Showing papers in "Canadian Journal of Fisheries and Aquatic Sciences in 2009"
TL;DR: In this article, a review of water chemistry data indicated that Sr:Ca (mmol:mol) levels were higher in marine water than in most freshwater systems, and that the variability of the water chemistry was lower in marine waters than in freshwater systems.
Abstract: Water chemistry is thought to be the primary factor influencing fish otolith chemistry. Experimental results with freshwater and diadromous fish have been consistent with this paradigm, but with marine fish, they have often been ambiguous or contradictory. A review of water chemistry data indicated that Sr:Ca (mmol:mol) levels were higher in marine water than in most freshwater systems and that Sr:Ca variability was lower in marine water than in most freshwater systems. We therefore hypothesized that lifetime otolith Sr:Ca profiles of freshwater fish would exhibit low levels of Sr:Ca with moderate variability, of diadromous fish would exhibit highly variable Sr:Ca levels, and of marine fish would exhibit high levels of Sr:Ca with low variability. Otolith Sr:Ca profiles from 81 species of freshwater, diadromous, and marine fish revealed that freshwater fish had low levels of Sr:Ca and lower variability than expected relative to marine fish, diadromous fish had Sr:Ca levels and variability that were consist...
185 citations
TL;DR: Different populations can be ar- rayed along a continuum from panmixia to complete reproductive isolation, and variation along this continuum might profitably be used for studying factors that can promote or constrain ''progress'' toward ecological speciation.
Abstract: Ecological speciation occurs when adaptation to different environments or resources causes the evolution of reproductive isolation. This process is now thought to be very important in the evolution...
184 citations
TL;DR: Some fishery characteristics such as total discards are often inferred from data collected by at-sea observers on a subset of fishing trips, predicated on the assumption that obse...
Abstract: Some fishery characteristics such as total discards are often inferred from data collected by at-sea observers on a subset of fishing trips. Such inference is predicated on the assumption that obse...
128 citations
TL;DR: In this article, a three-dimensional fluid dynamics model was developed to capture the spatial complexity of the effects of salmon redds on channel hydraulics, hyporheic exchange, and egg pocket habitat.
Abstract: A three-dimensional fluid dynamics model is developed to capture the spatial complexity of the effects of salmon redds on channel hydraulics, hyporheic exchange, and egg pocket habitat. We use the ...
119 citations
TL;DR: The POST array pro- vided direct measurements of movement and estimates of survival and demonstrated the feasibility of establishing conti- nental-scale acoustic arrays for management and conservation of marine species.
Abstract: Freshwater and early marine migration and survival of endangered Cultus Lake sockeye (Oncorhynchus nerka) salmon were studied using the Pacific Ocean Shelf Tracking (POST) array. Smolts were acoust...
119 citations
TL;DR: The effect of human land use on nutrient limitation of biofilm CR, GPP, and chl a was influenced by ecoregion, yet heterotrophic biofilms were consistently most sensitive to nutrient enrichment across ecore- gions.
Abstract: Nutrient diffusing substrata were used to determine the influence of inorganic nitrogen (N) and phosphorus (P) availability on community respiration (CR), gross primary production (GPP), and chloro...
115 citations
TL;DR: Using bomb- 14 C dating and growth ring counting methods, life spans and growth rates of six spe- cies of deep-sea corals collected at depths of between 400 and 900 m from the continental slope of Newfoundland and Labrador are calculated.
Abstract: Using bomb-14C dating and growth ring counting methods, we calculate life spans and growth rates of six species of deep-sea corals collected at depths of between 400 and 900 m from the continental ...
112 citations
TL;DR: Natural abundance stable isotope analyses indicate that this influx of marine-derived nitrogen is rapidly incorporated into the stream food web, and there was no significant effect of this nutrient influx on water chemistry, leaf decomposition, or periphyton accrual.
Abstract: Diadromous fish are an important link between marine and freshwater food webs. Pacific salmon (Oncorhynchus spp.) strongly impact nutrient dynamics in inland waters and anadromous alewife (Alosa pseudoharengus) may play a similar ecological role along the Atlantic coast. The annual spawning migration of anadromous alewife contributes, on average, 1050 g of nitrogen and 120 g of phosphorus to Bride Brook, Connecticut, USA, through excretion and mortality each year. Natural abundance stable isotope analyses indicate that this influx of marine-derived nitrogen is rapidly incorporated into the stream food web. An enriched δ15N signal, indicative of a marine origin, is present at all stream trophic levels with the greatest level of enrichment coincident with the timing of the anadromous alewife spawning migration. There was no significant effect of this nutrient influx on water chemistry, leaf decomposition, or periphyton accrual. Dam removal and fish ladder construction will allow anadromous alewife to regain...
