摘要:

A method that can be carried out within 24–72 hr is suggested for determining the tendency of fish muscle to become rancid. It consists of adding measured, trace amounts of copper ion to muscle that has been blended with water (1:3) followed by storage at 0 °C. Rancidity is observed subjectively by noting the odours that develop and objectively by means of the thiobarbituric acid reaction.

ISSN:0706-652X    

DOI:10.1139/f64-115

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

In a study of copper-catalyzed rancidity of cod fillets it has been found that: (1) muscle from the tail section goes rancid faster than muscle from the head or centre sections; (2) there is no apparent difference in the development of rancidity in the inner and outer halves of fillets that have been sliced lengthwise; and (3) sensitivity to rancidity changes with the season and is greater in the winter and early spring than in the summer and fall.

ISSN:0706-652X    

DOI:10.1139/f64-116

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Actively growing bacteria suppress the development of copper-catalyzed rancidity in lean fish muscle. Apart from the antioxidant effect of the bacteria themselves, it could not be shown that fish muscle undergoing microbial deterioration became any less susceptible to oxidative rancidity as spoilage progressed.

ISSN:0706-652X    

DOI:10.1139/f64-117

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

In the diatom,Skeletonema costatum, as well as in a zooplankton sample, the polyunsaturated fatty acids of the triglycerides were found accumulated in the β-position of the glycerol. This fatty acid distribution pattern is typical for animal fats, in particular for fish oils. Together with the recent demonstration that fish and invertebrates retain in part the structure of ingested triglycerides, the findings of the present study show that the typical structure of marine triglycerides originates in phytoplankton and is to a large degree retained through the marine food chains.The fatty acid composition of several other lipid fractions of the plankton samples was also determined.

ISSN:0706-652X    

DOI:10.1139/f64-118

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

A study of egg recruitment to pink salmon spawning beds in two southeastern Alaska streams (Indian Creek and Harris River) has shown that egg loss during spawning increases as the density of female spawners increases. Mortality was caused for the most part by superimposition of redds.A mathematical model of spawning success is derived. The model assumes that the curve describing the recruitment of eggs to a spawning bed is asymptotic and that pink salmon females spawning within any denned spawning ground select the sites of their redds at random. The model is used to estimate the asymptotic limit of the egg recruitment curve for a Harris River spawning bed. Levels of mortality associated with various densities of spawning female pink salmon are predicted for Harris River from the model.

ISSN:0706-652X    

DOI:10.1139/f64-119

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Sodium tripolyphosphate treatment before packaging and freezing of fillets of trap-caught cod (Gadus morhuaL.)in-rigorwas compared with treatment in plain water.The once-frozen treated fillets, evaluated by an analytical taste panel after frozen storage at −12°F (−24.5 °C) for periods up to 27 weeks, had significantly better texture characteristics than did the untreated control fillets.Thaw-drip was significantly smaller in treated samples but this effect was less pronounced after extended frozen storage.Lipid hydrolysis proceeded at the same rate in both treated and untreated fillets.There was no significant difference between the electrophoretic patterns of the proteins found in the treated and untreated samples. In both cases the muscle albumins constituted the major portion of the proteins in the drip.Results indicate that polyphosphate-treated fillets prepared from trap cod could have greater market acceptance than untreated fillets. The producer would benefit from improved quality of product and from increased yield.

