2016

Permanent URI for this collectionhttps://hdl.handle.net/1807/71216

Browse

Now showing 1 - 20 of 155

Sex-based tradeoffs between growth, mortality, and maturation in Great Lakes yellow perch stocks
(Canadian Science Publishing, 2016-09-25) Feiner, Zachary S; Chong, Stephen C.; Fielder, David G.; Hoyle, James A.; Knight, Carey; Lauer, Thomas E.; Thomas, Michael V.; Tyson, Jeffrey T; Höök, Tomas O.
Tradeoffs between growth, mortality, and reproduction form the basis of life history theory but may vary among populations due to local ecological conditions. We examined life history tradeoffs driving variation in maturation among 13 yellow perch (Perca flavescens) stocks in the Great Lakes using sex-specific age and length at 50% maturity (A50 and L50, respectively), and probabilistic maturation reaction norm midpoints (Lp50,a). Both sexes exhibited positive correlations between growth and mortality, and faster growing stocks were mature at younger ages but larger sizes. Male and female A50 and L50 were positively correlated among stocks, but Lp50,a estimates were negatively correlated among stocks, indicating stocks that matured at large sizes for a given age in females matured at smaller age-specific sizes in males. Female Lp50,a estimates were negatively related to growth and mortality while male Lp50,a estimates were positively related to growth. These results suggest that (a) sex-based life history tradeoffs sometimes act to differentially structure maturation schedules in males and females, and (b) males may be less responsive to changes in mortality than females.
Validation of a hidden Markov model for the geolocation of Atlantic cod
(Canadian Science Publishing, 2016-12-22) Liu, Chang; Cowles, Geoffrey W.; Zemeckis, Douglas R.; Cadrin, Steven X.; Dean, Micah J.
Models developed to geolocate individual fish from data recorded by electronic tags often require significant modification to be applied to new regions, species, or tag types due to variability in oceanographic conditions, fish behavior, and data resolution. We developed a model for geolocating Atlantic cod off New England that builds upon an existing hidden Markov model (HMM) framework and addresses region- and species-specific challenges. The HMM framework contains a likelihood model which compares tag-recorded environmental data (depth, temperature, tidal characteristics) with those derived from an oceanographic model and a behavior model which constrains the horizontal movement of the fish. Validation experiments were performed on stationary tags, double-electronic-tagged fish (archival and acoustic tags), and simulated tracks. Known data, including fish locations and activity metrics, showed good agreement with those estimated by the modified approach, and improvements in performance of the modified method over the original. The modified geolocation approach will be applicable to additional species and regions to obtain valuable movement information that is not typically available for demersal fishes.
Swimming performance of sauger (Sander canadensis) in relation to fish passage
(Canadian Science Publishing, 2016-12-21) Dockery, David R.; McMahon, Thomas E.; Kappenman, Kevin M.; Blank, Matthew
A lack of information on the swimming abilities may inhibit the design of effective passage structures for sauger (Sander canadensis), a highly migratory species particularly sensitive to habitat fragmentation. Passage success, maximum ascent distances, and maximum sprint velocities of sauger were estimated in an open-channel flume over a range of water velocities (51, 78, and 92 cm s
Hot eats and cool creeks: juvenile Pacific salmonids use mainstem prey while in thermal refuges
(Canadian Science Publishing, 2016-12-02) Brewitt, Kimberly S.; Danner, Eric M.; Moore, Jonathan W.
