2018
Permanent URI for this collectionhttps://hdl.handle.net/1807/81044
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Item Coupling acoustic tracking with conventional tag returns to estimate mortality for a coastal flatfish with high rates of emigration(Canadian Science Publishing, 2018-12-28) Scheffel, Trevor K.; Hightower, Joseph E.; Buckel, Jeffrey A.; Krause, Jacob R.; Scharf, Frederick S.The addition of acoustic telemetry to conventional tagging studies can generate direct estimates of mortality and movement rates to inform fisheries management. We applied a combined telemetry and tag-return design to southern flounder (Paralichthys lethostigma), a coastal flatfish that demonstrates limited movements within estuarine habitats coupled with extensive ontogenetic migrations that present unique challenges for estimating mortality rates. The fates of acoustically and conventionally tagged fish were followed during 2014–2016 to estimate annual rates of fishing mortality (F), natural mortality (M), and estuarine emigration (E). Multistate models estimated southern flounder annual F for each of the 3 years at two spatial scales (New River estuary F = 0.49–1.61; North Carolina coast F = 0.36–0.72). Annual rates of emigration were high (E = 1.06–1.67), and direct estimation of this source of loss considerably improved mortality estimates. The model estimated natural mortality as a constant annual rate (M = 0.84), which was similar in magnitude to life-history-based estimates for similar age groups. By accounting for unique behavioral attributes in the study design, the application of multistate tagging models provided robust estimates of mortality and emigration rates for a valuable coastal fishery resource that will inform future efforts to achieve yield and conservation goals.Item Size-specific apparent survival rate estimates of white sharks using mark-recapture models(Canadian Science Publishing, 2018-12-28) Kanive, Paul E.; Rotella, Jay J.; Jorgensen, Salvador J.; Chapple, Taylor K.; Hines, James E.; Anderson, Scot D.; Block, Barbara A.For species that exist at low abundance or are otherwise difficult to study, it is challenging to estimate vital rates such as survival and fecundity and common to assume that survival rates are constant across ages and sexes. Population assessments based on overly simplistic vital rates can lead to erroneous conclusions. We estimated sex and length-based annual apparent survival rates for white sharks (Carcharodon carcharias). We found evidence that annual apparent survival differed over ontogeny in a system with competitive foraging aggregations, from 0.63 (SE = 0.08) for newly recruiting sub-adults to 0.95 (SE = 0.02) for the largest sharks. Our results reveal a potential challenge to ontogenetic recruitment in a long-lived, highly mobile top marine predator, as survival rates for sub-adult white sharks may be lower than previously assumed. Alternatively, younger and competitively inferior individuals may be forced to permanently emigrate from primary foraging sites. This study provides new methodology for estimating apparent survival as a function of diverse covariates by capture-recapture study including when sex assignment is uncertain.Item Life in captivity: varied behavioural responses to novel setting and food types in first-generation hybrids of farmed and wild juvenile Chinook salmon (Oncorhynchus tshawytscha)(Canadian Science Publishing, 2018-12-10) Janisse, Kevyn; Capelle, Pauline M; Heath, John W; Dender, Mitchel G.E.; Heath, Daniel D; Semeniuk, Christina A.D.Aquaculture practices continuously seek to improve efficiency to produce larger fish at lower cost. Selective breeding within broodstocks can result in undesirable effects, promoting hatcheries to use outbreeding to increase or maintain genetic diversity. This practice however, could result in the introduction of wild behavioural phenotypes unable to adapt to captive-living conditions. Using four first-hatchery generation hybrid crosses and two fully domesticated stocks of Chinook salmon in British Columbia, we examined behavioural responses to common aquaculture practices such as abrupt environmental change and novel feed types in juvenile fish. Controlling for mass, we found crosses varied in their behaviours to a novel setting, and preferences for natural versus commercial diets. These differences were furthermore associated with rearing environment, and stock-level growth-rate and body size. Our results suggest selecting for phenotypes that behaviourally exhibit better coping mechanisms and greater flexibility in response to change is possible, and when in combination with growth metrics, should be an integral part of producing the desired farmed fish. Behaviours that allow commercial anadromous fish to easily transition to captive environmental conditions can benefit production and also