bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Controls for a Single Species Fishery and the Economic Value of Research
Authors: Huang C. C. , Vertinsky Ilan B. , Wilimovsky Norman J.
Published: April 2011

Mathematical proofs and analyses of solution methods are presented for determining optimal policies for the management of a single species fishery under equilibrium conditions. Previous intuitive arguments for solution of optimal policies controlling mesh size and fishing rate given complete information are explicitly proven. The analysis is extended to the case where some of the parameters describing the dynamics of the population are known only imprecisely to the manager. Using probability distributions for those unknown parameter values the problem is cast as a stochastic program where expected sustained net revenues from the fishery are maximized. The associated problem of optimal allocation of research resources under uncertainty conditions is considered by evaluating the direct value of such information to management activities.Examples and algorithms are presented for the class of problems discussed.
Growth and Survival of Young-Of-The-Year Emerald Shiners (Notropis atherinoides) at Different Temperatures
Authors: McCormick J. Howard , Kleiner Charles F.
Published: April 2011

Young-of-the-year emerald shiners (Notropis atherinoides) were exposed to mean constant temperatures of 6.9, 11.9, 16.0, 19.8, 24.0, 26.9, 28.9, 31.0, 32.8, 34.9, and 36.7 C for 6 wk. Maximum rates of growth and net biomass gain occurred at 28.9 C, but these rates were not statistically greater (P > 0.05) than those at 26.9 and 24.0 C. Death rates were low at test temperatures up to 32.8 C but high at 34.9 C and above. The upper incipient 7-day TL50 was estimated to be 35.2. The 1-day TL50 of fish taken from the natural habitat, where peak daily temperatures ranged between 20 and 25 C during the preceding few days, was 32.6 C. Natural production of this important forage species would probably be best where temperatures are at least 19 C but not above 29 C for extended periods.
Mixed Species Schooling of Postlarvae of Ammodytes hexapterus and Clupea harengus harengus
Authors: Richards Sarah W.
Published: April 2011

Small schools of post-larval Ammodytes hexapterus and Clupea harengus harengus were observed and captured at Margaree Harbor entrance in the Gulf of St. Lawrence on July 20, 1974 and captured at Goldsmith Inlet beach in Long Island Sound on April 18, 1975. These species appeared similar, yet A. hexapterus averaged 14 mm longer than C. harengus harengus at Margaree, but 9 mm shorter than herring at Goldsmith Inlet beach. In both areas sand lances were narrower than herring.Post-larval A. hexapterus do not bury in the sand, and they will school together with post-larval C. harengus harengus regardless of the differences in sizes between the two species.
Developmental Stages of Pontella meadi Wheeler (Copepoda: Calanoida)
Authors: Gibson Victoria R. , Grice George D.
Published: April 2011

The complete development of Pontella meadi is described and illustrated on the basis of nauplii and copepodids cultured in the laboratory and collected in the field. Development from nauplius to adult took from 18–25 days at 20 C when animals were fed dinoflagellates and Artemia nauplii.
Structured Aquaculture Development with a Canadian Perspective
Authors: Pritchard G. I.
Published: April 2011

Wild fisheries resources in Canada will be increasingly replaced or augmented by aquaculture as they diminish or encounter difficulty in satisfying market demands. Commercial forms of aquaculture still suffer from the lack of innovative policies, well-delineated strategies, and pilot-scale experimentation in operational planning. The aquaculture activities in Canada are reviewed and analyzed in this paper against a model for technological planning and social futures, and against developments elsewhere in food systems. It concludes that substantial research and experimental development effort are still needed, and that the lead time for undertaking these activities is short if risk capital is not to be jeopardized. High priorities are given in support of i) innovative policy development (resource inventories, public anticipations, etc.), ii) strategic forecasting and planning (business strategies, modular enterprise structures, marketing, disease control, a gene pool of aquatic stocks, sea-ranching, aquatic polycultures, introduction of nonindigenous species, waste utilization, etc.), and iii) commercial operations (feed formulation, brood stock selection, water reconditioning, product development, production tactics, pollution control, etc.). There is a shortage of skilled aquaculture practitioners, and a need for more highly trained scientific personnel to address themselves explicitly to aquaculture. In Canada, this industry has already begun to take on an innovative structure that makes it a model for other forms of fisheries development.
Farming Ocean Ranges for Salmon
Authors: Joyner Timothy
Published: April 2011

Recent advances in the culture of salmon point the way to a significant expansion of the scale on which the resource can be effectively managed. From the purely local efforts focused primarily on mitigation of the losses of spawning areas that have characterized traditional salmon culture, we can now progress to the manipulation of stocks on a worldwide scale. International cooperation in the management of salmon as a basic range crop for subpolar seas could provide the seed for the development of a truly international system of planetary aquaculture in which oceans and seas will be managed as range and farmland.
Systems of Polyculture of Fishes in the Inland Waters of India
Authors: Jhingran V. G.
Published: April 2011

