摘要:

Saanich Inlet is a fjord (24 km long) having a submerged (75-m) sill at the entrance, behind which there is a deep (234-m) basin. The properties of the water have been observed from time to time from 1927 through 1960. The resulting data are reviewed to provide representative values and structures of temperature, salinity, density (σt), dissolved oxygen content and sound velocity for each month throughout the year. Above the sill depth the properties of the water are normal and continuous with those in the approaches which connect with the Strait of Georgia. The waters below the sill depth are isolated, oxygen-deficient, and usually contain hydrogen sulphide. There is considerable ambient variation in the structures because the currents are too weak to disperse or mix the locally generated concentrations.The runoff into the head of the inlet is negligible. The major source of fresh water is in the approaches. It intrudes the inlet and provides a weak estuarine flushing mechanism above the sill depth. The waters below the sill are flushed only when the water in the approaches becomes sufficiently dense to cascade over the sill into the deep basin.The sound-ranging conditions are far from ideal. From March through July there is a major sound channel at mid-depths above the sill. This vanishes in August and a sound divergence zone develops and persists until December. In addition, the ambient variations provide anomalous transmission conditions.During the autumn (September through November) high concentrations of fish have been observed at the sill depth, associated with the oxycline. Probably the fish are attracted to the area by very large concentrations of zooplankton (Euphausids) that have been observed there at the same time.

ISSN:0706-652X    

DOI:10.1139/f62-001

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Trout taken from deep waters of Lake Superior are of two subspecies—a fat one and a lean one—that vary greatly from each other in physical characteristics and in chemical composition. The fat species has a smaller head, larger body, and lighter colour. The percentage of oil does not reach 20% in the fillets of the lean species, whereas it may reach 67% in fillets of the fat species, which has the highest known oil content of any fish.

ISSN:0706-652X    

DOI:10.1139/f62-002

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Oceanographic data gathered along the west coast of Vancouver Island since 1933 have been examined in an effort to derive an appreciation of oceanographic processes in this region.One area, which was the source of most data, was chosen as representative for the study, principally to satisfy continuity and partly to offset the tendency to use isolated sets of data as examples of "typical" coastal structure under rather general circumstances.The temperature and salinity structures and distributions are revealed as basically being functions of fresh water input, insolation, wind, and the ocean influence. The local climate is outlined, and some pertinent physical processes are reviewed, prior to a generalized description of the coastal oceanographic system.Predominant northwest winds and local runoff result in a shallow (20 to 40 m) springtime halocline in coastal waters. Summer insolation and the resulting stability of the thermocline, coincident with the halocline, limit the depth of mixing so that the summer runoff from mainland sources is mainly preserved in the shallow (10 to 20 m) upper zone of the salinity structure.Intermittent wind-induced divergence and an entrainment demand is offered as reason for the occurrence of cold, saline bottom water in this region during the summer.Autumnal cooling and southeasterly winds destroy the vertical structures and result in a near-shore accumulation of dilute surface water in winter. Relatively warm bottom temperatures offer evidence of a winter convergence, or relaxation of the divergence mechanism.Coastal oceanographic structures are often dominated by short-term variabilities. The significance of these is demonstrated by the ranges of variation obtained during time-series observations.

ISSN:0706-652X    

DOI:10.1139/f62-003

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

A two-man block seine about 16 feet (5 m) long has been modified for studying populations of small fish in the shallow, rapid salmon streams of eastern Canada. It is usually used in conjunction with DC electrofishing aids. The special feature of this seine is an extra strip of netting, the "apron", attached closely to the foot-line but extending back about 1 foot (30 cm) to a free edge over the main netting. This free edge of the apron is held about 4 inches (10 cm) above the main netting by wire gate frames fixed to the foot-line. Fish which would otherwise escape off the net are held in the space between main netting and apron. Construction and use are described in detail.

