2015

Permanent URI for this collectionhttps://hdl.handle.net/1807/67564

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Flood control structures in tidal creeks associated with reduction in nursery potential for native fishes and creation of hot-spots for invasive species
(Canadian Science Publishing, 2015-12-09) Scott, David Christopher; Arbeider, Michael; Gordon, Jennifer; Moore, Jonathan W.
Habitat connectivity is important for maintaining biodiversity and ecosystem processes, yet globally is highly restricted by anthropogenic actions. Anthropogenic barriers are common in aquatic ecosystems; however, the effects of small-scale barriers such as floodgates have received relatively little study. Here we assess fish communities in ten tributaries over the spring-summer season of the lower Fraser River (British Columbia, Canada), five with floodgates and five reference sites without barriers, located primarily in agricultural land use areas. While the Fraser River supports the largest salmon runs in Canada, the lower Fraser river-floodplain ecosystem has numerous dikes and floodgates to protect valuable agricultural and urban developments. Floodgate presence was associated with reduced dissolved oxygen concentrations, three-fold greater abundance of invasive fish species, and decreased abundances of five native fish species including two salmon species. These findings provide evidence that floodgates decrease suitable habitat for native fishes, and become hotspots for non-native species. Given climate change, sea-level rise, and aging flood protection infrastructure, there is an opportunity to incorporate biodiversity considerations into further development or restoration of this infrastructure.
Identifying blue whiting (Micromesistius poutassou) stock structure in the Northeast Atlantic by otolith shape analysis
(Canadian Science Publishing, 2015-12-09) Mahe, Kélig; Oudard, Clémence; Mille, Tiphaine; Keating, James P; Gonçalves, Patricia; Clausen, Lotte Worsøe; Petursdottir, Gróa; Rasmussen, Helle; Meland, Elna; Mullins, Eugene; Pinnegar, John K; Hoines, Åge; Trenkel, Verena M
Information on stock identification and spatial stock structure provide a basis for understanding fish population dynamics and improving fisheries management. In this study otolith shape analysis was used to study the stock structure of blue whiting (Micromesistius poutassou) in the northeast Atlantic using 1693 samples from mature fish collected between 37°N and 75°N and 20°W and 25°E. The results indicated two stocks located north and south of ICES Divisions VIa and VIb (54°5 to 60°5 N, 4° to 11°W). The central area corresponds to the spawning area west of Scotland. Sampling year effects and misclassification in the linear discriminant analysis suggested exchanges between the northern and southern stocks. The results corroborate previous studies indicating a structuring of the blue whiting stock into two stocks, with some degree of mixing in the central overlap area.
Latent Gaussian models to decide on spatial closures for bycatch management in the Barents Sea shrimp fishery
(Canadian Science Publishing, 2015-12-22) Breivik, Olav Nikolai; Storvik, Geir; Nedreaas, Kjell
In the Barents Sea and adjacent water, fishing grounds are closed for shrimp fishing by the Norwegian Directorate of Fisheries Monitoring and Surveillance Service (MSS) if the expected number of juvenile fish caught are predicted to exceed a certain limit per kilogram shrimp (Pandalus borealis). Today, a simple ratio estimator, which do not fully utilize all data available, is in use. In this research we construct a Bayesian hierarchical spatio-temporal model for improved prediction of the bycatch ratio in the Barents Sea shrimp fishery. More predictable bycatch will be an advantage for the MSS due to more correct decisions and better resource allocation, and for the fishermen due to more predictable fishing grounds. The model assumes that the occurrence of shrimp and juvenile cod can be modeled by linked regression models containing several covariates (including 0-group abundance estimates) and random effects modeled as Gaussian fields. Integrated Nested Laplace Approximations (INLA) is applied for fast calculation. The method is applied to prediction of the bycatch ratio for Atlantic cod (Gadus morhua).