Different systems of polyculture of fishes are traditionally practiced in India to utilize various types of inland water resources available in the country. The usually cultivated species of fish in freshwater polyculture are Catla catla, Labeo rohita, and Cirrhinus mrigala. Culture of Chinese carps along with major Indian carps has recently been developed in India as composite fish culture, and with this, production as high as 3000–5800 kg/ha per 6 mo and 7000–9000 kg/ha per yr has been obtained in still-water ponds in different parts of the country. The magnitude of production is significant considering its application to the large resource of ponds and tanks totaling about 1.6 million ha, thoughonly 1 million ha are presently available for carp culture. The remaining 0.6 million ha comprise swamps and derelict waters. The cost of swamp reclamation being high, techniques of mixed culture of air-breathing fishes are being developed to utilize these water bodies as such and already a production of 895 kg/ha per yr of murrels has been attained without any fertilization and supplementary feeding. Further, to utilize about 2.0 million ha of culturable brackish waters available in India, research investigations are well underway to manipulate the tidal impoundments for mixed culture of brackish water fish and prawns with proper scientific management.
Yellowtail (Seriola quinqueradiata) Farming in Japan
Authors: Fujiya Masaru
Published: April 2011

Yellowtail, Seriola quinqueradiata, culture has developed successfully on a commercial scale in Japan. Because of its suitability for aquaculture, it has become the most important species in marine fish farming.Artificial seed production technique has been advanced experimentally, and the artificially produced seed will supersede the natural source in the near future.The fish are cultured mostly in floating net cages in the shallow coastal regions, and in recent years the submerged cage culture technique has contributed to the expansion of production. At present, yellowtail growers, mostly family groups, can find a ready market for their product, and can realize middle-class incomes. On the other hand, consumers are able to obtain a stable supply of this staple food.In spite of the well-developed situation, there are still some problems. Diseases and the shortage of feeds are serious constraints for future progress. The development of suitable disease control techniques and new effective feeds will furnish a key for the solution of these problems.The techniques of intensive marine fish culture developed with yellowtail will be a valuable example for the development of marine farming in the future.
Photoperiod and Temperature Control in the Regulation of Reproduction in the Female Catfish Heteropneustes fossilis
Authors: Sundararaj Bangalore I. , Vasal Sudhir
Published: April 2011

The annual reproductive cycle of the catfish Heteropneustes fossilis is divided into the preparatory period (February–April), prespawning period (May–June), spawning period (July–August), and postspawning period (September–January). Ovarian recrudescence, which normally occurs during the prespawning period, can be advanced by photothermal manipulations. During the postspawning and preparatory periods, the tempo of ovarian recrudescence is much faster at 30 C than at other temperatures (ambient, 25 or 34 C) regardless of photoperiod (14L + 10D, 12L + 12D, or 9L + 15D).Warm temperature (30 C) postpones the postspawning ovarian regression only up to the first week of October regardless of photoperiod. The ovarian cycle is regulated by a circannual rhythm which can be activated 5 mo earlier, but its activity cannot be prolonged beyond October by photoperiodic and temperature manipulations.Interruption of the night of a short day (6L + 18D) treatment by 1 h of light between 0000 and 0100 induces ovarian recrudescence that is significantly greater than that obtained in the control group exposed to 7L + 17D. Scanning of the major part of the dark period (1800–0500) to determine the duration of the photo-inducible phase shows that it lies between 0000 and 0500 with peaks from 0000 to 0100 and from 0400 to 0500. Even 1 h of light in a regimen of 1L + 23D presented between 1900 and 0500 produces significant ovarian recrudescence with peaks between 2200 and 0100. These results clearly demonstrate the possible involvement of a circadian mechanism for photoperiod measurement in the catfish.Precociously gravid catfish obtained as early as April by photothermal treatment have been induced to spawn in the laboratory by administration of ovine luteinizing hormone (LH). Ripe eggs after fertilization hatched into seemingly normal fry. Further, the spent fish when subjected to the same photothermal treatment developed a fresh crop of yolky eggs within 1 mo; such gravid females have been again induced to spawn with LH. This process has been repeated so that the same set of fish have been spawned 4 times between April and July of the same year. Thus, it is possible to get catfish fry not only early but also 2.6 times more than that usually available from each female during the spawning season. The aquacultural potentialities of this laboratory discovery are discussed.
Prevention and Control of Viral Diseases of Salmonids
Authors: Amend Donald F.
Published: April 2011

Three viral diseases of salmonids are of worldwide concern: infectious pancreatic necrosis (IPN) viral hemorrhagic septicemia (VHS), and infectious hematopoietic necrosis (IHN). Six principal approaches are being used to prevent or control these diseases: 1) preventing contact o the pathogen with the host, 2) environmental manipulation, 3) immunization, 4) chemotherapy, 5 selective breeding for disease resistance, and 6) reducing stress conditions which augment disease conditions. Preventing the introduction of a pathogen into a new stock of fish has been accomplished mainly by implementing stringent laws to prevent transport of infected fish into uninfected areas. Stocks of fish already infected are sometimes destroyed, and the hatchery is disinfected and restocked with fish free of specific pathogens. Environmental manipulation (elevated water temperature) has been successfully used to control IHN. Chemotherapeutics such as povidone-iodine for IPN and benzipyrene for IHN show promise of controlling mortalities; however, the practicality of using these drugs to eliminate the carrier fish has not been evaluated. Salmonids are capable of developing immune responses to viruses; however, development of effective vaccines, selective breeding for disease resistance, and identification of stress conditions which augment disease are still in the experimental phase.
Mariculture — Ecological and Genetic Aspects of Production
Authors: Calaprice J. R.
Published: April 2011