108 citations
TL;DR: Genetic population structure of Pacific cod was examined across much of its northeast- ern Pacific range by screening variation at 11 microsatellite DNA loci, showing population structure at spatial scales relevant to fisheries management caused by limited dispersal along the coast and by sharp barriers to migration isolating smaller stocks in coastal fjord environments.
Abstract: Genetic population structure of Pacific cod, Gadus macrocephalus, was examined across much of its northeastern Pacific range by screening variation at 11 microsatellite DNA loci. Estimates of FST (...
105 citations
TL;DR: It is speculated that a combination of reduced primary production in the open waters and intensified planktivory due to the con- tinuing disappearance of Diporeia has accounted for the losses in crustacean biomass seen in recent years.
Abstract: Cladoceran populations in the open waters of Lake Huron declined abruptly in 2003 and have since remained at historically low levels. The two dominant cladocerans, Daphnia mendotae and Bosmina long...
101 citations
TL;DR: Mucus may provide a rapid turnover “tissue” for analysis of diet (or habitat) switching by fish and has the additional advantage that it may be sampled nonlethally in some fishes, thereby avoiding problems in studying threatened or endangered species.
Abstract: Stable isotope analysis of diet switching by fishes often is hampered by slow turnover rates of the tissues analyzed (usually muscle or fins). We examined epidermal mucus as a potentially faster tu...
TL;DR: It appears that VTG induction is not sufficient to predict effects of xenoes- trogens on fish populations, however, stronger predictions can be made when VTGs induction is assessed in conjunction with histopathological evidence of liver, kidney, and gonad tissue damage.
Abstract: Efforts to understand the effects of environmental estrogens on fish have shifted away from biochemical indica- tors towards population-level impacts. Ethynylestradiol (EE2) was added to a whole lake at environmentally relevant con- centrations for 3 consecutive years to examine links between vitellogenin (VTG) induction, histopathological impacts, and population decline in four species of fish. VTG induction and histopathological effects in tissues were most severe in fat- head minnow (Pimephales promelas) and pearl dace (Margariscus margarita). VTG was induced to a similar extent in lake trout (Salvelinus namaycush) but less so in white sucker (Catostomus commersonii). There were no histopathological effects in tissues of the two latter species. Population decline occurred in fathead minnows in the second year of EE2 addi- tions and there were some indications of population decline in pearl dace during the third year. White suckers were not af- fected but lake trout declined in year 3. Habitat selection probably altered EE2 exposure and the different effects in each species likely also reflect differing sensitivities. It appears that VTG induction is not sufficient to predict effects of xenoes- trogens on fish populations. However, stronger predictions can be made when VTG induction is assessed in conjunction with histopathological evidence of liver, kidney, and gonad tissue damage. Resume´ : Les efforts pour comprendre les effets des estrogenes de l'environnement sur les poissons se concentrent main- tenant sur les impacts au niveau des populations plutot que sur les indicateurs biochimiques. Nous avons ajoutede l'ethy- nylestradiol (EE2) aun lac entier ades concentrations pertinentes au niveau de l'environnement durant 3 annees consecutives afin d'examiner les liens entre l'induction de la vitellogenine (VTG), les impacts histopathologiques et le de ´- clin de la population chez quatre especes de poissons. L'induction de la VTG et les effets histopathologiques dans les tis- sus sont les plus importants chez la tete-de-boule (Pimephales promelas) et le mulet perle ´ (Margariscus margarita). L'induction de VTG est de niveau semblable chez le touladi (Salvelinus namaycush), mais moindre chez le meunier noir (Catastomus commersonii). Il n'y a pas d'effets histopathologiques dans les tissus de ces deux dernieres especes. Un declin demographique s'est produit chez la tete-de-boule durant la seconde annee des additions de EE2 et il y avait des signes de declin demographique chez le mulet perledurant la troisieme annee. Les meuniers noirs n'ont pas eteaffectes, mais les touladis ont diminuela troisieme annee. La selection des habitats modifie probablement l'exposition aEE2 et les effets distincts chez chaque espece refletent aussi vraisemblablement des sensibilites differentes. Il semble que l'induction de VTG ne suffise pas pour predire les effets des xenoestrogenes sur les populations de poissons. Il est, cependant, possible de faire de meilleures predictions lorsque l'induction de VTG est evaluee conjointement avec les signes histopathologiques de dommages dans les tissus du foie, des reins et des gonades. (Traduit par la Redaction)
TL;DR: Signatories of the 2002 World Summit on Sustainable Development declaration committed to maintain or restore fish stocks to levels that can produce the maximum sustainable yield (MSY), a goal that was defined by the authors of the declaration as mentioned in this paper.