ISSN:0706-652X    

DOI:10.1139/f62-004

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Toxicities recorded from 1944 to 1958 in blue mussels (Mytilus edulis) from Head Harbour, N.B., are examined in relation to some hydrographic and meteorological factors. Within-year variations in toxicity are correlated with summer rises in water temperature. Year-to-year variations are directly correlated with springtime insolation and salinity and inversely correlated with springtime river discharge and winter water temperature. The probable role of these factors in regulating the abundance of the causative organism, hence, levels of toxicity, is discussed.

ISSN:0706-652X    

DOI:10.1139/f62-005

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

A biological investigation of the longnose sucker, in Great Slave Lake, was carried out in 1950 and 1951. Specimens were obtained by use of gill nets and seines. Suckers taken along the south shore had a faster rate of growth than those in the more northern area. In both areas, males and females grew at the same rate in length and weight. Females lived longer and thereby became heavier. The average annual survival rate was 45%. The growth exponent was 2.88; the length-weight relationship, W = 0.000252 L2.88. Longnose suckers spawned in Hay River from the ice cover break-up in May to June 15. The water temperature did not exceed 59°F (15 °C). The majority of spawning-run fish were 10 to 12 years old. Although sexually mature at 7 years, no suckers younger than 9 years of age were found in the spawning run. Females contained from 17,000 to 60,000 eggs but may not spawn each year. Fingerlings from Hay River were 33 to 80 mm in length, and were in their first summer. They all had scales.

ISSN:0706-652X    

DOI:10.1139/f62-006

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Changes in the glycogen reserves of epaxial and heart muscle of trout were followed after stream planting. Muscle glycogen recovered quickly in large fish; more slowly in smaller ones, and was related to earlier reported changes in liver glycogen and blood lactic acid. Heart glycogen increased initially, but fell again shortly after feeding became stabilized. Muscle glycogen reserves of wild trout were lower in the presence of hatchery fish than in their absence. A depletion of some metabolite, such as glycogen, in conjunction with an increased body demand due to raised basal metabolism was suggested as a factor in delayed mortality.

ISSN:0706-652X    

DOI:10.1139/f62-007

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Techniques have been developed for observing and recording the behaviour of migrating adult salmon. Daytime movement through slow water (less than 5 ft/sec (1.5 m/sec)) is by steady swimming in schools. Such steady swimming is interrupted with resting periods at velocities between 3 and 5 ft/sec (1.0–1.5 m/sec) but can be sustained over long periods at velocities less than 3 ft/sec (1 m/sec). Movement through slow water in the Somass River system normally occurs along the line of the deepest channel, wherever this is well defined. Movement through rapids (velocities more than 5 ft/sec or 1.5 m/sec) is by darting interspersed with holding, salmon moving individually rather than in schools. Migration through pools, and through other obstructions such as fishways shows diurnal rhythms, modifications of which are associated with numbers of salmon moving, the time within the migratory season, and the species concerned. Nocturnal migration occurs.Entry of salmon into rivers during the migratory season occurs at intervals, the initiating stimulus for which is frequently related to the passage of atmospheric warm fronts over the river estuary.Techniques for field behaviour studies of salmon migration have a potential for management in that it is possible to undertake such studies in areas scheduled for industrial development and to utilize the revealed spatial and temporal migration patterns in the design of fish diversion facilities.

ISSN:0706-652X    

DOI:10.1139/f62-008

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Experiments to test radioactive caesium-137 as a fish and lamprey ammocoete mark are described. The biological half-life (turnover) of caesium in speckled trout (Salvelinus fontinalis) was 47.20 days. A successful field trial was carried out, using Cs-137 for marking ammocoetes for subsequent recapture in streams undergoing chemical treatment for lamprey control.

ISSN:0706-652X    

DOI:10.1139/f62-009

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

This paper examines the problem of estimating mortality rates from knowledge of catch and of the change in composition caused by selective fishing on one of two classes of a closed population.Estimators of fishing mortality in the presence and in the absence of natural mortality are given. An estimator of natural mortality is shown for the special case where final population size is known.A numerical example illustrates the method. Certain problems are discussed and two types of application are suggested.

ISSN:0706-652X    

DOI:10.1139/f62-010

出版商:NRC Research Press    

年代:1962

数据来源: NRC