摘要:

Irradiation of cooked lobster (Homarus americanus) meat with a dose of gamma radiation of 75,000 rads extended the storage life, in ice, to between 28 and 35 days for both tail and claw meats from 14 to 21 days for unirradiated iced samples. Higher irradiation levels caused an immediate loss of quality due to toughening and loss of flavour. The growth of trimethylamine-producing bacteria was inhibited 10 days longer on irradiated samples than on the unirradiated iced control.

ISSN:0706-652X    

DOI:10.1139/f67-022

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Two new species,Gaidius columbiaeandTharybis fultoni, from the Strait of Georgia, British Columbia, Canada, are described and illustrated in detail. The former can be distinguished from all previously known species of its genus by the shape of the postero-lateral process of the metasome, and the latter by the shape of the 5th pair of legs.

ISSN:0706-652X    

DOI:10.1139/f67-023

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The influence of feeding on the changes that occur in the skeletal muscle content of sodium, potassium, and water in sockeye salmon (Oncorhynchus nerka) during sexual development and spawning has been investigated. Feeding has little, if any, effect on the changes. Thus it appears that the period of starvation these fish undergo during their spawning migration under natural conditions is not the major cause of the degeneration of their skeletal muscle, but rather that these changes are associated in some manner with the development of the gonads, presumably through the mediation of hormones.

ISSN:0706-652X    

DOI:10.1139/f67-024

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The Ricker method for predicting the yield per recruitment from a stock of fish under various conditions is superior to that of Beverton and Holt (1957) under most conditions because it permits greater flexibility of the input of growth and mortality data. Such useful devices as the isopleth diagram and the eumetric fishing curve, usually associated with the Beverton and Holt method, can be used also with the Ricker method. A computer program for the Ricker method is described, and its use is demonstrated with an example.

ISSN:0706-652X    

DOI:10.1139/f67-025

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Bankia setaceaprefer to attack upper horizontal wooden surfaces, whereasLimnoriaspp. prefer the lower surfaces. Attack byB.setaceais heaviest at the mudline and decreases almost linearly with decreasing depth. Limnorial attack is heaviest in the intertidal zone, then is relatively constant with increasing depth. Statistical studies showed non-normal distribution of populations, with limited replicability, particularly for lowBankiacounts. The desirable period of immersion is greater than 2 weeks, but in most commercial monitoring situations is limited to 1 month. Attack data on immersion specimens are compared with those on floating logs. On the basis of the results, procedures have been designed for monitoring attack in the commercial evaluation of impregnants, as well as for estimating population densities.

ISSN:0706-652X    

DOI:10.1139/f67-026

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Glycerylphosphorylcholine in rainbow trout (Salmo gairdneri) muscle stored at −4 C showed an increase from 36 μmoles/100 g in fresh muscle to 46 μmoles/100 g after 2 weeks. During longer periods of storage an approximately threefold increase in concentration took place, reaching 123 and 105 μmoles/100 g muscle after 9 and 17 weeks. Liberation of free choline was found to take place after 6 weeks of storage. There was very little change in the concentration of choline after 6 weeks storage when the value was approximately 100 μmoles/100 g. The release of free fatty acid during cold storage showed a general trend, which was similar to the formation of glycerylphosphorylcholine, but quantitatively the changes were more pronounced. Free fatty acids amounted to 45 μmoles/100 g in fresh muscle and rose to a plateau of approximately 1200 μmoles/100 g after 9 weeks of storage. The results are discussed in relation to the enzymic activity present in fish muscle.

ISSN:0706-652X    

DOI:10.1139/f67-027

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Experimental plantings of fin-clipped lake trout (Salvelinus namaycush) of various ages have been made in southern Lake Superior since 1952. The catch of planted lake trout by the commercial fishery was used to measure the success of stocking. Estimates of total returns were based on samples of 8.2 to 21.2% of the Wisconsin catches in 1955–62 and 36.4 to 46.8% of the Michigan catches in 1959–62. Marked lake trout were assigned to various plantings according to the fin mark, length of fish, readings of age from scales, and locations of capture.Estimated returns from Wisconsin plantings of 9-month-old lake trout varied from 2.1 to 6.4%. Wisconsin releases of 16-month-old fish yielded returns of 5.7 to 37.3%. Returns from plantings in Michigan were 0.3% for 9-month-old fish and 1.5 to 3.8% for 16-month-old fish. The ratios of the returns from plantings of 16-month-old fish to those of 9-month-old fish were 3.9:1 for Wisconsin releases and 6.7:1 for Michigan releases. Lake trout planted in Wisconsin generally survived better than those released in Michigan. Returns from fish planted at ages of 17 to 40 months in Michigan in 1958–59 were far greater than those from 16-month-old fish released in Michigan, but were not as high as from the most successful plantings of 16-month-old fish in Wisconsin. Lake trout released in 1960 from shore and from boats survived equally well.Average size of lake trout at release was more closely related to survival than any other factor. All except 1 of 10 highly successful releases were of fish larger than 22 per lb, and all 6 poor releases were of fish smaller than 34 per lb. Fish that ran 22 to 33 per lb survived only moderately well. A size of 17 to 20 fish per lb appears to be close to optimum.Abundance of native lake trout, American smelt (Osmerus mordax), and sea lampreys (Petromyzon marinus) all appeared to be unrelated to stocking success. The only apparent method of rapidly improving the success of stocking is to rear all lake trout to an average size of 17 to 20 per lb.