Thermal refuges form important habitat for coldwater fishes in the face of rising temperatures. As fish become concentrated in refuges, food resources may become depleted. In this study, we used invertebrate drift sampling and fish density surveys to quantify potential in-refuge food limitation, temperature-sensitive radio-tagging studies to quantify thermal habitat use, and isotopic analyses to determine diet sources for juvenile Pacific salmonids using thermal refuges on Californiaâ s Klamath River. Juvenile salmonids using refuges formed by tributary junctions with the mainstem river obtained the majority (range = 47-97%) of their diet from mainstem prey sources. Mean steelhead body temperatures were significantly cooler (~3.5Â°C) than diet-inferred foraging temperatures. Thus, while fish seek cooler habitat for physiological benefits, they rely primarily on mainstem prey. Moreover, consistently high densities of fish in refuges (mean = 3.5 fish m
Finless porpoises (Neophocaena asiaeorientalis) in the East China Sea: Insights into feeding habits using morphological, molecular, and stable isotopic techniques
(Canadian Science Publishing, 2016-12-22) Chen, Bingyao; Wang, Lin; Wang, Hui; Li, Shanshan; Jefferson, Thomas Allen; Wang, Lian; Tang, Erin King; Xu, Xinrong; Yang, Guang
Describing feeding habits of cetaceans is crucial to understanding their feeding strategies and conservation status. Here, both morphological and molecular techniques were employed to identify the stomach contents of 122 finless porpoises (Neophocaena spp.) in the East China Sea for insight into their short-term feeding habits; and stable isotopes of Î´13C and Î´15N were used for analyzing prey resource use and trophic position as a manifestation of their long-term feeding habits. In total, 33 prey species comprising of 19 teleosts, 7 crustaceans, 5 cephalopods, and 2 gastropods were identified. In both short and long-term analyses, teleosts represented primary prey, cephalopods and crustaceans were secondary prey, and gastropods were occasional prey; but, the primary prey species composition is different between short and long-term diet. The composition of stomach contents showed sexual and age-related variation. This is supported by stable isotopic analyses which indicated the separation of trophic position of adult male, adult female and young male. Generally, finless porpoises prey on species which are primarily caught by fisheries.
Life history effects on hatchery contributions to ocean harvest and natural-area spawning
(Canadian Science Publishing, 2016-12-15) Davison, Raziel J.; Satterthwaite, William H.
Hatcheries can support salmon fisheries but also impact natural populations. We model the proportional hatchery contributions to ocean catch, natural-area spawning and egg production based on hatchery production, maturation, fecundity and straying. We develop indices of hatchery-origin catch per stray spawner measuring the trade-off between supplementing harvest and limiting natural-area impacts; higher values indicate success in increasing hatchery ocean harvest contributions relative to strays spawning in natural areas. Hatchery fish maturing early lowers catch per stray (and proportion hatchery-origin catch) by shifting the age distributions of both catch and spawners toward younger ages. Age-dependent fecundity may complicate predicted effects of changing maturation schedules. Increased straying does not affect catch but increases hatchery-origin spawning and decreases catch per stray. Differences in hatchery production affect hatchery contributions to both catch and spawning, exacerbating the tradeoff between these conflicting goals but with no net effect on catch per stray. Fishery intensity magnifies the effects of accelerated hatchery fish maturation by reducing spawning contributions of older fish, with contrasting effects depending on whether hatchery fish mature early versus late.
Optimal sampling methods for modelling the occupancy of Arctic Grayling (Thymallus arcticus) in the Canadian Barrenlands
(Canadian Science Publishing, 2016-12-19) Baker, Leanne F.; Artym, Kyle J; Swanson, Heidi K
In occupancy models, imperfect detectability of animals is usually corrected for by using temporally-repeated surveys to estimate probability of detection. Substituting spatial replicates for temporal replicates could be an advantageous sampling strategy in remote Arctic regions, but may lead to serious violations of model assumptions. Using a case study of site occupancy of adfluvial young-of-year Arctic Grayling in Barrenland tundra streams, we assessed reliability and efficiency of alternative sampling strategies; i) randomly distributed vs sequential adjacent spatial replicates; ii) visual vs electrofishing surveys; and, iii) spatial vs temporal replicates. Sequential, adjacent spatial replicates produced spatially auto-correlated data. Autocorrelation was relieved using randomly distributed spatial replicates, but using these randomly distributed spatial replicates introduced significant error into estimates of the probability of occupancy in streams. Models designed for spatially-autocorrelated data could minimize this bias. Visual and electrofishing surveys produced comparable probabilities of detection. Spatially-replicated surveys performed better than temporal replicates. The easiest and relatively most cost-effective sampling methods performed as well as, or better than, the more established, expensive, and logistically difficult alternatives for occupancy estimation.
