaks were collected belonging to nine species of fishes and one species of squid. Capelin (Mallotus villosus), Atlantic herring (Clupea harengus), and redfish (Sebastes marinus) were the three most important species in the diet by frequency of occurrence (83, 8, and 4.5%, respectively) and percent occurrence in the stomachs (52, 49, and 8.5%). Capelin and herring also made the greatest mass and caloric contribution to the diet of porpoise (>80%). The estimated mean mass and caloric value of the stomach contents of a nonlactating adults were 958 g and 7007 kJ, respectively.

Electrophoretic discrimination of blue mouth,Helicolenus dactylopterus(De La Roche, 1809), fromSebastesspp. in the Northeast Atlantic

Abstract Samples of blue mouth, Helicolenus dactylopterus (De La Roche, 1809). were collected in the areas between Shetland and the Faroe Islands, and analysed by starch gel electrophoresis and isoelectric focusing of haemoglobins and tissue enzymes. Moderate intraspecific variation was found, but most enzyme patterns were diagnostic for this species compared to the Sebastes species. The haemoglobin patterns were similar to the pattern of Sebastes marinus and S. viviparus, and thus diagnostic in relation to S. mentella. The estimated genetic distances between blue mouth and the Sebastes species were high (0.92–1.05) compared to corresponding values within the latter genus (0.03–0.13).

Thermal Conductivity, Heat Capacity and Moisture Isotherm of Ocean Perch at Different Moisture Levels and Temperatures

Thermal conductivity (W/m K) of ocean perch (Sebastes Marinus) was measured by the heated thermocouple method (moisture M 47%-76% wet basis (wb), temprature T 20-80°C). The equation k = 0.268 + 1.97 10-03 T + 3.41 -03 M was fitted to the data. Heat capacity (J/kg K) was measured by direct water immersion (M range 21% - 77% wb, T range 23 - 80 °C). The fitted equation was Cp = 2128.7 - 13.6 T + 23.7 M. Moisture isotherm was measured with a relative humidity probe (M range 14% - 77% wb, T range 28 - 39°). The fitted equation was: 1n(aw) = [1/M2 - 9.501 10-5]/[-4.2691 10-3 - 1.3101 10-4 T]. These equations could be used as estimations of the above properties for lean fish in these moisture and temperature ranges.

Statistical Models for Estimating CPUE from Catch and Effort Data

Catch-per-unit-effort (CPUE) provides one of the most commonly used abundance indices in fishery research. The literature, however, offers no unique method of estimating CPUE and its variance from catch and effort data. In this paper we develop two models (univariate and bivariate) that generalize previous approaches and remain valid under management restrictions on catch and/or effort. Both models estimate CPUE from measures of central tendency in the underlying catch and effort distributions. The models involve normalizing transformation parameters that, along with other parameters, are estimated by maximum likelihood. We illustrate the models using data from Pacific ocean perch (Sebastes alutus). For the four data sets examined, the univariate and bivariate models result in similar estimates of CPUE. However, other commonly used CPUE measures lead to inconsistent results, in particular for data sets in which catch was restricted by low trip limits. We recommend the bivariate model, since it accounts for the bivariate structure of catch and effort data. Furthermore, it can easily be adapted to accommodate alternative indices, for example, the effort required to attain a specified catch.

Rockfish (Scorpaenidae) Assemblages of Trawlable and Untrawlable Habitats off Vancouver Island, British Columbia

Abstract We compared assemblages of demersal rockfishes (Scorpaenidae) associated with two areas of the continental slope off northern Vancouver Island, British Columbia, Canada. Twenty and 21 sets of sunken gill nets were completed on trawlable and untrawlable areas, respectively. The species assemblages on the two areas were markedly different, as demonstrated by their diversity, evenness, and percent similarity and by cluster analysis. On the trawlable area, the catch was numerically dominated by Pacific ocean perch Sebastes alutus (37.6%), splitnose rockfish S. diploproa (23.5%), greenstriped rockfish S. elongatus (12.7%), and bocaccio S. paucispinis (7.3%). This contrasted with the untrawlable area, where the catch was numerically dominated by sharpchin rockfish S. zacentrus (70.8%), and redbanded rockfish S. babcocki made up half (14.5%) the remaining catch. We found no evidence to support the claim by some fishermen that exploited rockfishes on trawlable areas, especially Pacific ocean perch, are m...

