摘要:

Two methods of fitting the allometric weight–length relationship are described, one involving the common logarithmic transformation of variables in a multiplicative model and the other assuming an additive nonlinear model and general nonlinear estimation procedures. Differences in the assumptions involved in the two methods are emphasized and the practical significance of the different methods is demonstrated with the aid of a sample problem. A number of procedures are suggested to compensate for possibly unjustified assumptions.

ISSN:0706-652X    

DOI:10.1139/f69-011

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The method involves a trap of nylon netting placed over an individual redd with the trap's edges buried 15–20 cm in the gravel just outside the periphery of the redd. It has been used successfully on more than 70 coho salmon (Oncorhynchus kisutch) redds over the past 5 years, with as many as 2061 fry being captured from a single redd. The trap is relatively stable because it is flexible and conforms to the surface of the streambed, causing debris to float or roll over the surface. It can be used on individual redds; thus, emergent survival for separate parental combinations can be estimated. Field tests showed the efficiency of the trap approached 100%. Installation and presence of the trap had no significant effect on intragravel dissolved oxygen and gravel permeability. Mortality of fry in the traps averaged less than 1.5% when fry were removed at least three times a week. We concluded that the trap provides a more accurate estimate of survival from egg deposition through fry emergence than four other methods.

ISSN:0706-652X    

DOI:10.1139/f69-012

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Eighteen immature Greenland sharks (Somniosus microcephalus(Bloch and Schneider) 1801) were captured during the course of a study on the biology of the narwhal,Monodon monoceros. Most had been feeding on offal resulting from the whaling operation and on fish and seal meat discarded at the campsite. Other food consumed included two egg cases of the arctic skate,Raja hyperborea, previously unrecorded from this locality. Four narwhals and one white whale were attacked in the nets, the sharks removing large chunks of skin and blubber from the carcasses.

ISSN:0706-652X    

DOI:10.1139/f69-013

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The amount of enzyme-bound zinc is calculated from estimates of total enzyme concentrations and the number of zinc atoms per mole of these enzymes. This estimate is shown to be smaller than measured concentrations in marine organisms, indicating that zinc is accumulated in excess of the organisms' immediate needs. A minimum "potential fertility" for zinc is calculated; the results indicate that zinc is not limiting in the marine environment.

ISSN:0706-652X    

DOI:10.1139/f69-014

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The calanoid copepodsAcartia tonsaandEurytemora affiniswere successfully cultured in two commercial synthetic sea salts. Success of a medium was measured by its ability to sustain a population of copepods that was subjected to moderate rates of harvest.

ISSN:0706-652X    

DOI:10.1139/f69-015

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

A coldroom complex recently installed at the Fisheries Research Board of Canada, Freshwater Institute laboratory at Winnipeg features several design aspects that are considered novel. These include foamed-in-place urethane insulation, two alternating R-502 refrigeration systems incorporating automatic safety switch-over and adjustable defrost, "straight-line" pneumatic temperature control, hot gas bypass control, and a master panel. The facility combines a cold laboratory at +2 C, a long-term storage room at −37 C, a small anteroom at −26 C, and a room containing eight 10.0-ft3precise temperature cabinets at −40 C. Room temperature variation is ±0.25 degrees C during steady state conditions. Temperature rise during daily defrosting is less than 2 degrees C for a duration of 1 hr.

ISSN:0706-652X    

DOI:10.1139/f69-016

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The two types of curves were fitted to empirical weights-at-age for four commercially important species: sardines, haddock, lake trout, and chum salmon. For the range of observed data, both curves fit the empirical points well, and seem almost indistinguishable on this basis. The upper asymptotic limit of weight, however, was higher for the von Bertalanffy than for the Gompertz, in all four examples. Fitting complexity is similar for both types of curves, but the Gompertz does not require the assumption of cubic length–weight relation implicit in the Beverton–Holt treatment of the von Bertalanffy.

ISSN:0706-652X    

DOI:10.1139/f69-017

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The relationship between total gill area and body weight can be expressed as Y + aWbwhere "b" varies from about 0.8 to 0.9 for different species. The area for a 1-g fish ("a") ranges 22-fold for published data on different species. Expressed by the same general equation, the number of secondary lamellae per millimeter of filament ranges 4-fold for different species and decreases with increasing fish weight within each species by a power of about −0.1.

ISSN:0706-652X    

DOI:10.1139/f69-018

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Recent changes in depth and coastal morphology were investigated by comparing old and new charts. All major changes seem to be the result of normal morphological evolution. Artificial changes, induced by human activity, seem to be relatively slight. It is widely believed that the decline of oyster populations was caused by silt deposition, and this in turn was produced by increased runoff after human occupation (farming, forestry, etc.). Silting has occurred in certain areas, but this was due to natural causes. The decline of oyster populations was therefore due either to natural causes or to factors other than silting.

ISSN:0706-652X    

DOI:10.1139/f69-019

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Grooves and knobs on the vertebrae, ratio of length and width of scales, and ratio of lengths of rami of epipleural bones enabled us to separate northern pike and muskellunge in mutilated specimens, stomach contents, and archaeological material.

ISSN:0706-652X    

DOI:10.1139/f69-020

出版商:NRC Research Press    

年代:1969

数据来源: NRC