ISSN:0706-652X    

DOI:10.1139/f67-028

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The muscle myogens ofCatostomus catostomusexhibit polymorphism. Specimens from Great Slave Lake and Babine Lake were homozygous to pattern type A, whereas those from Lake Superior possessed patterns homozygous to A and B as well as the heterozygote AB. Those ofC.commersoni,Moxostoma macrolepidotum,M.anisurum, andM.erythrurumwere relatively uniform, showing only odd variants. The two specimens ofIctiobus bubalusexamined displayed different patterns. Blood hemoglobin patterns ofM.macrolepidotumexisted in five,M.anisurumin two, andC.commersoniin three polymorphic forms. The number of specimens ofI.bubalus,M.melanops, andCarpiodes cyprinusexamined was insufficient to assess the existence of polymorphism. Muscle myogen electropherograms of the eight species investigated reflect overall family resemblances, distinctive generic groupings as well as phylogenetic relationships which compare favorably with those in existence. Intergradations might occur upon a more extensive coverage of this family and which might somewhat obscure this overall picture are discussed.

ISSN:0706-652X    

DOI:10.1139/f67-029

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The amphipod sibling speciesAmpelisca vadorumandA.abditahave an overwintering generation and a summer generation. Breeding begins above 8 C. InA.abdita, breeding is probably correlated with the full moon. Curves of growth in length are linear, except where growth slows in winter. Length–weight curves are exponential, andA.vadorumis slightly heavier thanA.abditaat any given length. The slope of the length–weight curves is the same in both species. Growth in weight is not isometric; weight increases less rapidly than does length. In some allometric features the two species stop growth at different points on the same line, but other morphological features develop out of phase due to genetic differences in patterns of development. The two species differ in a number of biological features including egg size, metabolic contribution in egg production, relative gill area, and probably egg number. Reported "intersexes" are actually subadult males. The sex ratio in both species is always 1:1. Gonad growth and somatic growth have different temperature limits.Tubes, tube building, and feeding are described. Three major functional groups of ampeliscids show marked morphological adaptations to feeding type and sediment. Free swimming occurs at times of breeding, ensuring fertilization of eggs and dispersal of young to new and favourable environments.Ampelisca vadorumoccurs on course sand,A.abditaon fine sand to mud. Range, temperature, and depth preferences of these and other North AmericanAmpeliscaspecies are outlined. The fauna associated withA.vadorumandA.abditais described. The unique microtopography ofAmpeliscaareas affects the nature of the association.Ampelisca abditais successful in a crowded environment because it grows fast and breeds early. Ecological, life history, and taxonomic evidence all indicate thatA.vadorumandA.abditaare sibling species.

ISSN:0706-652X    

DOI:10.1139/f67-030

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Muscle tissue from four species of Atlantic fish (cod, dogfish, mackerel, and flounder) and one species of Pacific fish (sablefish) was examined for total lipid and α-tocopherol content. The values for α-tocopherol in both lean and fat major muscle tissues fell in the range 210–330 μg/g lipid. Lipids from cod and mackerel livers showed slightly higher values (430 μg/g lipid). These results are interpreted as the result of a lipid integration process in which the tocopherols produced by phytoplankton are redistributed with lipid through various lower life forms and small fish until similar levels are reached in the principal fats of larger fish. The metabolically active dark (lateral line) muscle of cod was twice as rich (630 μg/g) in α-tocopherol in proportion to lipid as white muscle tissue from cod. Lobster muscle was exceptionally rich (> 1200 μg/g) in α-tocopherol. Examination of starved cod indicated that large amounts of α-tocopherol remained after lipid depletion. Frozen flounder fillets showed no significant amount of α-tocopherol after 4 to 8 months frozen storage.Eight species of Atlantic shellfish were examinedin toto. Oysters and quahogs lost their α-tocopherol after several weeks of live-holding without food. In the oysters this was accompanied by muscle weakening and an objectionable odour. Most filter feeding species in the normal environment had 1–2.5% lipid and α-tocopherol values of 300–600 μg/g lipid, but a high proportion of organic detritus in the diet of mussels from one area reduced this level. The quahogs examined were extremely low (~0.60%) in lipid and therefore relatively high in α-tocopherol in proportion to lipid (> 1000 μg/g). Herbivorous periwinkles and accompanying predatory dogwinkles had the highest α-tocopherol contents on a fresh weight basis (35 and 21 μg/g tissue) and high values in proportion to lipid (~850 μg/g).

ISSN:0706-652X    

DOI:10.1139/f67-031

出版商:NRC Research Press    

年代:1967

数据来源: NRC