Variability of Salt Absorption by Brine Dipped Fillets of Cod (Gadus morhua), Blackback Flounder (Pseudopleuronectes americanus), and Ocean Perch (Sebastes marinus)

ABSTRACTMajor changes in sodium content of fillets of cod, blackback flounder, and ocean perch resulted from varying concentration of brine solution (5, 10, or 15%), duration of dip (30, 60 or 90 sec), fillet thickness, season of catch, and rinsing or skinning fillets before cooking. Postmortem age (1‐5 days) of fish, temperature of brine solution (6, 12, or 20°C), and cooking had minor effects on final sodium concentration.

Electrophoretic study of myosin isoforms in white muscles of some teleost fishes

1. 1. White skeletal muscle myosin of four marine teleost fish species (cod, blue whiting, Norway haddock, and spotted wolf-fish) was analyzed by native, SDS-PAGE, and 2-dimensional electrophoresis. 2. 2. Four types of native myosin were present in cod, blu whiting and Norway haddock. The second fastest migrating form was predominant. 3. 3. Myosin from spotted wolf-fish also resolved into four forms. The fastest migrating form was hardly noticeable. The other three were present in apparently similar amounts. 4. 4. In the myosin from each species there were three types of light chains. The pattern of light chains was species specific. 5. 5. Apparently, there was only one type of heavy chain in myosin from cod, Norway haddock and spotted wolf-fish. One preparation of cod showed an extra band of higher electroporetic mobility than the main band. In blue whiting we found two bands present in approximately equal amounts.

Texture Changes of Frozen Stored Cod and Ocean Perch Minces

ABSTRACTDuring frozen storage, minced cod and ocean perch were examined by expressible moisture (EM), water binding potential (WBP) and computerized texture profile analysis (TPA). The results suggested that a microcomputer interfaced with the Instron efficiently performed TPA. The texture and water loss of all fish minces changed more rapidly at ‐7°C storage than at ‐20°C and ‐40°C. Furthermore, cod, a gadoid with the ability to degrade trimethylamine oxide to dimethylamine and formaldehyde, deteriorated faster than ocean perch, which did not have this ability. EM was useful for examining the water loss of frozen fish at ‐ 7°C only during the first two weeks of storage. The WBP at ‐7°C storage showed a good correlation with storage time for cod and ocean perch. This suggests that WBP might be a good indicator for examining water holding ability of fish proteins.

Biochemical separation of Atlantic Canadian redfish: Sebastes mentella and Sebastes norvegicus

One of the problems for management of the redfish fishery in the Gulf of St. Lawrence is the difficulty in distinguishing between the different species: deepwater redfish (Sebastes mentella), golden redfish (Sebastes norvegicus), and Acadian redfish (Sebastes fasciatus). Controversy exists concerning whether S. mentella and S. norvegicus are separate species because of similarity of meristic characters and other attributes. We describe a procedure that distinguishes these two forms by isoelectric focusing using polyacrylamide gels of water-soluble muscle proteins. In our samples, the lower part of the gel of S. mentella consistently shows three major protein bands, while that of S. norvegicus shows only one major band. The isoelectric focusing banding patterns from our study agree with those found by other workers for redfish from Greenland and Norway. The unequivocal isoelectric focusing separation and its concordance with morphometric characters indicate that S. mentella and S. norvegicus are genetically distinct, reproductively isolated species.

