摘要:

Red cell numbers and haematocrit values were notable principally for their constancy during a 10-day experimental period following the exposure of goldfish acclimated to 20 C to an abrupt increase of 10 C in environmental temperature. Mean erythrocytic volume underwent a transient decrease while total blood iron (and presumably haemoglobin) and mean erythrocytic iron content fell slightly during the latter portion of the period of observation. Goldfish maintained at 5 C were typically characterized by two haemoglobin polymorphs, a third fraction being commonly found in animals acclimated at 12, 20, and 30 C. The observations are discussed in relation to the respiratory acclimation of this species to increases in environmental temperature.

ISSN:0706-652X    

DOI:10.1139/f66-104

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Embryos of the brook trout (Salvelinus fontinalisMitchill) were incubated in reduced levels of dissolved oxygen of approximately 2.5 ppm, 3.5 ppm, 4.5 ppm, and a control level near air-saturation (10 ppm) at each four temperatures, 2.5, 5.0, 7.5, and 10.0 C, from fertilization to a late stage of development. Embryos of the rainbow trout (Salmo gairdneriRichardson) were incubated in a similar experiment at levels of oxygen approximating 2.5 and 3.5 ppm and a level near air-saturation at each of the four temperatures, to a similar, late stage of development. A third small experiment was conducted in which embryos of rainbow trout were incubated at 12.5, 15.0, and 17.5 C, at a level of dissolved oxygen near air-saturation. In all instances for both species the velocity of embryonic development, measured by the times required to attain a series of selected embryonic stages, was accelerated by increasing temperature. The velocity of development was increasingly retarded by progressively lower levels of dissolved oxygen. The times required to affect hatching and the lengths of the periods of hatching were similarly influenced by temperature and by the level of dissolved oxygen. These findings are discussed in the light of pertinent literature.

ISSN:0706-652X    

DOI:10.1139/f66-105

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Sixteen species of oceanic shrimps, seven Penaeidea and nine Caridea, appeared in 244 collections made within the upper 1500 m at one station in the northeast Pacific off Oregon. Most of the species were primarily mesopelagic in distribution.The most abundant species,Sergestes similis, was the only shrimp common in epipelagic waters at night and the only species clearly demonstrating diel vertical migrations. Night catches exceeded day catches in near-surface waters, while day catches exceeded night catches at mid-depths.Sergestes similismigrated into the upper 50 m at night and on one occasion was collected at the surface.

ISSN:0706-652X    

DOI:10.1139/f66-106

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

On the Scotian Shelf,Argentina silusAscanius was found mainly along the continental slope but extended into the deep-water basins of the central shelf. It was not found in the Bay of Fundy, and only a few were found in the Gulf of St. Lawrence. It was found in largest numbers in depths between 100 and 150 fath (183–275 m) and at temperatures between 4 and 10 C.Although larger fish were usually found deeper, in general argentines from the slope region had a modal length of 21–28 cm and were from 2 to 7 years of age. Argentines taken from Emerald Basin had a modal length of 18–22 cm and were 1 or 2 years of age in autumn, but had a modal length of 30–36 cm and were 6–11 years of age in winter.Spawning occurred in the spring in Emerald Basin with males maturing around 25 cm and females around 30 cm.Since argentines grow slowly after the first few years and do not mature until several years after growth slows down, it is possible that heavy fishing might quickly reduce stocks and catches below current levels.

ISSN:0706-652X    

DOI:10.1139/f66-107

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The general distribution ofCentrolophus nigerin the North Atlantic is reviewed including the first two records from the Canadian area and two additional records off the New England coast to add to the four previously recorded from this area. Two new records from the Dana collections extend the distribution of this species westward in the oceanic area between Iceland and the Azores. All known records of the rarely capturedCentrolophus britannicusare presented. These include 34 previously published records from the northeastern Atlantic, eight new records from the northeastern Atlantic and the first seven records from the northwestern Atlantic, from Flemish Cap and the southern Grand Bank to North Carolina.In separatingC.nigerandC.britannicussome meristic characters are useful:C.niger, D. 35–41, A. 23–25, P. 20–23, gill-rakers on lower limb 1st arch, 13–15;C.britannicus, D. 44–51 (one, 55), A. 27–33 (one, 25), P. 18–21 (one, 16), gill-rakers on lower limb 1st arch, 11–13. Some body proportions are also important: the bases of the dorsal and anal fins are longer inC.britannicusand the distance from the snout to the anterior base of the dorsal fin usually greater. The length of the caudal peduncle is distinctly greater inC.niger.InC.nigerthe flesh is firm and the skin tough whereas inC.britannicusthe flesh is flabby and the skin delicate. The peritoneum ofC.britannicusis usually dark and that ofC.nigerusually light.