The culture of marine organisms may be classified into four categories. Marine animal husbandry: the intensive culture in floating pens or impoundments of salmonids in Europe and North America and yellowtail (Seriola quinqueradiata), puffer, and shrimp (Penaeus japonicus) in Japan yields 3,000–610,000 kg/ha per yr. Traditional mariculture: the culture of milkfish, mullet and shrimp in ponds and ground culture of oysters and mussels yields 200–5,000 kg/ha per yr. Float culture of sessiles such as oysters, mussels, and algae yields 80,000–750,000 kg/ha per yr. Sea ranching: the culture of salmonids in hatcheries, release prior to migration and subsequent recapture. Coho (Oncorhynchus kisutch), chinook (O. tshawytscha), and Atlantic salmon (Salmo salar) yield 0.76–2.5 million kg/ha per yr while pink (O. gorbuscha) and chum salmon (O. keta) yield 2.3–22.0 million kg/ha per yr. Data on nutritional and ecological requirements are discussed in relation to the feasibility of increasing yields using genetic methods.
Possibilities for Genetic Improvements in Salmonids
Authors: Gjedrem Trygve
Published: April 2011

No systematic breeding work has been done so far with salmonids except for some attempts with rainbow trout (Salmo gairdneri) and Pacific salmon.The possibilities for obtaining genetic change are particularly dependent on selection intensity, heritability, phenotypic variance, and length of generation interval. The very high fertility in salmonids makes it possible to practice an intensive selection for fish in captivity and a more moderate selection in wildlife cultivation. Very few estimates of heritability have been calculated for production traits in salmonids and most of them are based on limited data. The few estimates for growth rate are moderately large (h2 = 0.1–0.2). For most production traits studied, a remarkably high phenotypic variance has been found, and the coefficient of variation is 2–4 times as high as for production traits in farm animals. The length of generation interval varies from one species to another and with the production system applied; 2–5 yr will be the usual.To make a selection program possible, one must control the whole life cycle of the fish. Therefore, hatching, fingerling production, and cheap and efficient tagging methods are necessary requirements.Because of the high fertility, the large variation and a moderately long generation interval, it should be possible to obtain much higher genetic gain per time unit in salmonids than in farm animals.
Ontogenetic Variation in the Multiple Hemoglobins of Coho Salmon (Oncorhynchus kisutch) and Effect of Environmental Factors on Their Expression
Authors: Giles M. A. , Vanstone W. E.
Published: April 2011

Hemolyzates from the blood of coho salmon (Oncorhynchus kisutch) at various stages of development were subjected to micro-starch-gel electrophoresis. Three distinct electrophoretic patterns composed of different combinations of 18 hemoglobin tetramers were observed. Embryonic and yolk-sac alevins possessed 1 cathodic and 12 anodic components while fry retained only 3 of the 12 anodic polymorphs. During smoltification, 4 new cathodic components appeared and 2 of the anodic and the cathodic components of alevin hemolyzates reappeared. This latter pattern was retained until the fish spawned and died. Attempts to induce changes in the pattern of development of these hemoglobins by exposing fry and pre-smolts to extreme variations in dissolved oxygen, temperature, and salinity were completely unsuccessful.
Fecundity of Coho Salmon (Oncorhynchus kisutch) from the Great Lakes and a Comparison with Ocean Salmon
Authors: Stauffer Thomas M.
Published: April 2011

I measured fecundity of coho salmon (Oncorhynchus kisutch) that matured in the Great Lakes to make comparisons with Pacific Ocean coho salmon and among groups of Great Lakes salmon. Numbers of eggs produced (1600–3500) by Great Lakes salmon were comparable to production (1500–3300) by Pacific salmon of similar size. Average egg diameters of Lake Michigan (7.1–7.4 mm) and Pacific salmon (6.1–7.4 mm) were also comparable but Lake Superior eggs were smaller (5.1–5.4 mm). Fecundity of second generation freshwater salmon which originated from Lake Michigan eggs was similar to that of the first generation which originated from Pacific eggs because the average numbers (2938–3243) and diameters (7.1–7.4 mm) of eggs produced were about the same. On the average, Lake Michigan salmon contained more (2938) and larger (7.1-mm diam) eggs than did Lake Superior salmon (2150 and 5.1-mm diam) of the same year-class and early life history.
Acute Toxicities of Spruce and Hemlock Bark Extracts to some Estuarine Organisms in Southeastern Alaska
Authors: Buchanan David V. , Tate Paul S. , Moring John R.
Published: April 2011

Sitka spruce bark extracts were found to be toxic to adult and larval pink shrimp (Pandalus borealis) and larval Dungeness crab (Cancer magister). Sitka spruce and western hemlock bark extracts were found to be toxic to pink salmon (Oncorhynchus gorbuscha) fry. For salmon fry, toxic effects were observed as soon as 3 h after exposure to hemlock bark extracts. After a 96-h exposure, 50% of the test fry were killed at a concentration of 56 mg/liter (96-h LC50). With a 96-h exposure of spruce extracts, 50% of the fry were killed at concentrations of 100–120 mg/liter.Spruce bark extracts were consistently toxic to all invertebrates tested. The 96-h LC50 with larval shrimp, adult shrimp, and larval crabs were 415, 205, and 530 mg/liter, respectively. Using loss of swimming as the criterion, the 96-h EC50s for larval shrimp and larval crabs were 155 and 225 mg/liter, respectively (EC50: median effective concentration). Spruce bark pulp was found to be 2–6 times more toxic than extracts to shrimp larvae.
Survival and Growth of Rainbow Trout (Salmo gairdneri) in Four Prairie Lakes, North Dakota
Authors: Myers Gary L. , Peterka John J.
Published: April 2011