Reduction of hyperlipidemia in the LA/N-corpulent rat by dietary fish oil containing n − 3 fatty acids

The LA/N rat, when homozygous for the corpulent gene ( cp cp ), is obese, hyperphageous, hyperinsulinemic, hypertriglyceridemic and prone to the development of vascular and myocardial lesions. The hypertriglyceridemia, which in 3-month-old cp cp males is 282 ± 42 mg/dl and in females, 512 ± 83 mg/dl, results from the presence of a large triacylglycerol-rich VLDL. The moderate hypercholesterolemia in these animals is largely due to markedly elevated HDL levels, which reach 172 ± 21 mg total lipid/dl in males and 154 ± 22 mg total lipid/dl in females. The LA/N- cp rat is thus an interesting animal model of endogenous hypertriglyceridemia in which to examine the hypolipidemic effects of pharmacological agents and also dietary oil supplements containing the n − 3 fatty acids. In this study, 1-month-old male and female cp cp rats were fed a normal low fat laboratory chow supplemented with either 10% olive oil or 10% redfish ( Sebastes marinus) oil ad libitum for a period of 2 months. The redfish oil contained 4.9 ± 0.1% of its total fatty acids as eicosapentaenoic (20:5( n − 3)) and 2.3 ± 0.5% as docosahexaenoic acid (22:6( n − 3)), the predominant fatty acids being gondoic (20: 1( n − 3)), 21.9 ± 0.9% and cetoleic acid (22: l( n − 11)), 21.7 ± 1.7%, which are of dietary origin. Daily caloric intake was similar in the oil-fed versus control rats. However, the oil-fed animals weighed significantly more than the controls after 2 months of oil supplementation. Redfish oil reduced serum triacylglycerols by 54% in males and 45% in females after 2 months. VLDL levels, after the same time period, were reduced by 44% in males and 39% in females. HDL lipid mass was significantly reduced in both sexes (by 27% in males and 49% in females). However, the levels remained above those of male LA/N +/+ rats of the same age and Long-Evens rats. Olive oil feeding significantly reduced serum cholesterol, triacylglycerols and phospholipids in male but only cholesterol and phospholipids in female animals. This oil had no significant effect upon VLDL total lipid levels in either sex, but significantly increased the particle diameter with a concomitant reduction in the cholesterol and phospholipid content HDL total lipid levels were unaffected: However, HDL total cholesterol increased significantly in males only. Both oils markedly reduced serum LDL levels in both sexes. Female cp cp rats, at 11 weeks of age, fed fish oil for only 1 week had significantly reduced LDL (− 66%) and HDL (− 44%) levels with no significant change in VLDL when compared to controls. These data show that the LA/N- cp rat responds to dietary fish oil containing low levels of n − 3 fatty acids in a similar manner to other animal models and man, and suggest that HDL levels are more quickly modulated by the fish oil than VLDL levels.

Mathematical Model of Simultaneous Heat and Mass Transfer in Food with Dimensional Changes and Variable Transport Parameters

ABSTRACTThe variable grid central finite difference method was used in the solution of simultaneous heat and moisture transfer (SHMT) equations with variable transport parameters, providing predictions of local moisture content, temperature, and dimensional changes in an infinite slab at any time during processing. The model was applied to the air drying of ocean perch (Sebastes marinus). Good agreement between experimental results and model predications indicated that the method could be successfully applied to SHMT operations in foods involving dimensional changes.

A RESEARCH NOTE: PHYSICAL, CHEMICAL AND SENSORY CHANGES DURING THERMAL PROCESSING OF THREE SPECIES OF CANNED FISH

This study was conducted to determine the effect of species and formulation on the physical, chemical and sensory characteristics of catfish, ocean perch and Atlantic pollock during thermal processing. The results show that the changes in pH, thiamin, texture and Hunter ‘L’value during canning were different between species. There were no significant differences in the changes in cook-out volume, expressible moisture and TBA values between species. The formulation (water or oil) pack had no effect on the the physical, chemical and sensory tests conducted. The three canned species were judged by ten taste panelists as appetizing in color and flavor and moderate in fish aroma, tenderness, juiciness and overall acceptability.

