bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Crude Oil on American Lobster (Homarus americanus) Larvae in the Laboratory
Authors: Wells Peter G. , Sprague John B.
Published: April 2011

Four-day LC50s for Venezuelan Tia Juana crude oil were 0.86 mg/liter for first-stage larvae of the American lobster (Homarus americanus) and 4.9 mg/liter for third- and fourth-stage larvae. The 30-day LC50 was 0.14 mg/liter for larvae starting the test in their first stage. The threshold for retardation of larval development was about the same as the 30-day LC50. Decreased food consumption was demonstrated at 0.19 mg/liter. More "intermediate" larvae developed in oil exposures but no threshold was estimated. The ratio of "safe" to acutely lethal concentrations was about 0.03.Oil concentrations decreased during exposures; stated values could be multiplied by 0.59 to arrive at conventional average exposures. Stirring and ultrasonic vibration for 30 min dispersed averages of 7.4 and 18% of added oil. This and other techniques apparently dispersed similar components since toxicities were the same when based on measured concentrations. Aged dispersions were also equally toxic on a measured basis. Particles larger than 1.2 μm made up 84–96% of the dispersed oil and were about one-third as toxic as smaller particles and dissolved oil. For the reference toxicant DSS, the 4-day LC50 was 0.72 mg/liter for first-stage larvae indicating that lobster larvae are sensitive. Post-larval lobsters dug significantly more burrows when the substrate contained oil but did not avoid oiled substrate nor was growth or survival affected for substrates containing up to 1740 mg/liter of oil.
Evidence for the Presence of Molt-Inhibiting Hormone in the Sinus Gland of the Lobster Homarus americanus
Authors: Couch Ernest F. , Daily Carol S. , Smith William B.
Published: April 2011

Implantation of American lobster (Homarus americanus) sinus glands into the ventral hemocoele of the crayfish (Procambarus simulons), in which molting has been induced by eyestalk removal, significantly retarded the onset of molt (P < 0.001). Implanted animals required nearly twice as much time to molt as controls; implanted animals molted in approximately 15 days and controls in about 8. These findings support the hypothesis that the lobster sinus gland contains a molt-inhibiting hormone.
Variations in Fillet Lipid Content and Some Percent Lipid-Iodine Value Relationships for Large Winter Atlantic Herring (Clupea harengus harengus) from Southeastern Newfoundland
Authors: Ackman R. G. , Eaton C. A.
Published: April 2011

Lipid was extracted from fillets of large Newfoundland winter Atlantic herring (Clupea harengus harengus) gillnetted in Placentia Bay. In the period January through March percent lipid fell more sharply in females than in males, but lipid-iodine values declined at approximately the same rates. Lipid-iodine values were noticeably higher (about 20 units, maximum values ca. 160) than for the oils produced from fish seined in adjacent waters and commercially reduced. It is proposed that these particular herring are an isolated stock peculiar to Placentia Bay, but that they show certain aspects of lipid biochemistry that are influenced by the reproductive cycle in common with other herring from the Atlantic and Pacific oceans.
Life History Notes for a Population of Slimy Sculpin (Cottus cognatus) in an Alaskan Arctic Stream
Authors: Craig P. C. , Wells J.
Published: April 2011

The distribution of a slow-growing population of slimy sculpin (Cottus cognatus) extends farther than most fishes into the headwaters of the Chandalar River, Yukon River drainage. The maximum observed age was 7 by which time the fish averaged only 101 mm in length. Most sculpin matured at age 4. The spawning season appeared to be shortly after spring breakup (late May). Fecundity averaged 206 eggs (range 59–339 eggs). The fish fed almost exclusively on stream benthos, chironomid larvae being the most common food item.
Occurrence of the Woodborer, Limnoria lignorum (Rathke) at Amchitka Island, Alaska
Authors: Richards B. R. , Belmore C. I.
Published: April 2011

Three hundred and sixty-one Limnoria specimens collected from wood pilings at Amchitka, Alaska in 1971 and 1974 were all identified as Limnoria lignorum (Rathke). This is believed to be the first record of the species on Amchitka; the discovery fills a gap in the known distribution between the west and east coasts of the North Pacific Ocean. Female specimens outnumbered males approximately two to one.
Biological Notes on Eupera cubensis (Bivalvia: Sphaeriidae) from Kansas
Authors: Mackie G. L. , Huggins D. G.
Published: April 2011

The occurrence of Eupera cubensis (Prime) in Kansas represents a north central range extension. The species appears to be more common in root systems of the water willow, Justicia americana, than in riffle areas or backwater areas. Scanning electron photographs are given to illustrate important shell characteristics. The generative performance of E. cubensis appears to increase with increasing age up to 3 yr, with as many as 64 larvae, all in the same stage of development, in larger (older) parents.
Thyasira dunbari n.sp. (Bivalvia: Thyasiridae) from the Canadian Arctic Archipelago
Authors: Lubinsky Irene
Published: April 2011

The shell morphology and area of distribution of Thyasira dunbari n.sp. is described and illustrated. This species differs from its northern relatives, especially T. gouldi Phil., by its high, bent forward shell, and thin, long edentulous hinge with massive callus. It occurs in the northernmost part of the Canadian archipelago and off East Greenland. It is a high arctic shallow-water species, which seems to be endemic in the Canadian–Greenlandic region.
Toxicity of the Herbicides Dinoseb and Picloram to Cutthroat (Salmo clarki) and Lake Trout (Salvelinus namaycush)
Authors: Woodward D. F.
Published: April 2011

