Showing papers in "Canadian Journal of Fisheries and Aquatic Sciences in 1982"
TL;DR: Most vertical distributions of chlorophyll can be explained by the interaction between hydrography and growth, behavior, or physiological adaptation of phytoplankton with no special consideration of grazing by herbivores, even though vertical distribution of epizooplankon are not uniform.
Abstract: The relationship between chlorophyll a and phytoplankton biomass (organic carbon content) is highly variable as is the yield of in vivo fluorescence per unit chlorophyll. Thus, vertical profiles of...
824 citations
TL;DR: The coefficients of variation and the index of precision as discussed by the authors provide a statistical test of reproducibility of aging between readers, and they are free from the shortcoming of the percent agreement method.
Abstract: The coefficients of variation and the index of precision provide a statistical test of reproducibility of aging between readers. Because the coefficients of variation and the index of precision incorporate the averaged year-class of a fish species, they are free from the shortcoming of the percent agreement method. Because variance is a better estimator than absolute difference, the coefficient of variation is a stronger estimator than the index of average percent error in providing a test statistic.Key words: age determination, coefficients of variation, index of precision, average percent error, percent agreement
742 citations
TL;DR: A general theory for analyzing catch at age data for a fishery is presented and seems to be the first to address itself properly to the stochastic nature of the errors in the observed catch atAge data.
Abstract: We present a general theory for analyzing catch at age data for a fishery. This theory seems to be the first to address itself properly to the stochastic nature of the errors in the observed catch ...
438 citations
TL;DR: Two new indices, total phosphorus concentration and macrobenthos biomass/mean depth, are added to the literature to develop and compare predictors of fish biomass and yield in lakes.
Abstract: Data taken from the literature were used to develop and compare predictors of fish biomass and yield in lakes. Two new indices, total phosphorus concentration and macrobenthos biomass/mean depth, w...
307 citations
TL;DR: A large number of juvenile coho salmon were raised in six ponds at Rosewall Creek, Vancouver Island, British Columbia, from which releases were made at four times: April 14, May 12, June 10 and July 10.
Abstract: Juvenile coho salmon (Oncorhynchus kisutch) were raised in six ponds at Rosewall Creek, Vancouver Island, British Columbia, from which releases were made at four times: April 14, May 12, June 10 and July 8, 1975. Prior to each release a portion of the juveniles in each pond were graded into three size groups (small, medium, large) based on size distributions in each pond. The juveniles were nose-tagged according to size group, pond, and release date, and marked by adipose fin removal. A total of 57 groups were released. Returns of adults and precocious males (jacks) to the weir and to the fishery (commercial, sport) were subjected to response surface analysis. Maximum adult returns of 43.5%, to the weir and fishery, were predicted for release of 25.1-g coho juveniles on the 173rd (Julian) day from January 1 (June 22, 1975). A significant interaction was noted between release time and size: maximum returns from early (April 14) releases would be expected from release of 16- to 17-g juveniles. Returns of ja...
265 citations
TL;DR: Very different testicular structures and spermatogenetic patterns have been found in fish of the teleost group and studies of their endocrine patterns suggest that the GTH involved is controlled by external (mainly temperature but also photoperiod) and gonadal factors.
Abstract: Very different testicular structures and spermatogenetic patterns have been found in fish of the teleost group. Two types of structures may be identified: (i) a tubular type with no lumen (in cypri...
257 citations
TL;DR: A simplified preparation from gill tissue that yields adenosine triphosphatase activities comparable to some microsomal fractions is described.
Abstract: A simplified preparation from gill tissue that yields adenosine triphosphatase activities comparable to some microsomal fractions is described. The procedure uses two short (6 and 7 min), low speed (2000 Relative Centrifugal Force) centrifugations at room temperature in contrast to long, high speed, refrigerated centrifugations usually associated with microsomal preparations.Key words: gill ATPase, ATPase, fish
248 citations
TL;DR: In most of the chemically mediated interactions surveyed it is not clear that communication in a generally accepted sense is involved, or whether fish are simply responding adaptively to those metabolic products which inevitably "leak" into the environment and only fortuitously provide "information" to conspecifics.
Abstract: Chemical signals (pheromones) have been shown to be involved in schooling, territorial marking, species, sex and individual recognition, courtship, the induction of physiological readiness for mating, and in parent–young interactions. Alarm substances released from damaged skin elicit avoidance behavior. Pheromones may also be involved in homestream recognition in some anadromous species. Most pheromones investigated act as "releasers"; a few "priming" effects have been observed. In most of the chemically mediated interactions surveyed it is not clear that communication in a generally accepted sense is involved, or whether fish are simply responding adaptively to those metabolic products which inevitably "leak" into the environment and only fortuitously provide "information" to conspecifics. In a few cases, specializations in chemical secretions or secretory structures indicate that they have evolved for communication. It is proposed that a combination of factors — the availability of a wide array of solu...
