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Population assessments of fish species often rely on data from surveys with different objectives, such as measuring biodiversity or community dynamics. These surveys often contain spatial-temporal dependencies that can greatly influence conclusions drawn from analyses. Pygmy whitefish (PWF, Prosopium coulterii) populations in Lake Superior were recently assessed as Threatened by the Committee on the Status of Endangered Species in Canada, which motivated a thorough analysis of available data to improve our understanding of its population status. The US Geological Survey conducts annual bottom trawl surveys in Lake Superior that commonly capture PWF. We used these data (1989-2018) to model temporal trends in PWF biomass density and make lake-wide population projections. We used a Bayesian approach, integrated nested Laplace approximation (INLA), and compared the impact of including different random structures on model fit. Inclusion of spatial structure improved model fit and conclusions differed from models omitting random effects. PWF populations have experienced periodic fluctuations in biomass density since 1989, though 2018 may represent the lowest density in the 30-year time series. Lake-wide biomass was estimated to be 71.51. Les evaluations de populations d'especes de poissons reposent souvent sur des donnees de releves aux objectifs varies, comme la mesure de la biodiversite ou de la dynamique des communautes. Ces releves contiennent souvent des dependances spatiotemporelles qui peuvent grandement influencer les conclusions tirees des analyses. Le Comite sur la situation des especes en peril au Canada a recemment etabli que les populations de menominis pygmees (Prosopium coulterii) dans le lac Superieur sont menacees, ce qui a motive une analyse exhaustive des donnees disponibles dans le but d'ameliorer la comprehension du statut des populations de ce poisson. Le U.S. Geological Survey effectue des releves annuels au chalut de fond dans le lac Superieur qui capturent generalement des menominis pygmees. Nous avons utilise ces donnees (1989-2018) pour modeliser les tendances dans le temps de la densite de biomasse de menominis pygmees et etablir des projections concernant les populations pour l'ensemble du lac. Nous avons utilise une approche bayesienne, l'approximation de Laplace emboitee integree (ALEI), et compare l'incidence de l'inclusion de differentes structures aleatoires sur le calage des modeles. L'inclusion d'une structure spatiale ameliore le calage et mene a des conclusions differentes de celles decoulant de modeles qui n'integrent pas d'effets aleatoires. Si la densite de la biomasse de populations de menominis pygmees a connu des fluctuations periodiques depuis 1989, l'annee 2018 pourrait etre caracterisee par la plus faible densite de la serie chronologique de 30 ans. La biomasse dans l'ensemble du lac est estimee a 71,5 t. [Traduit par la Redaction], Introduction Fish population assessments, whether for the purposes of conservation or fisheries management, must often rely on data from monitoring surveys designed to meet other objectives. For example, monitoring surveys [...]

Human-driven environmental change underlies recent changes in water clarity in many of the world's great lakes, yet our understanding of the consequences of these changes on the fish and fisheries they support remains incomplete. Herein, we offer a framework to organize current knowledge, guide future research, and help fisheries managers understand how water clarity can affect their valued populations. Emphasizing Laurentian Great Lakes findings where possible, we describe how changing water clarity can directly affect fish populations and communities by altering exposure to ultraviolet radiation, foraging success, predation risk, reproductive behavior, or territoriality. We also discuss how changing water clarity can affect fisheries harvest and assessment through effects on fisher behavior and sampling efficiency (i.e., catchability). Finally, we discuss whether changing water clarity can affect understudied aspects of fishery performance, including economic and community benefits. We conclude by identifying generalized predictions and discuss their implications for priority research questions for the Laurentian Great Lakes. Even though the motivation for this work was regional, the breadth of the review and generality of the framework are readily transferable to other freshwater and marine habitats. Si des modifications de l'environnement causees par les humains sous-tendent les changements recents de la clarte de l'eau dans bon nombre des grands lacs de la planete, notre comprehension des consequences de ces changements sur les poissons et les peches qu'ils soutiennent demeure incomplete. Nous presentons un cadre pour organiser les connaissances actuelles, orienter la recherche future et aider les gestionnaires des peches a comprendre l'incidence possible de la clarte de l'eau sur les populations qu'ils gerent. En mettant l'accent, dans la mesure du possible, sur des constatations relatives aux Grands Lacs laurentiens, nous decrivons l'incidence directe que peuvent avoir les variations de la clarte de l'eau sur les populations et communautes de poissons en modifiant l'exposition au rayonnement ultraviolet, le succes d'approvisionnement, le risque de predation, le comportement de reproduction ou la territorialite. Nous abordons egalement l'incidence que peuvent avoir les modifications de la clarte de l'eau sur les prises et revaluation des peches par le biais d'effets sur le comportement des pecheurs et l'efficacite d'echantillonnage (c.-a-d., la capturabilite). Enfin, nous tentons d'etablir si les modifications de la clarte de l'eau peuvent avoir une incidence sur des aspects sous-etudies de la performance des peches, y compris les avantages economiques et pour les collectivites. Nous concluons en formulant des predictions generales et discutons des questions de recherche prioritaires qu'elles font ressortir pour les Grands Lacs laurentiens. Meme si l'intention a l'origine du present article etait regionale, la portee de la synthese et le caractere general du cadre font qu'ils peuvent etre transposes aisement a d'autres habitats marins et d'eau douce. [Traduit par la Redaction], Introduction Although scientists have increasingly documented changing water clarity in freshwater ecosystems worldwide, we do not fully understand its effects on aquatic food webs and the fisheries that they support. [...]