Seasonal dynamics in a near-shore isotopic niche and spatial subsidies from multi-trophic aquaculture
(Canadian Science Publishing, 2016-12-05) Weldrick, Christine; Jelinski, Dennis
A poorly understood food web dynamic concerns possible variation in spatial subsidies associated with multi-trophic aquaculture and their effects on extractive and naturally occurring organisms. We used the stable isotopes, δ13C and δ15N, and circular statistics to investigate niche overlap across a year-long period at an experimental multi-trophic aquaculture facility in British Columbia, Canada. A two-source mixing model revealed that particulate organic matter was the most important food source for all sample invertebrates (mean range 40-98%) compared to farm effluent (mean range 3-35%). There were significant month-to-month changes in δ13C and δ15N for all species except for the brooding transparent tunicate. We did not detect any directionality for the entire community, but did identify variable directional shifts for each species, suggesting resource partitioning driven by competition and/or morphology-based differences in feeding strategies. This was further supported by seasonal variation in inter- and intraspecific isotopic niche widths. Isotopic niche overlap among co-occurring invertebrates appeared to be stronger during winter and summer than autumn months. Our study provides valuable insights on the role of multi-trophic derived effluent on a near-shore marine community comprised of both natural and cultured species within the same feeding guild.
Prey predator interactions in the face of management regulations: changes in Mediterranean small pelagics are not due to increased tuna predation
(Canadian Science Publishing, 2016-10-31) Van Beveren, Elisabeth; Fromentin, Jean-Marc; Bonhommeau, Sylvain; Nieblas, Anne-Elise; Metral, Luisa; Brisset, Blandine; Jusup, Marko; Bauer, Robert Klaus; Brosset, Pablo; Saraux, Claire
Recently, the abundance of young Atlantic bluefin tuna (Thunnus thynnus) tripled in the North-western Mediterranean following effective management measures. We investigated whether its predation on sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) could explain their concurrent size and biomass decline, which caused a fishery crisis. Combining the observed diet composition of bluefin tuna, their modelled daily energy requirements, their population size and the abundance of prey species in the area, we calculated the proportion of the prey populations that were consumed by bluefin tuna annually over 2011-2013. To assess whether tuna could alter the size structure of the three small pelagic populations (anchovy, sardine and sprat), the size distributions of the consumed prey species were compared to those of the wild populations. We estimated that the annual consumption of small pelagic fish by bluefin tuna is less than 2% of the abundance of these populations. Furthermore, size selectivity patterns were not observed. We thus concluded that tuna predation is unlikely to be the main cause of major changes in the small pelagic fish populations from this area.
Predator-prey interactions influenced by a dynamic river plume
(Canadian Science Publishing, 2016-12-21) Phillips, Elizabeth M.; Horne, John K.; Zamon, Jeannette E.
Marine predator-prey interactions are often influenced by oceanographic processes that aggregate prey. We examined density distributions of seabirds and prey fish associated with the Columbia River plume to determine if variation in plume size (i.e., volume or surface area) or location influences predator-prey interactions. Common murre (Uria aalge), sooty shearwater (Ardenna grisea), and forage fish including northern anchovy (Engraulis mordax) and juvenile salmon (Oncorhynchus spp.) occurred disproportionately in plume waters relative to adjacent marine waters. Water clarity, an indicator of plume-influenced waters, was a significant predictor of seabird and prey densities throughout the survey area. Murres occurred within 20 km of the plume center of gravity (CG) whereas shearwaters occurred ~100 km north of the plume CG, concurrent with highest densities of prey fish. Global indices of collocation were relatively low between murres and prey, compared to high values between shearwaters and prey. Seabird densities were negatively correlated with plume size, suggesting that seabirds concentrate in the plume to maximize foraging effort. We conclude that variation in Columbia River plume size and location influences predator distributions, which increases predation pressure on prey, including threatened salmonid species.
Fish community assessment with eDNA metabarcoding: effects of sampling design and bioinformatic filtering
(Canadian Science Publishing, 2016-11-29) Evans, Nathan T.; Li, Yiyuan; Renshaw, Mark A.; Olds, Brett P.; Deiner, Kristy; Turner, Cameron R.; Jerde, Christopher L.; Lodge, David M.; Lamberti, Gary A.; Pfrender, Michael E.
