Showing papers in "Canadian Journal of Fisheries and Aquatic Sciences in 2010"
TL;DR: It is found that liver and blood are more useful than muscle as shorter-term dietary indicators for summer flounder and other migratory fishes.
Abstract: Migratory and mobile fishes such as summer flounder (Paralichthys dentatus) often utilize dietary resources with stable isotope signatures that vary over time and space, potentially confounding die...
261 citations
TL;DR: In many areas of the world, recreational fisheries are not managed sustainably as mentioned in this paper, which might be related to the omission or oversimplification of angler behaviour and angler heterogeneity in fisheries.
Abstract: In many areas of the world, recreational fisheries are not managed sustainably. This might be related to the omission or oversimplification of angler behaviour and angler heterogeneity in fisheries...
191 citations
TL;DR: Compilation of data from 211 stream restoration projects showed a significant increase in pool area, average depth, large woody debris, and percent cover, as well as a decrease in riffle area, following the installation of in-stream structures.
Abstract: Despite the widespread use of stream restoration structures to improve fish habitat, few quantitative studies have evaluated their effectiveness. This study uses a meta-analysis approach to test th...
162 citations
TL;DR: Movements of Atlantic bluefin tuna (Thunnus thynnus, ABFT) from specific western Atlantic forage grounds are not well described, and the extent of their spawning areas is mainly surmised as discussed by the authors.
Abstract: Movements of Atlantic bluefin tuna (Thunnus thynnus, ABFT) from specific western Atlantic forage grounds are not well described, and the extent of their spawning areas is mainly surmised. In 2005 a...
150 citations
TL;DR: In this paper, the feasibility of identifying major acoustic scatters in North Pacific ecosystems based on empirical measurements of relative frequency response was evaluated, and the authors concluded that the acoustic measurements in areas where...
Abstract: We evaluated the feasibility of identifying major acoustic scatters in North Pacific ecosystems based on empirical measurements of relative frequency response. Acoustic measurements in areas where ...
135 citations
TL;DR: By using lakes as thermal refugia, early-timed fish likely reduce rates of disease development and may better recover from physiological stress associated with high encountered tempera- tures.
Abstract: We coupled physiological biopsy and positional telemetry to examine survival to reach spawning grounds in re- lation to water temperature, timing, physiological condition, and holding location (river or lake) in adult migrating sockeye salmon (Oncorhynchus nerka). We tracked 83 fish across a large temperature range (13.5-21.5 8C), which included record highs. Only early-timed migrants that held in Harrison Lake survived to reach spawning grounds (16%, or n = 4). Normal- timed fish, those that migrated at historically observed times, survived at higher levels if they held in Harrison River (72%, or n = 18). Mortalities were identified on the bottoms of both the lake and river. Hypothetical degree-day (DD) ac- cumulation revealed that early-timed river fish would have greatly surpassed (~800 8C DD) a critical disease threshold value (~500 8C DD). There was no difference in hypothetical DD accumulation between normal-timed river fish and early- timed lake fish. Early-timed sockeye had elevated physiological stress (e.g., plasma lactate, glucose, and hematocrit), which may have contributed to high levels of mortality. By using lakes as thermal refugia, early-timed fish likely reduce rates of disease development and may better recover from physiological stress associated with high encountered tempera- tures.
128 citations
TL;DR: In this paper, the influence that a lake might have on a stream is dependent on its position within the stream, stream type and size, lake size and shape, and the inlet and outlet positions.
Abstract: Lakes and rivers are intimately connected in an alternating series of lentic and lotic reaches in many regions. The study of lakes and their outlets in hierarchical and branching river networks has not gained the attention of stream ecologists, and little effort has been focused on synthesizing the ecology of lake–stream interactions within a drainage network. Rapid and predictable changes in the ecological characteristics of streams occur at the interface with lakes. The influence that a lake might have on a stream is dependent on its position within the stream, stream type and size, lake size and shape, and the inlet and outlet positions. Little is known about the influences of multiple lakes within stream–lake networks and how these influences are determined by network shape and pattern. Fruitful collaborations and novel insights will come from the combined efforts of limnologists, stream ecologists, and landscape ecologists. Geographic information systems and network analyses will play an important ro...
128 citations
TL;DR: It is concluded that the 2010 CBD target represents a weak standard for recovering marine fish biodiversity and that meaningful progress will require population-specific recovery targets and associated time lines for achieving those targets.