Effective conservation requires that species recovery measures are informed by rigorous scientific research. For imperilled freshwater fishes and mussels in Canada, numerous research gaps exist, in part owing to the need for specialized research methods. The Canadian Freshwater Species at Risk Research Network (SARNET) was formed and identified or implemented approaches to address current research gaps, including (1) captive experimental research populations, (2) nonlethal methods for estimating abundance and distribution, (3) nonlethal field methods to measure life-history parameters, (4) species distribution models informed by co-occurring species, (5) conservation physiology to inform habitat and threat science, (6) evidence syntheses to evaluate threats and recovery measures, (7) disease-transmission models to understand mussel-host relationships, (8) experimental mesocosms and manipulative experiments to evaluate key habitat stressors, (9) threat and hazard models for predictive applications, and (10) rigorous evaluation of surrogate species. Over a dozen threat- and recovery-focused SARNET research applications are summarized, demonstrating the value of a coordinated research program between academics and government to advance scientific research on, and to support the recovery of, imperilled freshwater species. Des mesures de retablissement reposant sur des travaux de recherche scientifique rigoureux sont necessaires a une conservation efficace. Pour les especes de poissons d'eau douce et mulettes en peril au Canada, il existe de nombreuses lacunes dans la recherche, dues partiellement a la necessite de methodes de recherche specialisees. Le reseau canadien de recherche sur les especes d'eau douce en peril (SARNET) a ete cree et il a cerne ou applique differentes approches visant a combler ces lacunes, dont les suivantes : (1) des populations experimentales captives de recherche, (2) des methodes non letales d'estimation de l'abondance et de la repartition, (3) des methodes de terrain non letales de mesure de parametres du cycle biologique, (4) des modeles de repartition des especes integrant des donnees sur les especes cooccurrentes, (5) la physiologie de la conservation pour soutenir les travaux scientifiques sur les habitats et les menaces, (6) des syntheses de donnees probantes pour evaluer les menaces et measures de retablissement, (7) des modeles de transmission des maladies pour comprendre les relations mulettes-hotes, (8) des mesocosmes experimentaux et des experiences de manipulation pour evaluer des facteurs de stress cles des habitats, (9) des modeles de menaces et de dangers pour des applications predictives et (10) Revaluation rigoureuse d'especes substitutives. Un resume de plus d'une douzaine d'applications des travaux de recherche du SARNET axees sur les menaces et le retablissement est presente, qui demontre l'utilite d'un programme de recherche au sein duquel les travaux de chercheurs universitaires et gouvernementaux sont coordonnes afin de faire avancer la recherche scientifique sur les especes d'eau douce en peril et soutenir leur retablissement. [Traduit par la Redaction], Introduction An important goal of conservation biology is to prevent species extinctions caused by human activity (Soule 1985). When populations decline and become imperilled, various recovery measures are often enacted [...]

