bluuebunny/crossref_metadata_2025 huggingface dataset:
King Herring: His Place amongst the Clupeoids
Authors: Whitehead P. J. P.
Published: April 2011

Modern taxonomy, fishery science, and biology were born in Europe. This, together with the longstanding economic importance of the herring, has given Clupea harengus (and its close relative C. pallasi) a prestige and literature that quite outshadows those of any other clupeoid species. In fact, the two species of Clupea contribute about 8% to world clupeoid catches, coming fourth in the 20 economically important clupeoid genera. They belong to a group, the suborder Clupeoidei, with about 80 genera and over 330 species, with a long evolutionary history reaching back to the Cretaceous. The majority of these clupeoid species live in tropical or subtropical waters, where their fisheries are extensive; in total, the clupeoids are economically the most important single fish group, contributing up to one third of all fish catches. The vast Clupea literature (and the research effort that it represents), at times threatening to rival that of all other species put together, suggests an imbalance. Nevertheless, it has pioneered techniques and insights that are of great application to other clupeoids and their fisheries.
What Limits Clupeoid Production
Authors: Lasker Reuben
Published: April 2011

This review paper explores a number of hypotheses on the control of clupeoid populations. The following are discussed: the effect of fishing; egg mortality (predation); larval mortality (the critical period) with a consideration of starvation and predation and the biotic and abiotic factors that may be involved; larval transport and the oceanographic features that cause it; variable egg production; interspecific competition; and the effect of localized (e.g. storms and upwellings) and widespread (El Niño) oceanographic events. A review of the paleosedimentary record is also given showing the magnitude of natural fluctuations when no fishing occurred. Recent resurgences in clupeoid populations are reviewed and suggested causes are analyzed.
An Investigation of the Population Dynamics of Atlantic Menhaden (Brevoortia tyrannus)
Authors: Reish R. L , Deriso R. B. , Ruppert D. , Carroll R. J.
Published: April 2011

The following biological components concerning the population dynamics of Atlantic menhaden (Brevoortia tyrannus) were investigated: growth, natural mortality, migration, fishing mortality, and recruitment. We found that a hypothesis of density-dependent growth is strongly supported by the data and that the dependence of growth on abundance appears to occur prior to recruitment. Age-specific natural mortality estimates seem biologically reasonable, except the estimate for age 1 menhaden, which appears to be too low. Most of the estimated migration probabilities also seem to be biologically reasonable, especially during the summer season for age 2 fish. Estimated age-specific fishing mortality rates demonstrate the increased fishing pressure on age 3 and younger fish since the early 1960's. When the environmental variables (temperature and Ekman transport) are excluded from the spawner–recruit analysis, then the Beverton–Holt model fits as well as other models examined, and it is the only model that is significant at the 0.05 probability level. Of the environmental variables examined, only westward Ekman transport in the South Atlantic region shows a relationship with recruitment. The unnormalized gamma function, which includes the Ricker model as a special case, is more responsive to the inclusion of westward Ekman transport than the Beverton–Holt model.
Managing Herring Fisheries Under Uncertainty
Authors: Doubleday W. G.
Published: April 2011

The implications of the biological characteristics of the Atlantic herring (Clupea harengus harengus) on fishery management strategies are examined. Growth patterns and recruitment fluctuations limit opportunities to stabilize catches and stock biomasses without substantial loss of yield-per-recruit. The dynamics of herring stocks are much more dependent on recruitment than growth. Potential effectiveness of fishery management is also constrained by tendencies of herring populations to school, reducing self-regulatory possibilities by allowing catch rates to remain high when abundance is low, and to mix, complicating the estimation of catch-at-age and abundance indices. Given the vulnerability of herring to exploitation and the imprecision of abundance indices, achievement of relative stability of spawning stocks and catches requires adoption of fishing mortality rates near or below 0.2 in adult herring fisheries. Fisheries on immature herring reduce, and may destabilize, recruitment to spawning stocks and give lower yield-per-recruit than fisheries on mature herring although product prices may be higher. A simple stochastic model of the dynamics of an exploited herring population is examined. Analysis of this model demonstrated behaviour qualitatively similar to that observed in earlier studies of general production models subject to stochastic noise.
The Need for Formalization of Decision Algorithms and Risk Levels in Fishery Research and Management
Authors: Wilimovsky Norman J.
Published: April 2011

Application of the principles of error analysis and use of decision algorithms might significantly improve fishery management and provide a formalized method of priority allocation and justification of research effort. Verification of this thesis would also provide specific measures of the value of improved data on management success, which at present apparently do not exist. In several fisheries, research and management has reached the stage where codification of the decision making procedures is possible. The development of such decision algorithms coupled with statements of acceptable harvest risks could permit measurable efficiencies in management through a clear indication of the levels of precision and accuracy required for each step in the procedure. Firmly established techniques are available. Analysis of error as employed in geodetic surveying and in physics can serve as a basis for applying the principles to fishery management. The advantages to research and management agencies of the acceptable risk approach is in formally defining priorities for investigation through specification of precision, accuracy, and timeliness of each component of information. The necessary sampling and survey effort can be quantified in terms of acceptable error and provides budget justification. Perhaps the most compelling reason to evaluate these concepts is that their application would require the participation in risk evaluation of fishermen and industry with the management agency. This would provide a basis for mutual understanding of resource decision making and the rationale of prediction for the users. Attempts at applying the procedures to the British Columbia roe herring fishery are described and possible solutions to existing problems recommended.
Temporal and Spatial Trends in Metal Loadings to Sediments of the Turkey Lakes, Ontario
Authors: Johnson M. G. , Culp L R. , George S. E.
Published: April 2011

