Fully equipped to succeed : migratory contingents seen as an intrinsic potential for striped bass to exploit a heterogeneous environment early in fife

Migratory contingents, groups of individuals belonging to the same population that adopt different migratory patterns, have been identified in numerous Striped Bass (Morone saxatilis) populations along North American East Coast. We tested the hypothesis that migratory contingents may develop early in life to maximize the exploitation of the variety of habitats faced by a recently introduced fish population. Using the discriminatory power provided by otolith chemistry, we studied early-life history stages of Striped Bass in a recently reintroduced population in the St. Lawrence Estuary. Migratory patterns were inferred using multivariate analysis of four otolith trace elements (Sr, Ba, Mn, and Mg) on juveniles (0+ and 1+). Three migratory contingents were identified during early-life history stages: freshwater residents, oligohaline migrants, and mesohaline migrants. This study demonstrates the rapid establishment, in less than 10 years since initial stocking, of three migratory contingents initiated early in life among the St. Lawrence Striped Bass population. We postulate that diversification provided by the establishment of distinct migratory contingents among early-life history stages promotes the rapid colonization of new environments through the exploration and exploitation of an increased number of nursery habitats

Session C6: The Eel Ladders at Beauharnois Power Station, Canada

Abstract: The first anthropogenic obstacle encountered by juvenile American eel (Anguilla rostrata) in the St. Lawrence River (Canada) during their upstream migration from the Sargasso Sea, is a large hydro dam. The facility is located at Beauharnois, downstream of Lake Ontario, the largest and final growth habitat of this river system. Following preliminary tests from 1994 to 2001, the dam was equipped with a first eel ladder in 2002 on the left bank followed by a second on the right bank in 2004. Eel counts dropped from 1994 to 1998, and then increased from 1998 to 2011. In 2012 and 2013 a sharp decline of numbers was observed while 2014 presents some hope for a return to higher numbers. A strong inverse relationship (r²= 0.83) was observed between annual counts and mean annual length. In addition, an annual age-length key developed using otolith readings from 2004, 2009, 2011 and 2013 allows us to assign an age to every length-class recorded during these years. In 2004, we observed an age structure distributed from age-1 to age-21, where 83.9 % of specimens were within age-3 and age-6, and a mean age of 5.2 years (s.e. = 2.2). In 2009, the mean age had decreased to 4.1 years (s.e. = 1.8) while the age distribution had narrowed to between age-2 and age-11, with 80.0% of the specimens between 2 and 5 years old, in 2011 the mean age was 4, 4 (age-2 to age 13) and 4,8 in 2013 (age-2 to age-10). This later result reflects the decline of arrival of young eels at the Beauharnois ladders in 2012 and 2013

Le Réseau de détection précoce des espèces aquatiques exotiques envahissantes du Saint-Laurent : bilan des activités 2007-2010

Au Canada, l’introduction de nouvelles espèces est survenue dès l’arrivée des premiers explorateurs européens au pays. Bien que la plupart de ces espèces, dites exotiques, causent peu de dommages aux écosystèmes qu’elles colonisent, certaines, par contre, croissent et se dispersent rapidement causant ainsi des impacts négatifs importants. Une espèce exotique est qualifiée d’envahissante lorsque son établissement ou sa propagation constitue une menace pour l’environnement, l’économie ou la société. Afin de détecter et de suivre la progression des espèces exotiques, la Direction de l’expertise du Bas-Saint-Laurent du ministère des Ressources naturelles et de la Faune (MRNF) a mis sur pied, en 2007, un Réseau de détection précoce des espèces aquatiques exotiques envahissantes (EAEE) du fleuve Saint-Laurent. Ce réseau, formé de pêcheurs commerciaux oeuvrant dans tout le Saint-Laurent, permet d’avoir une connaissance actuelle des EAEE présentes dans le fleuve et de suivre leur évolution. En 4 ans, les pêcheurs ont rapporté la capture de 171 spécimens inhabituels appartenant à 7 espèces différentes, 2 en extension d’aire : le stromatée à fossettes (Peprilus triacanthus) et le balaou (Scomberesox saurus) ainsi que 5 EAEE : l’alose à gésier (Dorosoma cepedianum), l’alose d’été (Alosa aestivalis), la tanche (Tinca tinca), le crabe chinois à mitaines (Eriocheir sinensis) et le gobie à taches noires (Neogobius melanosomus)