244 citations
TL;DR: A really useful prey-selection index should be statistically testable, and a 2 × 2 contingency table formulation provides a simple way to test the significance of any degree of selection at any sample size.
Abstract: A really useful prey-selection index should be statistically testable. A 2 × 2 contingency table formulation provides a simple way to test the significance of any degree of selection at any sample ...
219 citations
TL;DR: A comparison of charr morphs of Vangsvatnet with the nearby Lonavatnet Lake suggested that the number of charR morphs is adapted to local environmental co-operation, indicating that the numbers of charrs adapted to different niches during the growth season.
Abstract: The aim of the present study was to test possible habitat and food segregation between two charr morphs in Vangsvatnet Lake. The charr population of Vangsvatnet consists of one pale phenotype with ...
208 citations
TL;DR: Scale analysis used to determine the timing and relative intensity of size-selective mortality in chum salmon (Oncorhynchus keta) during early sea life suggested that mortality was strongly size selective over the size range 45–55 mm fork length.
Abstract: Available evidence indicates that mortality of juvenile salmon during early sea life is high and probably size dependent. I used scale analysis to determine the timing and relative intensity of siz...
TL;DR: Fish use of Beaufort Sea coastal waters was examined during summer and winter periods 1977–80 and Arctic cod increased in abundance in the lagoon during late summer and some association was noted between their numbers and higher salinities but not temperature or turbidity.
Abstract: Fish use of Beaufort Sea coastal waters was examined during summer and winter periods 1977–80. Arctic cod (Boreogadus saida) were abundant but their occurrence was highly variable. They accounted f...
TL;DR: During summer stratification there was a consistent metalimnetic maximum in the smaller fraction, and there were small but significant differences in the concentrations found at two stations less than 1 km apart.
Abstract: Vertical and horizontal patterns in limnetic phosphorus concentrations ([P]) were detected in an oligotrophic lake by dividing the total phosphorus pool into two fractions: dissolved and particulat...
TL;DR: Techniques for sex control in trout, char, and salmon are reviewed in the context of their application to salmonid culture and alternative sterilization techniques which do not depend on steroid administration or zygote manipulation are reviewed.
Abstract: Techniques for sex control in trout, char, and salmon are reviewed in the context of their application to salmonid culture. Procedures for the production of all female, male, or sterile salmonids using estrogen or androgen treatment, respectively, are described and compared for Salmo, Salvelinus, and Oncorhynchus species. The production of homozygous monosex salmonids by radiation gynogenesis and techniques for the production of potentially sterile triploid and polyploid salmonids arc discussed. Finally, alternative sterilization techniques which do not depend on steroid administration or zygote manipulation are reviewed including irradiation, and autoimmune and surgical procedures. Direct and indirect hormonal techniques for production of all female salmonid groups are now sufficiently developed to permit pilot application as is the direct androgen sterilization technique. The procedure of radiation gynogenesis is available for the rapid experimental production of inbred lines. On the other hand, further...
TL;DR: Otoliths of sockeye salmon display daily rings in the microstructure when reared in temperatures above ~ 5 °C; the existence of an entrained biological rhythm is supported.
Abstract: Otoliths of sockeye salmon (Oncorhynchus nerka) display daily rings in the microstructure when reared in temperatures above ~ 5 °C. Otolith formation ceases in fed fry held at or below 5 °C, although body growth continues at a much reduced rate. Foraging periodicity is not a significant factor in ring periodicity; rather, the existence of an entrained biological rhythm is supported. Subdaily rings are present on some otoliths, but they are faint and poorly defined. A noticeable and consistent ring corresponding to the date of first feeding is identified. The otolith diameter—body length relationship varies significantly between fed and starved experimental groups. The relation measured for starved groups is thought to be a short-term response to brief periods of starvation.Key words: otoliths, daily rings, sockeye salmon, environmental factors
TL;DR: Analyses of the stomach contents of 399 male and female mako sharks (Isurus oxyrinchus) from shark fishing tournaments held in New Jersey, New York, Rhode Island, and from longline catches taken between Cape Hatteras and the Grand Banks show bluefish is the major inshore food item.
