摘要:

Four Cuvier's whale strandings in northern California within 26 minutes of latitude include two of known date (March and September) and three of known sex and inferred maturity (adult male, juvenile male, large and presumably adult female). The large male and female showed a variety of external white markings, including oval white marks and mottled white marks, and the male also had scratch-like marks on its back. Oval white marks were concentrated in the urogenital region. Based upon cranial features the large male and female were presumably adult, although indirect evidence indicates that absolute length is no good criterion of maturity inZiphius cavirostris. Study of the juvenile skull indicates that with increasing age in this species the orbitosphenoid bone projects progressively farther out of the optic foramen, and the mandibular symphysis fuses.

ISSN:0706-652X    

DOI:10.1139/f67-200

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Starry flounder fed mainly on priapulids, nemerteans, polychaetes, and lamellibranchs. Sand sole fed on fish, mysids, shrimp, and squid. Both species appeared to be daytime feeders.Starry flounder ceased feeding during the months of lowest water temperature. This indicates that the local commercial fishery for starry flounder takes fish when they are in poor physical condition. Sand sole showed little reduction in feeding during the cold-water months.The stomach of the starry flounder appeared to be used primarily as a holding organ and was emptied in about 9 hr. The sand sole stomach was used for digestion, which, for forage fish, took longer than 24 hr to complete.

ISSN:0706-652X    

DOI:10.1139/f67-201

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

A complete analytical solution is presented for the problem of finding the common rate of exploitation that maximizes total sustained yield from a mixture of stocks when each stock follows a Ricker reproduction curve. A computer program is described which solves this problem for up to 20 stocks varying in both reproductive potentials and absolute sizes. Some aspects of the management of Pacific salmon and fishing strategies are discussed in relation to the question of obtaining maximum yields when harvesting mixtures of stocks under various constraints.

ISSN:0706-652X    

DOI:10.1139/f67-202

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Of 2614 adult rainbow trout sampled from the Nottawasaga River of Georgian Bay during the period of 1961–67 inclusive, approximately 7.1% had one or more lamprey marks. The trout ranged in fork length from 10 to 33 inches (25 to 84 cm). However, lamprey marks were present only on fish over 16 inches (40 cm) in length. Multiple scarring was found on 30% of the trout that were marked. The incidence of marked fish reached a maximum of 17.2% in the spring of 1962, then declined to 1.3% in the fall of the same year. This decline was coincident with a reduction in the lamprey population after experimental lampricide treatment of the Nottawasaga River and adjacent lamprey spawning streams during 1960 and 1961. The incidence of marked fish remained at a relatively low level for a period of 4 years, then increased substantially, after the presumed recruitment of metamorphosed lampreys during 1966 and 1967.

ISSN:0706-652X    

DOI:10.1139/f67-203

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The structure of the white skeletal muscle of the cod (Gadus morhua) is described. The peripheral fibrils are ribbon-like and rectangular in cross section with the long axis normal to the sarcolemma. The inner fibrils are mainly polygonal in cross section. Most of the mitochondria and nuclei are peripheral to the fibrils and next to the sarcolemma. The arrangement of the contractile proteins is typical for striated muscle, and the sarcoplasmic reticulum and transverse tubular system are similar to those in other white skeletal fish muscle. A distinct N-band is apparent with indications of branching and reorientation of the actin filaments. Mitochondria are often closely associated with the Z line.

ISSN:0706-652X    

DOI:10.1139/f67-204

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

A sensitive method for assay of phospholipase A activity in the lateral line muscle of rainbow trout is described.14C labelled lecithin was converted to lysolecithin by the enzyme. Unreacted lecithin was removed by silicic acid column chromatography and the lysolecithin recovered by thin-layer chromatography. The amount of lysolecithin formed was between 43 and 87 mμmoles per gram lateral line muscle per hour under the experimental conditions. The amount formed was directly proportional to time between half an hour and 4 hr and the optimumpH was found to be approximately 7.5. The results are discussed in relation to the enzymic activity previously demonstrated in fish muscle.