Degradation of human epidermal keratin by fish pepsin

Stomach extract of Atlantic herring Clupea harengus, Atlantic salmon Salmo salar, cod Gadus morhua, redfish Sebastes marinus, and plaice Pleuronectes platessa, degraded human epidermal keratin effectively in vitro. The keratin-degrading activity of all extracts showed a pH optimum around 3.3-3.4, and sheets of plantar callus were degraded with about the same efficacy as keratin. Pepstatin sensitivity, heat lability, and the acidic pH optimum demonstrated that the keratin-degrading activity was pepsin. The keratin-degrading activity of cod stomach extract had a temperature optimum of around 42 degrees C at optimal pH, and showed a similar pH dependency with collagen as with keratin as substrate. The keratin-degrading activity of pepsin I and pepsin II purified from cod showed a pH optimum of 3.7 and 3.1, respectively, similar to that obtained with hemoglobin as substrate. Pig pepsin showed a pH optimum of about 2 with keratin, hemoglobin, and collagen as substrates. The present investigation demonstrates that fish pepsin is effective in degrading human epidermal keratin in vitro, and in a contemporary study the same was shown with fish trypsin. This may suggest a possible mechanism for the development of irritative hand eczema caused by exposure to fish and acidified fish material.

Anisakids and human anisakiasis. 2. Investigation of the anisakids of commercial fish in the district of Paris

1,173 fish belonging to 13 species were examined during 1986-1987, during a survey conducted among commercial marine fish in the Paris area (France). Anisakis simplex L3 were found in 10 different species, and most frequently in herring (Clupea harengus) 82.55% of 682 fish, red fish (Sebastes marinus) 86.11% of 36 fish, and hake (Merluccius merluccius) 88.57% of 35 fish, and in high number (average 8.8, 18.4 and 31 L3 per fish). Pseudoterranova decipiens L3 were recovered from 7 different species of fish but always in small amounts. Hysterothylacium spp. larvae were found in very high number out of 11 species of fish. They were inoculated to adult rats, but failed to develop. A 30 degree C temperature killed these larvae, avoiding any risk of human infestation. Few Contracaecum larvae were found in whiting (Merlangus merlangus).

Estimates of age and growth of ocean perch, Helicolenus percoides Richardson, in south-eastern Australian waters

Methods of age determination, age and the parameters of the von Bertalanffy growth function are described for ocean perch, Helicolenus percoides Richardson, from the continental slope in eastern Bass Strait. Comparison of scales and otoliths revealed the latter to be superior for age estimation. Annuli were used for age determination; 97% of whole otoliths with 2-15 annuli were readable, compared with only 37% of older (15 + annuli) otoliths. Of sectioned otoliths with 15 + annuli, 81% were readable and the oldest age estimated was 42 ( �3) years, compared with only c. 30 years from whole otoliths. For whole otoliths, the precision of intra-reader and inter-reader age estimates was, respectively, 89% and 79% within �1 annulus, and the average error was 4.6% and 5.0%. For sectioned otoliths, intra- and inter-reader precision was, respectively, 60% and 53% within k 1 annulus and the average error was 3.9% and 5.4%. Comparison of age estimates from whole otoliths and sectioned otoliths gave a precision of 84% within �1 annulus and average error of 2.8%. Precision of age determination decreased with increasing age for both methods. Age validation, using Petersen's length-frequency method and a marginal-increment method, was unsuccessful. Mean length-at-age and the values for the parameters of the von Bertalanffy growth function were estimated. For female and immature fish: K = 0.107 and L∞ = 44.68 fork length (cm), and for male and immature fish: K = 0.115 and L∞ = 43.19 fork length (cm). The growth of males and females was statistically different.