Abstract: The Convention on Biological Diversity (CBD) established a target in 2002 to reduce the rate of biodiversity loss by 2010. Using a newly constructed global database for 207 populations (108 species), we examine whether the 2010 target has been met for marine fishes, while accounting for population biomass relative to maximum sustainable yield, BMSY. Although rate of decline has eased for 59% of populations declining before 1992 (a pattern consistent with a literal interpretation of the target), the percentage of populations below BMSY has remained unchanged and the rate of decline has increased among several top predators, many of which are below 0.5BMSY. Combining population trends, a global multi- species index indicates that marine fishes declined 38% between 1970 and 2007. The index has been below BMSY since the mid-1980s and stable since the early 1990s. With the exception of High Seas pelagic fishes and demersal species in the Northeast Pacific and Australia - New Zealand, the multispecies indices are currently below BMSY in many regions. We conclude that the 2010 CBD target represents a weak standard for recovering marine fish biodiversity and that meaningful progress will require population-specific recovery targets and associated time lines for achieving those targets. Resume´ : La Convention sur la diversitebiologique (« CBD ») s'est donnee en 2002 comme objectif de reduire le taux de perte de la biodiversiteavant 2010. Utilisant une nouvelle base de donnees globale de 207 populations (108 especes), nous examinons si l'objectif 2010 de la CBD a eteatteint pour les poissons marins, tout en tenant compte de la biomasse des populations relative au rendement maximal durable, BMSY. Malgreune diminution du taux de declin chez 59 % des po- pulations en chute avant 1992 (une tendance qui correspond aune interpretation litterale de l'objectif 2010 de la CBD), le pourcentage des populations sous BMSY s'est maintenu constant et le taux de declin s'est accelerechez plusieurs des preda- teurs sommitaux, une majoritedesquels sont a un niveau inferieur a 0,5BMSY. Combinant les tendances des populations, un indice global multi-especes montre que les poissons marins ont diminuede 38 % entre 1970 et 2007. L'indice est inferieur aBMSY depuis le milieu des annees 1980 et stable depuis le debut des annees 1990. Avec l'exception des populations pela- giques de haute mer et des populations demersales du nord-est du Pacifique et de Nouvelle-Zelande - Australie, les indices multi-especes sont presentement sous BMSY dans plusieurs regions. Nous concluons que l'objectif CBD 2010 represente un faible standard pour recuperer la biodiversitedes poissons marins et qu'un progresr eel requerra des cibles claires de recu- peration specifiques achacune des populations et soumises ades echeanciers stricts pour atteindre les objectifs vises.
108 citations
TL;DR: It is documented that vitellogenesis generally starts at autumnal equinox and that oocytes growth and investment are greater in cod held at warmer temperatures, and that spawning occurred earlier when oocyte growth was more rapid.
Abstract: The timing and success of spawning in marine fish are of fundamental importance to population persistence and distribution and, for commercial species, sustainability. Their physiological processes...
104 citations
TL;DR: These models overcome many of the shortcomings of the fixed-effects approach and provide a connection with the more usual modeling of size-attained data through the use of growth functions such as the von Bertalanffy.
Abstract: Fish growth in a particular year has both intrinsic and environmental components. Intrinsic growth can depend on both the age and size of the fish and on particular characteristics of the individua...
103 citations
TL;DR: In this paper, environmental factors such as the Leeuwin Current (influenced by the El Nino and Southern Oscillation cycle) and westerly winds in late winter and early spring significantly affect puerulus settlement of the...
Abstract: Environmental factors such as the Leeuwin Current (influenced by the El Nino – Southern Oscillation cycle) and westerly winds in late winter – spring significantly affect puerulus settlement of the...
TL;DR: In this paper, a fishery management scheme, such as individual fishing quotas (IFQs) or marine protected areas, should be designed to be robust to potential shifts in the biophysical system.
Abstract: Any fishery management scheme, such as individual fishing quotas (IFQs) or marine protected areas, should be designed to be robust to potential shifts in the biophysical system. Here we couple poss...
TL;DR: The results both demonstrate the explanatory power of GDD with respect to fish growth and maturity and inform the development of regional management strategies for walleye.
Abstract: Growing degree-days (GDD, °C·days) are an index of ambient thermal energy that relates directly to an ectotherm’s cumulative metabolism but is rarely used to describe growth and development in fish...
TL;DR: In this paper, the present-day biogeography of native and non-native species is studied and an understanding of how natural and anthropogenic factors shape the present day biogeographies of these species is provided.