Abstract: Signatories of the 2002 World Summit on Sustainable Development declaration committed to maintain or restore fish stocks to levels that can produce the maximum sustainable yield (MSY), a goal that ...
TL;DR: In this article, the authors compared theoretical habitat volumes, determined from traditional combinations of temperature and dissolved oxygen concentration (DO) boundaries, with in situ habitat use by acoustically tagged animals.
Abstract: We compared theoretical habitat volumes, determined from traditional combinations of temperature and dissolved oxygen concentration (DO) boundaries, with in situ habitat use by acoustically tagged ...
TL;DR: In this article, the authors investigated the contribution of human activity in most watersheds in the Canadian Shield lakes in central Ontario and found that total phosphorus (TP) levels in these lakes have declined over recent decades despite increases in human activity.
Abstract: Total phosphorus (TP) levels in many Canadian Shield lakes in central Ontario have declined over recent decades, despite increases in human activity in most watersheds. To investigate the contribut...
TL;DR: In this article, it was shown that high biomagnification rates through the support of support vector machines (SVMs) in fish from acidic lakes (pH < 6.0) are typically elevated above those from near-neutral systems.
Abstract: Mercury (Hg) concentrations in fish from acidic lakes (pH < 6.0) are typically elevated above those from near-neutral systems. It is unknown whether high biomagnification rates through the supporti...
TL;DR: The results highlight the trade-off between the pre- sumed physiological benefits of thermal refugia use and a likely increase in harvest and other mortality risks that arise when preferred thermal habitats are severely constricted.
Abstract: We used radiotelemetry to assess thermoregulatory behaviors for 14 populations (n = 3985) of adult summer steelhead (Oncorhynchus mykiss) as they passed through the Columbia River migration corridor. Steelhead use of small cool-water tributaries (''thermal refugia'') rapidly increased when the Columbia River reached a temperature threshold of about 19 8C. When main stem temperatures were warmest (i.e., >21 8C), more than 70% of the tagged fish used refugia sites and these fish had median refugia residence times of 3-4 weeks. Thermoregulatory responses were similar across populations, but there were large among-population differences in the incidence and duration of refugia use likely linked to population-specific migration timing patterns. In survival analyses using 1285 known-origin steelhead, fish that used thermal refugia were significantly less likely to survive to natal basins, were harvested at relatively high rates in refugia tributaries, and had greater unknown mortality in the main stem. These results highlight the trade-off between the pre- sumed physiological benefits of thermal refugia use and a likely increase in harvest and other mortality risks that arise when preferred thermal habitats are severely constricted. Resume´ : La radiotelemetrie nous a servi aevaluer le comportement thermoregulateur de 14 populations (n = 3 985) de truites arc-en-ciel anadromes (Oncorhynchus mykiss) adultes d'etelors de leur passage atravers le corridor de migration du fleuve Columbia. L'utilisation par les truites arc-en-ciel anadromes de petits tributaires d'eau froide (« refuges thermiques ») augmente rapidement quand la temperature du Columbia atteint un seuil d'environ 19 8C. Lorsque les tem- peratures du cours principal sont maximales (c'est-a `-dire >21 8C), plus de 70 % des poissons marques utilisent les sites de refuge et la dureem ediane du sejour de ces poissons dans les refuges est de 3-4 semaines. Les reactions de thermoregula- tion sont les memes dans les diverses populations, mais il y a d'importantes differences entre les populations en ce qui concerne la frequence et la duree de l'utilisation des refuges, vraisemblablement liees aux patrons temporels de migration specifiques a chaque population. Des analyses de survie impliquant 1 285 truites arc-en-ciel anadromes d'origine connue montrent que les poissons qui utilisent les refuges thermiques sont significativement moins susceptibles de survivre jusqu'a ` leur retour a leur bassin versant de naissance, qu'ils sont recoltesades taux relativement eleves dans les tributaires refuges et qu'ils ont une mortalitede cause inconnue plus forte dans le cours principal. Ces resultats mettent en evidence le com- promis entre les benefices physiologiques presumes de l'utilisation des refuges thermiques et une vraisemblable augmenta- tion de la recolte et des autres risques de mortalitequi apparaissent lorsque les habitats thermiques preferes sont grandement reduits.