Genetic Variation and Population Structure of Pacific Ocean Perch (Sebastes alutus)

We conducted an allozyme analysis of 27 collections representing over 1500 individuals of Pacific ocean perch (Sebastes alutus). Data were gathered from 25 presumptive loci of which 20% were polymorphic. Average observed heterozygosity was 0.069. Samples originated from throughout the commercially important range of the species from the Washington coast to the Bering Sea. Pacific ocean perch are highly similar throughout the range, with only a slight amount of population differentiation (FST = 0.023). However, a cline of gene frequencies within the Gulf of Alaska exists at Ada2, and there are significant frequency differences between the extremes of the range for several additional loci. There is no evidence of an interruption of gene flow between the western Gulf of Alaska and the Bering Sea. Stock delineations based on age structure, age–length relationships, and ages at maturity were not supported by the allozyme data and are either influenced by nongenetic environmental factors or are under a selective regime not measured by allozyme analyses.

Ingestion of Fish Oil or a Derived n-3 Fatty Acid Concentrate Containing Eicosapentaenoic Acid (EPA) Affects Fatty Acid Compositions of Individual Phospholipids of Rat Brain, Sciatic Nerve and Retina

The effect of feeding redfish (Sebastes marinus or mantella) oil or a derived n-3 fatty acid concentrate containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the fatty acid compositions of individual phospholipids in selected neural tissues was studied in growing male rats. Control animals were given sunflower oil in the diet for the 5-wk feeding trial. Lipid analyses revealed that EPA (20:5n-3) became significantly enriched in all phospholipid fractions (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol) in the tissues studied (brain, retina and sciatic nerve) in the two n-3 fatty acid dietary groups relative to controls. Corresponding changes were also found in the 22:5n-3 contents of these tissues, whereas little or no significant elevation in DHA (22:6n-3) was found. In contrast, the percentages by weight of the n-6 fatty acids including 18:2n-6, 20:4n-6 (arachidonic acid, AA), 22:4n-6 and 22:5n-6 were generally lower in the various phospholipids/tissues of the animals given fish oil or the n-3 fatty acid concentrate; the levels of 22:5n-6 and 22:4n-6 were markedly affected in this regard. These results indicate that dietary n-3 fatty acids (as EPA plus DHA) can greatly affect the fatty acid compositions of the various membrane phospholipids in nervous tissues within a relatively short time. These biochemical alterations may be important for functional changes including altered membrane fluidity, cellular responses, ion transport and the biosyntheses of AA- and EPA-derived prostaglandins and leukotrienes.

U.S. Demand for Selected Groundfish Products, 1967–80: Comment

In a recent paper in this Journal, Tsoa, Schrank, and Roy (hereafter TSR) present a model of the demand for groundfish in the United States. Their modeling strategy is a departure from other analyses of this in that they estimate the reduced form of a system of inventory-price expectations equations rather than the more traditional system of demand and supply relationships. Using data from 1967 to 1980, they estimate a single equation derived from their simultaneous equations model. They find perverse elasticities; the demands for cod, haddock, and redfish (ocean perch) fillets are all inelastic in the short run, and all product forms (including frozen fish blocks) are income elastic. They thereby concluded that since the demand for various groundfish fillets is price inelastic, a recession in the United States will exert strong downward pressure on prices for these products if they are to be absorbed by the U.S. market (p. 489). They also draw conclusions as to the expected result of extended fisheries jurisdiction (EFJ): If EFJ results in an increase in the supply of fish products in the United States due to both increased do-

Shrinkage in Fish Muscle During Drying

ABSTRACTShrinkage of rectangular slabs of ocean perch (Sebastes marinus) in all three dimensions during air drying at 24.5°C, relative humidity 35% and velocity 35.6 m/min was determined. Percent change in dimensions with volume fraction of water was measured. It was observed that the dimension along the major axis of muscle fibers (length in this case) shrinks far less than the other two dimensions. Maximum shrinkage in length was 20%, while for width it was 50.5% and for thickness, 50.6%. At 95% confidence level, there was no significant difference between thickness and width shrinkage.

Morphometric Differences between Golden Redfish (Sebastes marinus) and Beaked Redfishes (S. mentellaandS. fasciatus)

Morphometric Differences between Golden Redfish (<i>Sebastes marinus</i>) and Beaked Redfishes (<i>S. mentella</i>and<i>S. fasciatus</i>)