ISSN:0706-652X    

DOI:10.1139/f64-120

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The ranges, habitats, and commercial importance are described for nine species of the family Pandalidae:Pandalopsis dispar,Pandalus jordani,P.borealis,P.platyceros,P.hypsinotus,P.danae,P.montagui tridens,P.stenolepis,P.goniurus. A key for their identification is given. Over 27,400 specimens were sampled, using trawl and trap gear, mostly from the Strait of Georgia.Pandalopsis disparis a male atyears, attaining a total length of 136 mm and body weight of 6.5 g; at 30 months, in the female phase, the length is 169 mm and weight 16.3 g.Pandalus jordanimatures as a male, and to a lesser extent a female, at about 18 months, reaching a length of 105 mm and weight of 3.8 g; atyears all are in the female phase, averaging 118 mm in total length and 5.8 g in body weight.P.platycerosis first a male atyears, attaining a length of 140 mm and weight of 14.2 g; most remain as males for another year, and atyears the total length is 180 mm and weight 35.5 g.Pandalus hypsinotusmatures as a male, and to some extent as a female, at aboutyears, at a total length of 124 mm and weight of 10.3 g; at 30 months the length is 130 mm and weight 12.7 g. Almost as many females as males ofP.borealismature atyears, attaining a length of 95 mm and weight of 3.2 g; at 30 months, in the female phase, the length is 119 mm and weight 6.1 g.Pandalus danaematures first as a male, and to some extent as a female, atyears, reaching 88 mm in length and 4.4 g; in the female phase, atyears the length is 105 mm and weight 8.5 g. Growth ofP.montagui tridens,P.stenolepis,and P.goniurusis uncertain, but all undergo sex change. Growth as related to habitat and early maturing of females as related to geographic and bathymetric ranges are discussed.

ISSN:0706-652X    

DOI:10.1139/f64-121

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The schooling behavior of both light- and dark-adaptedAstyanax mexicanus(Fillipi) was observed under sudden changes in illumination in the range 10−7to 100 ft-c at different times in the diel cycle. In darkness the fish were dispersed, swam slowly, and showed no signs of mutual recognition of one another. There was no simple relationship between the schooling response and the illumination, but in general the frequency, size, and durability of schools were proportional to the illumination. Schooling was maximal above 10−1 ft-c and approached zero at 10−6 ft-c. The schooling at any level of illumination varied with the testing procedures. The lowest responses were obtained with a gradual reduction of illumination in the evening. At illumination below 10−2 ft-c maximal schooling was obtained from dark-adapted fish. From 10−2 ft-c upward, it was obtained from light-adapted fish. The schooling rate (number of fish in a school) reached 100% for a few seconds at 10−3 ft-c and for longer periods at higher illumination, but was never sustained at the 100% level throughout any 4-min period. Schooling was generally enhanced by any sudden change in illumination but was never sustained at a high rate under monotonous conditions. The decline with monotony was equated with reduction of the fright situation. The decline with reduced illumination was attributed to the reduction of visual acuity and visibility, and occurred at a greater rate among faster-swimming fish.Notemigonus crysoleucas(Mitchill), swimming very slowly, exhibited high schooling rates at 10−5 ft-c. Earlier work showed that the retina ofAstyanaxin continuous darkness undergoes a rhythmic diel shift. The behavior showed that this retinal shift is not the classical transformation from scotopic to photopic vision. Dark-adapted during the day, the fish demonstrated rapid visual perception under sudden illumination at any value from 10−6to 10−0.69 ft-c. Dark-adapted fish at night exhibited increasingly longer light-shock reactions with sudden illumination above 10−2 ft-c. According to schooling responses the cone threshold was about 10−3 ft-c, and the rod threshold about 10−6 ft-c. The mesopic range extended from about 10−3to 10−2 ft-c.

ISSN:0706-652X    

DOI:10.1139/f64-122

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Calcium and carbonate ion concentrations have been measured in the upper 100 m in an area southwest of Greenland. The values indicated that these waters were about 100% supersaturated with respect to calcite and about saturated with respect to aragonite. Because of the large influx of CO2from the air in this region it was concluded that considerable CO2must have been utilized or there would have been evidence for the transport of this gas to lower levels.

ISSN:0706-652X    

DOI:10.1139/f64-123

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The compound responsible for the characteristic odour of fresh Pacific oysters,Crassostrea gigas(Thunberg), has been identified as dimethyl sulphide [(CH3)2S], by the formation of mercury salts, and by infrared analysis and gas chromatography. The effect of bacterial action on the oysters has been observed and a number of the volatile organo-sulphur decomposition compounds, produced during room storage at 20–21 °C, have been identified by gas chromatography and by the formation of their lead and mercury salts.

ISSN:0706-652X    

DOI:10.1139/f64-124

出版商:NRC Research Press    

年代:1964

数据来源: NRC