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The International Union for Conservation of Nature (IUCN) Red List identifies threatened and endangered species and is a key instrument in global biodiversity conservation efforts. Our understanding of the structure and value of genetic biodiversity below the species level is rapidly increasing. Nonetheless, the IUCN assessment criteria overlook genetic variation within species. Here, we address this blind spot and discuss the principles of species conservation status classification relative to intraspecific biodiversity. We focus on coastal species, which thrive in heterogeneous environments known to drive genetic differentiation. The focal example species, Atlantic cod and sugar kelp, have contrasting life histories, are ecologically and economically important constituents of the coastal ecosystem, and are currently not classified as threatened in Norway and Canada. We expose important variation in population structure, the presence of ecotypes and genetic-environment covariation, as well as loss of ecotypes that threatens the conservation of these species. Because the genetic makeup of species directly influences their resilience, omitting this information from conservation status assessments can result in loss of adaptive capacity to future stressors, such as climate change. Consequently, recognizing and preserving intraspecific variation emerges as vital for species' abilities to adapt to and survive in future ocean conditions. [ABSTRACT FROM AUTHOR]

Knowledge of functional dispersal barriers in the marine environment can be used to inform a wide variety of management actions, such as marine spatial planning, restoration efforts, fisheries regulations, and invasive species management. Locations and causes of dispersal barriers can be studied through various methods, including movement tracking, biophysical modeling, demographic models, and genetics. Combining methods illustrating potential dispersal, such as biophysical modeling, with realized dispersal through, e.g., genetic connectivity estimates, provides particularly useful information for teasing apart potential causes of observed barriers. In this study, we focus on blue mussels (Mytilus edulis) in the Skagerrak—a marginal sea connected to the North Sea in Northern Europe—and combine biophysical models of larval dispersal with genomic data to infer locations and causes of dispersal barriers in the area. Results from both methods agree; patterns of ocean currents are a major structuring factor in the area. We find a complex pattern of source‐sink dynamics with several dispersal barriers and show that some areas can be isolated despite an overall high dispersal capability. Finally, we translate our finding into management advice that can be used to sustainably manage this ecologically and economically important species in the future. [ABSTRACT FROM AUTHOR]

Coastal seine surveys contain some of the only direct measures of age-0 abundance for Atlantic cod (Gadus morhua) and Pacific cod (Gadus macrocephalus), yet their utility in forecasting future year-class strength has not been evaluated among regions. We analyzed coastal time series from the Gulf of Alaska, Newfoundland, and Norway to test the hypothesis that recruitment signals are stronger when assessed under thermal conditions that provide high juvenile growth potential. Weaker recruitment signals were associated with low growth potential from cold winters (Newfoundland) and recent warmer summers (Norway). We conclude that temperature-dependent growth strongly influences the utility of coastal surveys in recruitment forecasting among regions. Temporal changes in growth potential (e.g., via climate change) will likely affect recruitment signals by way of changes in juvenile mortality or spatial shifts to more favorable thermal habitats. Si les releves cotiers a la senne constituent un des rares moyens d'obtenir des mesures directes de l'abondance de la classe d'age 0 pour la morue franche (Gadus morhua) et la morue du Pacifique (Gadus macrocephalus), leur utilite pour predire la force future des classes d'age n'a pas ete evaluee entre differentes regions. Nous avons analyse des series chronologiques cotieres pour le golfe de l'Alaska, Terre-Neuve et la Norvege afin de verifier l'hypothese selon laquelle les signaux de recrutement sont plus forts quand ils sont evalues pour des conditions thermiques qui assurent aux juveniles un potentiel de croissance eleve. Des signaux de recrutement plus faibles etaient associes a un faible potentiel de croissance decoulant d'hivers froids (Terre-Neuve) et d'etes plus chauds recents (Norvege). Nous en concluons que la croissance dependante de la temperature a une forte incidence sur l'utilite des releves cotiers pour predire le recrutement entre regions. Des variations temporelles du potentiel de croissance (p. ex., decoulant de changements climatiques) auront vraisemblablement une incidence sur les signaux de recrutement, par l'entremise de modifications de la mortalite des juveniles ou de deplacements dans l'espace vers des niches thermiques plus favorables. [Traduit par la Redaction], Introduction Marine teleost fishes of the Family Gadidae comprise some the largest and most valuable wild fisheries in the world (e.g., Atlantic cod, Gadus morhua; walleye pollock, Gadus chalcogrammus) and [...]

