摘要:

About 1450 specimens of the decapod crustaceanPasiphaea multidentatawere collected in deep waters of the Gulf of Maine in 1966–69, and were examined for size, sex, weight, breeding, fecundity, and feeding. The sizes and sex ratios of the catches vary with the egg-bearing seasons, suggesting that ovigerous females are susceptible to greater predation. The data do not permit estimates of growth rates or age of maturity. The ratios of carapace length to total length differ in males and females. Two egg clutches per female per year were produced, the second clutch being smaller in numbers, probably because of "reproductive fatigue" in the female. In each clutch the number of eggs produced is a linear function of carapace length. About 50% of the stomachs were empty. Eighteen per cent contained crustacean remains of which about half could be identified as remains of the copepodsMetridia longa,M.lucens, andEuchaeta norvegica. Epizoic suctorians were found on a few shrimps.

ISSN:0706-652X    

DOI:10.1139/f69-187

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

A series of demersal fish studies were conducted throughout the northeast Pacific Ocean. The aims of these exploratory fishing surveys were: (1) to describe the zoogeographic distribution patterns of the animals encountered and the relationship of such patterns to observed environmental features; (2) to determine their relative abundance in time and space and to each other and their vulnerability to sampling gears; and (3) where possible, to establish approximations of the magnitude of important or potentially important commercial species together with estimates of the physical yields that these resources might provide. A general review is given of U.S. demersal fish explorations in the northeast Pacific Ocean along with the methodology employed. Methods for estimating standing stocks based on fish densities determined from catch-per-unit-of-effort data are given. Using this procedure, estimates have been made for the more abundant demersal fish forms in the northeast Pacific. Means of determining yield possibilities are suggested, based on natural mortality rates and standing stock sizes. This method assumes that the maximum sustainable catch will range from.4 to.5 of the virgin stock size times the natural mortality. Finally the authors evaluate the reliability of exploratory fishing surveys based on subsequent development of commercial fisheries in the northeast Pacific. The data appear to have provided a good basis for describing the distribution and availability of important demersal fish elements in this area. Although estimates of yield potentials are still being studied, the history of fisheries development has, to date, followed quite well what might have been expected as a result of the preliminary yield forecasts.

ISSN:0706-652X    

DOI:10.1139/f69-188

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Gross epibenthic algal production and benthic community respiration in Marion Lake, British Columbia, were measured during 1968 by following changes in dissolved oxygen over undisturbed sediment cores. No measurable chemical uptake of oxygen occurred during short-term experiments. Multiple regression analyses showed that in situ oxygen production by epibenthic algae was directly related to temperature, light, and community respiration and inversely related to day length. Mean weekly values of these variables were substituted into the regression to estimate annual gross algal production on sediment at various depths in Marion Lake. Photosynthetic efficiency ranged from 0.4 to 3.1% and increased with depth of water over the sediment. Sedimentary chlorophyll was stratified with highest concentrations in the upper few centimeters of sediment which corresponded to the depth of oxygen penetration.Measurements of in situ oxygen consumption showed that community respiration was related to temperature, oxygen concentration, and day length in a curvilinear manner. Oxygen uptake was minimal at midday and increased during the night. A multiple linear regression was derived, after suitable transformations, and mean weekly values of variables substituted to estimate annual community respiration.Bacterial respiration was measured as the difference in total community respiration when antibiotics were added to water over undisturbed sediment cores. Less than 30% of community oxygen consumption was inhibited by antibiotic treatment during the summer, whereas over 45% reduction occurred during the winter. Bacterial respiration was directly related to temperature and showed no significant correlation with oxygen concentration or other variables shown to affect community respiration. Macrofauna respired 33% of the total oxygen consumed by sediment cores during June, and epibenthic algae were estimated to account for 23% of community respiration. Net epibenthic algal production, calculated by correcting gross oxygen production for estimated algal respiration, was 85% of gross production during the summer.Annual carbon flux across the sediment in Marion Lake was estimated by comparing processes of carbon addition and removal. From previous studies, phytoplankton and macrophytes added 0.8 and 18 g C m−2year−1. Organic particulate matter from the inlet stream, other than macroscopic debris, contributed 143 g C m−2year−1and average gross epibenthic algal production was 40 g C m−2year−1. Community respiration consumed 57 g C m−2year−1. An additional 143 g C m−2year−1was lost as particulate matter in the outlet stream and emerging insects could remove 1.3 g C m−2year−1. Only 8 g C m−2was estimated to accumulate below the aerobic surface–sediment layer annually.