In static tests of the toxicity of two herbicides, dinoseb (2,4-dinitro-6-sec-butylphenol) and picloram (4-amino-3,5,6-trichloropicolinic acid), to cutthroat (Salmo clarki) and lake trout (Salvelinus namaycush), the 96-h LC50s ranged from 32 to 1400 μg/liter for dinoseb and from 2050 to 8600 μg/liter for picloram. Decreasing pH from 8.5 to 6.5 increased the toxicity of dinoseb by a factor of 43 and decreased that of picloram by a factor of 0.5. Generally, toxicity increased with increasing water temperature. Sensitivity of both species of fish increased with water hardness in tests of dinoseb but was not affected by water hardness in tests of picloram. The toxicity of both chemicals was not changed by aging in water for up to 4 wk or by exposing the fish longer than 96 h. Rate of yolk sac absorption and growth of lake trout fry was reduced in flow-through tests at concentrations as low as 0.5 μg/litev dinoseb or 35 μg/liter picloram. Chronic toxicity of both compounds on early life stages of lake trout is more significant than might be anticipated on the basis of only acute tests with fingerlings.
DDT Residues in Benthic Invertebrates and Demersal Fish in St. Margaret’s Bay, Nova Scotia
Authors: Hargrave Barry T. , Phillips Georgina A.
Published: April 2011

Organochlorine residues (p,p′-DDT and its metabolites) were measured in samples of benthic invertebrates and demersal fish taken from St. Margaret’s Bay, Nova Scotia. No other organochlorine compounds were present in detectable amounts. ΣDDT levels in whole organisms, excluding lipid-rich tissues, grouped as benthic epifauna, infauna, and demersal fish were not significantly different and thus no accumulation occurs in this food chain. Atmospheric supply is probably the major source of low levels of contamination and a detritus-based food web may equalize residue concentration between various feeding types.
Theoretical and Experimental Analysis of the 14C Technique and Its Use in Studies of Primary Production
Authors: Hobson Louis A. , Morris W. James , Pirquet Kathleen T.
Published: April 2011

Theoretical and experimental field studies of 14C uptake by marine phytoplankton were carried out to determine environmental conditions required for the technique to measure net photosynthesis. Results of theoretical studies indicate that rapidly metabolizing populations (rate constants for gross photosynthesis and respiration of 0.1 h−1 and 0.007 h−1 respectively) may saturate with 14C after about 30 h of continuous irradiation. Results of field studies indicate that a minimum of 24 h are required for net photosynthesis to be measured when daily irradiations exceed 20 cal cm−2 and nutrient limitation of photosynthesis does not occur. Additional measurements that may be made to aid in interpreting results obtained by the 14C technique are briefly discussed.
Long-Term Effects of Lead Exposure on Three Generations of Brook Trout (Salvelinus fontinalis)
Authors: Holcombe G. W. , Benoit D. A. , Leonard E. N. , McKim J. M.
Published: April 2011

Exposure of three generations of brook trout (Salvelinus fontinalis) to mean total lead concentrations (0.9–474 μg/liter) showed that all second-generation trout exposed to 235 and 474 μg Pb/liter and 34% of those exposed to 119 μg Pb/liter developed severe spinal deformities (scoliosis). Scoliosis also appeared in 21% of the newly hatched third-generation alevins exposed to 119 μg Pb/liter, and weights of these fish 12 wk after hatch were significantly reduced. Gill, liver, and kidney tissues of first- and second-generation brook trout accumulated the greatest amount of lead. Only small amounts accumulated in the edible muscle. An equilibrium of lead residues was reached in liver and kidney tissue from second-generation fish after 70 wk of exposure, but not in gill tissue. Fish exposed to 119 μg Pb/liter and then placed in uncontaminated control water for 12 wk showed a 70, 78, and 74% loss in micrograms Pb per gram for gill, liver, and kidney tissue, respectively, and a 39, 56, and 35% loss, respectively, in the total micrograms of Pb in the whole tissue. Residue analysis of eggs, alevins, and juveniles showed that lead was accumulated during these life stages. The maximum acceptable toxicant concentration (MATC) for brook trout in water with a hardness of 44 mg/liter (as CaCO3) and a pH of 6.8–7.6 lies between 58 and 119 μg/liter for total lead and between 39 and 84 μg/liter for dissolved lead. The MATC was based on the development of scoliosis in second- and third-generation fish and the reduced growth of 12-wk-old third-generation trout. The 96-h LC50 for brook trout was 4100 μg/liter based on total lead and 3362 μg/liter based on dissolved lead; therefore, the application factor (MATC/96-h LC50) lies between 0.012 and 0.029 for both total and dissolved lead.
Recruitment Mechanisms of Southern Gulf of St. Lawrence Atlantic Herring (Clupea harengus harengus)
Authors: Winters G. H.
Published: April 2011

Estimates of abundance of the southern Gulf of St. Lawrence herring complex by cohort analysis indicate that both biomass and population fecundity were reduced to low levels in the late 1950s following a widespread fungus disease in the mid-1950s. As a result of two strong year-classes in the late 1950s, however, abundance increased dramatically up to 1964 but has declined continuously since then due mainly to subsequent poor recruitment. Mackerel were also at low levels of abundance in the late 1950s and remained so until the mid-1960s when a series of strong year-classes produced a rapid increase in abundance to the extent that mackerel replaced herring as the dominant pelagic fish in the southern Gulf ecosystem. Changes in herring recruitment, growth, and maturation rates are investigated in relation to changes in herring biomass and total pelagic (herring + mackerel) biomass. Density-dependent changes in all three parameters have occurred in herring; mackerel also have interacted with the growth and recruitment of southern Gulf herring. This suggests that the carrying capacity of the southern Gulf for pelagic fish is limited and that competition and predation by mackerel intensifies the logistic response of herring. Thus, recruitment of southern Gulf herring in the period under consideration was largely controlled by the total pelagic biomass, acting mainly through herring up to the mid-1960s and through mackerel since then. The increase in mackerel abundance is attributed to a combination of favorable temperature regime and optimum spawning biomass. That being so, the probability of large year-classes of herring in the near future will depend heavily on the interaction between favorable survival conditions for mackerel and the effectiveness of ICNAF regulations to maintain mackerel biomass at maximum recruitment levels.
Effect of Diets Containing Dogfish (Squalus acanthias) Meal on the Mercury Content and Growth of Pen-Reared Coho Salmon (Oncorhynchus kisutch)
Authors: Spinelli John , Mahnken Conrad
Published: April 2011