The use of translocations to recover populations requires a sufficiently large number of individuals from source populations, but removing too many individuals could lead to source population collapse. To understand the trade-off between the probabilities of source population extirpation and translocation success, matrix population models that incorporate Allee effects, density dependence, and demographic and environmental stochasticity were combined with a model that simulates removals from source populations. We apply these models to eastern sand darter (Ammocrypta pellucida; Species at Risk Act status: Threatened) translocation scenarios in Canada. The results suggest that translocations most often require source populations >20 000 individuals, as source population extirpation probability increased with the number and frequency of removals. Transport mortality or losses immediately following introduction further affected translocation success. Uncertainty around life-history parameters and the strength of Allee effects led to additional uncertainty about the required source population size. Although stochastic processes affected the probability of translocation success, factors such as stocking density and frequency can be controlled, and translocation may therefore be a viable strategy for eastern sand darter recovery, even when applying cautious thresholds to guard against uncertainty. Si l'utilisation de deplacements pour retablir des populations necessite un nombre suffisamment grand d'individus de populations sources, le retrait de trop d'individus peut mener a l'effondrement de ces populations. Pour comprendre le compromis entre les probabilites de disparition de populations sources et le succes du deplacement, des modeles demographiques matriciels qui integrent des effets Allee, la dependance a la densite et une stochasticite demographique et environnementale ont ete combines a un modele qui simule des retraits de populations sources. Nous appliquons ces modeles a des scenarios de deplacement de dards de sable (Ammocrypta pellucida; etat de la Loi sur les especes en peril: menaces) au Canada. Les resultats donnent a penser que les deplacements necessitent le plus souvent des populations sources de plus de 20 000 individus, puisque la probabilite de disparition d'une population source augmente parallelement au nombre et a la frequence des retraits. La mortalite liee au transport ou les pertes immediatement apres l'introduction ont egalement une incidence sur le succes du deplacement. L'incertitude entourant des parametres du cycle biologique et la force d'effets Allee accroissent l'incertitude associee a la taille requise des populations sources. Bien que des processus stochastiques aient une incidence sur la probabilite de succes du deplacement, des facteurs comme la densite et la frequence d'ensemencement peuvent etre controles, de sorte que le deplacement pourrait etre une strategie viable pour le retablissement du dard de sable, meme si des seuils prudents sont appliques pour contrer l'effet de l'incertitude. [Traduit par la Redaction], Introduction The number of species that are currently at heightened risk of extinction continues to rise (Chapin et al. 2000; Rockstrom et al. 2009). Reversing this trend requires rigorous evaluation [...]

In data-poor regions, modeled river temperatures are essential for predicting potential stressors for species at risk. With limited data from the Grand, Thames, and Sydenham rivers in southern Ontario, Canada, we evaluated simple mixed-effect regression models to predict water temperature using air temperature from nearby weather stations. Model performance was assessed for periods relevant to the fitness of the black redhorse (Moxostoma duquesni): June to August, when heat events may be likely; and May, when spawning occurs. All of the models performed better when trained on data from these periods, compared with using data from the entire growing season. The best model was a linear regression using 5 days of lagged air temperature. This model had a root mean square error for summer means of 1.5[degrees]C. The differences in prediction error at different times of year highlight the importance of considering species ecology in model interpretation. However, the improvement in model fit when using only data from the relevant time of year suggests that relatively simple models can be used effectively in a management arena when applied appropriately. Dans les regions pour lesquelles peu de donnees sont disponibles, les temperatures modelisees des rivieres sont d'importance fondamentale pour la prediction de facteurs de stress potentiels pour les especes en peril. A partir de donnees limitees pour les rivieres Grand, Thames et Sydenham, dans le sud de l'Ontario (Canada), nous avons evalue des modeles de regression a effets mixtes simples pour la prediction des temperatures de l'eau a partir de temperatures de l'air mesurees a des stations meteorologiques a proximite. La performance des modeles a ete evaluee pour des periodes importantes pour l'aptitude du chevalier noir (Moxostoma duquesnii), soit de juin a aout, quand des episodes de chaleur sont probables, et en mai, quand le frai a lieu. Tous les modeles ont donne de meilleurs resultats quand ils etaient prealablement entraines avec des donnees pour ces periodes que lorsque des donnees pour toute la saison de croissance etaient utilisees. Le meilleur modele est une regression lineaire integrant cinq jours de donnees de temperatures de l'air decalees (ecart-type moyen estival 1,5[degrees]C). Les differentes erreurs de prevision a differents moments de l'annee soulignent l'importance de tenir compte de l'ecologie de l'espece pour l'interpretation des modeles. L'amelioration du calage sur les modeles que produit l'utilisation de donnees seulement pour les periodes importantes de l'annee donne cependant a penser que, s'ils sont bien appliques, des modeles relativement simples peuvent etre utilises efficacement en gestion. [Traduit par la Redaction], Introduction Water temperature is one of the primary factors that determine the survival, growth, and reproduction of aquatic organisms in flowing systems (Wismer and Christie 1987; Caissie 2006; Hasnain et [...]