The migration of stocked, trapped and transported, and wild female American silver eels through the Gulf of St. Lawrence

The stocking of juvenile eels and trap and transport programs of large yellow eels were initiated in Ontario to mitigate mortalities observed at hydroelectric dams and to increase escapement from the upper St. Lawrence River and Lake Ontario (Canada). A total of 380 migrating female silver eels (« Stocked », « Trapped and Transported », and « Wild ») were tagged with acoustic transmitters between 2011 and 2014. Their migration and escapement at the exit of the Gulf of St. Lawrence, the Cabot Strait, were recorded using acoustic receivers. Escapement rates varied between 8.9 and 20.0% annually (mean= 11.4%). A high proportion of stocked eels were detected (N=27 of 43 detected at Cabot) demonstrating their ability to escape the Gulf. No differences in migration speed, and crossing locations at Cabot Strait, were found among the 3 categories. Eels crossing Cabot Strait did not display diel and tidal patterns but their estimated swimming depth indicated diel vertical migrations. The low escapement rates observed may be related to predation events and/or the low and variable detection efficiency of the acoustic receivers’ line.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Data from: Population genetics of the American eel (Anguilla rostrata): FST = 0 and NAO effects on demographic fluctuations of a panmictic species

We performed population genetic analyses on the American eel (Anguilla rostrata) with three main objectives. First, we conducted the most comprehensive analysis of neutral genetic population structure to date in order to revisit the null hypothesis of panmixia in this species. Second, we used this data to provide the first estimates of contemporary effective population size (Ne) and to document temporal variation in effective number of breeders (Nb) in American eel. Third, we tested for statistical associations between temporal variation in the North Atlantic Oscillation (NAO) index, the effective number of breeders and two indices of recruit abundance. A total of 2142 eels from 32 sampling locations were genotyped with 18 microsatellite loci. All measures of differentiation were essentially zero, and no evidence for significant spatial or temporal genetic differentiation was found. The panmixia hypothesis should thus be accepted for this species. Nb estimates varied by a factor of 23 among 12 cohorts, from 473 to 10 999. The effective population size Ne was estimated to be around 22 382. This study also showed that genetically based demographic indices, namely Nb and allelic richness (Ar), can be used as surrogates for the abundance of breeders and recruits, which were both shown to be positively influenced by variation during high (positive) NAO phases. Thus, long-term genetic monitoring of American glass eels at several sites along the North American Atlantic coast would represent a powerful and efficient complement to census monitoring to track demographic fluctuations and better understand their causes

Dispersion récente de la tanche au Québec

La tanche (Tinca tinca) est une des nombreuses espèces exotiques envahissantes qui font maintenant partie intégrante de l’écosystème fluvial du Saint-Laurent. Importée au Québec en 1986, cette espèce a par la suite colonisé divers secteurs de la rivière Richelieu et du fleuve Saint-Laurent. Depuis 2011, les observations de tanche sont de plus en plus nombreuses dans le corridor fluvial du Saint-Laurent, particulièrement au lac Saint-Pierre, et l’espèce a même atteint les régions de Montréal et de Québec. La tanche est décrite comme une espèce opportuniste ayant une capacité d’adaptation à des conditions environnementales extrêmes. Cette caractéristique soulève plusieurs inquiétudes quant à son éventuel impact sur les communautés ichtyologiques et benthiques du lac Saint-Pierre, du Richelieu et du fleuve Saint-Laurent. Dans cet article, nous présentons en détail la progression de cette espèce depuis son introduction dans la rivière Richelieu jusqu’à ses plus récentes observations dans le corridor fluvial du Saint-Laurent et discutons de l’impact que cette espèce pourrait avoir sur le chevalier cuivré, espèce unique au Québec, et sur la population de perchaude au lac Saint-Pierre