The use of dogfish (Squalus acanthias) meal as a complete replacement for herring or other low mercury (Hg) content fish meal in rations intended for rearing cultured salmon introduces the risk of producing fish that exceed the current U.S. FDA tolerance level of 0.5 ppm Hg. The amount of Hg that accumulates in the muscle is related not only to the total Hg content of the fish, but is probably also related to the form in which it is present in the diet and to other constituents that may react with the Hg in the diet. Our results indicate that dogfish meal may be used as a partial (< 50%) replacement for the fish meal portion of the diet without encountering Hg values (in the muscle) that exceed 0.5 ppm Hg. No evidence was found that naturally occurring chelating agents in dehydrated orange peel or polygalacturonic acid–cellulose complexes (PG) have the ability to chelate and prevent the deposition of Hg in either the muscle or the liver of the fish. It was observed that growth is decreased in coho salmon (Oncorhynchus kisutch) fed OMP-type diets in which 50% or more of herring meal was replaced with dogfish meal.
Increased Invertebrate Drift in an Experimental Stream Caused by Electrofishing
Authors: Bisson Peter A.
Published: April 2011

Electrofishing stimulated a tenfold increase in total macroinvertebrate drift in an experimental stream channel. While nearly all aquatic taxa exhibited elevated drift rates during shocking, turbellarians and chironomids showed the greatest total increases. A few taxa were relatively unaffected. Except for the Chironomidae, benthic invertebrate biomasses were not significantly depressed immediately following electrofishing.
Influence of Temperature and Wind on the Survival of Early Stages of Yellow Perch, Perca flavescens
Authors: Clady Michael D.
Published: April 2011

Survival from the egg to larval stage was estimated for the 1969–75 year-classes of yellow perch, Perca flavescens, in Oneida Lake. Egg production was determined from mark-and-recapture estimates of adult stock and measurements of fecundity, and abundance of the resulting cohort was estimated from annual larval surveys. Early survival, which varied from 1.6 to 18.4% was correlated positively with temperature and negatively with wind. Two variables, mean daily air temperature during the 3 wk prior to the date the larvae attained a mean length of 8 mm and mean daily wind velocity for 4 wk prior to this date, accounted for 87% of the variability in survival of perch. Physical destruction and movement of eggs by high winds and greater mortality of prolarvae caused by low temperature could account for the differences in survival between years, but do not appear severe enough to account for the 80+% base mortality that occurred in all years. The low year-to-year variation in survival suggests that temperature and wind influenced year-class size through a complex of many relatively minor mortality factors, rather than through one catastrophic event.
Selection of Artificial Spawning Sites by the Spotfin Shiner (Notropis spilopterus)
Authors: Gale William F. , Gale Cynthia A.
Published: April 2011

In 1975 experiments were conducted in the Susquehanna River, near Berwick, Pennsylvania, to investigate spawning-site selection of the spotfin shiner (Notropis spilopterus), a crevice spawner. Results of experiment A revealed that visual cues and water currents were important in spawning-site selection. Spotfins deposited 43.638 eggs on black discs and only 2 eggs on clear discs; 87% of the eggs were in horizontal crevices and the remainder in vertical crevices paralleling (7%) and perpendicular (6%) to the current. Fish spawned over the entire disc in slow currents but avoided strong currents (0.57 m/s) by spawning on the downstream side of the discs. Nearly 90% of the eggs were deposited in crevices 1.5 and 3.0 mm wide, the two smallest sizes. In angular crevices 15–90° from horizontal, fish deposited 74% of 8,358 eggs in the 15° crevice and 24% in the 30° crevice.In experiment B, a stack of black acrylic plates was placed near the river surface, at midwater, and near the bottom; in July fish deposited 91% of 13.088 eggs in the bottom stack. By mid-August stack usage had changed and 80% of 11,456 eggs were in the surface stack; the others were in the midwater stack. Rate of egg deposition on acrylic plates between July 10 and August 20 peaked in early August.In experiment C, 95% of 46,328 eggs were placed in crevices between blue (55%) and black (40%) plates; other colors were green (4%), red (1%), and white, yellow, and orange (< 1%). Fish usually spawned on the plates between 0600 and 1000; spawning did not occur at night.The spotfin has potential as a bioassay organism because of its wide distribution, the ease with which large numbers of its eggs can be collected, its extended breeding season, and the simplicity of rearing the young.
Significance of the Timing of Initial Feeding in Hatchery Rainbow Trout, Salmo gairdneri
Authors: Twongo Timothy K. , MacCrimmon Hugh R.
Published: April 2011