More than 15 years have passed since Canada's Species at Risk Act was enacted. To evaluate scientific progress in support of the Act, we identified research accomplishments up to 2017 for imperilled aquatic species in the Great Lakes--St. Lawrence River basin based on recovery documents and an expert survey, spanning 1182 activities across 68 research topics for 45 fish and mussel species. Greatest progress was observed for population ecology (38% of activities with major progress) and habitat science (28%), with comparably less progress on threats (mechanisms and impacts; 19%) and recovery (threat mitigation and reintroduction; 21%). As a result of lagging progress, threat and reintroduction topics were prioritized for a Canadian Freshwater Species at Risk Research Network (SARNET; 2017-2020), which focused on addressing key knowledge gaps with novel applications. This special issue outlines the SARNET projects, which span novel field, laboratory, and analytical activities. Continued research investment into novel and existing approaches is necessary to advance scientific achievements for fishes and mussels in support of the Species at Risk Act in Canada. Plus de 15 annees se sont ecoulees depuis la promulgation de la Loi sur les especes en peril du Canada. Afin d'evaluer les avancees scientifiques a l'appui de la loi, nous avons recense les realisations en recherche jusqu'en 2017 touchant aux especes aquatiques menacees dans le bassin des Grands Lacs et du fleuve Saint-Laurent a la lumiere de documents concernant le retablissement et d'un sondage aupres de specialistes qui couvrent 1182 activites portant sur 68 sujets de recherche visant 45 especes de poissons et de moules. Les plus grandes avancees sont observees dans les domaines de l'ecologie des populations (38 % des activites presentant des avancees majeures) et de la science des habitats (28 %), relativement moins d'avancees etant observees dans les domaines des menaces (mecanismes et impacts, 19 %) et du retablissement (attenuation des menaces et reintroduction, 21 %). Au vu du retard au plan des avancees, les themes des menaces et de la reintroduction ont ete priorises pour un reseau canadien de recherche sur les especes d'eau douce en peril (SARNET, 2017-2020), dont les travaux ont mis l'accent sur d'importantes lacunes dans les connaissances offrant de nouvelles applications. Le present numero special offre un aperqu des projets du SARNET, qui portent sur un eventail d'activites analytiques, de terrain et de laboratoire originales. Un investissement soutenu en recherche sur des approches nouvelles et existantes est necessaire a la poursuite d'avancees scientifiques concernant les poissons et les moules, a l'appui de la Loi sur les especes en peril au Canada. [Traduit par la Redaction], Introduction The United Nations Convention on Biological Diversity (CBD) was established in 1992 to recognize the profound value of protecting biodiversity. The global response to the CBD was substantial, with [...]

Keywords: compensation; conservation; development; evaluation; lake; management; mitigation; river; stream; wetland; arroyo; compensacion; conservacion; desarrollo; evaluacion; humedal; lago; manejo; mitigacion; rio Abstract Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects' compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes. Article Note: Article impact statement: Despite legislation in places like the United States, EU, Australia, and Canada, biodiversity offsets do not show high levels of ecosystem function. CAPTION(S): Synthesis protocol (Appendix S1), additional references (Appendix S2), function and compliance in relation to location (Appendix S3), and positive and negative effects of project targets and methods (Appendix S4) are available online. The authors are solely responsible for the content and functionality of these materials. Queries (other than absence of the material) should be directed to the corresponding author. Byline: Sebastian Theis, Jonathan L.W. Ruppert, Karling N. Roberts, Charles K. Minns, Marten Koops,Mark S. Poesch