ISSN:0706-652X    

DOI:10.1139/f69-189

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Proximate analysis data for whole beach-spawning capelin from various parts of Newfoundland collected over a period of 20 years is generally similar when allowance is made for trends occurring during the brief spawning season. These trends, more evident in males, are, concurrently, a sharp decline in fat content, a slight increase in moisture, and a small decrease in protein. Ranges observed for these variables on a wet weight basis were, respectively, 8.1–1.8%, 77.1–82.3% and 15–12.9% (crude protein). Similar values were obtained for muscle tissue.

ISSN:0706-652X    

DOI:10.1139/f69-190

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Total lipids, triglycerides, and phospholipids from several lots of beach-spawning capelin and one lot of prespawning, offshore capelin have been determined and examined in detail for fatty acid composition. Generally, but not invariably, female fish contain more fat, the difference being apparent in the triglycerides. These are also usually of higher iodine value than triglycerides in the males. During frozen storage the lipids, including triglycerides, in most samples of male capelin undergo more severe hydrolysis than in the females. It is believed that these phenomena are related to bioenergetic relationships by which the males require very rapid catabolism of depot fat and hence nonspecific hydrolysis of fatty acids, whereas the less active females show some selectivity and preferentially catabolize the longer-chain monounsaturated fatty acids.When allowances are made for 16:1 and 18:1 being interchangeable, Newfoundland capelin triglycerides are shown to be essentially similar to eastern Atlantic commercial capelin oil, and may be distinguished by certain composition characteristics from other Canadian commercial oils of comparable iodine value. Details of fatty acid compositions are summarized for nutritional evaluation of capelin and capelin products.

ISSN:0706-652X    

DOI:10.1139/f69-191

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The reproductive biology of the blackspotted stickleback (Gasterosteus wheatlandi) closely parallels that reported elsewhere forG.aculeatus, with certain noteworthy exceptions.Gasterosteus wheatlandinests in brackish water of low salinity rather than in fresh water. The mature males are gold on the dorsal and lateral surfaces and white on the ventral surface with an irregular series of black spots along the ventro-lateral surfaces of the tail stalk, in contrast to the blue and red highlights of mature colouration inG.aculeatusmales. There are marked differences also in the behaviour by which males of the two species lead females to the nest. In the blackspotted stickleback leading consists in an intricate series of movements along the substrate, the male in a head-down position and quivering, the female in a head-up posture with her snout touching the male between his pelvic spines; in contrast,G.aculeatusmales simply swim to the nest entrance, the female following with no physical contact. Reproductive isolation between the two species probably depends on breeding habitat separation and female recognition of species-specific male colour patterns. When these fail, incompatible leading behaviours constitute an effective block to interspecific hybridization. Parental fanning inG.wheatlandiresembles that inG.aculeatusexcept that average bout duration is substantially less. Vertical quivering, a post-spawning activity of unknown function, is unique toG.wheatlandi.