The age of initial food ingestion and the influence of age at initial food presentation on alevin food intake, survival, and subsequent growth were determined for rainbow trout, Salmo gairdneri. Alevins did not show any ingestive behavior nor was any food found in their gut, before initiation of swim-up. The withholding of food from the young fish for some time after swim-up did not impair their ability to learn to feed. Further, the most satisfactory time to initiate exogenous feeding of hatchery fish is when yolk reserves have been completely absorbed, bearing in mind that a considerable quantity of yolk may yet remain in the abdominal cavity after the externally visible yolk sac has disappeared.This study contradicts the hypothesis that delayed feeding of young rainbow trout causes or enhances the likelihood of nonfeeding.
Influence of Food Competition, Predation, and Cannibalism on Walleye (Stizostedion vitreum vitreum) and Sauger (S. canadense) Populations in Lake of the Woods, Minnesota
Authors: Swenson William A. , Smith Jr. Lloyd L.
Published: April 2011

Feeding relationships between walleye, Stizostedion vitreum vitreum, and sauger, Stizostedion canadense, in Lake of the Woods, Minnesota, were investigated. Effectiveness of food consumption estimates in measuring feeding interactions was defined. Differences in walleye and sauger distribution, food habits, and feeding strata reduced interactions. Walleye feeding rate varied from 0.5 to 4.1% of body weight per day and was limited by prey abundance during June and July. Higher August and September prey densities did not influence walleye food consumption. Daily food consumption of sauger varied from 0.5 to 3.5% of body weight independent of changes in food availability. Relationships between the number of prey consumed daily by walleye and sauger and the decline in abundance of prey species suggested that predation was important in controlling food availability, and was the major cause of food competition and its limiting effect on walleye growth.Analysis of commercial catch statistics suggested that factors other than predation influenced walleye survival. However, the relationship between the number of young-of-the-year walleye consumed and their abundance in the lake demonstrated predation by sauger may be important to walleye survival.
Metabolism of Single and Combined Doses of 14C-Aldrin and 3H-p,p′-DDT by Atlantic Salmon (Salmo salar) Fry
Authors: Addison R. F. , Zinck M. E. , Leahy J. R.
Published: April 2011

Atlantic salmon (Salmo salar) fry were injected intramuscularly with 3H-p,p′-DDT and 14C-aldrin either alone or as a mixture at concentrations similar to those found in "naturally" contaminated fish; their rates of metabolism and clearance were then compared 3H-p,p′-DDT was cleared slowly from the fish: approximately 60% of the injected material remained 8 wk after injection. 14C-aldrin was cleared much more rapidly, only 55% of the injected material remaining in the fish 1 day after injection and less than 10% remaining at the end of the experiment 3H-p,p′-DDT was dehydrochlorinated to p,p′-DDE; assuming an exponential rate of conversion, its half-life was 60 days. In contrast, 50% of the aldrin residues in the fish were epoxidized to dieldrin within 2 days. No interactions between the insecticides were observed although aldrin apparently induced a slight increase in the fraction of total body weight accounted for by liver.
Phytoplankton Adaptation to Environmental Stresses from Toxicants, Nutrients, and Pollutants — a Warning
Authors: Stockner John G. , Antia Naval J.
Published: April 2011

Examples are cited from the literature of phytoplankton-related pollution and nutrition studies where the possibility of successful adaptation and subsequent growth could have been overlooked because of insufficient duration of algal exposure to the pollutant or nutrient tested. We present evidence from our investigations where: a) initial algal exposures as long as 20–40 days to the pollutant or alternative nutrient may be required for successful adaptation, and b) phytoplankters initially tolerating only a low level of pollutant concentration could be trained to accept severalfold higher levels by repeated exposure to gradually increasing pollutant concentration A plea is made for future investigators to recognize the importance of long-term bioassays ascertaining algal potential for adaptation, in order that their results may be ecologically realistic for the purpose of environmental protection against chronic pollution and eutrophication. The short-term "shock" response should be clearly distinguished from the long-term habituation response of phytoplankters to the test chemical in these bioassays. Possible problems raising questionable objections to the long-term bioassay approach are discussed.
Science for Canada’s Atlantic Inshore Seas Fisheries
Authors: McCracken F. D. , Macdonald R. D. S.
Published: April 2011

This study is a sequel to "Science for Canada’s Shelf Seas Fisheries" by Regier and McCracken (1975).Inshore seas fisheries cannot be defined rigorously and only acquire meaning on the Atlantic coast where there are many weakly organized fishermen based in about 2000 communities.This paper attempts to identify the science effort necessary to help resolve the problem of making decisions about many small fisheries-based communities. Particular attention is paid to the east coast of Newfoundland and Labrador and the Gulf of St. Lawrence.Science effort has not been related to an inshore–offshore seas relationship, and there is little difference in natural science needs between inshore and shelf-seas fisheries, with the exception of research on such important invertebrates as lobster, local mapping and monitoring of invertebrates, studies on seaweeds, and development of a viable extension service. An understanding of the cod–capelin–mammal complex off the east coast of Newfoundland and Labrador is urgent. Managing the aquatic resources of the Gulf of St. Lawrence on a multiple-use and multiple-species basis has high priority.These science needs are seen in the perspective of a manipulative sociopolitical subsistence system which perpetuates high unemployment, low income, and much dependency on government; and of three broad policy options. The only untried option aims for a balanced corporate–noncorporate fishery and attempts to counter the manipulative system by suggested measures which promote equity, productivity, and creativity. A broad congruence of issues on an international scale points to greater theoretical acceptance of this option; however, the greater degree of material sacrifice may not be acceptable to those affected.If this course is followed, demand to resolve the natural science problems identified above will be much greater. Social science activity will also have to change direction towards (a) more interdisciplinary study and input in decision-making, (b) more emphasis on innovation rather than analysis, (c) more countervailing sources of expertise. Community development is of critical importance in its role of stimulating self-help and of being a mirror image of corporate planning.It is essential to greatly increase inshore fisheries representation in fisheries decision-making. Some principles developed in this paper may also apply to other areas where rural communities suffer encroachments from corporate interests.
Viruses Associated with Lymphocystis Disease and Dermal Sarcoma of Walleye (Stizostedion vitreum vitreum)
Authors: Yamamoto Tats , Macdonald Richard D. , Gillespie Douglas C. , Kelly Russell K.
Published: April 2011

