摘要:

The development of large modern fisheries has led to the overexploitation, with resulting less than optimal production, of many of our fish stocks. A need to develop management techniques which would make it possible to hold stocks and exploitation rates more nearly at optimal levels has led to the development and extensive study of mathematical theory relating to fishing. An essential feature of this theory is the yield equation which relates the obtainable yield to such stock parameters as the number of recruits, rate of growth at various stages of life, natural mortality rate, and intensity of fishing. A widely used form of the yield equation is that developed by Beverton and Holt (U.K. Min. Agr. Fish. Food, Fish. Invest. 19: 1–533, 1957). In this equation the growth component is represented by the well-known Bertalanffy growth equation (Bertalanffy, Human Biol. 10: 181–213, 1938):It is not possible, however, to represent the growth of all fish satisfactorily by this equation, and where this is not possible, the Beverton and Holt yield equation also does not give satisfactory results. This situation calls for the need to develop a more generalized equation, using a more widely applicable form of the growth curve. As Bertalanffy (Helgolaender Wiss. Meeresuntersuch. 9: 5–37, 1964) has pointed out, the original equation assumes that catabolic processes are proportional to the weight of the animal, whereas anabolic processes are assumed to be proportional to the surface area or to the 2/3 power of the weight, but in practice at least the latter relationship frequently does not hold. The present paper examines the effect of different values of the exponent in the catabolic and anabolic components of the growth equation upon the shape of the growth curve and particularly upon the proportion of final size at which the point of inflection occurs. The modified yield equation embodying the generalized growth equation can be solved by means of tables of the incomplete beta-function by an extension of the method of Jones (Joint Meeting ICNAF/ICES/FAO, Lisbon, Doc. P21, 1957).

ISSN:0706-652X    

DOI:10.1139/f69-222

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Five species of haustoriid amphipods from Cape Cod, Massachusetts, differed in their tolerances to high temperature, desiccation, low salinity, and low oxygen concentration and in preferences for different sediment sizes. Two intertidal species,Haustorius canadensisBousfield andNeohaustorius biarticulatusBousfield, survived longer in air at 100% relative humidity and were more resistant to high water temperature than three species that are basically subtidal,Acanthohaustorius millsiBousfield,Parahaustorius longimerusBousfield, andProtohaustorius deichmannaeBousfield. All five species preferred sediments of a particular size range, the intertidal species selecting coarser sediments than the subtidal species. The sediment preference shown by the intertidal species could be changed by altering the organic conditions of the sediment by either drying or igniting the sediment.Acanthohaustorius millsiwas the species most tolerant to low oxygen concentration andH.canadensishad the lowest oxygen consumption rate of the five species.The ecological significance of these findings is discussed in relation to the distribution of the five species on Cape Cod.

ISSN:0706-652X    

DOI:10.1139/f69-223

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Hemoglobin, catalase, myoglobin, and inorganic iron were added to blended muscle from cod, flounder, scallops, and lobsters to determine the effects of these various forms of iron on the oxidation of the muscle lipids as indicated by increased malonaldehyde and rancid odours. Hemoglobin and catalase were very active catalysts; myoglobin was relatively inert. Scallop muscle was slightly more susceptible to hemoglobin-induced rancidity than muscle from cod or flounder; lobster muscle was highly resistant. There was a difference in the odours accompanying the development of rancidity after the addition of free Fe++and hemoglobin-bound Fe++. An increase in the free fatty acid content of the muscle retarded the hemoglobin-induced rancidity. Certain free amino acids, notably tryptophane and proline, also had an inhibitory action, whereas other amino acids had a prooxidant effect.

ISSN:0706-652X    

DOI:10.1139/f69-224

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Treatment of trout eggs with classical disinfectants such as sulfo-merthiolate, merthiolate, and acriflavine proved unreliable for destroyingAeromonas liquefacienson the eggshell. These bacteristatic agents washed free leaving viable bacteria on the shell.An organic iodine compound, povidone–iodine, was found to be bactericidal at dosages readily tolerated by trout eggs. No reduction in the rate of development was observed after treatment.Transmission ofA.liquefaciensfrom parents to offspring follows the route reported forAeromonas salmonicida. Viable bacterial cells are carried on the outer surface of the shell only, enabling the use of surface disinfection.

ISSN:0706-652X    

DOI:10.1139/f69-225

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The results of a study to assess the kinds and degrees of parasitism that exist in or on inshore fishes of British Columbia are presented. The report contains a listing of 68 taxa of parasites recovered from a total of 814 host specimens representing 61 species.Observations on host–parasite relationships made during the course of the study are discussed.