Sediment core profiles of metal concentration and 210Pb activity were used to calculate metal loadings to five small Precambrian Shield lakes of the Turkey Lakes system near Sault Ste. Marie, Ontario. Background, natural concentrations (pre-1900) of Al, Fe, Mn, Cu, Ni, Zn, Pb, Cd, Cr, and Hg reflected concentrations in local bedrock. Surface loading rates of Al, Cu, Ni, and Cr were not significantly greater than background rates. Fe and Mn enrichment of surface sediment and the downstream accumulation in the five lakes indicated the mobility of these elements. Four metals, Pb, Cd, Hg, and Zn, had significant anthropogenic inputs, which averaged 18, 1.7, 1.4, and 0.6 times background loadings, respectively. Precipitation loadings of Pb and Hg were several times greater than background accumulation in lake sediments. Precipitation loadings of Cu, Ni, Zn, and Cd were the same order of magnitude as background inputs to sediments.
Trophic Status of 19 Subarctic Lakes in the Yukon Territory
Authors: Shortreed Ken S. , Stockner John G.
Published: April 2011

Limnological investigations were carried out on 19 Yukon River basin lakes in the summer of 1982 and on 10 of the lakes in March of 1983. Their surface areas ranged from 1.6 to 90 km2 and mean depths from 2.5 to 93 m. Regression analyses were carried out using various chemical and biological variables and results were compared with similar studies in other geographic areas. Based on range in total phosphorus concentrations (3.2–12.9 μg∙L−1), average chlorophyll levels (0.62–3.76 μg∙L−1), and average bacterioplankton numbers (7.8 × 105 to > 107∙mL−1), most lakes were oligotrophic, several were mesotrophic, and one was close to eutrophy. Particulate concentrations of phosphorus, nitrogen, and carbon indicated that most lakes were predominantly phosphorus limited, but in a number, nitrogen was also important in limiting phytoplankton production. The picoplankter Synechococcus sp. was the most abundant phytoplankton species, and common zooplankters were Cyclops scutifer, Daphnia spp., and Diaptomus pribilofensis.
Interaction between Pacific Cod (Gadus macrocephalus) and Herring (Clupea harengus pallasi) in the Hecate Strait, British Columbia
Authors: Walters Carl J. , Stocker M. , Tyler A. V. , Westrheim S. J.
Published: April 2011

Pacific cod (Gadus macrocephalus) and herring (Clupea harengus pallasi) in the Hecate Strait have shown fluctuations consistent with the hypothesis that herring recruitment rates are strongly influenced by cod predation. Regression analyses of herring juvenile survival, as measured by log recruits per herring spawner, on Pacific cod abundance indicate that the cod may cause a total instantaneous mortality rate averaging around 0.75∙yr−1 with each cod consuming several hundred herring. Somewhat lower estimates of herring consumption per cod were expected on the basis of stomach contents data, but the discrepancy may well be due to systematic underestimates of cod abundance. Cod recruitment rates are positively correlated with herring abundance, but it is impossible to determine from historical data whether this correlation reflects predator–prey interdependence or the impacts of older cod on their own offspring, since cod and herring abundances are inversely correlated. Peak cod abundances in northern British Columbia during the late 1950's may be partly responsible for the collapse of the herring reduction fishery of the 1960's, and management of the two species should be coordinated to reflect the possibility of similar events in the future.
Contribution of Early Life Stages to Interannual Variability in Recruitment of Northern Anchovy (Engraulis mordax)
Authors: Peterman Randall M. , Bradford Michael J. , Lo Nancy C. H. , Methot Richard D.
Published: April 2011

We tested Hjort's and Lasker's hypotheses that the abundance of recruits in fishes is determined at an early life stage. Using 13 yr of data on components of population dynamics of the well-studied northern anchovy (Engraulis mordax), we reconstructed the abundance of anchovy in each year at three stages: eggs, 4.5-d-old yolk-sac larvae, and 19-d-old larvae. No abundance measure was significantly correlated with age 1 recruits, resulting in rejection of Hjort's and Lasker's hypotheses. We give reasons why the low correlations are not an artifact of estimation error. The lack of correlation exists because of the large variability (CV = 171%) in survival rate between age 19 d and age 1 yr. Therefore, attempts to understand interannual variability in recruitment in this, and perhaps other, marine fish species may have to rely not only on data on eggs and larvae, but especially on data on abundances estimated after 20 d, closer to the age at recruitment.
Relative Contributions of Dietary and Waterborne Zinc in the Rainbow Trout, Salmo gairdneri
Authors: Spry D. J. , Hodson P. V. , Wood C. M.
Published: April 2011