Gross examination of a spawning run of walleye (Stizostedion vitreum vitreum) showed a large proportion of fish to have tumors on the body and fins that appeared to be characteristic of lymphocystis disease. Light and electron microscopic examination revealed the presence of two distinct tumor types. One was characteristic of lymphocystis, consisting of typical enlarged nonneoplastic cells surrounded by hyaline layers and containing many 260 nm diameter lymphocystis virus particles in the cytoplasm. The other tumor, referred to as a dermal sarcoma, consisted of a solid mass of normal-sized cells and contained in the cytoplasm large numbers of 135 nm diameter virus particles referred to as walleye dermal sarcoma (WDS) virus. The WDS virus was similar in appearance to the leukoviruses and, with its outer layer sectioned tangentially, exhibited symmetry like a member of a leukovirus group designated by Fenner as subgenus C.
Analysis of Seasonal Distribution Patterns of Young Largemouth Bass (Micropterus salmoides) by Use of Frequency-of-Capture Data
Authors: Van Den Avyle Michael J.
Published: April 2011

Frequency-of-capture data indicated that behavioral patterns of tagged age II largemouth bass (Micropterus salmoides) influenced catchability with shoreline electrofishing so that midsummer population estimates were too low. The population separated into offshore and shoreline groups during the summer, and there is evidence of persistence in habitat preference from one year to the next.Tests of catchability were based on the agreement between observed frequencies of capture and those predicted from a bivariate model that allowed mortality and migration during the study. Though frequency-of-capture data have been widely utilized in studies of terrestrial animal populations, this information has been generally ignored by fishery biologists.
Ecology of Arctic Populations of Lake Trout, Salvelinus namaycush, Lake Whitefish, Coregonus clupeaformis, Arctic Char, S. alpinus, and Associated Species in Unexploited Lakes of the Canadian Northwest Territories
Authors: Johnson Lionel
Published: April 2011

The available data on the fish populations of 35 lakes in the Northwest Territories are examined. The lakes range in size from Great Bear Lake (31, 156 km2) to Keyhole Lake (46 ha); they are situated between lat. 60 and 75° N, east from the Mackenzie River to the west coast of Hudson Bay. Lake trout (Salvelinus namaycush) and whitefish (Coregonus clupeaformis) form the main populations of the mainland lakes and together make up to 95% of the total catch. There is a trend toward increasing importance of whitefish with decreasing severity of conditions. Most populations show a uni, bi-, or trimodal length distribution; age distributions are unimodal. No change in these distributions was observed over a large number of years in certain lakes. These populations are considered to have reached a climax condition comparable with a vegetational climax, and are therefore in equilibrium with their environment. All incoming energy is ultimately used in respiration to support a high biomass of fish.
Energy Dynamics of Two Benthic Crustaceans in Relation to Diet
Authors: Swiss J. J. , Johnson M. G.
Published: April 2011

Energy dynamics were studied in Asellus racovitzai (Crustacea: Isopoda) and Gammarus fasciatus (Crustacea: Amphipoda) fed various selected algal species (Cyanophyta — Oscillatoria sp., Anabaena flos-aquae, Anacystis nidulans, Microcystis aeruginosa; Chorophyta — Chlorella ellipsoidea, Scenedesmus dimorphus, Ankistrodesmus falcatus) and lake sediments. Calculations of growth, production, assimilation, and growth efficiency were made from measurements of weight change, respiration rate, and caloric content of experimental animals. Although growth rate, production, and growth efficiency were often highest in animals fed green algae, differences were not attributable solely to green vs. blue-green taxonomic groups. The relationship between assimilation rate and growth efficiency was examined, and the possible consequences of lower values of assimilation were discussed in terms of delayed development to maturity and reproduction.
Glomerular Mesangial Fibrosis in Hatchery-Reared Rainbow Trout (Salmo gairdneri)
Authors: Hinton David E. , Jones Raymond T. , Herman Roger Lee
Published: April 2011

Light and electron microscopic studies were performed on tissues of hatchery-reared rainbow trout (Salmo gairdneri) having a disease of currently unknown etiology with external symptoms of severe edema which causes increased mortality rate. Comparison with unaffected trout tissues revealed loss of cellularity in glomerular tufts with a replacement of mesangial cells by connective tissue. Ultrastructural studies showed the material to be collagen and established the diagnosis of glomerular mesangial fibrosis. The glomerular lesion was associated with alterations in lining epithelium of proximal tubules and extensive debris within tubule lumens. The findings are compared to glomerular lesions in mammalian and amphibian kidney.
Deteriorative Changes During Frozen Storage in Fillets and Minced Flesh of Silver Hake (Merluccius bilinearis) Processed from Round Fish Held in Ice and Refrigerated Sea Water
Authors: Hiltz Doris Fraser , Lall Barbara Smith , Lemon D. W. , Dyer W. J.
Published: April 2011

