摘要:

The variation in the K+/Na+and Ca++/Na+ratios in highly diluted sea waters near the heads of two British Columbia inlets has been determined flame photometrically. Although the values agree in general with those calculated from the effect of dilution, discrepancies larger than the analytical error appear. These discrepancies may be explained by cation exchange processes taking place where the silt suspended in the river meets the sea.

ISSN:0706-652X    

DOI:10.1139/f56-017

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Removal of the gills from Atlantic cod and haddock definitely retarded the development of off odours and spoilage when the fish were examined as whole gutted fish. It did not make any observable or measurable difference in the quality of fillets cut from these fish.

ISSN:0706-652X    

DOI:10.1139/f56-018

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The waters south of Nova Scotia are characterized by extremely sharp boundaries both in the horizontal and vertical planes. Temperature changes of the order of 3 Centigrade degrees per metre depth and of 1.5 Centigrade degrees in 100 metres' travel have been observed. Such boundaries must constitute significant barriers to the migration of marine life forms.

ISSN:0706-652X    

DOI:10.1139/f56-019

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

A comparison of the temperature–salinity relationships of waters found in the Arctic Ocean, Baffin Bay and Smith Sound shows that the deep Baffin Bay water originates in the Arctic Ocean rather than through an influx of a mixture of Labrador Sea deep water and Baffin Bay surface water, the salinity of which has been increased sufficiently by freezing to cause the water to sink, as suggested previously by other investigators.

ISSN:0706-652X    

DOI:10.1139/f56-020

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Pink salmon fry which have never schooled are negatively phototactic, prefer a cover of stones and do not emerge into bright light. Those which have schooled show a strong cover reaction when exposed to a rapid increase in light intensity but do not seek cover unless the change is abrupt. In general they remain in bright light after they have schooled. This change in behaviour occurs rapidly (15 minutes or less) when the fry school for the first time. Chum salmon fry establish a definite direction of swimming in the quiet water of a circular channel or basin. The established direction is stable and not permanently disturbed by light or darkness, by water currents, by strong avoiding reactions, by changing the location or by excluding direct skylight. The direction may be initially established in relation to water currents.

ISSN:0706-652X    

DOI:10.1139/f56-021

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Interspecific competition is defined as the demand of more than one organism for the same resource of the environment in excess of immediate supply. When two species are "competing for a niche" the term competition has been used to include phenomena such as predation of the two species on each other, competition to avoid a parasite, etc. Making this distinction in natural situations is unrealistic. In the limited sense in which interspecific competition is defined above, it is a discrete phenomenon, which with other phenomena such as predation, can be measured as a factor involved in interaction between species.Freshwater environments offer comparatively few opportunities for specialization in fishes. In consequence many species have a relatively wide tolerance of habitat type, a flexibility of feeding habits and in general share many resources of their environment with several other species of fish. Cannibalism and mutual predation are common complications of competitive relationships between species. The organization of freshwater fish communities is thus characterized by breadth at each level of the food chain rather than by a height of a pyramid of numbers. Flexible growth rate and high reproductive potential permit fish populations to tide over unfavorable periods of competition. In these circumstances it is difficult to separate the role of interspecific competition from other phenomena as a factor of population control. As a subordinate factor, predisposing fish to loss from other causes, interspecific competition may act to influence population levels. There is need for quantitative data and mathematical models for study of the types of population interaction typical in freshwater fish associations.

ISSN:0706-652X    

DOI:10.1139/f56-022

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

LarvalPorrocaecumsp. commonly infect Atlantic cod (Gadus callarias) in Canadian waters. Some of these larvae are known to be young stages ofP.decipiens, but this is not proof that only one species ofPorrocaecumparasitizes cod.The distribution of 13 marine species of adultPorrocaecumis reviewed. Only one species,P.decipiens, is known from Canadian Atlantic waters; its distribution is consistent with the distribution of infected cod.The frequency distribution of the lengths of about 875 larvalPorrocaecumfrom cod was examined, as was that of the lengths of the oesophagus, ventriculus, and intestinal caecum of about 200 larvae. These suggest that only one species is present in the samples.Body proportions of larvalPorrocaecumfrom cod agree more closely with those of adultP.decipiensthan with those of 10 other marine species of adultPorrocaecum.It is concluded that the larvalPorrocaecumin cod are probably conspecific.

