ICES Journal of Marine Science: Journal du Conseil

Quintela, María; Mateos-Rivera, Alejandro; Westgaard, Jon-Ivar; Johansen, Torild; Staby, Arved

doi: 10.1093/icesjms/fsag013pmid: N/A

The stock delineation of European hake, Merluccius merluccius has long been debated due to the persistent discrepancies between biologically defined populations and management units, despite the species’ significant economic importance. This study investigated population genetic structure within the northern European hake stock using 44 SNP markers following linkage disequilibrium-pruning. Whereas two of the loci were identified as consensus candidate outliers for positive selection, no balancing selection was detected. We found further evidence to challenge the current stock delineation by identifying a genetically distinct subunit in the Skagerrak. Likewise, and beyond the management delineation of the northern stock, European hake in a coastal/fjordic area of the Norwegian Sea was found to be significantly different. Our findings suggest that fine-scale genetic population structure should be explored in combination with life history traits to align biologically meaningful units with stock boundaries and facilitate sound resource management. Additionally, this study also contributes to the growing body of literature documenting marine species with populations in the Skagerrak that are genetically or ecologically distinct from those in adjacent seas; a differentiation that is partially driven by the strong salinity gradients resulting from the mixing of saline Atlantic and brackish Baltic waters.

Grant, William Stewart

doi: 10.1093/icesjms/fsag006pmid: N/A

The past 150 years have seen enormous advances in the development of genetics theory and molecular methods to survey genetic variability in natural populations. In the late 1800s, the identification of “races” among populations of fishes paralleled concepts in the human Eugenics movement at the time. Later, the developments of population genetics theory and of statistical tests provided the foundations for the application of genetic concepts to fishery problems. The methods used to study natural populations were restricted to the analysis of phenotypic traits, such as morphology and meristics, which had an unknown genetic basis. Tag recoveries and analyses of otoliths, scale rings, fin and vertebral counts, and spawning timing were used to define biologically discrete population units. Genetic markers to define genetic boundaries between stocks of fish appeared only in the 1960s. Early methods included the electrophoretic analyses of proteins to produce genetic population tags that could be rigorously analysed with statistics. The analysis of DNA was initiated in the 1970s with the discovery of restriction enzymes to probe DNA sequence variation. The development of the polymerase chain reaction to amplify specific regions of DNA led to the development of random amplified polymorphic DNA markers, microsatellite markers, DNA sequences (especially of mitochondrial DNA), and more recently single nucleotide polymorphisms. The analysis of DNA in archived tissues, such as fish scales and otoliths used for aging, provides insights into historical population dynamics and the analysis of environmental DNA aids in biodiversity assessments. The development of cost-effective genomic DNA analysis underpins new approaches for better understanding adaptation to local habitats. From its inception, the ICES Journal of Marine Science has published articles that recognized the importance of incorporating genetic principles into fishery management. While the Journal has published genetic research on numerous species, this review follows the development of genetic methods in three commercially important species: Atlantic herring, Atlantic cod and Atlantic salmon.

Hunt, George L

doi: 10.1093/icesjms/fsag018pmid: N/A

As a child, I had an interest in nature which, in my teen years, developed into a passion for birdwatching. During my undergraduate studies, small discussion courses helped me hone my ideas about ecology, while various research-related summer employment helped me to develop a clearer idea of the kinds of research that provided the greatest satisfaction and the habitats in which I most enjoyed working. Throughout my career I was afforded many opportunities that resulted from serendipity rather than planning. I also jumped at opportunities and took risks, including using a strong radioisotope to trace ant behavior and accepting a one-year teaching position at a research-oriented university before completing the analyses for my doctoral thesis. As my career matured, despite no training in oceanography, I began investigations of how seabirds depended on physical processes in the ocean. Later, I became interested in aspects of fisheries oceanography, again absent any formal training. My research was driven by curiosity and was facilitated by serendipity and superbly supportive colleagues. I greatly benefited from teaching both undergraduate and graduate students. I cherish the friendships that developed from mentoring graduate students, without whom much of my success would not have been possible. Supportive wives, first Molly Warner and later Peggy Williamson, were critical for my successes in many ways. Without them, much of what I accomplished would not have been possible.