Year class variation drives interactions between warm water predators and yellow perch
(Canadian Science Publishing, 2015-12-31) Fetzer, William W; Farrell, Collin J; Jackson, James R; Rudstam, Lars G
Walleye (Sander vitreus), smallmouth bass (Micropterus dolomieu), and largemouth bass (Micropterus salmoides) are common top predators across many north temperate lakes, but no previous analyses have assessed factors driving their combined impact on mortality of a shared prey, yellow perch (Perca falvescens). We estimated consumption dynamics of walleye, smallmouth bass, and largemouth bass during three years that differed in age-0 yellow perch year-class strength and evaluated the relative contribution of each predator to age-0 yellow perch (Perca flavescens) mortality, in Oneida Lake, New York, USA. Habitat-specific diet composition and population densities were integrated with temperature and growth rates to parameterize a bioenergetics model and estimate annual consumption of major diet items. Walleye were the dominant predator in both offshore and inshore habitats, while smallmouth bass and largemouth bass were also important inshore predators. Consumption of age-0 yellow perch by all three predators was positively correlated to age-0 yellow perch year-class strength, but our ability to account for age-0 yellow perch mortality decreased during years when year-class strength was strong. Within each year, predation by the three species accounted for all observed age-0 yellow perch mortality in late summer and fall, but not in the early summer, suggesting other predators in the lake likely predate on the youngest, most vulnerable yellow perch. These results are important for understanding how diverse predator communities can alter the spatial and temporal availability of prey refuges and influence mortality of a shared prey.
Statistical arrival models to estimate missed passage counts at fish weirs
(Canadian Science Publishing, 2015-12-09) Sethi, Suresh A.; Bradley, Catherine
Missed counts are commonplace when enumerating fish passing a weir. Typically connect-the-dots linear interpolation is used to impute missed passage; however, this method fails to characterize uncertainty about estimates, and cannot be implemented when the tails of a run are missed. Here, we present a statistical approach to imputing missing passage at weirs which addresses these shortcomings, consisting of a parametric run curve model to describe the smoothed arrival dynamics of a fish population and a process variation model to describe the likelihood of observed data. Statistical arrival models are fit in a Bayesian framework and tested with a suite of missing data simulation trials and against a selection of Pacific Salmon (Oncorhynchus spp.) case studies from the Yukon River drainage, Alaska, U.S.A. When compared against linear interpolation, statistical arrival models produced equivalent or better expected accuracy and a narrower range of bias outcomes. Statistical arrival models also successfully imputed missing passage counts for scenarios where the tails of a run were missed.
Energetic costs of activity in wild Lake Trout: a calibration study using acceleration transmitters and positional telemetry
(Canadian Science Publishing, 2015-12-20) Cruz-Font, Liset; Shuter, Brian J.; Blanchfield, Paul J.
Acceleration telemetry transmitters offer the opportunity to estimate the cost of behaviours in free-ranging fish, but a methodology to translate acceleration data into metabolic equivalents is still needed. This study extends previous calibration studies, explores how well tail-beat frequency transmitters fulfill their role, and presents a procedure to convert acceleration data into metabolic cost within a framework consistent with traditional fish bioenergetics models and thus facilitates comparisons of energetic costs between natural fish populations. These objectives were achieved by comparing data from Lake Trout in a laboratory setting with data from three natural populations. In the laboratory, tail-beat frequency, acceleration values, and oxygen consumption increased progressively with swimming speed. In the wild, individual swimming speeds estimated from positional telemetry were consistently underestimated by, but positively related to, transmitter-based acceleration values. The proposed rationale to estimate metabolic rate from acceleration data accounts for variation in fish weight and environmental temperature. We demonstrated how this novel method permits comparison of metabolic costs associated with the levels of activity typical of Lake Trout living in two different lakes.
Causes and consequences of invertebrate drift in running waters: from individuals to populations and trophic fluxes
(Canadian Science Publishing, 2015-12-28) Naman, Sean M; Rosenfeld, Jordan S; Richardson, John S
Invertebrate drift, the downstream transport of aquatic invertebrates, is a fundamental ecological process in streams with important management implications for drift-feeding fishes. Despite longstanding interest, many aspects of drift remain poorly understood mechanistically, thereby limiting broader food web applications (e.g., bioenergetics-based habitat models for fish). Here, we review and synthesize drift-related processes, focusing on their underlying causes, consequences for invertebrate populations and broader trophic dynamics, and recent advances in predictive modelling of drift. Improving predictive models requires further resolving the environmental contexts where drift is driven by hydraulics (passive drift) vs. behaviour (active drift). We posit this can be qualitatively inferred by hydraulic conditions, diurnal periodicity and taxa-specific traits. For invertebrate populations, while the paradox of population persistence in the context of downstream loss has been generally resolved with theory, there are still many unanswered questions surrounding the consequences of drift for population dynamics. In a food web context, there is a need to better understand drift-foraging consumer-resource dynamics and to improve modeling of drift fluxes to more realistically assess habitat capacity for drift-feeding fishes.