TL;DR: In this article, the authors monitored 94 mottled sculpins (Cottus bairdii) marked with passive integrated transponder (PIT) tags to examine seasonal movement patterns.
Abstract: We monitored 94 mottled sculpins (Cottus bairdii) marked with passive integrated transponder (PIT) tags to examine seasonal movement patterns. High detection efficiency (mean ± standard error = 0.7...
TL;DR: A survey of 46 thaw ponds in the Canadian arctic and subarctic re-gions showed that these ecosystems have high concentrations of dissolved organic matter (DOM) and nutrients and are relatively productive as discussed by the authors.
Abstract: Arctic warming has recently accelerated, triggering the formation of thaw ponds and the mobilization of a car- bon pool that has accumulated over thousands of years. A survey of 46 thaw ponds in the Canadian arctic and subarctic re- gions showed that these ecosystems have high concentrations of dissolved organic matter (DOM) and nutrients and are relatively productive. This activity was reflected in the optical properties of DOM that indicated a dominance of allochtho- nous sources but a significant contribution of low molecular weight compounds. Several subarctic ponds were stratified in summer, resulting in a hypoxic hypolimnion. Most ponds were supersaturated in CO2 and CH4, with higher gas concentra- tions in bottom waters. However, arctic thaw ponds colonized by benthic microbial mats showed lower CO2 concentra- tions, likely caused by active photosynthesis. CO2 was correlated with both the quantity and the optical properties of DOM, suggesting the significant role of dissolved compounds from melting organic soils and catchment vegetation on the balance between heterotrophy and autotrophy. The large variability observed in limnological properties of this series of ponds precludes generalisations about their role in greenhouse gas production. However, the fact that all thaw ponds were supersaturated in CH4 underscores the importance of estimating their global significance. Resume ´ : Le rechauffement arctique s'est recemment accelere ´, activant la formation des mares de fonte du pergelisol et la mobilisation d'une reserve de carbone accumulee sur plusieurs millenaires. L'etude de 46 mares de fonte en regions arc- tique et subarctique canadiennes montre que ces ecosystemes possedent des concentrations elevees en matiere organique dissoute (MOD) et en nutriments, ainsi qu'une productiviterelativement elevee. Cette activitese reflete dans les proprietes optiques de la MOD qui indiquent une dominance des sources allochtones mais une contribution significative par les com- poses de faibles poids moleculaires. Plusieurs mares subarctiques etaient stratifiees l'ete ´, avec presence d'un hypolimnion hypoxique. La plupart de ces mares etaient supersaturees en CO2 et en CH4, avec des concentrations de gaz superieures au fond. Toutefois, les mares arctiques colonisees par d'epais tapis microbiens montraient de plus faibles concentrations en CO2, probablement causees par l'activitephotosynthetique. Le CO2 etait correleavec la quantiteet les proprietes optiques de la MOD, suggerant le role significatif des composes dissous provenant de la fonte des sols organiques et des plantes du bassin versant sur l'equilibre entre l'heterotrophie et l'autotrophie. La grande variabilitedes conditions limnologiques ob- servees dans cette serie de mares nous garde de faire des generalisations sur leur role dans la production de gaz aeffet de serre. Toutefois, le fait que toutes les mares etaient supersaturees en CH4 souligne le besoin d'estimer leur importance globale.
TL;DR: The importance and availability of information on behavioural toxicity is reviewed and opportunities for its inclusion in ecological risk assessments (ERAs) are identified.
Abstract: Chemical pollutants rarely attain acutely lethal concentrations in nature; thus the majority of their effects are expected to be sublethal. Estimation of the likelihood of effects from exposures to sublethal concentrations of contaminants in effluent plumes downstream of point sources poses a challenge when conducting ecological risk assessments (ERAs). This is an issue for regulatory agencies worldwide. This paper reviews the importance and availability of information on behavioural toxicity and identifies opportunities for its inclusion in ERAs. One of the major advantages of using data on behavioural effects is that they are more sensitive indicators of potential for impacts on survival in the field than are measures of lethality. Indications from available data for fish suggest that behavioural effects of organic contaminants often occur at concentrations 1 to 2 orders of magnitude lower than those found to elicit mortality. As a result, it is believed that the use of data on behavioural toxicity in E...