Abstract: Freshwater conservation efforts require an understanding of how natural and anthropogenic factors shape the present-day biogeography of native and non-native species. This knowledge need is especia...
TL;DR: A DNA-based parentage analysis was used to measure the relative reproductive success of hatchery- and natural-origin spring Chinook salmon (Oncorhynchus tshawytscha) in the natural environment and found Spawning location within the river had a significant effect on fitness for both sexes.
Abstract: Understanding the relative fitness of naturally spawning hatchery fish compared with wild fish has become an important issue in the management and conservation of salmonids. We used a DNA-based par...
TL;DR: This article investigated the midterm effects of wildfire (in this case, five years after the fire) of varying severity on periphyton, benthic invertebrates, emerging adult aquatic insects, spiders, and bats by comparing unburned sites with those exposed to low severity (riparian vegetation burned but canopy intact) and high severity (canopy completely removed) wildfire.
Abstract: We investigated the midterm effects of wildfire (in this case, five years after the fire) of varying severity on periphyton, benthic invertebrates, emerging adult aquatic insects, spiders, and bats by comparing unburned sites with those exposed to low severity (riparian vegetation burned but canopy intact) and high severity (canopy completely removed) wildfire. We observed no difference in periphyton chlorophyll a or ash-free dry mass among different burn categories but did observe significantly greater biomass of benthic invertebrates in both high severity burned and unburned reaches versus low severity burned reaches. Moreover, a significantly greater flux of adult aquatic insect emergence occurred at sites that experienced high severity fire versus low severity burned and unburned sites. The greatest number of spiders and bat echolocation calls were also observed at sites of high severity fire. Our results suggest that fires of different severity may have very different affects on stream-riparian food ...
TL;DR: A cross-ecosystem comparison of data obtained from 20 French Mediterranean lagoons with contrasting eutrophication status provided the basis for investigating the variables that best predict chlorophyll a (Chl a) concentrations and nutrient limitation of phytoplankton biomass along a strong nutrient enrichment gradient.
Abstract: A cross-ecosystem comparison of data obtained from 20 French Mediterranean lagoons with contrasting eutrophication status provided the basis for investigating the variables that best predict chlorophyll a (Chl a) concentrations and nutrient limitation of phytoplankton biomass along a strong nutrient enrichment gradient. Summer concentrations of dissolved inorganic nitrogen (DIN) and phosphorus (DIP) comprised only a small fraction of total nitrogen (TN) and total phosphorus (TP). On the basis of inorganic nutrient concentrations, the most oligotrophic lagoons appeared to be phosphorus-limited, with a tendency towards the development of nitrogen limitation as eutrophication increased, as evidenced by decreasing DIN:DIP ratios. A weak but significantly positive relationship was found between dissolved silicate (DSi) and Chl a, reflecting DSi accumulation in the water column along the trophic state gradient and implying a progressive shift away from potential Si limitation of phytoplankton growth. Observed concentrations of Chl a were far better explained by TN and TP than by DIN and DIP concentrations, suggesting that a total nutrient based approach is likely to be the most appropriate for managing eutrophication in Mediterranean lagoons and other coastal waters. These results give credence to the idea that marine and freshwater environments respond in a similar fashion to nutrient enrichment.
TL;DR: Otolith microchemical analyses demonstrated that disproportionately more juvenile recruits emanated from the MRP than from non-MRP waters during both years, and warmer temperatures and higher zooplankton production in the MRp would underlie this expected recruitment difference through “bottom-up” effects on larval growth.
Abstract: Similar to coastal marine systems, Lake Erie exhibits open-water river plumes that differ physicochemically and biologically from surrounding waters. To explore their importance to yellow perch (Pe...
TL;DR: Investigation of diet and resource use among Greenland sharks and 14 teleosts inhabiting Icelandic waters revealed that log[Hg] was better described by both δ15N and δ13C-assigned resource use than by δ 15N alone, and Hg was useful for supporting the TPs suggested by ε15N.
Abstract: Stable carbon (δ13C) and nitrogen (δ15N) isotopes and total mercury (Hg) were used to investigate diet and resource use among Greenland sharks (Somniosus microcephalus) and 14 teleosts inhabiting I...
TL;DR: In this paper, the authors evaluated otolith chemistry as a tool for identifying natal origins of potamodromous fishes using historical Lake Erie water chemistry (1983-2001) and yellow perch (Perca flavescens) otolith.
Abstract: We evaluated otolith chemistry as a tool for identifying natal origins of potamodromous fishes using historical Lake Erie water chemistry (1983–2001) and yellow perch (Perca flavescens) otolith ele...