Species richness is a metric of biodiversity that represents the number of species present in a community. Traditional fisheries assessments that rely on capture of organisms often underestimate true species richness. eDNA metabarcoding is an alternative tool, which infers species richness by collecting and sequencing DNA present in the ecosystem. Our objective was to determine how spatial distribution of samples and â bioinformatic stringencyâ affected eDNA-metabarcoding estimates of species richness compared to capture-based estimates in a 2.2-ha reservoir. When bioinformatic criteria required species to only be detected in a single sample, eDNA metabarcoding detected all species captured with traditional methods plus an additional 11 non-captured species. However, when we required species to be detected with multiple markers and in multiple samples, eDNA metabarcoding detected only seven of the captured species. Our analysis of the spatial patterns of species detection indicated that eDNA was distributed relatively homogenously throughout the reservoir, except near the inflowing stream. We suggest that interpretation of eDNA metabarcoding data must consider the potential effects of water body type, spatial resolution, and bioinformatic stringency.
Evaluation of spatiotemporal imputations for fishing catch rate standardisation
(Canadian Science Publishing, 2016-12-21) Marriott, Ross J.; Turlach, Berwin A; Murray, Kevin; Fairclough, David V
As commercial fishing activity shifts to target different grounds over time, spatial gaps can be created in catch rate data and lead to biases in derived indices of fish abundance. Imputation has been shown to reduce such biases. In this study, the relative performance of several imputation methods was assessed using simulated catch rate datasets. Simulations were carried out for three fish stocks targeted by a commercial hook and line fishery off the south-western coast of Australia: Snapper (Chrysophrys auratus), West Australian Dhufish (Glaucosoma hebraicum), and Baldchin Groper (Choerodon rubescens). For High Growth scenarios, the mean squared errors (MSEs) of Geometric and Linear imputations were lower, indicating higher accuracy and precision, than Base method (constant value) imputations. For Low Growth scenarios, the lowest MSEs were achieved for Base method imputations. However, for the final standardised and imputed abundance indices, the Base method index consistently demonstrated the largest biases. Results demonstrate the importance of selecting an appropriate imputation method when standardising catch rates from a commercial fishery that changed its spatial pattern of fishing over time.
Forecasting the magnitude and composition of phytoplankton blooms in a eutrophic lowland river (Rivière Yamaska, Que., Canada)
(Canadian Science Publishing, 2016-12-11) Remmal, Yasmina; Hudon, Christiane; Hamilton, Paul; Rondeau, Myriam; Gagnon, Pierre
The mechanisms controlling phytoplankton biomass and composition in the lower reach of the eutrophic Rivière Yamaska were studied over six consecutive summers characterized by high (2008–2009) and low (2012–2013) discharge conditions. In the lower river reach, low river discharge favoured planktonic blooms dominated by centric diatoms, in contrast with public reports of simultaneous occurrence of cyanobacterial proliferation upstream. Daily cycles of hourly dissolved oxygen production were disrupted by floods but resumed in the days following flow abatement and persisted under low discharge conditions, suggesting that blooms in the lower river reach resulted from local production, rather than advection from upstream reservoirs. Flagellate chlorophytes and cryptophytes were more important under extreme high and low discharge whereas cyanobacteria co-occurred with centric diatoms under intermediate discharge and highly illuminated conditions. Although the Rivière Yamaska's flow remained sufficient to avoid cyanobacterial proliferation under lowest discharge conditions, our results suggest that increasing water residence time, either through severe drought or river damming, will amplify the risk of toxic algal blooms in the free flowing reaches of the lower Rivière Yamaska
A spatial-temporal model for snow crab (Chionoecetes opilio) stock size in the Southern Gulf of St. Lawrence
(Canadian Science Publishing, 2016-11-01) Cadigan, Noel G; Wade, Elmer; Nielsen, Anders
We develop a high resolution spatio-temporal model of stock size and harvest rates for snow crab (Chionoecetes opilio) in the Southern Gulf of St. Lawrence, which supports an economically important fishery off the east coast of Canada. It is a spatial and weekly model during 1997-2014 that utilizes within-season depletion based on catch per unit of effort (CPUE; kg per pot), and also biomass values from a survey designed specifically for this stock. The model is formulated in a state-space framework. The main contribution of the model is to provide a better understanding of fishery-dependent factors that affect CPUE. There is strong evidence of density-dependence in the relationship with CPUE and stock biomass, in addition to a general increase in CPUE catchability over time that may be related to changes in gear soak time, and spatial variation in catchability. We also find that a natural mortality rate of 0.4 provides a better fit to survey results. Model results suggest that there is no evidence of effort saturation in the fishery.