Survival of rainbow trout (Salmo gairdneri) in three North Dakota prairie lakes was low the 1st mo after stocking, ranging from 15 to 54%; high mortality may have been due to bird predation. In a fourth lake, where 77% survived the 1st mo, no predatory birds were observed. All fish in two lakes died in August when dissolved oxygen levels dropped to below 1.0 mg/liter following July blue-green algae blooms of 28 and 63 mm3/liter. In the other two lakes, harvests in October ranged from 0.1 to 4.4% of fish stocked. Mean wet weights at harvest of up to 272 g were sufficient for commercial use; however, special management to improve survival rates would be necessary in the lakes studied.
Infectious Pancreatic Necrosis: Transmission with Iodine-Treated and Nontreated Eggs of Brook Trout (Salvelinus fontinalis)
Authors: Bullock G. L. , Rucker R. R. , Amend D. , Wolf K. , Stuckey H. M.
Published: April 2011

Experiments conducted simultaneously at two laboratories have shown brook trout (Salvelinus fontinalis) egg transmission of the virus of infectious pancreatic necrosis with eggs treated with 100 ppm iodine (as Wescodyne®) and with nontreated eggs.
Smolt Transformation: Evolution, Behavior, and Physiology
Authors: Hoar William S.
Published: April 2011

Literature concerned with the appearance of smolts (silvery color, streamlined body form), their physiology (salinity relationships, endocrinology), and their behavior (territorial and schooling) is discussed in relation to key steps that may have been taken in the evolution of the parr–smolt transformation and seagoing behavior. In this discussion, it is assumed that Salmonidae evolved in fresh water, that the genus Oncorhynchus originated in a large area of brackish water such as the Sea of Japan, and that schooling oncorhynchids (for example O. gorbuscha and O. keta) are the most specialized of the seagoing salmonids while species of char (Salvelinus) and trout (Salmo) are more primitive.
Female Homogamety in Grass Carp (Ctenopharyngodon idella) Determined by Gynogenesis
Authors: Stanley Jon G.
Published: April 2011

Gynogenesis occurred in eggs of grass carp (Ctenopharyngodon idella) treated with X-irradiated milt from goldfish (Carassius auratus). Gynogenetic offspring were females, which indicates functional female homogamety in grass carp. Five of these gynogenetic fish were used as an egg source for a second generation of artificially gynogenetic fish. The percentage yield in this second generation was about the same as in the first, which suggests that the tendency to become diploid is not strongly heritable.
Arsenic Concentrations in Some Coexisting Marine Organisms from Newfoundland and Labrador
Authors: Kennedy Victor S.
Published: April 2011

Inorganic arsenic concentrations in sea water and mud, and total arsenic concentrations in bodies of shrimp, zooplankton, and fish from northern Newfoundland and southern Labrador were measured. There was a positive relationship between concentration and carapace length in Pandalus borealis and P. montagui and a negative relationship in Eualus macilentus. There was no relationship between concentrations in shrimp eggs and carapace length. Arsenic concentrations in zooplankton and fish muscle were relatively low compared with the shrimp species; amphipods contained more arsenic than copepods or euphausiids, and American plaice (Hippoglossoides platessoides) more than redfish (Sebastes marinus), turbot (Reinhardtius hippoglossoides), and Atlantic cod (Gadus morhua). There was no evidence of increasing arsenic concentrations through successively higher levels of the food chain.
Oxygen Isotope Studies on Sea Ice in the Gulf of St. Lawrence
Authors: Tan F. C. , Fraser W. D.
Published: April 2011

The fractionation of oxygen isotopes between sea ice and sea water in samples collected from the Gulf of St. Lawrence indicated that sea ice is enriched in its O18:O16 ratio with respect to coexisting sea water. Sources of sea ice in the Gulf of St. Lawrence may be identified on the basis of O18:O16 measurements.
Enteric Bacteria in Carp (Cyprinus carpio) and White Suckers (Catostomus commersoni)
Authors: Souter B. W. , Sonstegard R. A. , McDermott L. A.
Published: April 2011

Kidneys and intestines of 192 carp (Cyprinus carpio) and 49 white suckers (Catostomus commersoni) from five different sites in the Great Lakes were examined for enteric bacteria. Bacteria were identified using conventional methods, the New Improved Enterotube, and the API-20E System. In decreasing order of frequency, the 159 enteric bacteria isolated included members of the following genera: Proteus (70), Enterobacter (58), Providencia (12), Citrobacter (11), Salmonella (3), Serratia (3), and Escherichia (2).
Chemical Oceanography in Canada
Authors: Mann C. R.
Published: April 2011