Growth rate and abundance of common fishes is negatively related to dissolved organic carbon concentration in lakes
(Canadian Science Publishing, 2015-12-20) Benoît, Pierre-Olivier; Beisner, Beatrix E; Solomon, Chris T.
Dissolved organic carbon (DOC) can limit food web productivity in lakes, potentially imposing resource limitation on fishes. We asked whether the abundance or early growth rate of three fish species was negatively related to DOC in 59 lakes in southern Québec, Canada, where DOC concentrations ranged from 4 to 16 mg L-1 for lakes containing walleye (Sander vitreum) and yellow perch (Perca flavescens) and from 2.6 to 9 mg L-1 for lakes containing lake trout (Salvelinus namaycush). Estimates of abundance and growth rate were more precise for walleye and lake trout than for yellow perch due to differences in sample size. Abundance was negatively related to DOC for walleye, and perhaps also for lake trout and yellow perch. Early growth rate was negatively related to DOC for walleye and lake trout, but not yellow perch. These results support a growing body of literature suggesting that the productivity of fish populations may be negatively related to DOC concentrations in lakes.
Evaluating quantitative fatty acid signature analysis (QFASA) in fish using controlled feeding experiments
(Canadian Science Publishing, 2015-12-20) Happel, Austin; Stratton, Logan; Kolb, Colleen; Hays, Chris; Rinchard, Jacques; Czesny, Sergiusz J.
Accurate diet estimation has long been a challenging issue for researchers investigating predators due to constraints associated with stomach content analyses. Fatty acid signature analysis offers an alternative avenue to study long-term diet trends in consumers. Despite the wealth of experiments involving fatty acids of fish and their diets, few have evaluated quantitative fatty acid signature analysis (QFASA) with fish consumers. To this end we fed juvenile lake trout, round goby, and yellow perch various invertebrate species and back-classified each predator to its respective prey using only fatty acids. Estimates were highly accurate when metabolism of diets was natively accounted for by using fatty acid profiles of predators fed known diets as the “prey library”. While highly accurate results were obtained, accounting for each predator-prey relationship limits the use of QFASA to predators that consume a limited number of species. We call for predator-prey specific knowledge of metabolism before attempting to use fatty acids for quantifying consumer’s diets. Only after adequate incorporation of species metabolism will fatty acids provide an accurate view of individual’s diets when stomach content data are not available or invalid.
Disentangling individual- and population-scale processes within a latitudinal size-gradient in Sockeye Salmon
(Canadian Science Publishing, 2015-11-12) Freshwater, Cameron; Trudel, Marc; Beacham, Terry D.; Godbout, Lyse; Neville, Chrys-Ellen M.; Tucker, Strahan; Juanes, Francis
We examined how individual processes contribute to a latitudinal gradient in body size within populations of migrating juvenile Sockeye Salmon (Oncorhynchus nerka) while simultaneously testing for size-selective mortality, a potentially confounding population scale process. Using otolith microstructure techniques and structural equation modeling, we determined that ocean entry size and phenology had strong, direct effects on size at capture. Population identity and freshwater age also had strong indirect effects, moderated by size at entry. Conversely, marine growth rates immediately after entry or before capture were relatively weak predictors of size during migration. We next tested for shifts in size distribution indicative of selective mortality, but detected no evidence of smaller individuals experiencing lower survival during early marine migrations. These results indicate that the migratory distributions of juvenile Sockeye Salmon are influenced by body size and that this variation is predominantly driven by traits present prior to freshwater outmigration, rather than marine growth or differential survival. We suggest integrating individual variation in migratory characteristics with the effects of environmental conditions experienced en route to provide an improved understanding of migratory species.