animal welfare.Item Spatiotemporal variability in energetic condition of alewife and round goby in Lake Michigan(Canadian Science Publishing, 2018-12-14) Bunnell, David B.; Pothoven, Steven A; Armenio, Patricia M; Eaton, Lauren; Warner, David M; Elgin, Ashley K.; Burlakova, Lyubov E; Karatayev, Alexander YPelagic-oriented alewife (Alosa pseudoharengus) and benthic-oriented round goby (Neogobius melanostomus) are two important prey fish in the Laurentian Great Lakes. In 2015, we evaluated their seasonal total energy (TE) across nine Lake Michigan transects. Round goby contained at least 48% more kilojoules of TE than alewife of equal length during spring and summer. TE varied spatially for both species, but only large alewife exhibited a consistent pattern, with higher values along the eastern shoreline. Variation in TE was not explained by site-specific prey densities for either species. Round goby energy density (ED) was higher in Lake Michigan than in central Lake Erie, but comparable to other regions of the Great Lakes. Alewife ED in 2015 was similar to 2002-2004 in Lake Michigan, with the exception of November (small alewife ED was 21% higher) and April (large alewife ED was 30% lower). Despite oligotrophication, our study suggests that starvation of juvenile and adults has not been directly contributing to overall declining prey fish abundance, although future research should evaluate the potential for overwinter starvation.Item Sex-based differences in spawning behavior account for male-biased harvest in Lake Erie walleye (Sander vitreus)(Canadian Science Publishing, 2018-12-20) Bade, Andrew P.; Binder, Thomas R.; Faust, Matthew D; Vandergoot, Christopher S; Hartman, Travis J.; Kraus, Richard T.; Krueger, Charles C.; Ludsin, Stuart A.Sex- and size-specific reproductive behaviors can increase the vulnerability of certain demographic components of fish populations to exploitation, potentially leading to unsustainable harvest. Lake Erieâ s largest walleye (Sander vitreus) local spawning population, which aggregates on the Ohio reef complex during spring, is subject to angling. Information on the sex composition of harvest or how reproductive behavior might influence harvest is lacking. To address these uncertainties, 337 reef-spawning individuals were implanted with acoustic transmitters and their spawning behavior on the reef complex was monitored for four years using acoustic telemetry. Males arrived on spawning grounds earlier and remained on them longer than females. These behavioral differences led us to predict that recreational angler harvest during the spawning season would be male-biased. Creel surveys confirmed this prediction, although sex composition of the harvest was influenced by angling technique. Collectively, these findings suggest that sex-based differences in reproductive behaviors bias the recreational harvest toward males on the reef complex during the spawning season. This male-biased harvest seems unlikely to pose an undue risk to Lake Erieâ s walleye fishery.Item A seascape-scale habitat model to support management of fishing impacts on benthic ecosystems(Canadian Science Publishing, 2018-12-18) Smeltz, Timothy Scott; Harris, Bradley; Olson, John; Sethi, Suresh A.Minimizing fishing impacts on seafloor ecosystems is a growing focus of ocean management; however, few quantitative tools exist to guide seascape-scale habitat management. To meet these needs, we developed a model to assess benthic ecosystem impacts from fishing gear contact. The habitat impacts model is cast in discrete time and can accommodate overlapping fisheries as well as incorporate gear-specific contact dynamics. We implemented the model in the North Pacific using fishing data from 2003 to 2017, estimating that habitat in 3.1% of the 1.2 million km2 study area was disturbed at the end of the simulation period. A marked decline in habitat disturbance was evident since 2010, attributable to a single regulatory gear change that lifted trawl gear components off the seafloor. Running scenarios without these gear modifications showed these policies might have contributed to a 24% reduction in habitat disturbance since their implementation. Ultimately, model outputs provide direct estimates of the spatial and temporal trends of habitat effects from fishing — a key component of regulatory policies for many of the world’s fisheries.Item Moving repatriation efforts forward for imperilled Canadian freshwater fishes(Canadian Science Publishing, 2018-12-12) Lamothe, Karl A; Drake, D. Andrew R.Freshwater ecosystems are among the most threatened environments on our planet. Disturbances across the terrestrial landscape accrue within freshwater ecosystems and, combined with global stressors like climate change and invasive species, create a complex situation for recovering imperilled fishes. Given the drastic global trend of