Chemical oceanography is the most recently developed discipline of oceanography science in Canada. Only in the last few years have groups of chemists been formed in Canadian oceanographic institutions. Many of the chemists are new to chemical oceanography, they are still in the processes of developing their knowledge and sorting out those aspects of research in chemical oceanography that should be pursued in Canada.The problems posed by pollution have accelerated the development of chemical oceanography and have also had a considerable influence on the subject matter studied by the chemists. Concern with pollution has led to a concentration of the effort in estuarine and coastal zone problems. This will continue into the foreseeable future. It is desirable that the Canadian program be extended to include arctic studies, the continental shelves, and an effort should be made to acquire baseline into waters around Canada.More attention should be given to chemical oceanographic studies in support of fisheries, and the oceanography of the deep sea should not be neglected.Canada can not hope to undertake research in all aspects of such a complex subject as chemical oceanography. The best strategy at the present stage of development is to be selective, develop science of significance in the laboratories as well as addressing practical problems, and to ensure that there is adequate contact with work done elsewhere in the world.
Utilization of Artificial Shelters by the American Lobster (Homarus americanus)
Authors: Sheehy Daniel J.
Published: April 2011

Artificial shelters, fabricated of pumice concrete and placed in areas devoid of natural shelter, were readily colonized by American lobsters (Homarus americanus). Two designs, single chamber and triple chamber, were used for the shelters. Although they both afforded approximately the same available volume, it was demonstrated that those of triple chamber design were utilized by a larger number of lobsters per shelter. Spacing and orientation also had a significant effect on occupancy. Lobster abundance and biomass observed on shelter sites were equal to or greater than those reported for good natural grounds. The shelters were used by both juvenile and adult lobsters.
Taxonomy and Biology of Some Newfoundland Marine Leeches (Rhynchobdellae: Piscicolidae)
Authors: Khan R. A. , Meyer M. C.
Published: April 2011

Taxonomy and biology of 4 species of marine Piscicolidae belonging to the Malmiana–Oceanobdella complex were studied on the coast of Newfoundland from 1970 through 1974. Species include Malmiana brunnea, M. scorpii, and Oceanobdella microstoma, which infest shorthorn (Myoxocephalus scorpius) and longhorn sculpin (M. octodecemspinosus) and O. sexoculata, which occurs in the buccal cavity of ocean pout (Macrozoarces americanus). Laboratory studies included host proclivity, mating, deposition and hatching of cocoons, and growth of the progeny. Malmiana brunnea and M. scorpii have the potential of producing 2 generations each year, but the life cycle in nature is probably annual: the young emerge in July through September, mature and breed in the spring of the next year, and die by midsummer following cocoon deposition. Life cycles of O. microstoma and O. sexoculata are also annual. Although cocoons of O. sexoculata hatch in August, young of O. microstoma do not emerge until late November. Young of both species mature the following spring, deposit cocoons, and die. Cocoons of M. brunnea and M. scorpii each contain an average of 3 and 5 eggs, respectively, but those of O. microstoma and O. sexoculata contain only 1 egg.Malmiana nuda Richardson, 1970 and Platybdella buccalis Nigrelli, 1946 are considered junior synonyms of M. brunnea (Johansson, 1896) and Oceanobdella sexoculata (Malm, 1863), respectively.
Phosphorus Retention Capacity of Lakes
Authors: Larsen D. P. , Mercier H. T.
Published: April 2011

Mean annual lake phosphorus concentrations [Formula: see text] in a steady state system can be described as a function of two variables, the mean annual influent P concentration and the net annual P sedimentation: [Formula: see text] (see Rigler 1975). [Formula: see text] is the annual P supply/annual water supply and Rp is that fraction of inflowing P retained by the sediments annually. Since Rp is critical in determining [Formula: see text], lake properties were examined for their influence on Rp; the best fit empirical expressions developed related Rp to either areal water supply (annual water inflow rate/lake surface area) or hydraulic washout coefficient (annual water outflow rate/lake volume). The expressions were derived from characteristics of low productivity lakes; their validity for more productive lakes was not examined.A graph of [Formula: see text] vs. Rp is proposed to illustrate the relationship between [Formula: see text], [Formula: see text], and Rp, and, if lake P concentrations are used as measures of trophic state, this graph is useful for predicting trophic state and changes in trophic state caused by altering [Formula: see text] and/or Rp. It is conceptually similar to those of Vollenweider (1975) and Dillon (1975) but differs in that it separates the potential lake concentration ([Formula: see text] would be equal to [Formula: see text] if P were conservative) from those factors acting to reduce [Formula: see text], expressed as Rp, to produce lake concentrations.
Origin and Characteristics of "Fall-Run" American Shad (Alosa sapidissima) from the St. John River, New Brunswick
Authors: Gabriel W. L. , Leggett W. C. , Carscadden J. E. , Glebe B. D.
Published: April 2011

American shad (Alosa sapidissima) taken from the St. John River, New Brunswick, during the fall of 1973 were studied to determine river of origin and duration of residence in the river. One-way analyses of variance and classification by discriminant function analysis of meristic characters suggested that most of these shad were part of the St. John River population. Fat and water content of the fish, maturity, and stomach contents suggested that the movement into the estuary was recent and not a spawning migration.
Sperm Density During Active Spawning of Pacific Herring (Clupea harengus pallasi)
Authors: Hourston A. S. , Rosenthal H.
Published: April 2011