Alternative reproductive tactics (ARTs) can generate considerable within-species life history variation but are often overlooked. Here, we use the invasive round goby (Neogobius melanostomus) to address a number of ecological and evolutionary questions about ARTs. Making use of a 12-year, multisite Laurentian Great Lakes data set, we show that the guarder male tactic was twice as common as the sneaker male tactic but that nonreproductive males were the most common morph. The ratio of guarder to sneaker males did not vary spatially despite a wide range of resource densities across sites. Guarders and sneakers spanned similar age ranges, suggesting that the ARTs are nonsequentially expressed. Based on short-term (gut contents) diet analyses, both reproductive tactics consumed fewer types of food and tended to consume fewer items overall when compared with nonreproductive males. Long-term (isotope) diet analyses showed that guarder males fed at a higher trophic level (higher [[delta].sup.15]N) and had a broader isotopic niche. Our results show that ARTs are an important aspect of this invasive species' breeding system and should be accounted for when assessing and managing populations. Si differentes tactiques de reproduction peuvent se traduire par des variations considerables du cycle biologique au sein d'une meme espece, dans bien des cas, elles ne sont pas prises en consideration. Nous utilisons le gobie a taches noires (Neogobius melanostomus), une espece envahissante, pour examiner differentes questions relatives a l'ecologie et Revolution touchant aux differentes tactiques de reproduction. A la lumiere d'un ensemble de donnees de 12 ans couvrant de multiples sites dans la region des Grands Lacs laurentiens, nous demontrons que les males gardiens etaient deux fois plus repandus que les males furtifs, mais que les males non reproducteurs representaient la tactique la plus repandue. Le rapport des males gardiens et furtifs ne variait pas dans l'espace, malgre une grande fourchette de densite des ressources entre les sites. Les fourchettes d'age des males gardiens et furtifs etaient semblables, donnant a penser que les differentes tactiques de reproduction ne s'expriment pas sequentiellement. A la lumiere d'analyses des regimes alimentaires a court terme (contenus stomacaux), les individus adoptant les deux tactiques de reproduction consommaient moins de types d'aliments et avaient tendance a consommer moins d'articles en general que les males non reproducteurs. Des analyses des regimes alimentaires sur le long terme (isotopiques) montrent que les males gardiens s'alimentaient a un niveau trophique plus eleve ([[delta].sup.15]N plus grands) et occupaient une niche isotopique plus large. Nos resultats montrent que l'adoption de differentes tactiques de reproduction est un aspect important du systeme de reproduction de cette espece envahissante qui devrait etre integre a l'evaluation et la gestion des populations. [Traduit par la Redaction], Introduction The round goby (Neogobius melanostomus) is a highly successful invasive species that has established new populations in both Europe and North America (Corkum et al. 2004; Kornis et al. [...]

Food web theory predicts that one of the consequences of oligotrophication is the decline in fisheries following the establishment of nutrient-deficient conditions and low biogenic production. However, emerging evidence suggests that more complex trophic interactions, induced by plankton composition, dietary diversification, temporal and spatial heterogeneity, variations in fish age and size structure can lead to ecosystem responses that deviate from theoretical predictions; especially in the shallow littoral zone. In this study, two end-to-end modelling strategies are used to characterize potential food web structural shifts and overall ecosystem productivity in response to oligotrophication. Our modelling strategy draws upon empirical and theoretical evidence from the Bay of Quinte, a semi-enclosed embayment in northeastern Lake Ontario that has been subjected to phosphorus (P) abatement strategies in the 1970s. We first show that the role of food abundance has been a primary factor shaping fish production, but the fish community gradually responded to the reduced availability of pelagic staples of their diet by displaying greater reliance upon alternative sources, including benthic and other autochthonous (or even allochthonous) food items. Our analysis further suggests that degree of diet overlap between competing trophic guilds can significantly modulate realized biomass levels. The composition of the autotrophic community is another major confounding factor that can induce significant variations from the predicted food web productivity patterns in response to oligotrophication. Overall, our analysis suggests that the proposed reduction of the ambient total phosphorus levels may not necessarily trigger a significant decline in fish biomass in the Bay of Quinte. [ABSTRACT FROM AUTHOR]