ISSN:0706-652X    

DOI:10.1139/f67-205

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Marine oils with iodine values in the range 83–108 from Newfoundland turbot or Greenland halibut (Reinhardtius hippoglossoides), sablefish (Anoplopoma fimbria), and certain Atlantic herring (Clupea harengus), were examined for fatty acid composition by gas–liquid chromatography. The herring oils differed from the other oils in having high levels of C20and especially C22fatty acids (chiefly monounsaturated). The sablefish oil had a high level of C18fatty acids, the turbot oil a composition intermediate between the herring and sablefish oils. All of these oils contained moderate amounts of polyunsaturated fatty acids (7.3–14.4%). The low iodine values were primarily due to monounsaturated fatty acids and not to saturated fatty acids (17.1–21.0%)

ISSN:0706-652X    

DOI:10.1139/f67-206

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Gadus morhuaL. occurs in Ogac Lake, a salt, meromictic lake on Baffin Island that receives influxes of seawater only during the highest summer tides. Cod of the order of 10,000 of lengths 25 cm and greater and 500 of lengths greater than 60 cm were present. The size ranges for various ages far exceeded those of oceanic populations. Feeding conditions were poor, and sea urchins predominated in the diet. Large cod (greater than 50 cm) were highly cannibalistic, and it was estimated that they consume of the order of 3500 fish of 20–40 cm annually. Maturation occurred at the unusually large size of 85 cm in females, and at about 65 cm in males. Apparently many of the cod never reach these sizes. Spawning was from late May to early July in 1962, and initiation of spawning appeared to be related to light. The hatching of cod larvae coincided with the appearance of the nauplii of the dominant copepod in the lake. Egg size was highly variable and exhibited a curious bimodalism. Variation in vertebral and fin-ray counts was slight in spite of high environmental variability, and thus appears largely genetically controlled. Possibly the first inhabitants came from Greenland stocks, which have high growth rates similar to the faster growing cod in the lake, and similar high length at maturity. Meristic characters also suggest affinity with Greenland rather than Labrador cod. The hydrography of the area and the possibilities of larval drift or adult migration into the lake are discussed. Cannibalism must exert continuing selection for high growth rates, but very poor feeding conditions and hierarchial dominance effects probably prevent general attainment of high growth rates.

ISSN:0706-652X    

DOI:10.1139/f67-207

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Rates of recapture of Atlantic salmon marked as naturally produced smolts in the Northwest Miramichi River, New Brunswick, were 2.9 for tagged and 3.9% for fin-clipped grilse and 0.7 for tagged and 1.8% for fin-clipped larger salmon. There are indications that survival to the adult stage is much higher for unmarked smolts than for tagged or fin-clipped fish. Length measurements of 117 tagged, 607 fin-clipped, and 301 unmarked grilse taken above tidehead in the Northwest Miramichi showed that those entering freshwater early in the season were smaller that those entering later. Tagged grilse were shorter than fin-clipped grilse which returned at the same time, and the fin-clipped grilse were shorter than unmarked ones. Rates of increase in size among tagged, fin-clipped, and unmarked grilse during the season of return to freshwater (June through October) did not differ significantly.

ISSN:0706-652X    

DOI:10.1139/f67-208

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Eggs of sockeye salmon taken from tributary, outlet, and beach spawners at Karluk, Alaska, were treated identically from time of egg fertilization through time of testing as fry in a laboratory. Test lots were released during the day and at night in a central release pool from which the fry could migrate either upstream or downstream through simulated stream channels. Oxygen-saturated water at 50 F (10 C) was pumped through the 40-ft (12.2-m) gravel-bottomed simulated stream at about 0.3 ft/sec (9.1 cm/sec).Test results showed that directions (upstream or downstream) and times (day or night) of migration differed substantially between fry from the tributary and those from the outlet. Fry from beach spawning reacted in a manner similar to that of the tributary fry. These differences were concluded to be of genetic origin. The possible interaction of innate behavior and environment in controlling the migratory movements of salmonid fry is discussed along with the significance of choosing a donor stock with appropriate innate responses to make best use of a new environment.

ISSN:0706-652X    

DOI:10.1139/f67-209

出版商:NRC Research Press    

年代:1967

数据来源: NRC