Discharge of milt by spawning Pacific herring (Clupea harengus pallasi) produces a milky discoloration in the water which is readily observed under favorable conditions of weather and light. Echo-sounder tracings showed that only the inshore part of a spawning school that was in contact with the bottom participated in the early stages of spawning. Sperm densities at the surface for two spawnings averaged 148 and 129 sperm/ml (range 80–210 for 16 subsamples). This density is considered more than ample for high fertilization success but is only one-tenth that normally used for artificial fertilization in the laboratory at Nanaimo.
Relative Effect of Two Dietary Water-Soluble Analogues of Menaquinone on Coagulation and Packed Cell Volume of Blood of Lake Trout (Salvelinus namaycush)
Authors: Poston H. A.
Published: April 2011

Triplicate lots of fingerling lake trout (Salvelinus namaycush) (initial mean weight, 5.3 g) were fed a basal, semipurified diet, or this basal diet supplemented with either 1.0 or 2.0 ppm of either menadione sodium bisulfite (MSB) or menadione dimethylpyrimidinol bisulfite (MPB) for 18 wk at 14 C. Neither form of vitamin K had a significant effect on the growth, food conversion, or body composition of the fish.Fish fed 1 ppm of MSB had a significantly higher mean packed cell volume (PCV) than those fed 2 ppm of either analogue. Trout fed 2 ppm of MPB had an intermediate PCV which was not significantly different from that of trout fed either 1 ppm MPB or 2 ppm MSB. A dietary level of 1 ppm MPB (providing an equivalent menaquinone concentration of about 0.5 mg/kg of diet) is sufficient to insure normal coagulation of lake trout blood and a satisfactory PCV.
Identification of Four Northern Blennioid Fish Larvae in the Canadian Atlantic Ocean (Stichaeidae, Lumpenidae)
Authors: Faber Daniel J.
Published: April 2011

Four similar northern blennioid fish larvae from the Gulf of St. Lawrence can be identified on the basis of morphological features. The two larvae of the family Stichaeidae, Ulvaria subbifurcata and Stichaeus punctatus, can be distinguished from the two larvae of the family Lumpenidae, Leptoclinus maculatus and Lumpenus lampretaeformis, by total myomere counts, the position of intestinal myomeres, presence or absence of head melanophores, and presence or absence of internal melanophores along the abdominal part of the notochord. The identification of individual species is based mainly on myomere counts and ventromedial melanophore counts.
Preferred Temperature of Fish: a New Method
Authors: Müller Rudolf , Fry F. E. J.
Published: April 2011

A simple apparatus for establishing a short, steep vertical temperature gradient is described. The preferred temperature is found by determining calorimetrically the mean body temperature of fish in such a gradient. Preferred temperatures at various acclimation temperatures for a sample of young pumpkinseed, Lepomis gibbosus, are given.
Science for Canada’s Fisheries Rehabilitation Needs
Authors: Loftus K. H.
Published: April 2011

A brief, generalized review of the current status of salmonid fisheries on the west and east coasts, and of selected representative waters in the freshwater area is presented. It is concluded that many fish communities and/or fish stocks are depressed, collapsed, or extinct as a result of severe stresses imposed directly, or indirectly, by man’s activities. Rehabilitation of fish stocks and fish communities to levels approximating those of early years, and to levels capable of supporting more stable yields to meet growing client requirements appears practical. The need for explicit policy decisions with regard to sea ranching and rehabilitation as options for approaches to increasing fish abundance is stressed. Rehabilitation of stocks and communities will require additional science in areas such as hatching, rearing and selective breeding, fisheries engineering, and in the more precise definition of natural productive capacity of waters. Effective fisheries rehabilitation programs, and fisheries management generally, require: development of fisheries information systems; an adaptive or experimental approach; more social and economic data; synthesis and communication of science available; and fundamental reconsideration of the traditional institutional arrangements for fisheries work. Some important fisheries rehabilitation programs, carefully planned and assessed, can proceed immediately with confidence in their success; others must await improvement in water quality.
Effects of Sand Sedimentation on Colonization of Stream Insects
Authors: Luedtke R. J. , Brusven M. A.
Published: April 2011

Driftnets, basket samplers, and artificial streams were used to investigate the influence of heavy sand accumulations on insect drift, colonization, and upstream movements in Emerald Creek, northern Idaho. Most riffle insects successfully passed through low-velocity, sandy reaches 80 m long. Upstream movements on sand were impeded by flows as low as 12 cm/s, except for the heavily cased caddisfly Dicosmoecus sp.
Cadmium and Zinc Toxicity to flagfish, Jordanella floridae
Authors: Spehar R. L.
Published: April 2011

Cadmium and zinc toxicity to the flagfish (Jordanella floridae) was determined on the basis of 96-h median lethal concentrations (LC50) and significant decreases (P = 0.05) in survival, growth, and reproduction over the complete life cycle of the fish. The 96-h LC50 values for cadmium and zinc to juvenile flagfish were 2500 and 1500 μg/liter, respectively. In chronic tests, reproduction was the most sensitive indicator of cadmium toxicity and was inhibited at 8.1 μg/liter. Tissue-concentration analysis showed that fish exposed to concentrations of 1.7 μg/liter and above accumulated significantly greater amounts of cadmium than those in the controls. In zinc tests, survival of larvae (not exposed as embryos) and growth of females were the most sensitive measure of zinc toxicity and were reduced at respective concentrations of 85 and 51 μg/liter. Significant uptake of zinc occurred in fish exposed to concentrations of 47 μg/liter and above. The lowest cadmium and zinc concentrations causing adverse effects to the flagfish were similar to those affecting other fish species. Application factors for both metals were similar to those reported for cadmium exposed bluegills (Lepomis macrochirus) and zinc exposed fathead minnows (Pimephales promelas) in hard water.
Theoretical Effect of Schooling by Planktivorous Fish Predators on Rate of Prey Consumption
Authors: Eggers Douglas M.
Published: April 2011

