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In the Northwest Atlantic (NWA), the Atlantic mackerel (Scomber scombrus) has a northern and a southern contingent, which spawn in Canada and the United States (U.S.), respectively. Both contingents mix mostly along the U.S. shelf during overwintering. The discrimination of individuals from each contingent in fisheries could improve the management of this depleted species in both countries. Here, we used genome-wide markers (>10 000 single nucleotide polymorphisms (SNPs)) to assess genomic differences between mackerel of both contingents, and possibly infer the proportions of each contingent in NWA management units. Small but significant genetic differentiation was observed between the northern and southern contingents ([F.sub.ST] = 0.0010). Genetic assignments to reference samples from the two contingents were performed with predictive accuracy > 85%. Fish from both contingents were present along the U.S. shelf during late winter and early spring but also, without prior evidence of this, likely in Canadian waters from late spring to fall. Genetic assignments could be used as a stock discrimination tool so that fishery removals can be effectively determined and managed on a contingent level. Key words: population genomics, fisheries, Scombridae, migratory, pelagic, fish, Introduction Defining the population structure of marine migratory fish species is challenging. Long-distance migrants may cross multiple management jurisdictions each year and have multiple spawning areas (e.g., Puncher et al. [...]

Knowledge about sex‐specific difference in life‐history traits—like growth, mortality, or behavior—is of key importance for management and conservation as these parameters are essential for predictive modeling of population sustainability. We applied a newly developed molecular sex identification method, in combination with a SNP (single nucleotide polymorphism) panel for inferring the population of origin, for more than 300 large Atlantic bluefin tuna (ABFT) collected over several years from newly reclaimed feeding grounds in the Northeast Atlantic. The vast majority (95%) of individuals were genetically assigned to the eastern Atlantic population, which migrates between spawning grounds in the Mediterranean and feeding grounds in the Northeast Atlantic. We found a consistent pattern of a male bias among the eastern Atlantic individuals, with a 4‐year mean of 63% males (59%–65%). Males were most prominent within the smallest (< 230 cm) and largest (> 250 cm) length classes, while the sex ratio was close to 1:1 for intermediate sizes (230–250 cm). The results from this new, widely applicable, and noninvasive approach suggests differential occupancy or migration timing of ABFT males and females, which cannot be explained alone by sex‐specific differences in growth. Our findings are corroborated by previous traditional studies of sex ratios in dead ABFT from the Atlantic, the Mediterranean, and the Gulf of Mexico. In concert with observed differences in growth and mortality rates between the sexes, these findings should be recognized in order to sustainably manage the resource, maintain productivity, and conserve diversity within the species. [ABSTRACT FROM AUTHOR]

Based on collaboration with the Greenlandic fishing fleet, we document the presence of Atlantic bluefin tuna (Thunnus thynnus) in most years from 2012 to 2018 in the waters east of Greenland (northern Irminger Sea). In total, 84 individuals have been registered as bycatch in the commercial fisheries in Greenland waters, which indicates that the first catch of three individuals in 2012 was not a single extreme observation, but that East Greenland waters have become a new outer limit of an expanded tuna habitat. Genetic analyses indicate that specimens from this region are mostly of Mediterranean origin with a small proportion originating from the Gulf of Mexico stock. Stomach content analysis suggests that the main prey is Atlantic mackerel (Scomber scombrus). The tunas ranged in size from 140 to 270 cm, corresponding to an estimated age range of 5-16 years; most were probably mature. The wide size-age range suggests that many year classes are participating in the migration to this region. Sea temperatures during summer have been above the long-term average in recent years of interest. Summer residence of bluefin tuna in the region could be due to a combination of increasing temperatures and higher overall abundances of both bluefin tuna and a key prey species (Atlantic mackerel). Une collaboration avec la flotte de peche groenlandaise nous permet de documenter la presence de thons rouges de l'Atlantique (Thunnus thynnus) durant la plupart des annees de 2012 a 2018 dans les eaux a l'est du Groenland (mer d'Irminger septentrionale). Au total, 84 individus ont ete releves comme prises accessoires dans les peches commerciales dans les eaux groenlandaises, ce qui indique que les premieres prises de trois specimens en 2012 n'etaient pas des observations extremes isolees, mais que les eaux de l'est du Groenland constituent maintenant une nouvelle limite d'un habitat du thon en expansion. Des analyses genetiques indiquent que les specimens de cette region sont principalement originaires de la mer Mediterranee, une petite proportion provenant aussi du stock du golfe du Mexique. L'analyse de contenus stomacaux indiquerait que leur principale proie est le maquereau bleu (Scomber scombrus). La taille des thons recenses va de 140 a 270 cm, ce qui correspond a une fourchette d'ages estimes de 5 a 16 ans, la plupart des individus etant probablement matures. Cette grande fourchette d'ages donne a penser que de nombreuses classes d'age participent a la migration vers cette region. Au cours des dernieres annees, les temperatures estivales de la mer ont depasse la moyenne a long terme. La residence estivale de thons rouges de l'Atlantique dans la region pourrait etre due a une combinaison de temperatures croissantes et des plus grandes abondances globales des thons rouges et d'une importante espece proie (le maquereau bleu). [Traduit par la Redaction], Introduction Distributions and migratory behaviour of species depend on a range of abiotic and biotic factors. These include properties of the environment that directly affect bioenergetics and physiology of the [...]

Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapshot of the marine microbial biodiversity and function of the world's oceans. It is a simultaneous global mega-sequencing campaign aiming to generate the largest standardized microbial data set in a single day. This will be achievable only through the coordinated efforts of an Ocean Sampling Day Consortium, supportive partnerships and networks between sites. This commentary outlines the establishment, function and aims of the Consortium and describes our vision for a sustainable study of marine microbial communities and their embedded functional traits.

The co-authors of this paper hereby state their intention to work together to launch the Genomic Observatories Network (GOs Network) for which this document will serve as its Founding Charter. We define a Genomic Observatory as an ecosystem and/or site subject to long-term scientific research, including (but not limited to) the sustained study of genomic biodiversity from single-celled microbes to multicellular organisms.An international group of 64 scientists first published the call for a global network of Genomic Observatories in January 2012. The vision for such a network was expanded in a subsequent paper and developed over a series of meetings in Bremen (Germany), Shenzhen (China), Moorea (French Polynesia), Oxford (UK), Pacific Grove (California, USA), Washington (DC, USA), and London (UK). While this community-building process continues, here we express our mutual intent to establish the GOs Network formally, and to describe our shared vision for its future. The views expressed here are ours alone as individual scientists, and do not necessarily represent those of the institutions with which we are affiliated.