ISSN:0706-652X    

DOI:10.1139/f56-023

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Mean annual air temperature at San Francisco, California, New Westminster and Masset, British Columbia, all had a rising trend from 1920 to 1940, then declined to 1950. Amplitude was greatest at Masset, least at San Francisco. The 20-years' rise is similar to the story in the North Atlantic ocean, but the recent decline has no parallel there. Prior to 1920 there were considerable differences among the above three stations. Mean annual ocean temperature at Nanaimo, B.C., is similar to air temperature at New Westminster since 1915. "Winter" ocean temperatures (February–April) show similar but not identical trends, and are thought to best represent conditions at the time eggs and larvae of most commercial bottom fishes are in the water.Suggestive short-term correlations have been observed as follows: 1. a positive correlation between winter temperature and abundance of brill 6 years later; 2. a negative correlation between winter temperature and rock sole abundance 5 years later; 3. a negative correlation between winter temperature and strength of year-classes in lemon sole. Over a longer period, there is much resemblance between the temperature history since 1910 and the abundance of halibut broods, as indicated by catch per unit effort 10 years later (southern grounds) or 12 years later (Western grounds). The relationship is positive, and for western grounds is similar even in details. Over a somewhat shorter period, blackcod abundance has varied inversely with winter temperature. Marked changes in abundance and distribution of true (grey) cod since about 1900 cannot be related to temperature series available.

ISSN:0706-652X    

DOI:10.1139/f56-024

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

In the water surrounding the head ofPetromyzon marinuselectric triphasic spike potentials can be recorded which recur rhythmically at 0.4-second intervals and are synchronous with the externally visible movement of respiration. At a distance of 15 to 20 mm. from the animal, above the eye region, the potentials are from 200–300 μv in an adult lamprey, in fresh water. The electric field produced by these potentials extends several centimeters frontwards of the head depending on experimental conditions and factors now being studied. Posterior to the gill openings the potentials taper off sharply and no spikes could be recorded 50–70 mm. posterior to the last gill opening. The field is symmetrical around the longitudinal axis of the animal under the experimental conditions described. Strychnine and cocaine do not affect the characteristics of the spikes but curare decreases their potential considerably, depending on amounts injected and the condition of the experimental animal. Light conditions do not affect the production of the spikes. The possible function of the electric field for the sea lamprey is discussed.

ISSN:0706-652X    

DOI:10.1139/f56-025

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

During May–September, 1948, an oceanographic study was made of Chatham Sound, primarily to determine, if possible, whether there was any obvious characteristic of the water in the region which could be correlated with the known migration of salmon to the spawning grounds up the Nass and Skeena Rivers. A detailed analysis of the oceanographic data is presented.The path taken by the fresh water through the sound is shown to depend on the volume of fresh water being discharged from the rivers. These reach their peak discharge in late May or early June and during this period the amount of fresh water in the sound is three to four times the average. Data obtained at anchor stations occupied for 10 to 40 hours indicate that there is a good correlation between tidal, salinity and temperature cycles.Dynamic calculations have been made of the velocities, total volume and fresh water transports. During normal river conditions, the agreement with observed velocities, and with fresh water discharges determined from gauge readings, suggests that even in these coastal waters there is an approximate balance between the transverse pressure gradient and the Coriolis force. Stations at the mouth of Portland Inlet exhibit an apparent balance at all times which suggests that transverse inertial and frictional forces are slight compared with the transverse pressure gradient and Coriolis force. Evidence of a variation in geopotential slope associated with the tides is proposed.The relatively large tidal amplitudes together with the wide and rapid fluctuations in river discharge make it exceedingly difficult to obtain reliable synoptic observations over the entire sound.

ISSN:0706-652X    

DOI:10.1139/f56-026

出版商:NRC Research Press    

年代:1956

数据来源: NRC