Rainbow trout, Salmo gairdneri, were fed purified diets with zinc concentrations ranging from deficient to excessive (1, 90, 590 μg Zn∙g−1) and simultaneously exposed to a range of waterborne [Zn] (7, 39, 148, 529 μg Zn∙L−1). After 1 wk, fish fed the deficient diet, at ambient waterborne [Zn], had low plasma [Zn] which decreased further during the 16-wk experiment. Growth ceased after 12 wk; hematocrit and plasma protein were depressed. Both whole body [Zn] and body burden decreased by 16 wk, but most other elements were elevated. Increasing waterborne [Zn] alone increased plasma [Zn], whole body [Zn], and growth in a graded manner and normalized hematocrit, plasma protein, and other whole body elements. Increasing dietary [Zn] to 90 μg Zn∙g−1 at ambient waterborne [Zn] prevented depression of plasma [Zn] and permitted normal growth and whole body [Zn]. Zinc uptake from water, probably across the gills, was independent of uptake from the diet since at any dietary [Zn], increasing the waterborne [Zn] resulted in increased whole body [Zn]. Even when dietary [Zn] was adequate, the waterborne contribution was as high as 57%, and 100% when the dietary [Zn] was deficient. There were no toxic effects on any of the variables measured.
Response of Recently Metamorphosed Anadromous Parasitic Lamprey (Lampetra tridentata) to Confinement in Fresh Water
Authors: Clarke W. Craig , Beamish Richard J.
Published: April 2011

Recently metamorphosed Lampetra tridentata were collected from six rivers in British Columbia in early autumn and held in fresh water in the laboratory at ambient temperature and simulated natural photoperiod. Ability to survive in fresh water varied considerably among populations, ranging from the Babine River population which did not survive beyond February to the Chemainus River population which survived until July. Associated with the onset of mortality was a decrease in plasma sodium concentrations. Plasma sodium concentrations in individual lampreys were correlated with condition factor, indicating that osmoregulatory failure may have resulted from depletion of body energy reserves. In a separate experiment, postmetamorphic lamprey sampled from two rivers fed poorly in fresh water and feeding did not prolong their survival. We conclude that confinement of L. tridentata in fresh water does not easily result in the formation of landlocked populations.
The Mercury Problem in Recently Formed Reservoirs of Northern Manitoba (Canada): Effects of Impoundment and Other Factors on the Production of Methyl Mercury by Microorganisms in Sediments
Authors: Jackson Togwell A.
Published: April 2011

Creation of hydroelectric reservoirs by enlargement of riverine lakes and flooding of adjacent forested land along the Churchill River diversion route has led to a marked rise in rates of methyl mercury production by microorganisms in sediments. This phenomenon has resulted primarily from stimulation of microbial activity by organic matter in submerged land areas and is due both to utilization of organic nutrients by methylators and to concomitant oxygen depletion. Release of mercury from scattered low-level sources in this organic matter is a secondary contributing factor. Compared with submerged terrestrial organics, organic matter from aquatic biota has only been of minor importance in promoting methyl mercury production. In some regions, clay and silt eroded from shoreline deposits have inhibited methyl mercury production appreciably. The aerobic conditions prevailing in well-flushed main-stream regions tend to increase the "availability" of sediment-bound inorganic mercury for methylation while decreasing the rate at which microbes are able to methylate the mercury; under less aerobic conditions in quiet backwater regions, the reverse is true.
Gene Flow and Genetic Differentiation among California Coastal Rainbow Trout Populations
Authors: Berg W. J. , Gall G. A. E.
Published: April 2011

Present levels of genetic variability and estimates of historical rates of gene flow were obtained by analyses of allele frequency data from 31 California coastal rainbow trout populations. Genetic variability was higher than seen in most salmonid species. Seventy-one electrophoretic alleles were segregating at 24 loci. Seven loci were monomorphic. Between-population genetic indentities were high and there was only a weak relationship between geographic proximity of populations and genetic identity. Average within-population heterozygosity and percent polymorphic loci were 0.092 and 35.1, respectively. Estimated total heterozygosity was 0.106; therefore, 86.8% of the total gene diversity could be ascribed to within-population genetic variation. The remaining 13.2% of the total gene diversity represented genetic differences between rainbow trout populations. Both qualitative and quantitative methods of analyses suggested that historical rates of gene flow were high; realized gene flow was estimated to be at least 1.7 migrants per population per generation. It is argued that each population's allele frequencies may simply be expression of temporal fluctuations around the panmictic allele frequencies of the greater global population.
An In Situ Experimental Evaluation of the Elliott and Persson and the Eggers Models for Estimating Fish Daily Ration
Authors: Boisclair D. , Leggett W. C.
Published: April 2011

We compared estimates of daily ration developed using the theoretically rigorous and logistically demanding Elliott and Persson model and the more easily applied Eggers model which is infrequently used because of its assumptions about rigid fish feeding periodicity. Comparisons were based on ten 24-h samplings of six different yellow perch (Perca flavescens) populations. Daily ration estimates from the two models did not differ significantly. This consistency occurred in spite of the fact that in some cases the observed feeding periodicity violated the assumptions of the Eggers model. A simulation model demonstrated that 95% confidence intervals were smallest for the Eggers estimates and that the Eggers model was more robust than the Elliott and Persson model to changes in both sampling frequency and number offish sacrificed at each sampling event. The latter proved particularly sensitive to changes in sampling frequency. We concluded that the two models provide estimates of daily ration comparable in magnitude and accuracy and consequently that the restriction of the Eggers model to fish with rigid feeding periodicity is not justified. Furthermore, the Eggers model, because of its robustness, reduces the sampling requirements to determine daily ration, and hence, permits its estimation on a more frequent basis.
Factors Affecting the Time Series Bias in Stock–Recruitment Relationships and the Interaction Between Time Series and Measurement Error Bias
Authors: Caputi N.
Published: April 2011