TL;DR: Latitudinal variability in length and age at maturity and annual growth rate for the American eel along the Atlantic coast of North America was examined with respect to life history strategies and theory.
Abstract: Latitudinal variability in length and age at maturity and annual growth rate for the American eel (Anguilla rostrata) along the Atlantic coast of North America was examined with respect to life history strategies and theory. Maturing (silver phase) female lengths and ages increased with increasing latitude (and distance) from the Sargasso Sea spawning site, as did male ages but not lengths. Growth rates for females (and males) declined with increasing latitude south of 44°N latitude, approximately the entrance to the Cabot Strait, but were constant or increased within the Gulf of St. Lawrence and St. Lawrence River, depending on the analysis method. The growing season and the number of degree-days ≥ 10 °C declined with increasing latitude. Female growth rates adjusted for the number of degree-days were approximately constant south of 44°N but increased further north, suggesting countergradient variation in growth. The temperature–size rule (increase in body size at lower temperatures) evidently applies to...
TL;DR: This work provides the first experimental evidence of frequency-dependent selection during mating in the family Salmoni- dae and finds that adult male access to females, participation in spawning events, and adult-to-fry reproductive success in- creased with their decreasing frequency in a breeding group.
Abstract: As with other species, frequency-dependent selection during reproduction has long been proposed as an impor- tant mechanism in maintaining alternative male reproductive phenotypes in Pacific salmon (Oncorhynchus spp.). Jack sal- mon mature one year earlier than the youngest females in a population and are much smaller than older ''adult'' males. We tested the hypothesis that mating success of both phenotypes is consistent with the frequency-dependent selection model. By holding male density constant and varying the frequency of adults and jacks in eight separate breeding groups, we found that adult male access to females, participation in spawning events, and adult-to-fry reproductive success in- creased with their decreasing frequency in a breeding group. Jacks exhibited the same pattern (increasing success with de- creasing frequency), although the relationships were not as strong as for adults. Overall, jack and adult males mated with a similar number of females, but jacks sired only 20% of all offspring. Observational data suggested that adult males bene- fited from sperm precedence associated with their ability to court females and enter the nest first at the time of spawning. Our work provides the first experimental evidence of frequency-dependent selection during mating in the family Salmoni- dae.
TL;DR: In modern fishery stock assessments, the productivity of exploited stocks is frequently summarized by a scale-invariant "steepness" parameter, which describes the slope of the spawn slope.
Abstract: In modern fishery stock assessments, the productivity of exploited stocks is frequently summarized by a scale-invariant “steepness” parameter. This parameter, which describes the slope of the spawn...
TL;DR: It is found that arithmetic lipid correction models perform well with zooplankton samples, but taxonomic differences need to be considered, and separate mass balance-based lipid correction model for cladocerans and also cyclopoid and calanoid copepods are produced.
Abstract: We found considerable seasonal, latitudinal, and taxonomic differences in zooplankton lipid content and concur- rent d 13 C values of zooplankton. We collected cladoceran as well as cyclopoid and calanoid copepod zooplankton from boreal and subarctic lakes throughout a year, allowing us to study zooplankton likely subjected to different isotopic fractionation processes and with highly variable lipid contents. Considerable seasonal variation was observed in the differ- ence between bulk and lipid-extracted zooplankton d 13 C values, indicating that seasonally changing lipid content intro- duced notable variation in zooplankton d 13 C values. The difference between bulk and lipid-extracted material was most amplified in lipid-rich subarctic zooplankton in winter, d 13 C difference being >5 units. Significant differences were also observed among zooplankton taxa, with copepods showing a greater lipid impact on d 13 C than cladocerans. Published lipid correction models failed to produce satisfying fits to our data, and considerable variation was left even after recalibrating the model parameters. This was likely due to taxonomic differences in lipid effects on d 13 C values. We therefore produced separate mass balance-based lipid correction models for cladocerans and also cyclopoid and calanoid copepods. We con- clude that arithmetic lipid correction models perform well with zooplankton samples, but taxonomic differences need to be considered. Resume´ : Nous avons observedes differences saisonnieres, latitudinales et taxonomiques considerables dans le contenu li- pidique et les valeurs associees de d 13 C chez divers taxons zooplanctoniques. Nous avons recoltedes cladoceres et des co- pepodes cyclopoo¨des et calanoo¨des dans des lacs boreaux et subarctiques au cours d'une annee complete de facon aetudier le zooplancton sous divers