Gestion des poissons d’eau douce et migrateurs dans le Saint-Laurent : mandats, enjeux et perspectives

Bien que la pêche soit très présente dans la culture québécoise, la gestion et la conservation des poissons d’eau douce et des poissons migrateurs du Saint-Laurent sont peu connues du public. L’objectif de cet article est de présenter les acteurs, le cadre législatif et les pratiques de gestion applicables à ces espèces dans les eaux douces et saumâtres du Saint-Laurent. La croissance des usages du territoire québécois, déjà nombreux, génère des pressions grandissantes sur la faune et les habitats du Saint-Laurent. Cette réalité force à sortir des modèles classiques de gestion et à recourir à des approches globales nécessitant de protéger des habitats multi spécifiques plutôt qu’une espèce en particulier, et d’impliquer des intervenants provenant, entre autres, des domaines agricole, industriel et municipal. Dans le futur, les principaux défis consisteront à rassembler les acteurs liés au Saint-Laurent autour des cibles communes de restauration et de mise en valeur, de maintenir une expertise de pointe et de continuer à appuyer la gestion de la faune aquatique sur des données scientifiques rigoureuses. Dans un contexte de changements climatiques, où la menace liée aux espèces exotiques envahissantes et les pressions de diverses natures sont exercées sur les habitats, il sera primordial d’appliquer une gestion proactive en déployant les mesures nécessaires dès que l’état de situation d’une espèce le suggérera. L’état précaire de certaines populations, comme la perchaude du lac Saint-Pierre, doit d’ailleurs être interprété comme un indicateur parmi d’autres de la détérioration de certaines fonctions de l’écosystème exceptionnel que représente le Saint-Laurent et des défis qui devront être relevés dans le futur. Tous les défis ne sont cependant pas associés à des situations de déclins. Les exemples de la réintroduction du bar rayé et du rétablissement de l’esturgeon jaune démontrent, lorsque des mesures de gestion adéquates sont prises, que le système peut être résilient et que le futur peut être prometteur.While fishing is culturally important in Québec (Canada), public knowledge about the management and conservation of freshwater and migratory fish in the St. Lawrence River is generally poor. This article aims to present the key players, the legislative framework, and the management practices as applicable to fish species in the freshwater and brackish portion of the St. Lawrence in Québec. Human pressure throughout the southern part of the province continues to increase and this has important impacts on the habitats of the St. Lawrence, and the wildlife using them. This reality must be addressed using new global approaches, such as protecting multi-species habitats, rather than focusing on more traditional single-species management and protection plans. New approaches should also involve stakeholders from the agricultural, industrial and municipal sectors, among others. In the future, the main challenges will be to achieve consensus between stakeholders for the fixing of common targets for restoration and development; to maintain cutting-edge expertise; and to continue supporting the management of fisheries on a rigorous scientific basis. In the context of climate change, where invasive exotic species and a range of anthropogenic alterations add increased pressure on habitats, it will be important to implement a proactive management approach, allowing rapid action to be taken as soon the status of a species indicates that it is needed. The precarious status of some species, such as the yellow perch in the Lake Saint-Pierre area, is another indicator of the profound deterioration and the loss of key ecological functions of the St. Lawrence ecosystem, and the challenges that will have to be met in the future. The reintroduction of the northernmost population of striped bass and the successful reestablishment of lake sturgeon stocks highlight the potential for meeting these challenges, and restoring the St. Lawrence River and its species. These examples show that the future can be positive if the appropriate management actions are implemented when required

Early back-calculated size-at-age of Atlantic yellow eels sampled along ecological gradients in the Gironde and St. Lawrence hydrographical systems