freshwater fish declines, similarly extreme efforts are needed for their conservation and recovery - repatriation represents one such opportunity. Species repatriation describes the act of releasing a species in areas where extirpation has occurred. Paradoxically, a long history of fish introductions for recreational purposes exists, yet examples of repatriation for imperilled fishes are relatively rare compared to terrestrial species. Stemming from the restoration and species introduction literature, we identify five ecological themes to consider when evaluating repatriation potential of freshwater fishes and suggest that repatriation represents the "drastic" approach needed to achieve meaningful conservation milestones.Item Drivers of diet patterns in a globally distributed freshwater fish species(Canadian Science Publishing, 2018-09-11) Sánchez-Hernández, Javier; Finstad, Anders G.; Arnekleiv, Jo Vegar; Kjærstad, Gaute; Amundsen, Per-ArneWe analysed data of a globally distributed model organism (brown trout) in an attempt to understand relationships among biogeography, prey communities and climate on diet composition at regional spatial scales (Scandinavia), and thereafter explored whether diet patterns remained the same at global scales. At regional scales, we uncovered comprehensive patterns in diet composition among neighbouring freshwater ecoregions, with site-specific prey communities as the best predictor of the observed prey utilisation patterns. Thus, we posit that environmental gradients altering site-specific prey communities and consequently the trophic niche of the predator through bottom-up mechanisms are key in understanding spatial dietary patterns. Proximity was also important for the revealed biogeographic patterns at global scales. We suggest that geographic location (latitude and elevation) as a proxy of environmental heterogeneity is key at small spatial scales, and climate at global extents, to understand spatial dietary patterns. Our findings support the hypothesis that future shifts in prey communities due to climate change will strengthen biographical patterns in feeding of freshwater fishes, with consequences for invasiveness assessment and nature management and conservation.Item Behavioural and morphological changes in fish exposed to ecologically relevant boat noises(Canadian Science Publishing, 2018-12-23) Mickle, Megan F.; Harris, Christopher M.; Love, Oliver P.; Higgs, Dennis M.There is increasing concern about the effect of underwater noise on fish due to rising levels of anthropogenic noise. We performed experiments on the black bullhead (Ameiurus melas), a species with known hearing specializations and located within the Laurentian Great Lakes where there is considerable commercial and recreational boat traffic. We tested and compared physiology (baseline cortisol), behaviour (activity, sheltering), and morphology (ciliary bundles of hair cells) of bullhead to boat noise. At 140 dB re 1 μPa (−54.84 dB re 1 m·s−2), we saw clear behavioural effects in terms of both activity and sheltering levels despite no obvious morphological or physiological stress. Following both short- and long-period acute exposure to higher — but environmentally relevant — noise levels, bullhead were less active and sheltered more and also exhibited a decrease in ciliary bundles. These results suggest that there are sublethal effects of anthropogenic noise on fish behaviour and ciliary bundles, which may have direct implications on population health. Moreover, commonly used metrics such as stress hormones may not always offer the most relevant biomarker of the response to anthropogenic boat noise.Item Mercury trends and cycling in northern Wisconsin related to atmospheric and hydrologic processes(Canadian Science Publishing, 2018-07-28) Watras, Carl; Grande, David; Latzka, Alexander; Tate, LoriAtmospheric deposition is the principal source of mercury to remote northern landscapes, but its fate depends on multiple factors and internal feedbacks. Here we document long-term trends and cycles of mercury in the air, precipitation, surface water and fish of northern Wisconsin that span the past three decades; and we investigate relationships to atmospheric processes and other variables, especially the regional water cycle. Consistent with declining emission inventories, there was evidence of declining trends in these time series; but the time series for Hg in some lakes and most fish were dominated by a near-decadal oscillation that tracked the regional oscillation of water levels. Concentrations of important solutes (SO4, DOC) and the acid-base status of lake water also tracked water levels in ways that cannot be attributed to simple dilution or concentration. The explanatory mechanism is analogous to the â reservoir effectâ wherein littoral sediments are periodically exposed and re-flooded, altering