ISSN:0706-652X    

DOI:10.1139/f69-192

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Pacific and Atlantic herring after adjustment to water 36 cm deep had sinking-factors between 1000 and 1008 and showed an inverse relationship between oil content and swimbladder volume up to 12% oil. At higher oil contents a swimbladder volume between 2.6 and 3.0% of total body volume was maintained. The mean volumes and densities of various components of the Pacific herring held in captivity were: swimbladder gas 4.1% of total volume,.0013 g/ml; oil 3.5%,.926 g/ml; scales 0.5%, 1.966 g/ml; skeleton 1.2%, 1.993 g/ml; rest of fish 90.6%, 1.057 g/ml. These components on the average exerted upward forces of 41.4 and 3.3 dynes/ml of fish due to gas and oil, and downward forces of 4.6, 11.2, and 32.1 dynes/ml due to scales, skeleton, and the rest of the fish respectively. Under natural conditions herring usually have high oil contents so the relationship observed here suggests they have low swimbladder volumes. This combined with a duct direct from the swimbladder to the exterior and the lack of gas secretion would give the herring freedom of vertical movement and a low change of sinking factor with depth.

ISSN:0706-652X    

DOI:10.1139/f69-193

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

A population of yearling Atlantic salmon parr was held in the laboratory from July to June in a negligible current at seasonal temperatures and photoperiods. Indirect measurements of swimbladder volume (pressure of neutral buoyancy) were made monthly on groups of 14–20 fish held for 24 hr either in still water or in a current (0.13 m/sec).Parr were consistently less buoyant in the current than in still water. However, seasonal changes occurred, particularly in the current. For parr in a current, buoyancy was lowest in early winter but increased throughout the spring until the parr–smolt transformation, when smolts in the current were just as buoyant as smolts in still water. The seasonal development of smolt buoyancy in a current was related to body size and water temperature but did not seem to be affected by photoperiod.The seasonal changes in swimbladder volume were not significantly correlated with tissue density (density of the gas-free fish), which in turn was not significantly correlated with the level of ether-extractable fat. However, the level of ether-extractable fat was significantly correlated with the coefficient of condition. At parr–smolt transformation, tissue density, level of ether-extractable fat, and coefficient of condition decreased sharply.

ISSN:0706-652X    

DOI:10.1139/f69-194

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The variations in the serum proteins of lobsters were studied by quantitative protein determinations, starch gel and cellulose acetate electrophoresis, and immunodiffusion. A series of bleedings from 15 lobsters provided serum samples for each stage of the molt cycle. Total serum protein was highest before the molt and lowest directly after the molt. The total serum protein averaged 2.5 g/100 ml in the intermolt lobsters and variation among individuals was limited. Variation of serum proteins in an individual during the molt cycle included changes in the electrophoretic and immunodiffusion pattern. Quantitative changes during the cycle indicate a relative shift in the concentrations of various proteins. One component of serum protein was associated only with the development of eggs and another component was present only during premolt and directly after molt.

ISSN:0706-652X    

DOI:10.1139/f69-195

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Three sets of experiments are described, all based on the electrical responses recorded in the olfactory bulb of salmon (Oncorhynchus tshawytschaandO.kisutch) when various natural waters, or modified natural waters, were infused into the nostril.In the first experiments it was found that, generally, the most vigorous response was evoked by the home spawning area water and relatively less vigorous responses were evoked by waters in which the tested salmon had never been. However, an exceptional situation was found in which a strange water (Issaquah River) evoked olfactory responses in Soos Creek and University of Washington salmon that could not be distinguished from the home water response.Chinook salmon that had been reared in a freshwater hatchery for 2 years and then placed in sea water for 2 weeks retained their home water response in sea water. Placing chinook salmon in a small volume of fresh water, which had previously evoked only a slight bulbar electroencephalographic (EEG) response, rendered the water highly stimulatory. Keeping coho salmon under the same conditions did not make the water as stimulatory.Two-year-old adult chinook salmon placed in a new environmental water that was relatively weakly stimulatory at first developed a bulbar EEG response to the novel water in 3 days that was not distinguishable from the home water response.

ISSN:0706-652X    

DOI:10.1139/f69-196

出版商:NRC Research Press    

年代:1969

数据来源: NRC