Can recovery from disturbance explain observed declines in total phosphorus in Precambrian Shield catchments?
(Canadian Science Publishing, 2015-12-20) Crossman, Jill H.; Eimers, M. Catherine; Watmough, Shaun A.; Futter, Martyn N; Kerr, Jason; Baker, Scott R; Dillon, Peter J
The plausibility of land disturbance as a cause of declining P concentrations in oligotrophic lakes within south-central Ontario, Canada is evaluated using the process-based model INCA-P. The model was calibrated upon three catchments in the Muskoka-Haliburton region (MHR): Harp (HP), Dickie (DE) and Plastic (PC), which have varying degrees of declining P export, and different forms of historic disturbances (timber harvesting, tree-death, and soil acidification respectively). Hind-casts (1978-2007) were run with and without simulated disturbances. Model performance of both DE and HP was greatly improved when effects of wetland tree deaths (DE) and harvesting (HP) were included. In PC, with no record of timber harvesting and relatively minor declines in P, initial hind-casts successfully accounted for the majority of inter-annual P-fluxes; and performance was only marginally improved through the simulation of soil acidification. Vegetation decay, harvesting and catchment acidification accounted for 63%, 24% and 0.6% of P export over the past 30 years respectively. Of all disturbances, wetland vegetation death had the highest impact on areal P exports, indicating that riparian stability is particularly important.
Evolutionary impact assessment of the North Sea plaice fishery
(Canadian Science Publishing, 2015-11-01) Mollet, Fabian M.; Poos, Jan Jaap; Dieckmann, Ulf; Rijnsdorp, Adriaan D.
There is growing evidence that fishing causes evolution in life-history traits that affect the productivity of fish stocks. Here we explore the impact of fisheries-induced evolu-tion (FIE) on the productivity of North Sea plaice using an eco-genetic individual-based model by comparing management scenarios with and without an evolutionary re-sponse. Under status-quo management, plaice evolve towards smaller size at age, ear-lier maturation, and higher reproductive investment. Current reference points of maximum sustainable yield (MSY) and corresponding fishing-mortality rate ( ) that ignore FIE will decrease and cannot be considered sustainable. The nature and extent of the change through FIE depend on fishing effort and selectivity. The adverse evolutionary effects can be reduced – and even reversed – by implementing a dome-shaped exploitation pattern protecting the large fish. The evolutionarily sustainable maximum yield can be obtained by combining such a dome-shaped exploitation pattern with a reduction in fishing mortality and an increase in mesh size; it is similar to the maximum sustainable yield that would apply if life-history traits were static. Fisheries managers will need to trade off the short-term loss in yield associated with evolutionarily informed management with the long-term loss in yield FIE causes under evolutionarily uninformed management.
Size-related habitat use in juvenile Atlantic salmon: the importance of inter-cohort competition
(Canadian Science Publishing, 2015-11-26) Höjesjö, Johan; Kaspersson, Rasmus; Armstrong, John D.
In stream-living salmonids, an underlying mechanism for the critical period after emergence has generally been assumed to be size-dependent swimming capacity constraining fry (age-0) to low-velocity habitats with reduced food availability and intense competition. A further plausible mechanism is that inter-cohort habitat exclusion confines fry to marginal habitats. This possibility was tested using a semi-natural stream with 16 test arenas each comprising one high-velocity, deep, habitat and one low-velocity, shallow, habitat. We observed groups of newly emerged Atlantic salmon Salmo salar fry, either alone or in sympatry with one or two age-1 salmon. Salmon fry used high-velocity areas (42.2 ± 0.4 cm s-1) most extensively in the absence of inter-cohort competition, where they obtained more food than in low-velocity areas (3.3 ± 0.3 cm s-1), even though foraging efficiency was lower (though not significantly so). In sympatry with older cohorts, fry increased their use of the low-velocity habitat, with a reduced foraging activity, suggesting that strong older cohorts in natural populations may have the potential to influence the strength of the recruiting cohort by negative density-dependence due to interference competition for habitat.