the internal cycles of sulfur, carbon and mercury. These climatically-driven, near-decadal oscillations confound short-term time series and complicate relationships between Hg emissions, deposition and bioaccumulationItem Boreal river impoundments caused nearshore fish community assemblage shifts but little change in diversity: A multi-scale analysis(Canadian Science Publishing, 2018-07-02) Turgeon, Katrine; Turpin, Christian; Gregory-Eaves, IreneRiver flow regulation, fragmentation and changes in water quality caused by dams have varying effects on aquatic biodiversity and ecosystem functions, but are not clearly resolved in boreal ecosystems. We adopted a multi-scale approach to quantify fish community trajectories over 20 years using a network of sites spread across four reservoirs in two hydroelectricity complexes in northern QuĂŠbec, where other anthropogenic factors have been negligible. Across three spatial scales, we found little evidence of directional temporal trends in diversity relative to reference sites. Using beta-diversity analyses, we also detected a high degree of stability in fish composition over time and space at the complex and reservoir scales. However, changes in species assemblage following impoundment were detected at the scale of the sampling station. At this scale, we found that some species consistently benefited (coregonids and pikes) from impoundment whereas others were detrimentally affected (suckers and one salmonid). Overall, we conclude that examining different scales is key when trying to understand the impacts of humans on biodiversity and in formulating management recommendations.Item Size selectivity and length-dependent escape behaviour of haddock in a sorting device combining a grid and a square mesh panel(Canadian Science Publishing, 2018-09-28) Herrmann, Bent; Sistiaga, Manu; Grimaldo, Eduardo; Larsen, Roger B.; Olsen, Leonore; Brinkhof, Jesse; Tatone, IvanSize selectivity of a new sorting section combining a sorting grid and a square mesh panel was tested for haddock (Melanogrammus aeglefinus) in the Barents Sea demersal trawl fishery. Sampling data for a wide size range enabled investigating the selection process for this species in detail, both for the grid and the square mesh panel. Contrary to earlier studies modelling size selectivity for grids and square mesh panels, which assume that the escape behaviour of all sizes of fish is equal, we applied a model that accounted for that haddock of different sizes can show different escape behaviour. Our results demonstrated that this model could describe the experimental data collected better than existing models. Specifically, our results showed that the likelihood for smaller haddock to seek escape through the grid and the square mesh panel was higher than for bigger haddock that still would manage to escape through the devices if they attempted. The new modelling approach presented in this study may be applicable to other species, selection devices and fisheries.Item Changes in the condition, early growth, and trophic position of Lake Trout (Salvelinus namaycush) in response to an experimental aquaculture operation(Canadian Science Publishing, 2018-09-23) Kennedy, Patrick J.; Blanchfield, Paul J.; Kidd, Karen A; Paterson, Michael J.; Podemski, Cheryl L.; Rennie, Michael D.We analyzed changes in the condition, early growth and resource use of Lake Trout from a Boreal Shied lake in response to an experimental aquaculture operation. Annual small-scale commercial production of Rainbow Trout (Oncorhynchus mykiss) resulted in increased Lake Trout body condition during aquaculture operations which was positively related to minnow CPUE. Incremental increases in growth led to larger Lake Trout following aquaculture. While the littoral energy assimilated by Lake Trout did not change linearly from 2002-2009, we observed a shift towards littoral energy use in the last year of aquaculture and for two years after the experiment, coincident with low densities of Mysis diluviana. Lake Trout trophic position declined from 2002-2009, suggesting increased foraging on secondary vs. tertiary consumers. Minnow and Slimy Sculpin (Cottus cognatus) CPUE increased by 5.2 and 5.5-fold, respectively, and Mysis diluviana densities decreased by 93%. Changes observed in the experimental lake were much greater than those observed in a nearby reference lake. Our results suggest that moderate nutrient enrichment from aquaculture may benefit Lake Trout in oligotrophic Boreal Shield lakes.Item Improved approximations for estimation of size-transition probabilities within size-structured models(Canadian Science Publishing, 2018-08-26) Millar, Russell B; Nottingham, Christopher D.Modelling annual growth of individuals in a size-structured model requires calculation of the size-transition probabilities for moving from one size class to another. This