ISSN:0706-652X    

DOI:10.1139/f69-226

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Ages, lengths, and weights were determined for 124 female shiner perch,Cymatogaster aggregataGibbons, collected in Yaquina Bay, Oregon, from May 17 through June 29, 1968. Embryos (1005) were obtained from 111 gravid females either by dissection (737) or at parturition in the laboratory (268). Embryo lengths, weights, and numbers per female parent were determined.As females increased in age from 1 to 6 years, their mean fork length increased from 9.32 to 13.65 cm, their weight from 13.65 to 47.78 g, and the mean number of embryos per parent female increased from 5.83 to 20.00. The equations and their correlation coefficients (R) computed for the relationships of embryo number (Y) to parent female fork length, weight, and age are, respectively: log Y = −1.892 + 2.735 log X (R = 0.89); Y = 1.131 + 0.313 X (R = 0.70); and Y = 4.23 + 1.73 X (R = 0.51). Embryo size at birth was also directly related to female parent size. The equations computed for the relationships of total length of embryo at birth (Y) to parent female fork length and parent female weight are, respectively: Y = 24.211 + 1.620 X (R = 0.79); and Y = 0.384 + 0.015 X (R = 0.72). The equation computed for the relationship of embryo weight (Y) to embryo length at birth is Y = −2.266 + 0.712 X (R = 0.95).

ISSN:0706-652X    

DOI:10.1139/f69-227

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

In a study throughout 1 year at a station in St. Margaret's Bay, N.S., the caloric content per unit dry weight of zooplankton showed a fivefold variation. Along with all the available information from the literature, the data indicated that the dependence of caloric content of zooplankton (y) on per cent organic matter (x) could be described by the equationy = −3370 + 136x − 0.514x2. The caloric content may be predicted from per cent ash (A) and per cent carbon (C) by the equationy = 1351 + 106 C − 21.2 A. The relative stability of the caloric or carbon standing stock of zooplankton per unit water volume, compared with numbers or dry weight, may be an indication of some kind of regulatory mechanism controlling energy flow.

ISSN:0706-652X    

DOI:10.1139/f69-228

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Based on starch-gel electrophoretic analyses of serum proteins of 1092 specimens of Pacific halibut sampled from the eastern Bering Sea and northeastern Pacific Ocean southward to southern British Columbia, three molecular species of transferrins were encountered. A fourth rare type was postulated to explain the observation of some phenotypes involving this transferrin. These transferrins, either singly or in combinations of two, accounted for the theoretically possible 10 phenotypes of which 8 were actually observed. Hereditary control by four codominant alleles (TfA, TfB, TfC, and TfD) is postulated to explain the heterogeneity of the transferrin patterns. The collections were arbitrarily divided into 10 geographic areas and gene frequency analyses were used to determine population structure. Phenotypic distribution was shown to be independent of age and sex. Of the 10 areas, only the collection from southeastern Alaska proved not to be homogeneous. Preliminary analysis of blood hemoglobins indicated that these proteins are not of value in population analyses.

ISSN:0706-652X    

DOI:10.1139/f69-229

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The growth of young sockeye salmon (Oncorhynchus nerka) was studied at temperatures ranging from 1 to 24 C in relation to rations of 0, 1.5, 3, 4.5, and 6% of dry body weight per day, and at an "excess" ration. Optimum growth occurred at approximately 15 C for the two highest rations, shifting progressively to a lower temperature at each lower ration. The maximum growth rate for sockeye 5–7 months old was 2.6%/day; that for fish 7–12 months old was 1.6%/day. At 1 C a ration of 1.5%/day was sufficient to provide for a maximum growth rate of 0.23%/day. The maintenance ration was found to increase rapidly above 12 C, amounting to 2.6%/day at 20 C. No growth took place at approximately 23 C despite the presence of excess food.Isopleths for gross and net food-conversion efficiencies were calculated. A maximum gross efficiency of 25% occurred in a small area with a center at 11.5 C and a ration of 4.0%/day; a maximum net efficiency of 40% occurred within a range of 8–10 C for rations of 1.5%/day down to 0.8%/day, the maintenance level.Gross body constituents changed in response to the imposed conditions, varying in extreme from 86.9% water, 9.4% protein, and 1.0% fat for starved fish at 20 C to 71.3% water, 19.7% protein, and 7.6% fat on an excess ration at 15 C.It is concluded on the basis of growth and food-conversion efficiency that temperatures from 5 to 17 C are most favorable for young sockeye, and that a general physiological optimum occurs in the vicinity of 15 C.

ISSN:0706-652X    

DOI:10.1139/f69-230

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The extent of insecticide resistance in a resistant population of mosquitofish (Gambusia affinis) from Belzoni, Mississippi, was compared with that of a susceptible population from State College, Mississippi, using 28 insecticides of five major groups. Results of 48-hr bioassays show that resistant mosquitofish have developed high resistance only to the toxaphene–endrin related insecticides, even though insecticides from other groups were heavily applied. Spray records for the Belzoni area and insecticide characteristics such as stability and toxicity aided in evaluating cross-resistance patterns in the resistant population. Patterns of resistance in mosquitofish are similar to those in many resistant arthropods.

ISSN:0706-652X    

DOI:10.1139/f69-231

出版商:NRC Research Press    

年代:1969

数据来源: NRC