The stock–recruitment relationship (SRR) and the recruitment to spawning stock relationship (RSR) of the tiger prawn (Penaeus esculentus) in Exmouth Gulf, Western Australia, were used to examine the time series bias and measurement error bias by Monte Carlo simulations. The bias of the SRR parameters was decreased by adding environmental variables which reduced the variation about the SRR. However, because of the many variables which may be tested and the short time series of data usually available, one needs to be careful about possible spurious correlations. The variation about the RSR also needs to be taken into account, since it has an inverse relationship with the bias in the SRR. Simulating the effect of measurement error as well as the random variation about the SRR and RSR helps to determine the possible combinations of measurement error and random variation which may result in the observed variation about the SRR and RSR. These simulations also indicate that there is an interaction between measurement error and random variation about the SRR/RSR on the bias of the parameters of the SRR. This suggests that the time series bias and measurement error should be investigated simultaneously.
Effect of Experimentally Increased Intraspecific Competition on Sedentary Adult Brown Trout (Salmo trutta) Movement and Stream Habitat Choice
Authors: Heggenes Jan
Published: April 2011

Movements and habitat choice of 19 brown trout (Salmo trutta) resident in a stream was monitored during one season, while in the next season the population was increased by introducing 130 wild brown trout captured further downstream. No differences in the movement patterns of resident trout at the two population densities, or of residents compared with nonresidents, were found. Median movement distance was 0 m. Sixty-six percent of the movements were less than ±50 m, 11% were between 50 and 100 m, and 23% were greater than ±100 m. Introduced nonresident trout occupied habitats different from those occupied by residents. Nonresidents were more often observed in shallower areas with less cover and finer substrate, i.e. less preferred habitats. It is hypothesized that this was caused by dominance of resident trout due to their larger size and prior residence. Both resident and introduced trout exhibited preferences for deep stream areas, e.g. water > 50 cm deep, mean water velocities in the range 10–70 cm/s, coarse substrate > 128 mm, and a > 50% overhead cover compared with available habitat. At both low and high population densities, the trout inhabiting pools were significantly larger than trout inhabiting other habitat types. No homing tendency was observed for the displaced trout.
Feeding of Juvenile Coho Salmon (Oncorhynchus kisutch): Maximum Appetite, Sustained Feeding Rate, Appetite Return, and Body Size
Authors: Dunbrack Robert L.
Published: April 2011

Experimental investigations of the influence of body size and feeding rate on the voluntary consumption of live Tubifex by juvenile coho salmon (Oncorhynchus kisutch) showed that maximum appetite and sustained feeding rate increased allometrically with coho body size. There was no significant effect of body size on the rate of appetite return following a meal, although a comparison of these results with data from the literature suggests that the rate constant of appetite return may decrease with body size. The rate constant of appetite return following meals preceded by 96 h of starvation was significantly greater than that for meals preceded by 3–5 d of satiation feeding. If the latter effect also applies to the rate constant of gastric evacuation for live foods, the use of standard gastric evacuation models could overestimate the rate of food intake of wild fish feeding at close to their maximum rate.
A Weighted Duration-in-Beam Estimator for the Volume Sampled by a Quantitative Echo Sounder
Authors: Crittenden R. N. , Thomas G. L. , Marino D. A. , Thorne R. E.
Published: April 2011

Estimation of absolute fish density or abundance using the echo-count technique requires estimation of the volume sampled. The unknown parameter in the volume sampled is the sine of the half-angle of the effective conical beam. We derive the minimum variance, unbiased, linear estimator of this parameter. This estimator is based upon weighted regression through the origin and reduces to a computationally simple form. We use this estimate and its variance to estimate absolute density, absolute abundance, and their variances. We use a bootstrap procedure to contrast the performance of our method against that of a contemporary method, which is based upon the averages taken over range strata. Although both of these methods are unbiased, we show that our estimator has a standard deviation that is 23.5% smaller than that of the average-over-strata method.
Correspondence Between Ecoregions and Spatial Patterns in Stream Ecosystems in Oregon
Authors: Whittier Thomas R. , Hughes Robert M. , Larsen David P.
Published: April 2011

Multivariate analyses of biotic assemblages and physicochemical measures, species richness, diversity, and composition were used to evaluate the robustness of Omernik's ecoregion classification for small streams in the eight ecoregions of Oregon. Clearest differences were between the montane and nonmontane regions. For the three nonmontane regions, ordinations of fishes, macroinvertebrates, water quality, and physical habitat measures show the clearest differences, with the Willamette Valley ecoregion being consistently most unlike all other regions. Differences between the Columbia Basin and High Desert regions were clearest for water quality and physical habitat measures and fish assemblages. Differences among the montane regions were subtle. Of these regions, the East Cascade Slopes showed the greatest variability, as shown by the ranges of ordination scores for fishes, water quality, and physical habitat. Regional patterns in periphyton assemblages were markedly different from the patterns in the other groups of variables. Ecoregions can be used as a broad-scale geographic framework for classifying streams. This framework provides managers of lotic resources a useful alternative to river basins.
Structural Organization and Species Composition of a Lotic Periphyton Community in Response to Experimental Acidification
Authors: Planas Dolors , Lapierre Louise , Moreau Guy , Allard Martine
Published: April 2011