Absence of noticeable mercury effects on fish populations in boreal reservoirs despite threefold to sevenfold increases in mercury concentrations
(Canadian Science Publishing, 2015-12-02) Bilodeau, François; Schetagne, Roger; Therrien, Jean; Verdon, Richard
At the La Grande hydroelectric complex (Québec, Canada), total mercury concentrations were measured in more than 25,000 fish over a 20-year period. Fish population characteristics, such as fishing yield, growth rate, condition factor and recruitment, were also monitored. In reservoirs, total mercury concentrations in all species increased rapidly after impoundment, peaking after 4 to 9 years in non-piscivorous fish, and after 9 to 11 years in piscivorous species, at levels 3 to 7 times those measured in surrounding natural lakes, then declined gradually and significantly. Despite this increase, most species showed increases in fishing yields (by factors ranging from 2 to 8), growth rates and condition factors (for more than a decade). The percentage of small specimens of the main species was generally maintained or increased in the first years after flooding, indicating good recruitment.
Using time-varying asymptotic length and body condition of top piscivores to indicate ecosystem regime shift in the main basin of Lake Huron: a Bayesian hierarchical modeling approach
(Canadian Science Publishing, 2015-12-09) He, Ji X.; Bence, James R; Roseman, Edward F; Fielder, David G.; Ebener, Mark P
We evaluated the ecosystem regime shift in the main basin of Lake Huron that was indicated by the 2003 collapse of alewives, and dramatic declines in Chinook salmon abundance thereafter. We found that the period of 1995-2002 should be considered as the early phase of the final regime shift. We developed two Bayesian hierarchical models to describe time-varying growth based on the von Bertalanffy growth function and the length-mass relationship. We used asymptotic length as an index of growth potential, and predicted body mass at a given length as an index of body condition. Modeling fits to length and body mass at age of lake trout, Chinook salmon, and walleye were excellent. Based on posterior distributions, we evaluated the shifts in among-year geometric means of the growth potential and body condition. For a given top piscivore, one of the two indices responded to the regime shift much earlier than the 2003 collapse of alewives, the other corresponded to the 2003 changes, and which index provided the early signal differed among the three top piscivores.
Net rate of energy intake predicts reach-level steelhead (Oncorhynchus mykiss) densities in diverse basins from a large monitoring program
(Canadian Science Publishing, 2015-11-12) Wall, C. Eric; Bouwes, Nicolaas; Wheaton, Joseph M.; Saunders, W. Carl; Bennett, Stephen N.
Significant research effort has been devoted to understanding stream-dwelling salmonids’ use of summer rearing and growth habitat, with a subset of studies focusing on foraging position selection and the energetic tradeoffs of differential habitat use. To date, however, cost-benefit analyses for most foraging model studies have focused on small sampling areas such as individual habitat units. To address this knowledge gap, we applied a mechanistic foraging model to 22, 100 – 400 m stream reaches from two watersheds within the Columbia River Basin. We found a strong, positive correlation (R2 = 0.61, p
Consistent differential resource use by sympatric Lake (Coregonus clupeaformis) and Round Whitefish (Prosopium cylindraceum) in Lake Huron: a multi-time scale isotopic niche analysis.
(Canadian Science Publishing, 2015-12-01) Eberts, Rebecca L; Wissel, Björn; Manzon, Richard G; Wilson, Joanna Y; Boreham, Douglas R; Somers, Christopher M
Lake and Round Whitefish are sympatric benthivores in Lake Huron that are thought to coexist via niche partitioning. However, little is known about long-term resource use and niche overlap across different temporal scales. We used a multi-year (2010-2012) and multi-tissue (liver, muscle, and bone layers) isotopic niche analysis to characterize and compare resource use by Lake and Round Whitefish across several time scales. Lake Whitefish consistently used more diverse, 13C-depleted (mean δ 13C = –21.9‰) and 15N-enriched (mean δ 15N = +9.3‰) resources than Round Whitefish (mean: δ 13C = –18.2‰; δ 15N = +8.3‰). Niche overlap occurred only in liver, representing the spawning period, while niche segregation was highest in juvenile life stages. Individuals of both species made variable resource-shifts among time periods, suggesting that spawning aggregations are comprised of individuals representing a variety of feeding strategies and locations. Our study confirms that differential resource use is an important strategy for these fish as adults, and demonstrates life-long niche partitioning beginning before age 2.