During frozen storage at −10 C, deterioration in muscle of silver hake (Merluccius bilinearis) was marked by rapid and extensive production of dimethylamine, concomitant decrease in extractable protein, and by lipid hydrolysis. Evidence of lipid oxidation in this gadoid species of relatively high fat content (2–4%) was also obtained. In minced flesh the rates of deterioration were about twice as fast as in fillets. Holding round fish for up to 6 days in refrigerated sea water (RSW) at 0–1 C before processing extended the frozen storage life of fillets at −10 C by 2–3 wk and of minced flesh by 1 wk over that for comparable materials prepared from round fish held in ice. Materials prepared from winter (March) and summer (August) fish showed little or no difference in rates of deterioration. The susceptibility of silver hake to deterioration at −10 C is similar to cusk; deterioration is faster than in cod or haddock, but not as fast as in red hake (Urophycis chuss). In all silver hake materials negligible deterioration occurred during frozen storage at −26 C for up to 6 mo.During preprocessing storage of round silver hake in RSW, a firm texture and acceptable appearance were retained for several days longer than in round fish held in ice, where objectionable softening of the flesh occurred, particularly in summer-caught fish. Saturation of the sea water with CO2 retarded the onset of bacterial spoilage in RSW-held fish, which otherwise developed more rapidly than in iced fish.
Fin Erosion Disease of Starry Flounder (Platichthys stellatus) and English Sole (Parophrys vetulus) in the Estuary of the Duwamish River, Seattle, Washington
Authors: Wellings S. R. , Alpers C. E. , McCain B. B. , Miller B. S.
Published: April 2011

Fin erosion in the starry flounder (Platichthys stellatus) and English sole (Parophrys vetulus) of the Duwamish River, Washington, is characterized by ulcerating chronic inflammation and fibrosis with resorption of fin rays. The end result is deformation, shortening, and retraction of residual fin tissue with loss of functional surface. We suggest that the incidence of fin erosion in a particular population is related to an interaction between genetic constitution and multiple environmental variables, including a variety of chemical pollutants.
Postmortem Bile Damage to Rainbow Trout (Salmo gairdneri) Livers
Authors: Hendricks J. D. , Hunter L. J. , Wales J. H.
Published: April 2011

Peripheral liver necrosis in rainbow trout (Salmo gairdneri) was shown to result from pre- or postmortem exposure to bile. Accidental spillage of bile onto the liver during sampling or intentional submersion of liver tissue into bile resulted in a time-dependent destruction of liver tissue. Awareness of this caustic property of bile should prompt extreme care in the collection of trout livers for histology.
Atlantic Salmon (Salmo salar) of the Leaf River, Ungava Bay
Authors: Lee R. L.G. , Power G.
Published: April 2011

The Leaf River supports the most northerly known population of anadromous Atlantic salmon (Salmo salar) in Canada. River growth averaged 40–50 mm/yr, smolts averaged 258 mm fork length (range 190–300 mm) and 5.3 yr (range 4+ to 7+). Many males matured in fresh water and either incurred heavy mortality or became residual. Sex ratios among smolts were 5:1 in favor of females and among adults 3:1 in favor of females. Female 2-sea-winter salmon accounted for 75% of the fresh-run fish. Upstream migration peaked in August: kelts were still resident in the river 11 and 12 mo later.
Outbreak of Infectious Pancreatic Necrosis in Yearling Brook Trout (Salvelinus fontinalis)
Authors: Elazhary M. A. S. Y. , Lagace A. , Cousineau G. , Roy R. S. , Berthiaume L. , Paulhus P. , Frechette J. L.
Published: April 2011

Studies were conducted to determine the etiology of an epizootic disease occurring in fry and yearling brook trout (Salvelinus fontinalis); clinical signs, experimental infection, and pathological lesions suggested infectious pancreatic necrosis. Electron microscopy and physicochemical characteristics were used to identify the virus isolated from sick trout as IPN virus. The isolates showed only partial antigenic similarity to the reference strain IPN VR299. Increased susceptibility to IPN virus was observed in one genetic line of trout.
Aquatic Environmental Quality: Problems and Proposals
Authors: Harvey H. H.
Published: April 2011

An overview was prepared of research and monitoring of aquatic environmental quality by federal and provincial agencies, the university, and private sectors. The overall effort in Canada was found to be unbalanced. Areas of strength were monitoring of water quantity, chemical water quality, and fish physiology–toxicology. Areas of weakness were the use of organisms and the use of whole systems as indicators of environmental quality. The amount of innovation was modest, due in part to the underutilization of the university community. In some areas of monitoring, data interpretation lags seriously behind data collection. A number of constraints now exist to our understanding of the source, distribution, and life expectancy of toxic substances in our environment, and these are discussed in relation to mercury. Specific problems of aquatic environmental quality are discussed by economic sector.
Aquatic Environmental Quality: Toxicology
Authors: Hamilton R. D.
Published: April 2011

Canadian research and control activities regarding the impact of toxic chemicals on aquatic environments are reviewed. Evaluation of specific research programs or results is not treated but an attempt is made to raise and discuss issues common to the problems posed by the use of toxic chemicals.
Aqueous Leachate from Western Red Cedar: Effects on Some Aquatic Organisms
Authors: Peters G. B. , Dawson H. J. , Hrutfiord B. F. , Whitney R. R.
Published: April 2011