requires evaluation of two-dimensional integrals when there is individual variability in growth. For computational simplicity it is common to approximate the integrals by setting all individuals in a size-class to the mid-size of that class, or ignoring the individual variability. We develop a more accurate approximation that assumes a uniform distribution in size within each size class. The approximation is fast and hence feasible for Bayesian models in which the matrix of transition probabilities must be computed for each posterior sample. The improved accuracy of the new approximation is shown to hold over a diverse range of formulations for incremental growth. For the New Zealand Paua 5A stock assessment model, it was found to reduce the average approximation error of the size-transition probabilities by 86% and 98% compared to the midpoint and deterministic growth approximations, respectively. Moreover, the midpoint and deterministic approximations inflated the estimated maximum sustainable yield by 6% and 8% respectively, and the current biomass by almost 30%, in comparison to the more accurate approximation.Item Using fine-scale spatial analysis to study behavioural strategies prevalence in wild groups of drift-feeding fish(Canadian Science Publishing, 2018-12-28) Vivancos, Aurélien; Closs, GerardKey aspects of the social organisation of groups of drift-feeding fish can be inferred by the way space is shared between group members, because they inhabit a very dynamic environment where spatial positions have a direct impact on fitness-related traits. Therefore, the spatial analysis of such system can reveal insights into the behavioural ecology of fish, but so far, technical constraint limited this approach only to large salmonids. We used a digital imaging technique to monitor movements and behaviour of free-ranging groups of juvenile galaxiids (Galaxias anomalous) facing two contrasting physical and social contexts. We described the spatial structure of these groups and studied individual space-use in relation to their social behaviour. We found that prevalence of territorial behaviour differ greatly between sites, which suggests that groups were displaying different social organisation. This study showed that detailed spatial analysis of space-use and behaviour of drift-feeding fish could provide new insights into the social organisation of group-living animals.Item Evaluating the role of data quality when sharing information in hierarchical multi-stock assessments, with an application to dover sole(Canadian Science Publishing, 2018-12-23) Johnson, Samuel D N; Cox, Sean PAn emerging approach to data-limited fisheries stock assessment uses hierarchical multi-stock assessment models to group stocks, sharing information from data-rich to data-poor stocks. In this paper, we simulated data-rich and data-poor scenarios for a complex of dover sole. Simulated data for individual stocks were used to compare estimation performance for single-stock and hierarchical multi-stock Schaefer production model configurations. The single-stock and best performing multi-stock models were then used in stock assessments for the real dover sole data. Multi-stock models often had lower estimation errors than single-stock models when assessment data were of poor quality. Relative errors for productivity and relative biomass parameters were lower for multi-stock assessment models, and multi-stock models that estimated hierarchical priors for catchability performed the best under data-poor scenarios. We conclude that hierarchical multi-stock assessment models are useful for data-limited stocks and could provide a more flexible alternative to data-pooling and catch only methods; however, these models are subject to non-linear side-effects of shrinkage. Therefore, we recommend testing hierarchical multi-stock models in closed-loop simulations before application to real fishery management systems.Item TEMPORAL, SPATIAL, AND BIOLOGICAL VARIATION OF NEMATODE EPIDEMIOLOGY IN AMERICAN EELS(Canadian Science Publishing, 2018-11-25) Warshafsky, Zoemma T.; Tuckey, Troy D.; Vogelbein, Wolfgang K.; Latour, Robert J.; Wargo, Andrew R.American eels (Anguilla rostrata) are infected by the non-native parasitic nematode Anguillicoloides crassus, which can cause severe swimbladder damage. We investigated epidemiology of A. crassus to better understand its population-level effects on American eels. Nematode prevalence, abundance, and intensity, and swimbladder damage were quantified in glass eels, elvers, and yellow eels from the lower Chesapeake Bay and related to season of capture, river system, and total length. Age-variant force-of-infection and disease-associated mortality were estimated using a three-state irreversible disease model, which assumes recovery is not possible. Results showed glass eels have very low infection prevalence