Changes in species composition, richness, diversity, biomass (biovolume), and spatial community structure of a lotic periphyton community were observed under experimental acidification (mean pH 4.5) with and without aluminum, in troughs fed from an oligo-dystrophic creek (mean pH 6.7). in experimental and control troughs, the community was dominated by diatoms throughout the treatment. Achnanthes linearis was dominant in all troughs before treatment as well as in the control during the experiment. Eunotia pectinalis, which was rare in all troughs before treatment, became dominant in the acidified troughs. After 3 mo of acidification, algal cell density and biomass were respectively 30 and 40–70 times higher in the treated troughs as compared with that in the control. The Sow diversity (H = 1.45–2.30) characteristic of the control trough, increased to 3.3 in the treated troughs after 1 mo of acidification, but after 3 mo of experiment the diversity was slightly lower in experimental troughs. In the control trough, spatial organization of the community was characterized by monolayered arrangements during the whole experiment, in both acidified troughs (acid and acid plus aluminum) the community became multilayered (3–4 layers). The increased complexity of the community in the acidified troughs seemed to be related to a decrease in the abundance of grazers in the periphytic community, mainly the collector–gatherers Ephemeroptera and Orthocladiinae.
Reproductive Success of Amnicola limosa (Gastropoda) in Low Alkalinity Lakes in South-Central Ontario
Authors: Shaw Margo A. , Mackie Gerald L.
Published: April 2011

The reproductive success of the gastropod Amnicola limosa was examined in six lakes ranging in pH from 4.62 to 7.42 to determine which stages in the life cycle were most sensitive to acidification. Although fecundity was significantly greater (p < 0.01) for adults reared at pH 7.42 than at pH 5.89–6.64, a failure to oviposit was documented only at pH 4.62. Hatching success was uniformly high (88–97%) at pH 5.59 to 7.42, while embryos incubated at pH 4.62 suffered complete mortality. The most critical stage in the life cycle is the newly hatched stage. Survival during the 20 d post hatch ranged from 23% at pH 5.59 to 69% at pH 7.42. There was an order of magnitude difference in the cumulative percent survival of recruits in lakes ranging in pH from 5.59 (5.1%) to 7.42 (44.0%). Juveniles raised at low pH (5.59–5.70) were on average 0.20 mm (20%) smaller than those in circumneutral lakes (pH 6.64–7.42). The present low densities of Amnicola limosa in Heney Lake (pH 5.59) can be explained by low recruitment since 1980. Evidence presented suggests that the disappearance of this species from clear low pH lakes (pH < 5.8) is due to reductions in fecundity and hatchling survival.
A System of Simultaneous Dynamic Production and Forecast Models for Mulispecies or Multiarea Applications
Authors: Polovina Jeffrey J.
Published: April 2011

A system of simultaneous dynamic production models is presented for multispecies or multiarea applications. The system of equations arises by using a linear dynamic production model with one equation for each area or species. The parameter estimation for the system of equations is particularly efficient when some of the parameters are assumed to have the same value in more than one equation.
Subpopulation Status of Lake Whitefish (Coregonus clupeaformis) in Lake Winnipeg
Authors: Kristofferson A. H. , Clayton J. W.
Published: April 2011

Spawning lake whitefish in Lake Winnipeg from Dauphin River–Lake St. Martin, Traverse Bay, Berens River–Poplar River–Big Black River and Grand Rapids and in Little Playgreen Lake are accorded subpopulation status based on morphometric measurements, meristic counts, and differences in frequencies of alleles at the muscle glycerol-3-phosphate dehydrogenase (g-3-pdh-b) locus. The frequency of the g-3-pdh-b-3 allele in samples from Dauphin River–Lake St. Martin was 0.77 compared with 0.46 for whitefish from the remainder of Lake Winnipeg and Little Playgreen Lake. Two loci for isocitrate dehydrogenase and one lactate dehydrogenase locus are also polymorphic in these fish but no significant allele frequency differences were found at these loci among the samples of spawners compared above. Hatchery-reared lake whitefish, obtained from stock in Clearwater Lake and William Lake and planted as fry or eyed eggs in Lake Winnipeg at Dauphin River and Grand Rapids, do not appear to have made a detectable genetic contribution to the local whitefish stocks, based on differences in g-3-pdh-b and idh Bβ allele frequencies among parent stock and spawners captured near the release sites.
Effects of pH, Aluminum, and Calcium on Survival and Growth of Eggs and Fry of Brook Trout (Salvelinus fontinalis)
Authors: Ingersoll C G. , Mount D. R. , Gulley D. D. , Point T. W. La , Bergman H. L.
Published: April 2011

