摘要:

Larvae of the blue king crab,Paralithodes platypus(Brandt), were hatched and reared in the laboratory. All larval stages obtained developed in a manner similar to the development reported for other lithodid anomurans. In culture,P.platypushad four zoeal stages and a single glaucothoeal stage. The feature which distinguishes all zoeal stages of this species from zoeae of the other two North Pacific species ofParalithodes—P.camtschaticaandP.brevipes— is the presence of 9 + 9 telson processes (including a hair-like second process) rather than 8 + 8 telson processes. Glaucothoes ofP.platypushave one more pair of spines in the branchial region of the carapace than do those ofP.camtschatica. Glaucothoes ofP.platypushave 15 pairs of spines on the dorsal surface of the carapace, not including the spines of the frontal area (rostral complex) or the suborbital spines, whereas glaucothoes ofP.camtschaticahave 14 pairs of spines, and those ofP.brevipeshave 13 pairs.

ISSN:0706-652X    

DOI:10.1139/f68-039

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

In 1964 and 1965 three midwater trawl cruises off the continental slope near the Queen Charlotte Islands were made to study the relationship of the catches to sound scattering layers.During the daytime four layers were distinguished, not all necessarily present at one time. In summer the most intense and persistent layer lay at 220–230 m; others were at 330–400, 185, and 90 m. In fall the main and deep layers were shallower. Vertical migration occurred at dusk and dawn. The main layer frequently split into three parts with different vertical migration patterns. At dawn a layer gradually appeared at about 90 m, intensified rapidly, and descended to the daytime level.Catches show fishes are associated with the sound scattering layers. The largest day catches were from the main layer. At night fish did not appear to be concentrated to the same extent relative to the layers. The largest night catches were usually smaller than the largest day catches and shallower.Myctophids of eight species, four common, made up 80% of the catch, chauliodontids 6%, argentinids 4%, melamphids, rockfish, and larval flatfish 2% each. The remaining 2% comprised 27 species in 21 families. Depth distribution and vertical migration varied considerably with the species.Myctophids with gas-filled swim bladders were apparently dominant in the main layers whereas species without swim bladders — stomiatoids, argentinids, and melamphids — or myctophids with fat-filled swim bladders were dominant below the main layer and in the deep layer. Fish with no swim bladders or with fat-filled ones may make longer vertical migrations than those with gas-filled bladders.

ISSN:0706-652X    

DOI:10.1139/f68-040

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Blood lactate concentrations in 306 sockeye salmon (Oncorhynchus nerka), taken at sea in 1965 and 1966 by purse seine, gillnet, and longline, and in 98 starved or fed immature chinook salmon (O.tshawytscha) that had been exercised in a saltwater pond were generally below those reported in the literature as related to stress-induced mortality in salmon. No sockeye salmon held in shipboard tanks for observation died within 2 days after capture, although most of the fish died later. Few fish died among starved or fed immature chinook salmon in salt water within 10 days after capture by hook and line or after being chased to exhaustion; blood lactate concentrations in these fish were generally higher than in sockeye salmon after stress but were still usually below the reported critical level of 125 mg/100 ml.We concluded that neither the adult sockeye nor immature chinook salmon suffered immediate fatigue-related mortality, but the possibility that fatigue could induce delayed mortality was not excluded.

ISSN:0706-652X    

DOI:10.1139/f68-041

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

In 1965, spawning was studied on the island beaches of the eastern part of Iliamna Lake from a 5.5-m tower mounted on a 9.1-m boat and with the use of scuba. Over 3 million sockeye salmon,Oncorhynchus nerka(Walbaum), utilized nearly 130 ha of the beaches surveyed during the period August 8–21. The total spawning population and utilized area of shoreline of all the islands in the lake were greater since each area was surveyed only once and possible multiple waves of spawners were not taken into account, and not all of the island shoreline was surveyed by the above methods. The salmon generally spawned in dense groups, over immovable rock, in exposed areas with no upwelling ground water, and with little display of territorial defense. Density ranged from less than 0.1 fish to more than 5 fish per 0.84 m2(1 yard2). The latter density prevailed on reefs and outside points of the islands. Seventy-three per cent of spawning took place over bottom with irregular rocks from 102 to 305 mm (4–12 inches) in diam, and over 90% at depths from 2 to 6 m (6–20 ft) on bottom with slopes from 15 to 25°. Commonly, in a group of fish, one or more of the females were seen with their vents down in rock interstices, emitting eggs, while the males in close proximity were observed releasing milt. Eggs on the beaches are probably aerated by wind-generated lake currents and seiches. Of 3553 eggs collected from several island beaches, 6.8% were infertile.Several features of the spawning behavior and environment are favorable to the survival of eggs and fry. The bottom is not scoured. Most eggs are deposited between immovable rocks and are thus not disturbed by subsequent spawners. Fry emerging from the beaches have immediate access to the large food supply in the lake. Some hazards are predation on eggs by fishes, freezing, and ultraviolet radiation of eggs in shallow water, and smothering of eggs in areas with a high density of eggs or algal growth.