To share or not to share in the emerging era of big data: Perspectives from fish telemetry researchers on data sharing
(Canadian Science Publishing, 2016-11-28) Nguyen, Vivian M.; Brooks, Jill; Young, Nathan; Lennox, Robert J.; Haddaway, Neal; Whoriskey, Frederick G.; Harcourt, Robert; Cooke, Steven J.
The potential for telemetry data to answer complex questions about aquatic animals and their interactions with the environment is limited by the capacity to store, manage, and access data across the research community. Large telemetry networks and databases exist, but are limited by the actions of researchers to share their telemetry data. Promoting data sharing and understanding researchersâ views on open practices is a significant step toward enhancing the role of big data in ecology and resources management. We surveyed 307 fish telemetry researchers to understand their perspectives and experiences on data sharing. A logistic regression revealed that data sharing was positively related to researchers with collaborative tendencies, who belong to a telemetry network, who are prolific publishers, and who express altruistic motives for their research. Researchers were less likely to have shared telemetry data if they engage in radio and/or acoustic telemetry, work for regional government, and value the time it takes to complete a research project. We identify and provide examples of both benefits and concerns that respondents have about sharing telemetry data.
Comparing compound-specific and bulk stable nitrogen isotope trophic discrimination factors across multiple freshwater fish species and diets
(Canadian Science Publishing, 2016-12-21) Blanke, Chelsey; Chikaraishi, Yoshito; Takizawa, Yuko; Steffan, Shawn; Dharampal, Prarthana; Vander Zanden, M. Jake
Compound-specific nitrogen stable isotope analysis provides an approach for estimating animal trophic position that may overcome key issues associated with stable isotope analysis of bulk tissue. Yet compound-specific trophic discrimination factors have not been estimated for a broad range of habitats, taxa, and diets. We conducted a controlled-feeding experiment to characterize the variation in compound-specific (TDFAA) and bulk (TDFBulk) trophic discrimination factors of four freshwater fish species fed on three distinct diets. We also compared TDFAA of fish muscle and scale to evaluate the viability of scales for making food web inferences. Mean TDFBulk was 2.2±0.9‰ (±1 SD) and there were significant effects of species and diet trophic position on TDFBulk. Mean TDFAA was 6.9±0.8‰ (±1 SD). Although there was no effect of species on TDFAA, there were significant differences in TDFAA across the three diets. TDFAA from fish scales were not significantly different from those of muscle. Our study illustrates the advantages of estimating trophic position using compound-specific stable isotopes and the need for continued investigation of factors resulting in variation in TDF values.
Impacts of eutrophication and oil spills on the Gulf of Finland herring stock
(Canadian Science Publishing, 2016-12-05) Rahikainen, Mika; Hoviniemi, Kirsi-Maaria; Mäntyniemi, Samu; Vanhatalo, Jarno; Helle, Inari; Lehtiniemi, Maiju; Pönni, Jukka; Kuikka, Sakari
The Baltic Sea is one of the world’s most stressed sea areas. Major threats to the ecosystem include eutrophication and oil spills. The progression of anthropogenic nutrient enrichment is lengthy and gradual while oil spills cause rapid changes in the system, with varying impact time. We quantify the impact of eutrophication and the key ecological covariates on the population dynamics of the major pelagic fish stock, the Baltic herring, in the Gulf of Finland. The full life-cycle of herring is represented with a probabilistic state-space model. Moreover, we analyse the impact of the oil spill from M/T Antonio Gramsci, in 1987, on herring survival. The results confirm impact of the spill on the early life-stage survival: the observed high frequency of malformed herring larvae in surveys signaled elevated mortality of the year-class. The optimal July-August chlorophyll α concentration for herring reproduction is approximately 5 µg/l. This level is currently exceeded suggesting recruitment impairment due to eutrophication. The herring stock was also recruitment overfished. Analysis suggests deceleration of herring growth as salinity descends below 6 psu.