Exploited marine resources can be managed more effectively when accurate information on geographic population structure is available. Genetic markers offer a powerful tool for fisheries management, because they reveal biologically sound management units. Single nucleotide polymorphisms (SNPs) markers derived from restriction-site associated DNA sequencing (RAD-seq) were developed and used to investigate the stock structure of Greenland halibut (Reinhardtius hippoglossoides). A total of 96 SNPs were analyzed from 384 individuals and eight locations across the Atlantic. Our results suggest a subdivision of Greenland halibut into two populations, an eastern Atlantic population and a western Atlantic population, with a proposed border across the Denmark Strait. In general, Greenland halibut display weak but significant population structure (overall [F.sub.ST] = 0.003; p < 0.001), which can be explained by connectivity among populations owing to the migratory behavior or egg and larval drift. Les ressources marines exploitees peuvent etre gerees plus efficacement quand de l'information exacte sur la structure geographique de leurs populations est disponible. Les marqueurs genetiques constituent un puissant outil pour la gestion des peches parce qu'ils font ressortir des unites de gestion coherentes sur le plan biologique. Des marqueurs de polymorphismes mononucleotidiques (SNPs) derives du sequenqage d'ADN associe a un site de restriction (RAD-seq) ont ete developpes et utilises pour etudier la structure des stocks de fletan noir (Reinhardtius hippoglossoides). Un total de 96 SNP ont ete analyses de 384 individus et huit emplacements dans l'Atlantique. Nos resultats semblent indiquer le regroupement des fletans noirs en deux populations, une de l'est de l'Atlantique et l'autre de l'ouest de l'Atlantique, la frontiere proposee entre les deux traversant le detroit du Danemark. En general, les fletans noirs presentent une structure de populations faible mais significative ([F.sub.ST] global = 0,003; p < 0,001) qui peut s'expliquer par la connectivite des populations decoulant du comportement migratoire ou de la derive des reufs et des larves. [Traduit par la Redaction], Introduction Marine fish populations typically consist of large numbers of individuals with high dispersal potential in one or several life-history stages (Conover et al. 2006), which can result in a [...]

Cryptic population structure in exploited fishes poses a major challenge for fisheries management. In Atlantic cod, sympatric ecotypes are well-known, for instance off the coast of northern Norway. Recently, two sympatric cod ecotypes have also been documented in the Skagerrak and Kattegat, where adult cod has declined dramatically. One ecotype has an apparent offshore origin and displays a more migratory lifestyle than the other, which is generally resident at the coast throughout its life. To investigate their relative abundances along the Swedish west coast, juvenile cod were collected at high spatial resolution along the coast and genetically assigned to ecotypes. The results reveal large proportions of the coastal ecotype in the southern Kattegat, Öresund, and inshore Swedish Skagerrak, whereas the offshore ecotype dominates in offshore areas. A regression model comparison suggests that differences in bottom depth, rather than distance from the open sea, explain the heterogeneous spatial distribution of the two ecotypes. In addition, the two ecotypes display genetic differences suggesting adaptation to different environments. The results underline that successful fisheries management requires identification and consideration of locally adapted sympatric ecotypes. [ABSTRACT FROM AUTHOR]

As human exploration and harvesting moves to the high seas, ecological understanding of the deep sea has become a priority, especially in those commercially exploited species whose life cycle, habitat use, and demographic structure remain poorly understood. Here we combine otolith trace element and stable isotope analyses with microsatellite data to investigate population structure and connectivity in the migratory deep-sea black scabbardfish (Aphanopus carbo), sampled along a latitudinal gradient spanning much of the known species range in the Northeast Atlantic. In each sampled life stage, otolith trace element and oxygen isotope compositions are similar among fish from different capture locations, but otolith compositions vary greatly between life stages. Oxygen isotope compositions indicate ontogenetic migrations from relatively warm water conditions during larval growth to cooler waters with increasing age. Analysis of microsatellite DNA also suggests lack of genetic structure among the areas sampled. The multidisciplinary approach employed collectively suggests that A. carbo individuals undergo an ocean-scale ontogenetic migration, beginning with spawning in southern, warm-water Macaronesian areas (potentially dominated by Madeira), followed by a large proportion of immature fish moving to and feeding on the continental slope in northern areas. The results lend the first conclusive evidence for defining the life-history circuit of this species and the perception of its stock structure across the North Atlantic. L'exploration humaine vers la haute mer et l'exploitation de cette derniere font en sorte que la comprehension ecologique des profondeurs marines devient prioritaire, particulierement en ce qui concerne les especes exploitees a des fins commerciales dont les cycles biologiques, les habitudes d'utilisation de l'habitat et les structures demographiques demeurent mal compris. Nous combinons l'analyse des elements en traces et des isotopes stables des otolites a des donnees de microsatellites pour etudier la structure et la connectivite des populations de sabres noirs (Aphanopus carbo), une espece demersale migratrice, echantillonnees le long d'un gradient couvrant une bonne partie de l'aire de repartition connue de l'espece dans le nord-est de l'Atlantique. Pour chaque etape du cycle de vie echantillonnee, les poissons captures dans des lieux differents presentent des concentrations semblables d'elements en traces et d'isotopes stables dans les otolites, alors que la composition des otolites varie grandement d'une etape du cycle de vie a l'autre. Les concentrations d'isotopes d'oxygene indiquent l'existence de migrations ontogeniques a partir de lieux caracterises par des eaux relativement chaudes durant la croissance des larves, vers des eaux plus froides a mesure que les poissons vieillissent. L'analyse de microsatellites d'ADN semble egalement indiquer une absence de structure genetique entre les differents lieux echantillonnes. L'approche multidisciplinaire employee donne collectivement a penser que les individus d'A. carbo effectuent une migration ontogenetique d'echelle oceanique qui commence par le frai dans des regions meridionales d'eau chaude de la Macaronesie (potentiellement dominees par la region de Madere), suivi du deplacement d'une grande partie des poissons immatures vers les pentes continentales de regions septentrionales, oU ils s'alimentent. Nos resultats constituent les premieres donnees concluantes permettant de circonscrire le circuit emprunte par cette espece au cours de son cycle de vie et d'entrevoir la structure du stock a l'echelle de l'Atlantique Nord. [Traduit par la Redaction], Introduction For most deep-sea fish, there is rather limited information on general ecology, life cycles, and population structure (Begg et al. 1999). In particular, the extent of large-scale migrations in [...]