Abstract: Analyses of the stomach contents of 399 male and female mako sharks (Isurus oxyrinchus) ranging from 67 to 328 cm are presented. Samples are from shark fishing tournaments held in New Jersey, New York, Rhode Island, and from longline catches taken between Cape Hatteras and the Grand Banks. Teleost remains occur in 67% of the stomachs with bluefish (Pomatomus saltatrix) constituting 77.5% of the diet by volume. Bluefish is the major inshore food item. Cephalopoda amount to 15% of the stomach contents by frequency of occurrence and are consumed primarily offshore. Consumption and diet are the same for both sexes. The average capacity of the stomach is 10% of the body weight. Estimates of daily ration average 2 kg (range from 1.4 to 2.7 kg). Makos may consume 4.3 to 14.5% of the available bluefish resource in the area between Cape Hatteras, NC, and Georges Bank.Key words: shortfin mako, Isurus oxyrinchus; elasmobranchs, food habits, stomach content analyses, daily ration, Pomatomus saltatrix, biomass
TL;DR: The effects of inorganic and organic tin compounds on pure cultures of green and blue-green algae and natural phytoplankton in lake water were tested by.
Abstract: The effects of a number of inorganic and organic tin compounds on pure cultures of green and blue-green algae and natural phytoplankton in lake water were tested. Organic tin compounds were general...
TL;DR: Salmon held above 10 °C experienced reduced survival, hatched and emerged precociously, and were smaller at hatching, at emergence, at maximum tissue weight and at complete yolk absorption than fish at lower temperatures.
Abstract: Growth, development and survival of chinook salmon (Oncorhynchus tshawytscha) during the yolk absorption period (fertilization to complete yolk absorption) were examined at 6, 8, 10, and 12 °C. Hig...
TL;DR: An increase in prostaglandin F (PGF) levels associated with GtH-induced ovulation occurs in vivo in the pond loach and goldfish and, in goldfish, PG injection reverses this blockade.
Abstract: Prostaglandins (PGs) have been identified in gonads, semen, ovarian fluid, blood, and in vitro ovarian incubates from a variety of teleosts. In teleosts, PGs appear to be involved in ovulation (fol...
TL;DR: The generality of winter cessation of feeding suggests that the above hypothesis may also be applicable to a wider range of species, and such a mechanism may account for the extreme geographic variation in life history parameters of American plaice, Hippoglossoides platessoides, and witch flounder.
Abstract: This paper examines the factors determining the age and size at maturity of temperate species of flatfish. In some species maturity is governed by size, not age. I propose that the most likely determinant of this size is size-dependent predation. Many species fast during the winter months and rely upon reserves stored in the body tissues to provide energy for gonad maturation. The stress placed upon a fish by the breakdown of body tissues may be very substantial and could significantly affect the predation function. Under these conditions selection may favor the deferment of maturity until a size is achieved at which predation is relatively low. I suggest that such a mechanism may account for the extreme geographic variation in life history parameters of American plaice, Hippoglossoides platessoides, and witch flounder, Glyptocephalus cynoglossus. The generality of winter cessation of feeding suggests that the above hypothesis may also be applicable to a wider range of species. By contrast, in several spe...
TL;DR: Although otolith growth is isometric with respect to increase in fish length under these experimental regimes, otolith microstructure will differ in fish of the same size reared under different environmental conditions.
Abstract: The effects of photoperiod, feeding frequency, and water temperature on formation of otolith daily growth increments in juvenile chinook salmon (Oncorhynchus tshawytscha) were examined. Feeding fre...
TL;DR: Large numbers of juvenile chinook salmon, chum salmon, and pink salmon were present within tidal channels of a marsh area in the Fraser Estuary between March and June 1978, showing an increase in average length which was attributable to estuarine growth.
Abstract: Large numbers of juvenile chinook salmon (Oncorhynchus tshawytscha), chum salmon (O. keta), and pink salmon (O. gorbuscha) were present within tidal channels of a marsh area in the Fraser Estuary b...
TL;DR: Endocrinology has, or may have, important applications in four major activities of fish culture viz induced breeding, larval rearing, "grow-out," and broodstock development and management.
Abstract: Endocrinology has, or may have, important applications in four major activities of fish culture viz induced breeding, larval rearing, "grow-out," and broodstock development and management. The curr...
TL;DR: It is demonstrated that competitive interactions between dace and sculpin for preferred microhabitat wer...
Abstract: Two morphologically dissimilar stream fishes occupied the same microhabitat in different riffles of Deer Creek, Tehama County, California. In a 12.5 km reach of the creek, speckled dace (Rhinichthys osculus) dominated riffles at the lower end while riffle sculpin (Cottus gulosus) dominated the riffles at the upper end, where dace were confined to slower water. Between these sets of riffles, relative abundances of the two species were negatively correlated. Routine metabolic rates of sculpin increased rapidly with temperature and indicated that sculpins were unable to tolerate temperatures in the low elevation riffles in the summer. Dace swimming performance appeared to be adequate at low temperatures to permit them to occupy the sculpin-dominated riffles. However, stream tank experiments indicated that at low temperatures sculpin were able to displace dace from cover in high velocity water. Our analysis thus demonstrated that competitive interactions between dace and sculpin for preferred microhabitat wer...