Water-soluble extractives from western red cedar heartwood, bark, and foliage were investigated for their toxicity to aquatic organisms. The heartwood lignans and bark extractives were found to be moderately toxic, but the foliage terpenes and heartwood tropolones were more toxic, causing 50% mortality to coho salmon (Oncorhynchus kisutch) fry at 0.33 and 2.7 mg/liter, respectively. Tropolones were significantly less toxic to invertebrates than to free-swimming stages of the fish tested. Fry were found to be the stage of development of coho salmon (O. kisutch) most sensitive to the tropolones, and eyed eggs the least sensitive. Sensitivity of the coho fry to tropolones was moderated by previous sublethal exposure or the presence of a chelatable cation. Results from field studies and a leaching study indicate that directly releasing cedar leachate from landfills or allowing logging debris to enter streams should be avoided.
Long-Term Effects of Methylmercuric Chloride on Three Generations of Brook Trout (Salvelinus fontinalis): Toxicity, Accumulation, Distribution, and Elimination
Authors: McKim J. M. , Olson G. F. , Holcombe G. W. , Hunt E. P.
Published: April 2011

During a 144-wk period three generations of brook trout (Salvelinus fontinalis) were continuously exposed to mean water concentrations of methylmercuric chloride (MMC) of 2.93, 0.93, 0.29, 0.09, 0.03, and <0.010 (control) μg Hg/liter. During the first 39 wk the highest concentration (2.93 μg Hg/liter) produced deformities and 88% mortality of first-generation adults. At an MMC concentration of 0.93 μg Hg/liter, second-generation trout developed deformities and all but one female died during the 108-wk exposure. No significant effects on survival, growth, or reproduction of second-generation trout were noted at any of the lower MMC concentrations. No toxic symptoms were observed in the third generation at the three lowest MMC concentrations. The maximum acceptable toxicant concentration (MATC) for brook trout exposed to MMC in this water with a hardness of 45 mg/liter (as CaCO3) and a pH of 7.5 fell between 0.93 and 0.29 μg Hg/liter. The mean 96-h LC50 for yearling (200 g) and 20-wk-old (12 g) juvenile brook trout exposed to MMC was 75.0 μg Hg/liter, and the application factor (MATC/96-h LC50) lies between 0.004 and 0.013. The accumulation rate of mercury by eight selected tissues of first-generation trout exposed to MMC was relatively rapid at all MMC concentrations tested. The 2-wk tissue Hg: water Hg concentration factors ranged from 1 × 103 to 12 × 103, depending on the tissue, whereas after 28–38 wk of exposure the maximum tissue Hg: water Hg concentration factors for both first- and second-generation trout ranged from 6.9 × 103 to 6.3 × 104. The blood, spleen, and kidney accumulated mercury most rapidly and contained the highest residues in both first- and second-generation trout followed by liver, gill, brain, gonad, and muscle in order of decreasing mercury residues. There was no significant elimination of mercury from the tissue of first- or second-generation fish, yet a "steady state" (micrograms mercury per gram = constant) was reached in all tissues after 20–28 wk of continuous water exposure. Monomethylmercury made up 90–95% of the total mercury present in muscle, the only tissue analyzed for this compound. Mean muscle residues in first-generation trout, dying after 16–28 wk of exposure to 2.93 μg Hg/liter and in second-generation trout, dying after 64–100 wk of exposure to 0.93 μg Hg/liter, were 23.5 and 9.5 μg Hg/g, respectively.
Evaluation of a Toxicant on the Metabolism of Model Stream Communities
Authors: Maki Alan W. , Johnson Howard E.
Published: April 2011

The effects of a toxicant, the lampricide TFM (3-trifluoromethyl-4-nitrophenol), on the metabolism of benthic communities were studied in a series of six indoor model streams resembling typical woodland streams. Each artificially illuminated stream consisted of a 4-m pool section and a 4-m riffle section.A specially developed in situ stream respirometer was used for measurements of net primary production and community respiration in pool and riffle communities. Pretreatment levels of gross primary production ranged during summer, fall, and early winter from 10.7 to 79.0 mg O2∙m−2∙h−1 and were suppressed by 25–50% during exposure to 9.0 mg/liter TFM. Community respiration ranged from 10.5 to 36.2 mg O2∙m−2∙h−1 during the same time period and was increased 3–50% by the 9.0 mg/liter lampricide treatment. Calculated photosynthesis to respiration (P:R) ratios proved to be sensitive indicators of the influence of the toxicant. The stream communities demonstrated a capacity to adjust to the toxicant influence as evidenced by the rapid return of metabolic rates to pretreatment levels following the exposure period.
Vertebral Number in North American Sculpins of the Myoxocephalus quadricornis-Complex
Authors: McAllister Don E. , Aniskowicz Jadwiga
Published: April 2011

X-rays of 438 North American specimens of the Myoxocephalus quadricornis-complex (Cottidae) showed mean vertebral counts (including urostyle) of 38.433 in the deepwater sculpin which inhabits inland continental lakes; 41.097 in the freshwater relict in lakes on Victoria Island, Northwest Territories; 41.417 in newly discovered freshwater relicts in Nauyuk, Stanwell-Fletcher, and Sophia lakes, Northwest Territories; and 41.821 in the coastal fourhorn sculpin living in brackish and marine coastal waters and certain adjacent fresh waters. Except for the Victoria and the three lake relicts, the vertebral means of all pairs of these groups differed at P <.01 or <.001. Of the coastal fourhorn sculpin and the deepwater sculpin 91% are identifiable using only vertebral number, of the Victoria relict and the deepwater sculpin 68%, and of the Victoria relict and the coastal fourhorn only 10%.Vertebral counts alone permit recognition of the deepwater sculpin as a subspecies, Myoxocephalus quadricornis thompsonii Girard, 1852, distinct from the arctic coastal fourhorn sculpin provisionally referred to M. q. hexacornis (Richardson, 1823) and suggest classification of the Victoria Island, Nauyuk, Stanwell–Fletcher, and Sophia lake relicts with the coastal form, rather than with the deepwater sculpin. Relicts in the latter three lakes are suggested to be postglacial in origin.
Phosphorus Kinetics in Lake Water: Influence of Membrane Filter Pore Size and Low-Pressure Filtration
Authors: Lean D. R. S.
Published: April 2011