ISSN:0706-652X    

DOI:10.1139/f68-042

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Eggs of the English sole were incubated at a number of salinity–temperature conditions within the ranges of 10–40‰ salinity (S) and 2–12 C. Temperatures of 2 C were lethal in all cases. Development time from fertilization to 50% hatch ranged from 3.5 days (12 C) to 11.8 days (4 C) and was shortest at salinities around 25‰ between temperatures of 6–12 C. Larvae were classified as viable (normal) or abnormal on the basis of several subjective criteria.Response surfaces were computed and salinity–temperature conditions were estimated at which several responses were maximized, namely: larval size: 28.1‰, 7.9 C; total hatch, 25.6‰, 9.0 C; viable hatch, 25.9‰, 8.4 C. In general, optimum conditions for survival appeared to be associated with salinities and temperatures of 25–28‰ and 8–9 C. Temperatures associated with the production of 50% viable hatch or better at optimum salinity conditions (25.9‰) were calculated to be those bounded by 4.5 and 12.5 C.Incidental observations were obtained in several cases on egg density and oxygen consumption. At 30‰ S, 6 C, eggs floated for about 93% of the incubation period and sank just prior to hatching. Salinities of neutral buoyancy of these eggs rose from 27.8‰ at fertilization to 30.8‰ at hatching. Oxygen consumption tests and calculation of rates of oxygen transfer to the eggs indicated that rates of development were independent of oxygen availability in all tests.Several inferences are drawn from the experimental evidence regarding effects of salinity and temperature on distribution and abundance. Over the geographic range of the species, salinity would appear to have little influence on egg viability. Temperature, however, may limit abundance at the northern and southern boundaries of the range of commercial exploitation by lowering egg viability, and be lethal to eggs near the boundaries of geographic distribution.

ISSN:0706-652X    

DOI:10.1139/f68-043

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Methods are described for the isolation of chlorophyllsaandb, and for the preparation of 12 chlorophyll derivatives, including crystalline pheophorbidea, from these starting compounds. Laboratory cultures ofChlorellawere fed C14O2. After 9 days growth the cells were heat-killed, their pigments extracted, and chlorophyllsaandbisolated chromatographically. The following C14-labelled compounds were prepared: chlorophylla, allomerized chlorophylla, chlorophyllidea, pheophytina, allomerized pheophytina, pheophorbidea, methyl pheophorbidea, chlorophyllb, chlorophyllideb, methyl chlorophyllideb, allomerized chlorophyllideb, allomerized methyl chlorophyllideb, pheophorbideb, and allomerized pheophorbideb. Assuming uniform distribution of carbon-14 label in the parent chlorophyll molecules, specific and molar absorption coefficients were calculated from the specific radioactivities of these derivatives.

ISSN:0706-652X    

DOI:10.1139/f68-044

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Polinices lewisi(Gould) possesses an aquiferous system for the expansion of the podial complex. The haemal system is highly modified and entirely separate from the aquiferous system. Postpodial ostia and haemal sheaths are demonstrated. The morphology of the aquiferous and blood systems is traced.

ISSN:0706-652X    

DOI:10.1139/f68-045

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A chemically defined medium is described for the growth and spore production ofClostridium botulinumtype E, strain Minnesota. With the exception of valine, omitting any amino acid or vitamin did not prevent growth, although marked changes in morphology or reduced growth were usually evident. Choline was shown to be an essential factor in promoting cell division and was capable of exerting this action after maximum growth was attained. Spore development in the medium was markedly influenced by the source of available carbon and ranged from complete sporulation of cultures grown on maltose and glucose to complete inhibition with galactose.

ISSN:0706-652X    

DOI:10.1139/f68-046

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The Gulf of St. Lawrence cod stock supports a fishery with recent annual landings around 65,000 metric tons. Traditionally, fish have been taken by baited hooks, but beginning in 1947 trawl fishing has gradually become the major fishing method.Introduction of trawling with concurrent increase in landings from an average of 30,000 metric tons prior to 1947 to 65,000 metric tons since then appears to have greatly changed the composition of the stock. The changes were characterized by the lowering of the average size of fish and of the abundance in weight of the commercially fished sizes, and the increasing of the abundance of the pre-commercial sizes.Available statistics permit estimation of growth, recruitment, and productivity parameters for the stock. Analysis suggests an inverse relationship between stock density and both growth and recruitment, the overall effect being an increased productivity.If the observed population changes are responses to increased fishing, then per-recruit models are not appropriate to predict the effects of any past or future regulations. Models providing for differential growth efficiencies, and competition and food-related recruitment relationship are required.

ISSN:0706-652X    

DOI:10.1139/f68-047

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f68-048

出版商:NRC Research Press    

年代:1968

数据来源: NRC