Freshly fertilized eggs, eyed eggs, yolk-sac fry, and swim-up fry of brook trout (Salvelinus fontinalis) were exposed to a matrix of 84 combinations of pH (4.0–6.5), aluminum (0–1000 μg/L), and calcium (0.5–8.0 mg/L) in 21–91-d experiments. The response to pH, aluminum, and calcium exposure was dependent on life stage. Sensitivity to acid toxicity generally decreased with age (freshly fertilized eggs>eyed eggs>yolk-sac fry = swim-up fry). Survival or hatching of freshly fertilized and eyed eggs decreased at pH 5.2 and below, whereas survival of yolk-sac and swim-up fry was reduced at pH 4.4–4.0. Sensitivity to aluminum toxicity generally increased with age (freshly fertilized eggs = eyed eggs<yolk-sac fry<swim-up fry). At low pH, survival of freshly fertilized and eyed eggs increased with exposure to increasing aluminum concentrations, in contrast, elevated aluminum [Formula: see text] was often toxic to fry. Increasing calcium was beneficial to all life stages, although the magnitude of this benefit depended on life stage and on the specific pH and aluminum concentration. Survival after previous exposure to toxic combinations of pH, aluminum, and calcium generally improved during a post-exposure recovery period at pH 6.5. However, increased mortality in many exposure combinations did not begin until this recovery period.
Effects of Water Acidity, Calcium, and Aluminum on Whole Body Ions of Brook Trout (Salvelinus fontinalis) Continuously Exposed from Fertilization to Swim-Up: A Study by Instrumental Neutron Activation Analysis
Authors: Wood C. M. , McDonald D. G. , Ingersoll C. G. , Mount D. R. , Johannsson O. E. , Landsberger S. , Bergman H. L.
Published: April 2011

Water Ca, rather than pH or Al, was the most important factor affecting whole body electrolyte levels in fry exposed from fertilization to swim-up (91 d) to 84 combinations of pH (6.5, 5.2, 4.8, 4.4, 4.0), Ca (0.5, 1, 2, 8 mg/L), and Al (0, 12, 37, 111, 333, 1000 μg/L) in flowing soft water. Aluminum accumulation occurred only at water Al levels > 111 μg/L; Al accumulation was inhibited both by increasing Ca and decreasing pH. Under control conditions (pH = 6.5, Ca = 2 mg/L, Al = 0 μg/L), whole body Na, Cl, K, and Ca levels all increased greatly during development, while Mg decreased. Body Ca levels were elevated up to 3-fold, and Na, Cl, and K up to 2-fold by increasing water Ca at the same pH and Al. Low pH had a small negative influence, intermediate levels of Al (37, 111) a slight positive influence, and higher levels of Al a negative influence on Na, Cl, K, and Ca levels. Whole body Mg showed opposite trends, reflecting delayed development under adverse conditions. At pH = 6.5, the positive influence of increasing water Ca on most whole body ions showed a clear threshold between 0.5 and 1 mg/L. At lower pH, this threshold was shifted to between 2 and 8 mg/L, indicating that Ca levels sufficient to support healthy development at circumneutral pH may prove inadequate under acidified conditions.
Responses of Brook Trout (Salvelinus fontinalis) Fry to Fluctuating Acid, Aluminum, and Low Calcium Exposure
Authors: Mount D. R. , Swanson M. J. , Breck J. E. , Farag A. M. , Bergman H. L.
Published: April 2011

Brook trout fry were exposed for thirty days to temporal combinations of two water qualities: (1) pH 5.21, 51 μg/L total aluminum, with 2.39 mg/L calcium (baseline); and (2) pH 4.59, 329 μg/L total aluminum, with 1.56 mg/L calcium (pulse). Although continuous exposure to the latter conditions caused nearly complete mortality, exposures alternating between the two conditions caused much less mortality. In fact, fish experiencing 18 d of baseline conditions before their first pulse exposure had mortality rates equal to fish never experiencing a pulse, indicating acclimation to acid/aluminum/low calcium stress. We conclude that the pattern of fluctuating acid/aluminum/low calcium exposure is very important in determining its toxicity, and that the toxicity of acidic "pulses" in field situations may be lower than would be expected from laboratory exposures using naive fish, due to the existence of acclimation.
Variation within and between Rivers in Adult Size and Sea Age at Maturity of Anadromous Brown Trout, Salmo trutta
Authors: L'Abée-Lund Jan Henning
Published: April 2011

I compared adult size and sea age at sexual maturity among nine populations of anadromous brown trout, Salmo trutta, in two Norwegian rivers to determine the extent of inter- and intrariverine variations. Variation in the mean length of spawners and in the mean sea age at sexual maturity were mainly dependent on the variations found within rather than between rivers. Mean lengths and mean age at maturity of males increased significantly with increasing altitude of the spawning area and with migration distance in freshwater. In females, positive significant correlations were found with mean lengths and altitude of the spawning area and with mean sea age at maturity and both spawning site altitude and migration distance. Mean lengths and ages of males and females were not significantly correlated with the rate of water discharge in the streams during spawning. The size of gravel substrate for spawning was of minor importance in explaining interpopulation variation in mean female size. The increase noted in mean length and in mean sea age at maturity of both males and females is probably an adaptation to greater energy expenditure to reach the uppermost natal spawning areas.
Relationship between Chronic Toxicity and Bioaccumulation of Cadmium in Hyalella azteca
Authors: Borgmann U. , Norwood W. P. , Babirad I. M.
Published: April 2011