Effect of schooling on the rate of prey consumption by planktivorous fish is deduced by extending the Holling disk equation (i.e. the rate of prey consumption by solitary feeding fishes can be expressed by the Holling disk equation) to account for lateral visual-field overlap and reduction of prey density due to removal of prey by forward-occurring members of the school. Effect of schooling is expressed as the rate of prey consumption per member of the school relative to that by a solitary individual. This study suggests that schooling of predators occurs at the expense of prey consumption. Cost of schooling is reduced if prey densities are high, if distance between members is high, or if school size is small. There may be some advantage to schooling when prey have a clumped distribution.
Diel Movement of Walleye, Stizostedion vitreum vitreum, in West Blue Lake, Manitoba, as Determined by Ultrasonic Tracking
Authors: Kelso J. R. M.
Published: April 2011

Eight walleye (Stizostedion vitreum vitreum) between 2 and 5 yr of age were equipped with ultrasonic transmitters, released, and followed for periods up to 24 h. During the study period, September 24–October 2, 1975, West Blue Lake was thermally stratified. Movement was limited to the homothermous epilimnion, above 10 m, and to the region of steeply sloping bottom of about 5–10 m which was usually within 100 m of shore. Midbasin crossings of the lake were infrequent. Transmitter attachment caused temporary high activity after which a more normal rhythm was apparent with peaks of activity at dusk and dawn. The majority, 86%, of observed swimming speeds were under 1 body length s−1. Since much localized activity, too restricted to measure, was apparent, these observations must be regarded as only approximations of natural activity.
Effects of Pulpmill Effluent on Phytoplankton Production in Coastal Marine Waters of British Columbia
Authors: Stockner John G. , Cliff David D.
Published: April 2011

Phytoplankton production adjacent to two kraft pulpmills in Howe Sound, British Columbia, was considerably lower than daily rates at control stations removed from the zone of influence. Average daily production at the Port Mellon mill was 29 and 24 mg C∙m−2∙day−1 in 1973 and 1974, in contrast with 332 and 367, in respective years at the control. Less difference in production was seen between Woodfibre mill and its control, because this mill is situated in a more actively flushed location. Howe Sound studies showed little qualitative or quantitative difference between chlorophyll a levels or phytoplankton assemblages among mill and control stations. Skeletonema costatum and Thalassiosira spp. were dominant phytoplankton species. Light attenuation and selective absorption of 400–500 nm wavelength light by kraft mill effluent was considered the major factor responsible for reduced production in the zone of influence. Axenic culture studies with marine phytoplankton showed that phytotoxicity occurs only at high effluent concentrations. Our laboratory experiments suggest that, given sufficient time, it is possible for phytoplankton to adapt to relatively high effluent concentrations, if pH remains normal.
Respiration Rates, Energy Budgets, and Molting Frequencies of Three Species of Euphausiids Found in the Gulf of St. Lawrence
Authors: Sameoto D. D.
Published: April 2011

Respiration rate experiments at different temperatures were conducted on three species of euphausiids, Meganyctiphanes norvegica, Thysanöessa raschii, and T. inermis, found in the Gulf of St. Lawrence. The slopes of the respiration regression lines at different temperatures for the same species were not significantly different. Thysanöessa inermis acclimated to temperature changes with the result that its respiration rates remained relatively stable over most of the temperatures tested.Feeding rates were measured for M. norvegica and T. inermis at different temperatures using Artemia nauplii as food. The number of calories ingested, expressed as a percentage of the total body calories of the euphausiid, decreased with body size and water temperature. Thysanöessa inermis ingested fewer calories than M. norvegica in relation to total body calories at all temperatures. Both species showed a linear relationship between molting frequency and water temperature, T. inermis having a shorter intermolt period than M. norvegica.Results were used to estimate the energy consumption of the natural populations of euphausiids in the upper part of the Gulf of St. Lawrence estuary.
Method of Counting Tailbeats of Free-Swimming Fish by Ultrasonic Telemetry Techniques
Authors: Stasko A. B. , Horrall R. M.
Published: April 2011

Rhythmic beats in ultrasonic signals from free-swimming fish fitted with continuous-wave transmitters were noted during tracking of four species. Such signal beats corresponded with visually observed tailbeats of salmon and are presumed to have resulted from a Doppler effect due to undulations of the body and tail. The beats cannot be detected from pulsed transmitters. Tailbeat frequencies of white bass (Morone chrysops) were higher than those of salmon for the same swimming speed in body lengths per second.
Effects of Air-Supersaturated Water on Adult Sockeye Salmon (Oncorhynchus nerka)
Authors: Nebeker Alan V. , Stevens Donald G. , Stroud Richard K.
Published: April 2011