TL;DR: In this article, the amount of material moving annually from terrestrial ecosystems to the ocean is largely based on an incomplete understanding of events occurring throughout the hydrologic year, and only a vague comprehension of in-stream processes controlling that export.
Abstract: Estimates of the amount of material moving annually from terrestrial ecosystems to the ocean are largely based on an incomplete understanding of events occurring throughout the hydrologic year, and only a vague comprehension of in-stream processes controlling that export. Discharge, suspended sediment, particulate organic matter (POM; > 0.5 μm), dissolved organic carbon (DOC; <0.5 μm diameter), and the percentage of organic matter were measured from 1979 to 1981 in five pristine Quebec streams: First Choice Creek (1st order; watershed area: 0.25 km2), Beaver Creek (2nd order; 1.83 km2), Muskrat River (5th order; 204 km2), Matamek River (6th order; 673 km2), and the Moisie River (9th order; 19 871 km2). All streams, with the exception of First Choice Creek, have a strong spring freshet when 43–55% of the annual discharge occurs. By describing sediment and organic carbon export throughout the annual hydrologic cycle, 1 showed that during the 2-mo spring freshet 71–92% of the annual sediment load is exported...
TL;DR: Monthly variations in capelin and Atlantic herring abundance were in agreement with the seasonal trends previously reported, and short-term fluctuations in the abundance and vertical distribution of the two species were interpreted in terms of the Fickian representation of transport for partially mixed estuarie.
Abstract: We studied the regulation of ichthyoplankton dispersion in the two-layer circulation of the St. Lawrence upper estuary by determining larval abundance and vertical distribution during high frequenc...
TL;DR: The relationship between prey availability and predator growth and mortality was established through field measurements of consumed energy and growth and consumption of largemouth bass in Watts Bar Reservoir, Tennessee, was lower in 1979 than in 1980 as a result of lower winter water temperature, which reduced the abundance and availability of adequate-sized prey.
Abstract: Temperature can control the structure of a predator population by regulating the abundance and size availability of prey. Relatively small differences in winter temperatures between years can have a major influence on largemouth bass (Micropterus salmoides) population structure because of the threshold relationship between temperature and the lower lethal limits of shad. The relationship between prey availability and predator growth and mortality was established through field measurements of consumed energy. Growth and consumption of largemouth bass in Watts Bar Reservoir, Tennessee, was lower in 1979 than in 1980 as a result of lower winter water temperature in 1979, which reduced the abundance and availability of adequate-sized prey. Depending on the severity of the winter, bass that do not attain 25 ± 5 cm by the end of their first growing season do not survive to annulus I formation because of the unavailability of appropriate-sized prey in the spring and the inability of small bass to store sufficien...
TL;DR: The difference in response at the two temperatures indicates that the vitamin C requirement for resistance to infection is possibly higher when channel catfish are infected at lower temperatures, where the natural resistance is reduc...
Abstract: Channel catfish (Ictalurus punctatus) fingerlings were fed semipurified diets containing 0–150 mg/kg of vitamin C for 14 wk and subsequently at two temperature regimes infected with the pathogenic ...
TL;DR: A downward trend from the most contaminated lake to the least was found in levels of zinc in the water, of cadmium and copper in high molecular weight fractions, and of copper in low molecular weight fraction and metallothionein.
Abstract: Hepatic metallothionein was measured in livers of freshly killed rainbow trout (Salmo gairdneri) using differential pulse polarography. The fish were caught in metal-contaminated lakes of the Campb...
TL;DR: The abundance, biomass, vertical distribution, and seasonal succession of planktonic ciliates were studied over a 13-mo period in a small monomictic lake.
Abstract: The abundance, biomass, vertical distribution, and seasonal succession of planktonic ciliates were studied over a 13-mo period in a small monomictic lake. Measurements made concurrently of bacterial abundance (attached and free), chlorophyll a, and pheopigments were analyzed for correlations with the biomass of the major protozoan species and total protozoan biomass. Ciliate community structure varied primarily between periods of winter mixis and summer stratification. Oligotrich, tintinnid, and peritrich ciliates dominated the community during mixis (November to March). Vertical distributions tended to be uniform except for some species containing algal symbionts which occurred primarily in the photic zone. A more diverse community occurred during stratification. At this time species either tended to be restricted to the epilimnion or had sharply defined metalimnetic or hypolimnetic maxima. With the development of anoxia in the hypolimnion (June), bacterivorous scuticociliates reached high densities in t...