The chronic toxicity of Cd to Hyalella in Burlington City tap (Lake Ontario) water with additions of complexing agents, distilled water, or sediments was much more constant if toxicity was expressed as a function of Cd bioaccumulated, rather than the Cd concentrations added or measured in the water. Additions of 20 mg humic acid/L or 0.5 μM EDTA increased the 6-wk EC50 from 0.53 to 4.6 and 19 μg/L, respectively. The EC50 based on bioaccumulated Cd, however, increased from 38 to only 44 μg/g (dry weight). Addition of sediments increased the 4-wk EC50 by > 1000-, 13-, or 2.3-fold for EC50s based on nominal Cd added, Cd concentrations measured in water, or Cd concentrations accumulated by Hyalella, respectively. A 10-fold reduction in hardness caused a twofold increase in the 6-wk EC50 based on Cd accumulation. The relationship between survival and Cd bioaccumulation by Hyalella was, therefore, affected less by complexing agents, hardness, and sediments than was survival compared with concentrations in water. Published Cd concentrations in Hyalella from a number of Ontario lakes are close to levels associated with toxicity in the laboratory.
Modeling the Stability of Fish Schools: Exchange of Individual Fish between Schools of Skipjack Tuna (Katsuwonus pelamis)
Authors: Hilborn Ray
Published: April 2011

Three data sets that involve intensive mark and recapture of schools of skipjack tuna (Katsuwonus pelamis) are examined for information about exchange of individuals between schools. A formal exchange model is proposed, and maximum likelihood estimates of the parameters are found. It appears that individuals exchange quite rapidly between schools of skipjack; 16–63% of individuals apparently leave a school each day to join other schools. It is possible, however, that what are operationally defined as schools by fishermen consist of smaller more stable subunits.
Controls on Domoic Acid Production by the Diatom Nitzschia pungens f. multiseries in Culture: Nutrients and Irradïance
Authors: Bates S. S. , Freitas A. S. W. de , Milley J. E. , Pocklington R. , Quilliam M. A. , Smith J. C. , Worms J.
Published: April 2011

Nitzschia pungens f. multiseries (clone NPARL) was grown in nonaxenic batch culture under a range of growth conditions. Domoic acid (DA) was not detected during exponential growth, but production promptly started at a rate of approximately 1 pg DA∙cell−1∙d−1 at the onset of the stationary phase, in this case induced by silicate limitation. Cellular DA reached a maximum of 7 pg∙cell−1; thereafter, DA production continued at the same rate, with cellular levels remaining relatively constant due to concurrent release of DA into the culture medium. DA production ceased in the absence of nitrogen during the stationary phase, but resumed when nitrate was added back to the medium. Low irradiance slowed the division rate and consequently delayed the attainment of the stationary phase, but DA production rates were comparable with the control once stationary phase was reached. Cells during the dark period of a light–dark cycle, or placed into darkness, or in the presence of the photosynthetic inhibitor DCMU promptly ceased DA production. We conclude that at least three conditions are required for DA production by clone NPARL: cessation of cell division, availability of nitrogen during the stationary phase, and the presence of light. Growth in medium f/2 fulfils these requirements.
Indexing Deformities in Ligulae and Antennae of Procladius Larvae (Diptera: Chironomidae): Application to Contaminant-Stressed Environments
Authors: Warwick W. F.
Published: April 2011

The severity of deformities in the ligulae and antennae of Procladius is indexed and both indices are expanded to include population and community indices and a general index of Chironomid Community Response. These biological indices are compared with Indices of Contamination derived from chemical data from the St. Lawrence River, Port Hope Harbour, Southern Indian Lake – Notigi Reservoir, Tobin Lake, and Last Mountain Lake. Biological and chemical indices both identified Lac St. Louis Site 4 on the St. Lawrence River as the most highly contaminated site and the Wupaw Bay site in the Southern Indian Lake – Notigi Reservoir as the least contaminated of the 23 sites studied. The increase in frequency and severity of deformities in spring and summer data from the Rat Lake basin suggests that larvae are sensitive to increased mercury availability resulting from the greater activity of mercury-methylating bacteria in warmer summer waters.
Orientation des déplacements de crabes des neiges mâles (Chionoecetes opilio) marqués dans le sud-ouest du golfe du Saint-Laurent
Authors: Lefebvre Louise , Brêthes Jean-Claude F.
Published: April 2011

A total of 7760 Chionoecetes opilio males were marked and released on the bottom at the entrance to Chaleur Bay and near the Îles-de-la-Madeleine in the southwestern Gulf of St. Lawrence in 1986 and 1987. Of this number, 976 individuals, all morphometrically mature, were recovered between 1987 and 1989. The average distance covered was 9.6 km for Chaleur Bay (maximum 47.0 km) and 13.7 km for the Îles-de-la-Madeleine (maximum 89.5 km). Size had no significant effect on distance covered or direction of movement. Individuals released at higher or intermediate bottom depths followed the slope downward. In the Chaleur Bay sector, the crabs at greater depth showed a tendency to move up the slope. Near the Îles-de-la-Madeleine, most of the individuals released at greater depth stayed on the valley floor, but there was also a tendency to move upward. It appears that there are two types of travel, a general downward movement, disturbed by seasonal shifts which are undoubtedly related to reproduction. Large movements suggest the possible existence of contacts between local substocks.
Temperature Acclimation of Xenobiotic Metabolizing Enzymes in Cultured Hepatocytes and Whole Liver of the Gulf Toadfish, Opsanus beta
Authors: Kennedy Christopher J. , Gill Kenneth A. , Walsh Patrick J.
Published: April 2011