An international sampling program investigating the causes of the decline of American eels (Anguilla rostrata) and European eels (Anguilla anguilla) in the St. Lawrence (Canada) and Gironde (France) rivers systems provided the opportunity to compare early growth of eels of each species among habitats using back-calculated sizeâ at-age from 1 to 5 years old. Our study supports previous studies showing that the early back-calculated lengths of A. anguilla were higher in downstream and more saline Gironde system habitats than in the upstream fluvial section, and provides a new indication that length at 1-year-old is twice higher than that reported 10 years earlier. However, our data contradict the current paradigm for A. rostrata by providing evidence that early size-at-age of eels from the upstream St. Lawrence system, most distant from the spawning area, exceeds those of eels sampled downstream, at less distant sites in the estuarine section. Overall these observations are consistent with the hypothesis that the observed spatial variations in early growth rate of yellow eels sampled in the St. Lawrence and Gironde systems are the consequence of processes occurring in the first year of age such as genetic selection and/or genetically-dependent habitat choice.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Urinary Elimination of Bile Acid Glucuronides under Severe Cholestatic Situations: Contribution of Hepatic and Renal Glucuronidation Reactions

Biliary obstruction, a severe cholestatic complication, causes accumulation of toxic bile acids (BAs) in liver cells. Glucuronidation, catalyzed by UDP-glucuronosyltransferase (UGT) enzymes, detoxifies cholestatic BAs. Using liquid chromatography coupled to tandem mass spectrometry, 11 BA glucuronide (-G) species were quantified in prebiliary and postbiliary stenting serum and urine samples from 17 patients with biliary obstruction. Stenting caused glucuronide- and fluid-specific changes in BA-G levels and BA-G/BA metabolic ratios. In vitro glucuronidation assays with human liver and kidney microsomes revealed that even if renal enzymes generally displayed lower KM values, the two tissues shared similar glucuronidation capacities for BAs. By contrast, major differences between the two tissues were observed when four human BA-conjugating UGTs 1A3, 1A4, 2B4, and 2B7 were analyzed for mRNA and protein levels. Notably, the BA-24G producing UGT1A3 enzyme, abundant in the liver, was not detected in kidney microsomes. In conclusion, the circulating and urinary BA-G profiles are hugely impacted under severe cholestasis. The similar BA-glucuronidating abilities of hepatic and renal extracts suggest that both the liver and kidney may contribute to the urine BA-G pool

genotype_age_location_Dryad2012

American glass eels recruitment begins in Florida around December and progresses northward to Newfoundland–Labrador until June/July (Helfman et al. 1987). The first waves of glass eels at each location were sampled in 2008 following this latitudinal trend at 17 sites evenly distributed along eastern North America up to the St. Lawrence estuary. For each location, 50 individuals were measured and preserved in 95% ethanol. Yellow eels were also collected between May and September 2008 at 15 locations ranging from the upper St. Lawrence River to the Atlantic coast of Canada. The emphasis on yellow eel sampling in this region was motivated by the occurrence of strikingly different recruitment trends reported between Atlantic Canada versus the upper St. Lawrence River and Lake Ontario (Cairns et al. 2008). Sample size varied from 69 to 100 yellow eels per location. Fin clips were preserved in 95% ethanol for DNA extraction and genotyping, and heads were kept for otolith extraction. Yellow Eels collected in 2007 were finally rejected since they were frozen before being preserved in ethanol, wich caused a bias in microsattelits amplification. AGE DETERMINATION: Age was determined for 946 yellow eels, which allowed us to subdivide them into annual cohorts. Sagittal otoliths were extracted, stored in glass vials in a 95% ethanol: glycerine solution (1 : 1 ratio), and cleaned with successive baths of bleach, water, and 95% ethanol. Once dried, otoliths were embedded in a mix of epoxy resin and hardener (4:1 ratio) inside gelatine capsules for 24 h, ground to the core on the sagittal plane, and polished with alumina powder on a polishing disc. Sections were etched, decalcified in 5% EDTA for annuli enhancing, stained in 0.01% toluidine blue solution, and digitally photographed (e.g., Tremblay 2009). The first annulus after the dark central nucleus was considered as the elver check (metamorphosis from leptochephalus larva to glass eel) and subsequent annuli as winter checks (e.g., ICES 2011). Eels were considered by convention to be of age 0 + in their year of arrival in continental waters, and their “cohort year” was thus defined as so. Each otolith was aged twice by two eel experts to confirm aging. A total of 946 yellow eel otoliths were readable, representing 17 different cohorts, each comprising 1 to 127 individuals