摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f64-084

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Adult females and males ofCaligus clemensisp. nov. from the body surface of British Columbia fishes are described. The known hosts areOncorhynchus kisutch,O.gorbuscha,O.keta,Clupea pallasi,Gasterosteus aculeatus,Hexagrammossp. andTheragra chalcogrammus. This is the only species ofCaligusknown from the coastal waters of British Columbia. "Caligus gurnardiKrøyer" of Fraser, 1920, is synonymous with the new species.

ISSN:0706-652X    

DOI:10.1139/f64-085

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The vertical distribution of Pacific salmon in the high-seas areas of the Gulf of Alaska was investigated from mid May through July in 1959 and 1960 by fishing with gillnets (constructed from 41/2–inch nylon web and measuring 40 ft in depth and initially 400 fathoms in length) at five depth intervals from the surface with the deepest between 160 and 200 ft.Sockeye salmon exhibited diurnal and seasonal differences in their vertical distribution while chum salmon showed diurnal differences. The downward movement of sockeye salmon appeared limited by the thermocline, especially during late June and July. This relationship was observed for chum salmon during hours of darkness only in late June and July. Other factors must also influence seasonal and diurnal vertical movements of sockeye and chum salmon. Within the conditions of the experiment, no consistent differences in the vertical migrations between fish of different age were apparent. Catches showed pink and coho salmon were nearer the surface than either sockeye or chum salmon.

ISSN:0706-652X    

DOI:10.1139/f64-086

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Records of length of pink and chum salmon computed from scale annuli are summarized, and are converted to show rate of growth in weight. Information is available on 11 pink stocks or groups of stocks originating at points from the Strait of Georgia to Sakhalin and Primorye, and for 7 chum stocks taken from Tillamook Bay to the Amur River and Sakhalin. Estimates of increase in weight from the time of formation of the final annulus to time of capture near shore vary from 190% to 590% for pinks maturing at age 1+, and from 60% to 92% for chums maturing at age 3+. At the end of the first year, pinks are computed to average 356 g in weight, and chums 287 g. Average instantaneous rate of growth per month in the final year is 0.28 for pinks and 0.12 for chums, each available locality being given equal weight. The seasonal distribution of growth in the final year has been estimated for pink salmon of the Bering Sea (by Birman) and for those of the central British Columbia coast (by LeBrasseur and Parker); for chum salmon an approximate seasonal distribution can be deduced from comparisons of growth rates. Combining these with the best available estimate of natural mortality (0.02 per month for salmon more than 30 cm long), calculations of net yield from high-seas fishing can be made for any desired date, and compared with the yield from a purely coastal fishery (the same escapement being provided in both cases). In all situations the catch taken on the high seas is less than that taken from the survivors of the same fish in coastal waters. The loss of yield exceeds 50% for pinks taken early in their final season, and also for chums taken early in their penultimate season.

ISSN:0706-652X    

DOI:10.1139/f64-087

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

A new species,Pholis clemensi, referred to the family Pholidae, is named and described from 12 specimens taken in southern British Columbia waters and the Strait of Juan de Fuca.Pholis clemensiis compared with other members of the genus, and a key is given to the North American species.

ISSN:0706-652X    

DOI:10.1139/f64-088

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

There are eight climatic regions from the Equator to the Arctic in the Pacific Ocean. In each region the distinct oceanographic temperature structures and their seasonal sequences are described and related to surface weather processes and transport. Procedures for observation and interpretation of data must be adapted to suit the regional models of structure and behaviour. However, a rational universal system of information presentation is feasible and is demonstrated. The concepts may be extended to other oceans.

ISSN:0706-652X    

DOI:10.1139/f64-089

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Full descriptions of both sexes ofHolophryxus alaskensisRichardson are given. The host is the decapodPasiphaea pacificaRathbun.Holophryxus californiensisRichardson andHypodajus georgiensisNierstrasz and Brender à Brandis are considered synonymous withHolophryxus alaskensis. The generic nameHypodajusNierstrasz and Brender à Brandis is a synonym ofHolophryxusRichardson. The type-species ofHolophryxusremains asH.alaskensis.

ISSN:0706-652X    

DOI:10.1139/f64-090

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Disagreement exists in the literature as to whether lake trout survived Wisconsin glaciation north or south of the ice sheet. Other freshwater fishes whose range in North America equals or exceeds that of lake trout all survived in both northern and southern refugia. Arguments in favour of a southern refugium for lake trout include their wide distribution eastward to Nova Scotia and New England, their presence in some Mississippi headwaters, and possible late-Wisconsin date of a fossil lake trout south of glaciation. Absence from some habitable lakes along the southern margin of glaciation is attributable to northward shift of isotherms during the hypsithermal period. A northern refugium is suggested by occurrence of lake trout in remote parts of Alaska, and the improbability of their having failed to reach and persist in Alaska prior to last glacial advance. They do not now closely approach Bering Strait, and may be held in check by ecological factors which have been operative also during previous glacial and interglacial periods, on the Bering land bridge as well as on the continent.Hucho taimenis a related Asian counterpart whose dispersal may be similarly controlled. Large lampreys may prevent dispersal of lake trout into lower water courses and the sea.

ISSN:0706-652X    

DOI:10.1139/f64-091

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

An examination of the modal salinity preferences of five Pacific salmon species showed the following pattern of temporal changes. The sequence began with a preference for fresh water, then changed gradually, in the direction of increasing seawater concentration. The terminal pattern indicated a preference for water of open ocean concentration. This temporal progression of salinity preference changes was shown to parallel closely the salinity gradients typical of river outflows through which young salmon pass on their way to the ocean. On the basis of this evidence the following orientation mechanism was proposed: that juvenile Pacific salmon are able to use estuarial salinity gradients as one of the directive cues in their seaward migration.

ISSN:0706-652X    

DOI:10.1139/f64-092

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Seaward migrating pink salmon fry at Hook Nose Creek, British Columbia, were estimated to total 1,153,000 in 1961. Of these, 41.5% or 479,000, were marked by amputation of both ventral fins (BV). Following this marking 36,900 fingerling were captured in the marine environment and marked by removal of the adipose and right ventral fins (ARV). During the 1962 fishing season 1,160,645 adult pinks were examined and 7050 BV and 184 ARV marks recognized. For the Hook Nose Creek stock, survival at sea from natural causes is shown to approximate 22% and the rate of exploitation was 95%. This stock is shown to be more exposed to fishing than the Bella Coola stock, for which a rate of exploitation of 69–80% is estimated. Rate of exploitation for Dean Channel stocks is even lower. These differences are explained as due to times of entry and rates of travel through the fishery. The two-stage marking experiment failed to estimate the natural mortality rate of juvenile pinks during the initial 5 weeks of sea life because of this dissimilarity between rates of exploitation on the stocks in the area.

ISSN:0706-652X    

DOI:10.1139/f64-093

出版商:NRC Research Press    

年代:1964

数据来源: NRC