摘要:

The effects of severe muscular exercise were studied in-year-old rainbow trout (Salmo gairdneri). Changes in the oxygen and carbon dioxide content of blood taken from the heart together with alterations in blood levels of pyruvate and lactate were followed in 14 separate conditions. Observations were also made on fish swimming steadily in a rotating annulus.

ISSN:0706-652X    

DOI:10.1139/f66-072

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

A study of herring was undertaken at the onset of a period of increased exploitation. Catches were examined for length and age composition, growth rates, length–weight relationship, sex, maturity, and fatness.Mean length (33.0 cm) and mean age (8.2 years) were smaller than recorded from earlier investigations, but growth rates have not changed appreciably. Winter-caught herring are of poor quality ranging in fat content between 2.3 and 7.7% of their wet weights.An increase in the proportion of herring with immature gonads as the season progresses and a complete gradation of otolith types from spring-spawned to fall-spawned types suggests: (1) exploitation of fish that previously did not enter the fishery until later in the season, and (2) a spawning season that extends over the spring, summer, and autumn months.

ISSN:0706-652X    

DOI:10.1139/f66-073

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

A new speciesBradyidius saanichifrom Saanich Inlet, Vancouver Island, British Columbia, Canada, is described and illustrated in detail. This species is closely related toB.pacificus(Brodsky, 1950) among the six previously known species in the genus, but can be readily distinguished from the latter by the strongly divergent rostral rami in addition to some other differences.

ISSN:0706-652X    

DOI:10.1139/f66-074

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Kraft pulp mill bleachery effluents and those from the unbleached screening operation were tested, separately and in combination in the proportions as they would exist in the main effluent of a particular mill, for toxicity to young Atlantic salmon,Salmo salar.The bleachery component from the chlorination stage, tested under neutralpH conditions, was considerably more toxic than the other components.Major reductions in the toxicity of the chlorination stage component were accomplished by treating it with small quantities of sulphur dioxide. Lesser but still appreciable toxicity reductions were observed in the whole effluent when the chlorination component was thus treated before combination with the other components.The toxicities of laboratory-produced filtrates from certain modified first-stage (chlorination) bleaching procedures were also evaluated. Notably, much less toxic filtrates resulted when substantial mixtures of chlorine dioxide and chlorine were substituted for the normal chlorine dosage in the first bleaching stage.A number of other treatments, methods, and their relative effectiveness are discussed.

ISSN:0706-652X    

DOI:10.1139/f66-075

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Oceanographic observations taken along the line between Ocean Station P (50°N, 145°W) and Swiftsure Bank (48°32′N, 125°00′W) from January 1959 through January 1962 showed that the annual variation of temperature was determined primarily by the heat exchange across the surface and only secondarily by currents. Salinity variations were related to freshwater runoff from land and the component of Ekman transport normal to the coast. Variations of depths of isopycnal surfaces appeared to be related to the curl of wind stress, except near the coast. However, the observed vertical movement of isopycnal surfaces was much larger than that calculated from the wind stress. Near the coast, the vertical movement was related to the component of Ekman transport normal to the coast.The average total transport through the section, as calculated from the curl of the wind stress, was 5.8 million metric tons per second and was directed northward. The average baroclinic flow was 13 million metric tons per second. These transports were consistent if the mean depth of no motion was at 1400 m with southward flow in the bottom portion.

ISSN:0706-652X    

DOI:10.1139/f66-076

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

In an earlier paper we described the growth of fishes, ΔW/Δt, in relation to the experimentally measurable variables, body weight (W), food intake (R), and total metabolism (T). Here we review experimental evidence of the nature of the relation between T and W, and its dependence on R and temperature. Making use of the basic energy equation,pR = T + ΔW/Δt, wherepis the term for correction from injested to utilizable energy, we calculate T as the difference between the energy equivalents of R and ΔW/Δt, for comparison with results of oxygen consumption studies. Application to a number of published experimental results suggests that with constant food availability, this index of total metabolism, T, derived from feeding experiments, shows the same rate of change with body weight, W, as has been found by oxygen consumption studies under standard conditions. That is, the two sources of data provide estimates of a common γ in the relationwhere α and γ are the fitted parameters for the curve.When fish are fed on a "maintenance" diet, the value of α calculated from the food-growth difference (the growth change is rarely nil in a given experimental observation period), appears to correspond with that characterizing the "routine" metabolic level in oxygen consumption studies. Higher α levels result from higher levels of food availability, and atad libitumfeeding α appears to approach the levels known in oxygen consumption studies as "active" metabolic levels. Temperature effects in the experiments were estimated from multiple regression analyses and showed an elevation of α with increasing temperature. The long-term effect of temperature on α was comparable with that predicted by the Krogh correction atad libitumfeeding, but was significantly lower when food was limited, as at "maintenance" feeding.From a survey of effects of different designs of feeding experiments on these metabolic parameters, it appeared that apparently aberrant values of the weight exponent γ may instead be mistaken interpretations of changes in the level of metabolism α. That is, within the limiting conditions of standard or active metabolism, changes in temperature during experiments or manipulations of the availability of food by the experimenter, sometimes unintentionally, elicit adaptative responses in the level of metabolism, α. These show up in the results as effects on γ when the changes in conditions are gradual, hence confounded with body-size changes during growth.The ability to make distinctions between effects of various factors on these two metabolic parameters appears to depend upon a distinction between experiments conducted with a view to learning what fish do under particular circumstances, and experiments designed to explore what fish are capable of doing. The former type reveal a remarkable conservatism in the basic relation between metabolism and body size, γ. Results from the latter reflect possibilities of metabolic adaptation to environmental circumstances. The apparent predictability of the response of the total metabolism to various conditions of food energy supply and dissipation suggests that the remainder of the energy system, represented by the growth, may be similarly predictable. If this is true outside the laboratory, measurements of the metabolic parameters, α and γ, already familiar in physiological and behavioural research, could be directly used as indices of the (relative) positions of various sizes and species of fish in natural production systems.

ISSN:0706-652X    

DOI:10.1139/f66-077

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Gadus morhuaL. in captivity of ten develop unilateral or bilateral exophthalmia, characterized by the accumulation of gas bubbles in the eye.Rete mirabile-like organization of capillaries in the choroid "gland" in association with the glandular pseudobranch, which is a rich source of carbonic anhydrase in fishes, are involved in gas secretion in the eye of cod. Intraperitoneal injections of Diamox and pseudobranchectomy prevented exopthalmia in the fish.Presence of glycogen and carbonic anhydrase in the choroid gland in relation to gas secretion in the eye suggests a parallel with the process of gas secretion in the teleostean swimbladder.Gas secretion in the eye of cod resulting in exopthalmia would seem to be a malfunctioning of the choroid gland-pseudobranch complex in the fish triggered by unknown stimuli.

ISSN:0706-652X    

DOI:10.1139/f66-078

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f66-079

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f66-080

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f66-081

出版商:NRC Research Press    

年代:1966

数据来源: NRC