processus de fractionnement isotopique et une forte variation de contenus lipidiques individuels. Des variations saisonnieres considerables ont etenotees dans les valeurs de d 13 C entre des extraits d'organismes entiers et leurs lipides seuls. Ceci montre que les variations saisonnieres du contenu lipidique du zooplancton peuvent influencer les valeurs de d 13 C du zooplancton. D'ailleurs, cette difference de d 13 C entre les organismes entiers et les lipides extraits pou- vait atteindre plus de 5 unites pour le zooplancton riche en lipides des milieux subarctiques en hiver. Des differences signi- ficatives ont aussi eteobservees entre taxons zooplanctonique, les lipides des copepodes affectant davantage les valeurs de d 13 C que ceux des cladoceres. Les modeles de correction pour les lipides provenant de la litterature ne montrent pas un ajustement satisfaisant avec nos donnees, meme avec une re-calibration de leurs parametres, ceci etant probablement du ˆ aux differences d'impact des valeurs lipidiques sur le d 13 C entre les groupes taxonomiques. C'est pourquoi, nous avons mis au point des modeles correctifs pour les lipides bases sur le bilan massique separement pour les cladoceres et les copepodes cyclopoo¨des et calanoo¨des. Nous concluons que les modeles correctifs arithmetiques du contenu en lipides produisent de bons resultats avec des echantillons zooplanctoniques, mais les differences entre les taxons doivent toutefois etre considerees.
TL;DR: Angling-induced selection might alter the physiological characteristics of wild large- mouth bass populations, with unknown outcomes for long-term population viability.
Abstract: Although the selective pressures of commercial fishing are well known, few studies have examined this phenomenon in recreational fisheries. This study used a unique population of largemouth bass (M...
TL;DR: The Laurentian Great Lakes host more than 180 non-native species, including several that have resulted in major economic and ecological effects as discussed by the authors, including the round goby (Neogobius melanos).
Abstract: The Laurentian Great Lakes host more than 180 non-native species, including several that have resulted in major economic and ecological effects. This list includes the round goby (Neogobius melanos...
TL;DR: In this paper, the authors revisited the stock-recruit and temperaturerecruit relationships underpinning the currently used environmental parameter for sardine assessment and found that the relationship no longer holds for the SIO pier when time series are updated with data from more recent years.
Abstract: The harvest guideline for Pacific sardine (Sardinops sagax) incorporates an environmental parameter based on averaged surface temperatures at the Scripps Institution of Oceanography pier (SIO pier) in La Jolla, California, USA, which would be invoked after a series of cool years to reduce commercial catches using a precautionary decision rule. We revisit the stock-recruit and temperature-recruit relationships underpinning the currently used environmental parameter for sardine assessment and found that the temperature-recruit relationship no longer holds for the SIO pier when time series are updated with data from more recent years. The significance of the correlation between temperature and recruitment was also artificially increased by autocorrelation in the time series. In contrast, the stock-recruit relationship was still valid when recent data were added. SIO pier surface temperatures are warmer than 10 m-depth Southern California Bight (SCB) temperatures where the sardine spawn, and the difference has increased since the late 1970s. Sardine recruitment was also not related to offshore temperatures in the SCB. We demonstrate that the environmental proxy derived from SIO pier tem- perature, which has never affected the harvest guideline since its implementation, no longer predicts recruitment of Pacific sardine, and should be removed from sardine management.
TL;DR: Paired differences between isotopic values of tissues were relatively small but varied significantly with shark total length, suggesting that shark size can be an important factor influencing the magnitude of differences in isotope values of different tissues.
Abstract: Stable isotopes are important tools for understanding the trophic roles of elasmobranchs. However, whether different tissues provide consistent stable isotope values within an individual are largel...
TL;DR: In this paper, an empirical model was developed that describes the influence of lake productivity, climate, and morphometry on coldwater fish oxythermal habitat, and the model was applied to coldwater fishes.
Abstract: An empirical model was developed that describes the influence of lake productivity, climate, and morphometry on coldwater fish oxythermal habitat. An oxythermal habitat variable called temperature ...
TL;DR: A general life history model for fish is presented in which three common relationships link natural mortality to life history traits and behaviour, and fish that invest heavily in reproduction suffer from decreased survival due to costly reproductive behaviour or mor- phology that makes escapes from predators less successful.
Abstract: When trade-offs involving predation and mortality are perturbed by human activities, behaviour and life histories are expected to change, with consequences for natural mortality rates. We present a...