TL;DR: In this paper, the intrinsic flight responses of fish have been used to direct downstream migrant fish away from deleterious conditions at dams and to avoid potentially threatening situations, allowing pre-emptive avoidance of potentially threatening situation.
Abstract: Fish have evolved intrinsic flight responses, allowing pre-emptive avoidance of potentially threatening situations. To direct downstream migrant fish away from deleterious conditions at dams and ot...
TL;DR: This study examined whether ontogenetic contributions to morphological and ecological differences in fishes are poorly understood and found that the answer is yes.
Abstract: Resource polymorphisms are widely observed in fishes; however, ontogenetic contributions to morphological and ecological differences are poorly understood. This study examined whether ontogenetic c...
TL;DR: A strong func- tional relationship between DO concentration and the growth rate of juvenile fishes in an estuarine nursery is suggested and growth rates of wild-caught fishes appear to be more negatively impacted by diel cycling hy- poxia than would be expected from published laboratory data.
Abstract: The ratio of RNA to DNA (RNA:DNA) in white muscle tissue of juvenile summer flounder (Paralichthys dentatus) and weakfish (Cynoscion regalis) was used as a proxy for recent growth rate in an estuar...
TL;DR: An improved lead-radium dating technique provided independent age estimates from sagittal otoliths, indicating that fish in the oldest age group were at least 93 years old, providing robust support for a centenarian life span.
Abstract: Life-span estimates for orange roughy (Hoplostethus atlanticus) range from ~20 years to well over 100 years. In this study, an improved lead–radium dating technique provided independent age estimat...
TL;DR: There is evidence that hybridization increases the likelihood of reproductive overlap in time and space, promoting extinction by introgression, and that the spread of hybridization is likely to continue if hybrid source populations are not reduced or eliminated.
Abstract: We used radiotelemetry to assess spatial and temporal spawning distributions of native westslope cutthroat trout (Oncorhynchus clarkii lewisi; WCT), introduced rainbow trout (Oncorhynchus mykiss; R...
TL;DR: A coupled biophysical model of the Strait of Georgia (SoG), British Columbia, Canada, has been developed and successfully predicts the timing of the spring phytoplankton bloom as discussed by the authors.
Abstract: A coupled biophysical model of the Strait of Georgia (SoG), British Columbia, Canada, has been developed and successfully predicts the timing of the spring phytoplankton bloom. The physical model i...
TL;DR: The spawning stock of blue whiting (Micromesistius poutassou), an economically important pelagic gadoid in the North Atlantic Ocean, increased threefold after 1995 as mentioned in this paper.
Abstract: The spawning stock of blue whiting (Micromesistius poutassou), an economically important pelagic gadoid in the North Atlantic Ocean, increased threefold after 1995. The reproductive success of the ...
TL;DR: The restoration and rehabilitation of native species in the Laurentian Great Lakes is a priority for fisheries management agencies as mentioned in this paper, and restoration efforts are increasingly incorporating a perspective that is different from ours.
Abstract: Restoration and rehabilitation of native species in the Laurentian Great Lakes is a priority for fisheries management agencies. Restoration efforts are increasingly incorporating a perspective that...
TL;DR: The authors investigated the impact of predation by double-crested cormorants (Phalacrocorax auritus) on spawning adult alewives in south-central Connecticut, USA.
Abstract: The decline of anadromous alewife (Alosa pseudoharengus) threatens an important recreational and commercial fishery. While the cause of this decline is uncertain, predators could be trapping alewives at low abundance by preying on them during spawning migrations. Here we investigate the impact of predation by double-crested cormorants (Phalacrocorax auritus) on spawning adult alewives in south-central Connecticut, USA. We use a bioenergetic model together with estimates of cormorant diets and cormorant and alewife population sizes to estimate the consumption of alewives by cormorants both in Bride Lake, Connecticut, and regionally. We find that cormorants are important predators of spawning adult alewives at Bride Lake but do not have a notable impact on alewife mortality or population size. We also find that cormorants have little effect on alewife populations across south-central Connecticut because few alewives are consumed away from Bride Lake. We conclude that cormorants are important predators for a...
TL;DR: A three-dimensional coupled hydrodynamic–ecological model was used to investigate how lake currents can affect walleye recruitment in western Lake Erie and found low disturbance-based egg mortality and a temporal and spatial match betweenWalleye first feeding first feeding.
Abstract: We used a three-dimensional coupled hydrodynamic–ecological model to investigate how lake currents can affect walleye (Sander vitreus) recruitment in western Lake Erie. Four years were selected bas...