The paradox of ‘premature migration’ by adult anadromous salmonid fishes: Patterns and hypotheses
(Canadian Science Publishing, 2015-11-12) Quinn, Thomas P.; McGinnity, Philip; Reed, Thomas E.
In several groups of anadromous fishes but especially the salmonids, some populations migrate from the ocean to fresh water many months prior to spawning. This ‘premature migration’ reduces growth opportunities at sea, compels them to occupy much less productive freshwater habitats, and exposes them to extremes of flow and temperature, disease, and predation. We first review migration in salmonids, and find great variation in timing patterns among and within species, relative to the timing of reproduction. Premature migration is widely distributed among species but not in all populations, and we propose two hypotheses to explain it. First, the fish may be making ‘the best of a bad situation’ by entering early because access to suitable breeding sites is constrained seasonally by flow or temperature regimes, so they sacrifice growing opportunities at sea. Alternatively or additionally, some populations may be ‘balancing risks and benefits’ as they trade off the benefits of growth at sea against the risk of mortality there. In this model, the reduced risk of mortality at sea must be balanced against the risk of mortality in freshwater habitats from thermal stress, disease, and predators. Premature migration may be favored where temperatures and flows are moderate, or where lakes provide safety from predators and reduce energetic expenditure. Consistent with this hypothesis, early return is characteristic of larger, older salmonids (that would benefit less from additional time at sea to grow than would smaller fish). Finally, we consider the vulnerability of premature migrants to climate change and selective fisheries. Migration timing is an important part of the portfolio of phenotypic diversity that conveys resilience to species, population complexes, and the fisheries that depend on them. The premature migrants are often especially valued in fisheries and also often of particular conservation concern, and the phenomenon merits further research.
Modeling and mapping fish abundance across wadeable streams of Illinois, USA based on landscape-level environmental variables
(Canadian Science Publishing, 2015-11-22) Cao, Yong; Hinz, Leon; Metzke, Brian; Stein, Jeffrey A; Holtrop, Ann M
To effectively conserve and restore stream ecosystems, we need to better understand the distribution and abundance of individual fish species in relation to natural environments and anthropological stressors. In this study, we modeled the abundance of 97 fish species in small wadeable streams of Illinois, USA, based on random-forests regression and landscape-level environmental variables. Model R2-values for intermediately-common species were higher than for common species, but highly variable among rare ones. Models for 50 species reached R2 of 0.2 – 0.70 and were tested with a separate set of samples and applied to unsampled wadeable reaches to show the population hotspots of each species across the state. Furthermore, we evaluated the importance of individual environmental variables to a given fish species as well as the directional responses of each species to top 10 key predictors. Climate and land-use were the best predictors for most species, followed by topography, geology, and soil permeability. Spatial connection of a stream also was associated with a large number of species. These findings improved our understanding of the relationships between fish species and landscape environments. The distribution maps could guide resource management, restoration, and monitoring of stream fish assemblages.
Fish distribution, abundance, and behavioral interactions within a large electric dispersal barrier designed to prevent Asian carp movement
(Canadian Science Publishing, 2015-12-02) Parker, Aaron D; Glover, David C.; Finney, Samuel T.; Rogers, P. Bradley; Stewart, Jeffrey G.; Simmonds Jr., Robert L.
We evaluated the abundance and behavior of wild fish within the electric barrier system in the Chicago Sanitary and Ship Canal. This electric barrier system serves to prevent the upstream migration of bighead carp (Hypophthalmichthys nobilis) and silver carp (H. molitrix) to Lake Michigan from the Illinois River. We found that fish were most abundant below the electric barrier during the summer and fall, were observed near areas of peak voltage, and sometimes persistently challenged the barrier. Fish were relatively scarce within the barrier system during the winter and spring. Fish that were able to penetrate the farthest into the barrier system were smaller and tended to aggregate at the water surface, near the canal walls. The accumulation of fish that we observed below the barrier, and the persistent challenging behavior, raises concerns about breaches any time the barrier is de-energized for maintenance or during intermittent power outages. Entrainment and breach caused by barges traversing the barrier are concerns as well because of the water movements they create and how they alter the electrical field.

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