ISSN:0706-652X    

DOI:10.1139/f66-108

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Oxygen dissociation curves were constructed at three tensions of carbon dioxide, viz: 0–1 mm Hg, 10 mm Hg, and 40 mm Hg; and at five temperatures: 0, 5, 15, 20, and 25 C. Carbon dioxide dissociation curves were constructed at 5 C only. Gas tensions in mixed venous blood were determined for four salmon at 5 C. Oxygen dissociation curves at three temperatures were carried out for fish acclimated to summer and winter conditions.The physiological function of the blood of Atlantic salmon (Salmo salar) is well adapted for the range of temperatures encountered. As is the case for other salmonids, the adverse effect of low temperature is opposed by an increased sensitivity of the blood to carbon dioxide. No influence of acclimation was observed for the effect of carbon dioxide on the equilibrium between oxygen and hemoglobin.

ISSN:0706-652X    

DOI:10.1139/f66-109

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Acoustical, underwater photographic, and bottom sediment sampling data indicated that the major geomorphological features of the shelf throughout the southern Gulf of St. Lawrence are not related to the present environmental conditions. Submarine troughs and tunnel valleys give ample morphological evidence of extensive Pleistocene glaciation. Bottom samples and acoustical records revealed that sandstone bedrock with an intermittent veneer of sediments occurs on the sea floor between Prince Edward Island and the Magdalen Islands, as well as to the north of the Magdalen Islands. In contrast, the shelf areas west and east of the Magdalen Islands have an almost continuous sediment cover with only small exposures of bedrock. These sediments are considered to be mainly the erosional products of the local bedrock. Areas of elevated bottom relief such as Bradelle Bank are bedrock elevations on top of which there is a nearly continuous but relatively thin sediment cover. A submarine terrace between approximately 28 and 34 fath, well developed around the Magdalen Islands, is considered to mark a former sea level.

ISSN:0706-652X    

DOI:10.1139/f66-110

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Reexamination of published data on growth and feeding of fishes shows that when fish are fed on one type of food, the logarithm of the gross growth efficiency (log K) decreases with increase in rations. For a number of species and experimental situations this relation is adequately described by the linear equationwhencewhere ΔW is the growth, R the rations intake during the period of time Δt, andaandbare the parameters fitted to the linear form of the equation. With a single food-supply level, rations are highly correlated with body weight so that either one may be used to predict the growth efficiency. However, comparison with experimental situations which induce changes in rations intake at given body size, suggests that body size is not the determining factor as long as environmental conditions are within the normal biokinetic range. That is, the basic pattern of distribution within the animals of the energy intake is described by a knowledge of the rate of intake and two parameters.The action of various environmental factors appears to be reflected in this equation in different ways. In the experiments examined changes in temperature, which are known to affect the level of total metabolism, affected the value of R but the parametersaandbremained unchanged. That is, temperature changes appeared to affect only the energy turnover rate, not the distribution of energy in the fish. By contrast, changes in factors such as salinity and metabolic wastes, which are known to affect the metabolic load, affected the values ofaandb, and showed interaction with body-size as well. The factor having the most important influence on the parameters seemed to be the type of food, especially with respect to particle-size. We infer that this simple effect on the linear equation is a characteristic expression of the complex integration of expenditures during searching and grazing with the success of this activity.These observations imply that the growth efficiency equation, or what we term K-line, provides a useful index of the costs of particular behaviour patterns in particular ecological situations. Together with observations on metabolic rates it may also be used to describe the growth of fishes in relation to their food supplies. It is thus a potential indicator of the relative positions of life-history phases of various species in the production system represented by a natural community.

ISSN:0706-652X    

DOI:10.1139/f66-111

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Corpuscles of Stannius tissue of Atlantic cod (Gadus morhuaL.) transformed [4-14C] pregnenolone to progesterone and [4-14C] progesterone to 11-desoxycorticosteronein vitro. These results establish the presence of 3β-hydroxysteroid dehydrogenase, Δ5-3-ketoisomerase and 21-hydroxylase. Transformation of the14C-steroid precursors to several as yet unidentified substances also occurred.

ISSN:0706-652X    

DOI:10.1139/f66-112

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f66-113

出版商:NRC Research Press    

年代:1966

数据来源: NRC