and severity compared to elvers and yellow eels. Nematode abundance varied by season, river, and eel length, whereas swimbladder damage varied by season and eel length. Nematode abundance and swimbladder damage were weakly positively correlated. Force-of-infection, based on swimbladder damage, peaked at age 2 and disease positive eels had an estimated lower annual survival probability of 0.76 compared to disease negative eels. Full understanding of American eel population dynamics will require broader knowledge of cryptic disease-associated mortality throughout North America.Item Effect of temperature on chlorine treatment for elimination of freshwater phytoplankton in ballast water: bench scale test(Canadian Science Publishing, 2018-11-20) Casas-Monroy, Oscar; Vanden Byllaardt, Julie; Bradie, Johanna; Sneekes, Andrea; Kaag, Klaas; Bailey, Sarah AChlorine efficacy as a biocide for ballast water treatment was investigated under warm-cold temperatures, across winter and summer seasons. Freshwater phytoplankton samples were collected and acclimated under in situ environmental conditions ranging from 2-22 °C. Samples were exposed to seven chlorine treatments (from 0.02 to 5.0 ppm), in addition to a control (0.0 ppm). Free chlorine concentrations, phytoplankton abundance and photosynthetic efficiency were measured up to 48 h following treatment. After 4 h of treatment at concentrations less than 0.2 ppm, phytoplankton densities were reduced more than 50 % without cell resurgence. Similar reduction was recorded immediately after exposure when chlorine concentrations were higher than 3 ppm. After 8 h, free chlorine neared 0.0 ppm for initial chlorine concentrations below 1.2 ppm irrespective of temperature regime. Winter phytoplankton exhibited slightly lower mortality to chlorine exposure regardless of the temperature although they also exhibited lower photosynthetic efficiency. Despite a general absence of significant effect of temperature on the chlorine decay, our results suggest that higher doses of chlorine or longer exposure times may be required during winter to achieve full treatment effect. Tests at large scales are needed to further confirm these findings.Item Thermal landscapes in a changing climate: biological implications of water temperature patterns in an extreme year(Canadian Science Publishing, 2018-11-06) Steel, E. Ashley; Marsha, Amy; Fullerton, Aimee H.; Olden, Julian D; Larkin, Narasimhan K.; Lee, Se-Yeun; Ferguson, AkidaRecord-breaking droughts and high temperatures in 2015 across the Pacific Northwest, USA provide an opportunistic glimpse into potential future thermal regimes of rivers and their implications for freshwater fishes. We applied spatial stream network models (SSNMs) to data collected every 30 min for four years at 42 sites on the Snoqualmie River (Washington, United States) to compare water temperature patterns, summarized with relevance to particular life stages of native and nonnative fishes, in 2015 to more typical conditions (2012-2014). Although 2015 conditions were drier and warmer than what had been observed since 1960, patterns were neither consistent over the year nor on the network. Some locations showed dramatic increases in air and water temperature whereas others had temperatures that differed little from typical years; these results contrasted with existing forecasts of future thermal landscapes. If we will observe years like 2015 more frequently in the future, we can expect conditions to be less favorable to native, coolwater fishes such as Chinook Salmon and Bull Trout but beneficial to warmwater nonnative species such as Largemouth Bass.Item Using an individual-based model to simulate the Gulf of Maine American lobster (Homarus americanus) fishery and evaluate the robustness of current management regulations(Canadian Science Publishing, 2018-11-25) Mazur, Mackenzie; Li, Bai; Chang, Jui-Han; Chen, YongIndividual-based models (IBMs) can capture complex processes with a flexible probabilistic approach, which makes them useful for studying organisms with complex life history and fishery processes such as the American lobster (Homarus americanus). This research aims to modify and parameterize an individual-based lobster simulator (IBLS) to simulate the American lobster fishery in the Gulf of Maine. To simulate the fishery, the IBLS was tuned to match the seasonal catch and size composition from the 2015 American lobster stock assessment by adjusting the values of coefficients for select parameters. With appropriate coefficients for the initial abundance, recruitment, and seasonal encounter probability levels, the tuned IBLS accurately simulated the historical landings. Given the uncertainty in future American lobster recruitment, the tuned IBLS was then used to evaluate the effectiveness of current management regulations under different levels of recruitment.