Changes in cytochrome P-450 and microsomal and soluble protein content and the activities of several microsomal and cytosolic xenobiotic metabolizing enzymes were examined in the whole livers of gulf toadfish, Opsanus beta, following acclimation to 18 or 28 °C and in isolated hepatocytes (prepared from 18 or 28 °C acclimated gulf toadfish) which were maintained in primary culture for 29 d on L-15 media. Cells isolated from both acclimation groups were cultured at 18 and 28 °C. In whole livers, significant differences were found in the activities of sulfotransferase (which showed perfect compensation) and UDP-glucuronosyltransferase (which showed "inverse compensation") between fish acclimated to 18 and 28 °C, but several other trends were obscured by interindividual variation. However, in hepatocyte cultures, temperature adaptations were seen in cytochrome P-450 content and in the activities of the microsomal enzymes aryl hydrocarbon hydroxylase, epoxide hydrolase, and UDP-glucuronosyltransferase. Glutathione-S-transferase activity appeared to be rather temperature insensitive in both whole livers and in cultured hepatocytes. Incomplete temperature acclimation for all enzymes was observed in cultured cells and this may be due to systemic factors which were not present in cell culture media.
Abundance and Freshwater Migrations of the Anadromous Parasitic Lamprey, Lampetra tridentate, in a Tributary of the Fraser River, British Columbia
Authors: Beamish Richard J. , Levings Colin D.
Published: April 2011

The migration of young adult Lampetra tridentata out of the Nicola River during 1984–85 through 1987–88 was estimated to be approximately 176 000,19 000,90 000, and 102 000; at the same time, approximately 749 000, 909 000, 920 000, and 605 000 large ammocoetes, age 4 and 5 yr, left the river. Migration of young adults started in September, with the largest number migrating from mid-March to mid-May. Ammocoetes behaved similarly except that movement continued throughout the year. Most young adults metamorphosed at age 4 or 5 and were age 5 or 6 when they migrated to sea. It was not determined when lamprey from the Nicola River reached salt water; however, L. tridentata entered the Strait of Georgia from the Fraser River from March until July. Maturing adults first returned to the Nicola River from the ocean in August when water levels in the river were at their lowest. This is the first estimate of abundance of young adult L. tridentata in any river in the Fraser River drainage. The very large number of young adults and older ammocoetes leaving the Nicola River indicate that parasitic lamprey are abundant in the Fraser River and that they are potentially a common predator of commercially important fishes.
Locally Based Water Quality Planning: Contributions to Fish Habitat Protection
Authors: Pinkerton Evelyn
Published: April 2011

Successful fish habitat protection occurs in areas of urban/industrial development when responsible citizens in rural watersheds can produce and implement local water quality plans binding on all agencies. In 1985, legislation in the state of Washington, USA, authorized a central planning agency — the Puget Sound Water Quality Authority — to initiate local watershed planning exercises through counties or other local agencies. The essential elements of community mobilization to the goals and activities of water quality planning were analyzed by comparing key factors in highly successful planning processes with factors in less successful ones. This permitted generalizations about basic organizing principles, educational procedures, and techniques of consensus building in the planning and implementation of water quality rehabilitation and protection for watersheds. The analysis contributed to a general theory of how and why community participation can improve the effectiveness of fish habitat protection.
Ecological and Genetic Impacts of Introduced and Translocated Freshwater Fishes in Australia
Authors: Arthington Angela H.
Published: April 2011

The inland waters of Australia have been colonized successfully by 20 species of freshwater fishes introduced to the continent, including 6 poeciliids, 3 salmonids, 4 cyprinids, 5 cichlids, 1 percid and 1 cobitid, all of which reproduce there in the wild. The ecological and genetic consequences of fish introductions and translocations have concerned scientists and water authorities since the late 1960's, although the earliest introductions of salmonids for sport were made towards the end of the 19th century. Impacts of introduced fishes, including hybridization problems, habitat and water quality alterations, competition for space and food, predation and the introduction of exotic parasites and diseases are reviewed. Emphasis is placed on sub-tropical and tropical species, since they appear to present the greatest threat to natural ecosystems. Problems in the translocation of indigenous Australian fishes between drainage systems to supplement recreational fishing are noted; a review of the Lake Eacham rainbowfish, supposedly brought close to extinction in its natural habitat by translocated Australian piscivores, demonstrates that unanticipated predator–prey interactions may result from the thoughtless addition of piscivores to an endemic community. A theoretical perspective on the assessment of candidate species for introduction and translocation is given, and areas of theoretical ecology that may assist in predicting future impacts of introduced species are discussed.
Introduced Freshwater Fishes: A Review of the North American Perspective With Emphasis on Canada
Authors: Crossman E. J.
Published: April 2011

The introduction of fishes into North America began in the late 1600's. The number of species has increased over the years, with pulses in the late 1800's and following the 1950's. By 1989, there were 45 established exotic fishes in the continental USA, and 16 in Canada. By 1989, the number brought into, invading, or transferred within Canada was 92 species plus 13 subspecies and hybrids. A special situation for Canada is the steady invasion from U.S. waters. Over the years, 38 such species have been identified. A variety of societal pressures led to the introductions, and the species introduced represent a number of realized or potential environmental impacts. Various international, national, state and provincial agencies or programmes have developed to investigate introductions and/or judge individual applications for the importation or transfer of live fishes. The number and nature of species being moved is still not well known. For Canada, 125 forms (species, hybrids, selected strains) which fit the new definition of Introduced are summarized by province and mode of introduction.