We developed a spatially explicit simulation model of poaching behaviour to quantify the relative influence of the intensity, frequency, and spatial distribution of poaching on metapopulation viability. We integrated our model of poaching with a stochastic, habitat-based, spatially explicit population model, applied it to examine the impact of poaching on northern abalone (Haliotis kamtschatkana) metapopulation dynamics in Barkley Sound, British Columbia, Canada, and quantified model sensitivity to input parameters. While demographic parameters remained important in predicting extinction probabilities for northern abalone, our simulations indicate that the odds of extinction are twice as high when populations are subjected to poaching. Viability was influenced by poaching variables that affect the total number of individuals removed. Of these, poaching mortality was the most influential in predicting metapopulation viability, with each 0.1 increase in mortality rate resulting in 22.6% increase in the odds of extinction. By contrast, the location and spatial correlation of events were less important predictors of viability. When data are limited, simulation models of poaching combined with sensitivity analyses can be useful in informing management strategies and future research directions. Nous avons developpe un modele de simulation spatialement explicite du comportement de braconnage pour quantifier l'influence relative de l'intensite, de la frequence et de la repartition spatiale du braconnage sur la viabilite de metapopulations. Nous avons integre notre modele de braconnage a un modele de population stochastique spatialement explicite base sur l'habitat, l'avons applique pour examiner l'incidence du braconnage (Haliotis kamtschatkana) sur la dynamique de metapopulations d'ormeaux nordiques dans la baie Barkley (Colombie-Britannique, Canada) et avons quantifie la sensibilite du modele aux parametres de depart. Si les parametres demographiques demeurent importants pour la prevision des probabilites de disparition pour l'ormeau nordique, nos simulations indiquent que les chances de disparition sont deux fois plus grandes quand les populations font l'objet de braconnage. La viabilite est influencee par des variables associees au braconnage qui ont une incidence sur le nombre total d'individus retires. De ces variables, la mortalite par braconnage est celle qui influence le plus la prediction de la viabilite de metapopulations, chaque augmentation de 0,1 du taux de mortalite se traduisant par une hausse de 22,6% de la probabilite de disparition. En revanche, l'emplacement et la correlation spatiale des evenements sont des variables moins importantes pour ce qui est de predire la viabilite. Quand les donnees sont limitees, les modeles de simulation du braconnage combines a des analyses de la sensibilite peuvent etre utiles pour eclairer les strategies de gestion et orienter les travaux de recherche futurs. [Traduit par la Redaction], Introduction Considered to be one of the primary threats to biodiversity, overexploitation has led to the decline and disappearance of many species worldwide (Wilcove et al. 1998; Venter et al. [...]

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessed Purple Wartyback (PWB, Cyclonaias tuberculata) as Threatened in Canada. Here population modelling is presented to assess the impacts of harm, determine abundance and habitat recovery targets, and conduct long-term projections of population recovery in support of a recovery potential assessment (RPA). The model incorporated parameter uncertainty, environmental stochasticity, and density-dependence into population projections. The analysis demonstrated that PWB populations were most sensitive to perturbations to adult survival under most circumstances. As population growth rate (λ) increased the sensitivity of juvenile survival to perturbation increased and surpassed adult survival sensitivity when λ > 1.2. Estimates of the level of harm that would reduce population growth rate to 1 were estimated for populations in the Sydenham and Thames rivers. Population viability analysis was used to identify potential recovery targets. Demographic sustainability, (i.e., a self-sustaining population over 250 years) can be achieved with population sizes of ~2,800 (CI: 1,900-4,000) adults. It was estimated that populations of minimum viable population (MVP) size would require 623.3 m² (CI: 251.9-1,396.9) and 2,900 m² (CI: 301.5-17,166.3) in the Sydenham and Thames rivers respectively. Therefore, there is sufficient habitat to support PWB populations in both systems. [ABSTRACT FROM AUTHOR]

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has assessed Lake Chubsucker (Erimyzon sucetta) in Canada as Endangered. Population modelling is presented to assess the impacts of harm and determine abundance and habitat recovery targets in support of a recovery potential assessment (RPA). This analysis demonstrated that Lake Chubsucker were most sensitive to perturbations to adult survival. Population viability analysis was used to identify potential recovery targets. Demographic sustainability (i.e., a selfsustaining population over the long term) can be achieved with population sizes of ~ 33,600 individuals of age-1 and older with a catastrophe frequency of 15% per generation and desired persistence probability of 99% over 100 years. Such a population would require 0.41 km2 of lacustrine habitat or 0.12 km² of riverine habitat. [ABSTRACT FROM AUTHOR]