Adult sockeye salmon (Oncorhynchus nerka) were exposed to air-supersaturated water in the laboratory from July 8 to August 13, 1974, approximately the same time period that they are exposed to supersaturated water during their movement through the lower and middle sections of the Columbia River. The first mortality occurred after 77 h exposure at 120% saturation; 40% of the fish were dead after 127 h. At 115% saturation the first mortality occurred after 523 h (21 days) and 40% were dead after 835 h (35 days). No further mortality occurred at 120 or 115%. However, at 120 and 115% saturation, survivors exhibited many sublethal lesions such as hemorrhaging and emphysema (bubbles) in the mouth, on the gill arches, body surface, and fins, etc. No deaths or signs of gas bubble disease occurred in fish held at 110% saturation in water 2 ft (60 cm) deep. The lethal threshold was near 114% saturation.
Vertical and Horizontal Distributions of Coho Salmon (Oncorhynchus kisutch), Yellow Perch (Perca flavescens), and Cisco (Coregonus artedii) in Pallette Lake, Wisconsin
Authors: Engel Sandy , Magnuson John J.
Published: April 2011

Coho salmon (Oncorhynchus kisutch), stocked in Pallette Lake, Wisconsin, remained inshore in April and early May, moved offshore in late May and June, and returned to shore in October. From June to September the vertical distribution of offshore coho salmon overlapped that of yellow perch (Perca flavescens) and cisco (Coregonus artedii). Yellow perch were gillnetted mainly in epilimnetic water of 16–22 C; coho salmon and cisco were mostly caught in metalimnetic water of 12–17 and 8–12 C, respectively. Vertical separation broke down during other months of the year.From June to September diel, horizontal movements were found for yellow perch within the epilimnion and for cisco within the metalimnion. Yellow perch moved offshore around sunrise and onshore around sunset; cisco moved toward shore around sunrise and away from shore around sunset. Yellow perch were mainly active during the day and cisco at night. Perch and Cisco were, therefore, largely temporally and spatially segregated from each other but not from coho salmon.
Survival and Propensity for Homing as Affected by Presence or Absence of Locally Adapted Paternal Genes in Two Transplanted Populations of Pink Salmon (Oncorhynchus gorbuscha)
Authors: Bams R. A.
Published: April 2011

An experiment was carried out on pink salmon (Oncorhynchus gorbuscha) at the Tsolum River, Comox Bay, B.C., comparing an introduced pure donor stock with a hybrid stock created by crossing females from the donor with males of the local residual stock. Progeny of both treatments were raised in gravel incubators and released as unfed fry. Upon return from the ocean, marked fish were recaptured from catch and escapement.At the fry stage times of emergence differed, but mean fry lengths, weights, and stages of development were the same in both treatments. Survivals from fry to returning (coastal) adult were identical and comparable to that of other years, as was timing of adult migrations.Large differences occurred in returns to the river. At the hatchery stream the expected relative rate of return of the hybrid was p = 0.53, observed [Formula: see text]. Returns to the river below the hatchery stream also favored the local genotype, but less strongly so. The results demonstrated that 1) imprinting alone brought back some pure donor stock, 2) addition of the local male genetic complement improved return to the natal river system to a normal level, and 3) the male complement alone was not sufficient to achieve normal accuracy of return to the natal tributary within the system."Hybrid" transplants may hold considerable potential for salmon rehabilitation and enhancement, but genetic and managerial implications should be carefully evaluated. Possibilities exist of seriously affecting fitness and abundance of other stocks and ecosystems.
Gonadotropic Hormone Treatment of Rainbow Trout (Salmo gairdneri): Plasma Hormone Profile Following a Single Injection
Authors: Crim L. W. , Evans D. M.
Published: April 2011

Immature rainbow trout (Salmo gairdneri) were treated with salmon gonadotropic hormone to determine the presence of this hormone in circulation, to describe the plasma profile with time after exogenous hormone treatment, and to determine the difference in plasma gonadotropin levels resulting from treatment with two different hormone doses. The effect of three selected temperatures on the plasma hormone profile was also studied. The plasma concentration of the injected hormone following a low dose (0.02 μg/g) and a high dose (0.2μg/g) suggested that plasma hormone levels were directly related to the hormone quantity injected. For fish maintained at 6 C, plasma gonadotropin values declined over a period of 7 days reaching low but detectable levels. Lower plasma gonadotropin profiles were observed for fish held at 6 and 15 compared with fish at 2 C ambient temperature. These data suggest the plasma gonadotropin levels and ambient temperature are related in an inverse manner.
Effects of Light and Turbidity on the Reactive Distance of Bluegill (Lepomis macrochirus)
Authors: Vinyard Gary L. , O’brien W. John
Published: April 2011

Changes in the reactive distance of bluegill (Lepomis macrochirus) to various sizes of Daphnia pulex were measured at light intensities ranging from 0.70 to 215.3 lx (0.065–20.0 ft-c) and at turbidities ranging from 1 to 30 Jackson Turbidity Units (JTU). Both reduced illumination and increased turbidity caused substantial reduction in the reactive distance of bluegill for all prey sizes, and particularly for large prey. This result should be considered in efforts to determine fish feeding rates in lakes, and may be particularly relevant to vertically migrating zooplankton, or those inhabiting more turbid waters.