Radiotracer kinetics using carrier-free 32P-PO4 were conducted on samples of water from Heart Lake, Ontario. Results obtained using 0.45-μm membrane filters were compared with those for 0.1 μm at vacuums of 400 mm Hg and to those for 0.45-μm filters using very low-pressure (4 mm Hg) filtration. The difference between 0.45 and 0.1 can reach 8–20% of the total radioactivity during the first 10 min of the experiment. After 60 min the fraction removed by 0.1, but not 0.45-μm filters, declines to only 1% of the total radioactivity, but this may represent as much as 50% of that which goes through 0.45 μm. The low-pressure filtration techniques provided similar results to those for normal filtration when kinetics were monophasic. Later in the season, the low-pressure method was shown to provide confusing artifacts that were explained by the hypothesis that tiny filaments extend from the surfaces of some species of aquatic algae and bacteria and are often dislodged during filtration.
Catastrophe Theory and Fisheries Regulation
Authors: Jones Dixon D. , Walters Carl J.
Published: April 2011

Catastrophe theory is a mathematical approach for analyzing systems that show abrupt changes. This paper attempts to apply the theory to fishery development and collapse, where the key variables are assumed to be stock size, level of economic investment or fleet size, and technological efficiency of the fishery gear. The analysis produces no new predictions about uncontrolled development and its consequences, but it appears to provide a useful way of exploring the implications of regulatory policies involving taxation, development subsidies, and technological improvement.
Trace Metals (As, Cd, Cu, Fe, and Zn) in Arctic cod, Boreogadus saida, and Selected Zooplankton from Strathcona Sound, Northern Baffin Island
Authors: Bohn Arne , McElroy R. O.
Published: April 2011

Arctic cod (Boreogadus saida) were captured by bottom trawl at depths of 120–300 m. Zooplankton were obtained by bottom to surface tows from the Arctic cod habitat. Average concentrations of arsenic (As) and zinc (Zn) were higher in Arctic cod fillets than in livers from the same fish; cadmium (Cd) and iron (Fe) concentrations were higher in livers. The difference between copper (Cu) concentrations in muscle and liver was not significant. As and Zn in whole fish, and As in fillets from seven specimens, were positively correlated to body weight. Cu and Fe in whole fish were negatively correlated to body weight, whereas Cd was not related to body weight. Examination of Arctic cod stomach contents indicated that planktonic copepods were important in the diet. Cd levels were 5–8 times higher in the unsorted copepods than in the Arctic cod, whereas As, Cu, Fe, and Zn were higher in the fish than in the copepods.
Acute Toxicity of Residual Chlorine in Wastewater to Coho Salmon (Oncorhynchus kisutch) and Some Resultant Hematologic Changes
Authors: Buckley James A.
Published: April 2011

Juvenile coho salmon (Oncorhynchus kisutch) were exposed to treated wastewater containing lethal levels of total residual chlorine (TRCl2) with seawater diluent under continuous flow conditions. The 96-h TL50 was 0.07 mg/liter TRCl2 (4% effluent). Exposure resulted in a slight reduction (significant P =.05) in hemoglobin, a slight increase (significant P =.05) in methemoglobin, and a temporary decrease (not significant P =.05) in percentage of circulating immature erythrocytes.
Relative Resistances of Three Transferrin Genotypes of Coho Salmon (Oncorhynchus kisutch) and Their Hematological Responses to Bacterial Kidney Disease
Authors: Suzumoto Bruce K. , Schreck Carl B. , McIntyre John D.
Published: April 2011

Juvenile coho salmon (Oncorhynchus kisutch) of three transferrin genotypes (AA, AC, and CC) were experimentally infected with the causative agent of bacterial kidney disease (BKD) and mortalities observed. Six experimental and control groups were used: 1) bacteria-infected + no Fe+3; 2) bacteria-infected + low Fe+3 levels; 3) bacteria-infected + high Fe+3 levels; 4) saline control; 5) high Fe+3 control; and 6) low Fe+3 control. In all experimental groups, the AA genotype was the most susceptible to BKD and the CC genotype the most resistant. Addition of exogenous iron did not appear to increase the pathogenicity of the disease. Distribution and uptake of radioiron (59Fe) in control and BKD-infected fish was studied. BKD-infected fish were found to have consistently higher levels of 59Fe in whole blood, plasma, and liver than control fish. In control and experimental fish, spleen, head kidney, and liver tissues were found to accumulate 59Fe, while white muscle and gall bladder tissues did not. The effect of BKD on certain hematological characteristics also was determined. Hemoglobin, packed cell volume, total plasma protein, plasma iron, and plasma corticoid levels all may have decreased with the progression of BKD.
Bicinctus-Group of the Genus Cricotopus Van der Wulp (Diptera: Chironomidae) in the Nearctic with a Description of a New Species
Authors: Oliver D. R.
Published: April 2011

Three species, Cricotopus bicinctus (Meigen), C. vierriensis Goetghebuer, and C. mackenziensis n.sp., in the bicinctus-group of the genus Cricotopus Van der Wulp are now known to occur in the Nearctic. The new species is described from the Fort Simpson area, Northwest Territories, and compared with a closely related species, Cricotopus (s.s.) bicinctus. Most of the differences between the two species are related to the smaller size of C. mackenziensis.