Habitat loss represents the greatest threat to freshwater biodiversity. The potential for life history attributes to correlate with the risks associated with habitat loss represents a possible mechanism for more effective and rapid assessments, especially in data-limited situations. Body size correlates with many other life history attributes and is a good starting point for investigating correlates with habitat loss. Here, we use a generic stage-based matrix population model, parameterized using length-based allometries, to investigate if such a mechanism exists. Our analysis revealed that small species (shorter maximum body length) were initially more sensitive to the loss of habitat. Moreover, distinct stage-based patterns exist showing an increased sensitivity of population growth rate for small species to both habitat loss and vital rate perturbations of pre-adult stages. This indicates that the pre-adult period represents a critical stage for the continued production of small species and increased importance of the conservation of habitat used by young-of-the-year and juvenile fishes. La disparition d'habitat represente la plus grande menace pour la biodiversite des milieux d'eau douce. La possibilite que des attributs du cycle biologique soient correles aux risques associes a la disparition d'habitat constitue un mecanisme possible pour des evaluations plus efficaces et rapides, particulierement dans des situations oU les donnees sont limitees. La taille du corps est correlee a de nombreux autres attributs du cycle biologique et represente un bon point de depart pour l'etude des correlats de la disparition d'habitat. Nous utilisons un modele matriciel generique base sur les stades dont les parametres sont etablis en utilisant des allometries axees sur la longueur pour verifier si un tel mecanisme existe. Notre analyse revele que les petites especes (longueur du corps maximum plus courte) sont initialement plus sensibles a la disparition d'habitat. En outre, il existe des motifs distincts selon les stades qui indiquent une sensibilite accrue des taux de croissance des populations de petites especes tant a la disparition d'habitat qu'aux perturbations des rythmes vitaux des stades pre-adultes. Cela indique que la periode pre-adulte constitue une etape critique pour la production continue des petites especes et souligne l'importance de la conservation des habitats utilises par les jeunes de l'annee et les poissons juveniles. [Traduit par la Redaction], Introduction Freshwater ecosystems are vulnerable to anthropogenic disturbance due to landscape influences on habitat and fishes (e.g., Chu et al. 2014; Kaufmann et al. 2014; Tanentzap et al. 2014). Fishes [...]

Recent food-web changes in the Laurentian Great Lakes are affecting energy and nutrient allocation to lake whitefish (Coregonus clupeaformis) with potential downstream effects on egg condition and recruitment. We tested whether egg condition was conserved or varied with maternal condition in eight stocks from Lakes Erie, Michigan, and Superior. Egg condition was conserved across stocks based on (i) a lack of correlation between females and eggs for total lipid, DHA, and other essential fatty acids; (ii) higher levels of energy and long-chain polyunsaturated fatty acids (LC-PUFA) in eggs compared with females; and (iii) no among-stock differences for those same variables in eggs. Females from northern Lake Michigan generally made the greatest trade-offs between egg size and fecundity. Highly fecund females provisioned less lipid, but more n-3 LC-PUFA to their eggs. A lack of stock-level patterns in energy and nutrient allocation suggests that trade-offs occur at the level of individual females and that females in poor condition make greater trade-offs among egg size and fecundity, total lipids, and n-3 LC-PUFA than females in good condition. Resume: Des modifications recentes des reseaux trophiques dans les Grands Lacs laurentiens ont une incidence sur l'allocation d'energie et de nutriments chez les grands coregones (Coregonus clupeaformis), incluant des effets en aval potentiels sur l'etat des reufs et le recrutement. Nous avons tente d'etablir si l'etat des reufs etait conserve ou variait selon l'etat d'embonpoint maternel au sein de huit stocks des lacs Erie, Michigan et Superieur. L'etat des reufs etait conserve dans tous les stocks a la lumiere (i) de l'absence de correlation entre les femelles et les reufs sur le plan des lipides totaux, de l'ADH et d'autres acides gras essentiels, (ii) de niveaux plus eleves d'energie et d'acides gras polyinsatures a longue chaine (AGPLC) dans les reufs que chez les femelles et (iii) de l'absence de variation au sein des stocks en ce qui concerne ces memes variables dans les reufs. Les femelles de la partie nord du lac Michigan sont celles qui presentaient les compromis les plus importants entre la taille des reufs et la fecondite. Les femelles tres fecondes transferaient moins de lipides, mais plus d'AGPLC n-3 a leurs reufs. L'absence de tendance en matiere d'allocation d'energie et de nutriments a l'echelle des stocks donne a penser que les compromis s'exercent a l'echelle individuelle chez les femelles et que les femelles en mauvais etat d'embonpoint font de plus grands compromis entre la taille des reufs et la fecondite, les lipides totaux et les AGPLC n-3 que les femelles en bon etat. [Traduit par la Redaction], Introduction Lake whitefish (Coregonus clupeaformis) support important commercial, recreational, and aboriginal subsistence fisheries throughout the Laurentian Great Lakes. From 1995 to 2005, lake whitefish growth and body condition declined precipitously [...]