Estimates of Chinook salmon consumption in Washington State inland waters by four marine mammal predators from 1970 – 2015
(Canadian Science Publishing, 2016-11-17) Chasco, Brandon; Kaplan, Isaac; Thomas, Austen; Acevedo-Gutiérrez, Alejandro; Noren, Dawn P.; Ford, Michael J; Hanson, M. Bradley; Scordino, Jonathan; Jeffries, Steven J.; Pearson, Scott F.; Marshall, Kristin; Ward, Eric J.
Conflicts can arise when the recovery of one protected species limits the recovery of another through competition or predation. The recovery of many marine mammal populations on the west coast of the United States (U.S.) has been viewed as a success; however, within Puget Sound in Washington State (U.S.) the increased abundance of three protected pinniped species may be adversely affecting the recovery of threatened Chinook salmon (Oncoryhnchus tshawytchsa) and endangered killer whales (Orcinus orca) within the region. Between 1970 and 2015, we estimate the annual biomass of Chinook salmon consumed by pinnipeds has increased from 68 to 625 metric tons. Converting juvenile Chinook salmon into adult equivalents, we found that by 2015 pinnipeds consumed double that of resident killer whales, and six times greater than the combined commercial and recreational catches. We demonstrate the importance of interspecific interactions when evaluating species recovery. As more protected species respond positively to recovery efforts, managers should attempt to evaluate trade-offs between these recovery efforts and the unintended ecosystem consequences of predation and competition on other protected species.
Simulating future climate impacts on tropical fisheries: are contemporary spatial fishery management strategies sufficient?
(Canadian Science Publishing, 2016-12-07) Kapur, Maia R.; Franklin, Erik C
We demonstrated a possible future wherein coral reefs shift to an algae-dominated state that retains low coral cover and a functional biomass of herbivorous fishes that sustains a reef fish fishery. We evaluate the effect of no-take MPAs and increased coastal nutrients under two IPCC climate scenarios for years 2000-2100, which are implemented as coral bleaching events. Coral mortality from bleaching events drove a lagged increase in herbivorous fish populations, via a shift from coral-dominated to algae-dominated habitats. Biomass and catch of piscivorous fish declined significantly with the fishery shifting to the harvest of herbivorous fish. No-take MPAs for 20% of reef areas represented a threshold that had a positive effect on herbivorous fishes but no influence on the steep declines of corals and piscivorous fishes. Contemporary no-take MPAs protect less than 1% of coral reef areas around the Hawaiian Islands; significant management action would be required to approach the 20% area threshold.
Separating wild versus stocking components in fish recruitment without identification data: a hierarchical modelling approach
(Canadian Science Publishing, 2016-10-26) Dauphin, Guillaume J.R.; Brugel, Catherine; Legrand, Marion; Prévost, Etienne
Salmonid juvenile stocking programs are often poorly monitored due to the lack of identification between stocked and wild fish. In this study, a hierarchical Bayesian model is developed to take advantage of spatio-temporal variations of stocking and wild recruitment for estimating these two components despite the absence of identification data. It is first tested by means of simulated data, and then applied to the 37 years abundance data set of the Atlantic salmon population of the Allier catchment (France). Despite the absence of identification data, juvenile densities could be estimated and split into wild and stocked components. We found that the stocked juveniles contributed significantly to the total juvenile production, while the wild reproduction continued to provide an important contribution. This approach is encouraging and promising from a management advice perspective. It is flexible enough to accommodate for case study specificities and shows that long term monitoring of abundances can be useful to assess the impact of stocking programs even in the absence of direct means of identifying stocked vs wild fish.

Browse

Recent Submissions