Opdal, Anders Frugård; Alix, Maud; Kjesbu, Olav Sigurd; Jørgensen, Christian; Langangen, Øystein; Karlsen, Ørjan; McQueen, Kate; Nyqvist, Daniel; Olsen, Esben Moland; Thorsen, Anders; Skjæraasen, Jon Egil

doi: 10.1093/icesjms/fsag020pmid: N/A

At high latitudes, early life stage survival of fish is often associated with how spawning time relates to the timing of the spring bloom. With ocean warming, basic physiological rates of ectotherms, like fish, will speed up—including gonadal development rates, which dictate spawning time. Since warmer water is thought to influence the spring bloom timing differently than that of fish spawning time, the two may fall out of synchrony in the future. The precise mechanisms between temperature and gonadal development and spawning time have, however, been difficult to disentangle. Here, we take advantage of a series of independent laboratory experiments measuring individual oocyte development up to or near spawning for 153 Atlantic cod (Gadus morhua) kept between 3 and 12°C. From these data we derive a predictive, mechanistic equation for daily oocyte growth rate as a function of temperature and oocyte developmental status (diameter). The vitellogenic oocyte growth follows an accelerating pattern, and the model predicts that spawning can advance by up to 7 days per 1°C increase. Within-treatment variation is, however, of comparable magnitude to between-treatment temperature effects. The model was also tested in the field by back-calculating oocyte development of 82 fish (2018–2021) sampled at two locations along the Norwegian coast, using daily ambient temperatures from telemetry tags during vitellogenesis as model input. We find that Atlantic cod are able to initiate vitellogenesis over a period of several months in late summer and autumn, as well as regulate the oocyte development rate across a wide range of temperatures—both leading to significant phenotypic plasticity in spawning phenology.

Schadeberg, Amanda; Kraan, Marloes; Groeneveld, Rolf; Greene, Mary; Bush, Simon R

doi: 10.1093/icesjms/fsag012pmid: N/A

Scientific research vessels produce vital data for marine science and fisheries management, yet the social dimensions of data production at sea remain underexplored. Drawing on participant observation, interviews, and workshops, we employ practice theory to examine how scientific data are produced on research vessels. We find that research cruises contain four key complexes of practices: searching, retrieving, sorting, and datafication. We zoom in on three examples to show how the routinized practices performed on research vessels can embed certain ways of knowing the ocean into primary data about the deep ocean. In this case, discarding practices render certain organisms invisible, which has the effect of reproducing the single-species management paradigm while investigating a potential mesopelagic fishery. Zooming out shows how research vessel work connects to and reinforces existing analytical, commercial, and management practices. The selections and omissions that result from the routine nature of at-sea work fundamentally shape scientific understanding of the deep ocean, which in turn informs and determines future governance decisions. Finally, this framework and methodology demonstrate how interdisciplinary approaches can identify small realignments in scientific practices that can enhance research vessel work and adapt to rapidly changing knowledge needs.

Silva, Angela; Seara, Tarsila; Martinez, Kiara Acevedo; Christel, Douglas; Methratta, Elizabeth T

doi: 10.1093/icesjms/fsag002pmid: N/A

The increasing development of offshore wind energy creates challenges due to competing ocean usage. Given that offshore wind energy development (OWED) often overlaps with traditional fishing grounds, there is a need to establish a standardized process to monitor OWED impacts on socio-economic conditions. To that end, this paper proposes a standardized two-tiered project-level socio-economic monitoring framework. The monitoring framework focuses on OWED-specific risk factors (i.e. structure presence, vessel traffic, and port utilization) that significantly affect fisheries socio-economic conditions. The two tiers separate effects into direct (Tier 1) and indirect (Tier 2) impacts of OWED on commercial and recreational fishing. For example, the presence of structures (e.g, turbines) directly affects fishing vessels’ access to fishing grounds, which indirectly affects fisheries attributes such as where and how vessels conduct fishing activity. Consequently, this could affect costs and revenues. The structure employed in this paper allows for more effective prioritization of data collection since understanding the effects of the risk factors on Tier 1 elements is key for characterizing the effects of OWED on Tier 2 elements. The paper also recommends key indicators and assessment tools to evaluate changes in the fisheries socio-economic conditions throughout the lifespan of offshore wind projects. Future research should focus on operationalizing and testing this framework, taking into account specific contexts within the geographic area where monitoring occurs. Fishery socio-economic monitoring within the OWED context is needed to understand shifts in existing conditions, reduce conflict, and ensure that OWEDs respect and support fishery sustainability as well as the livelihood and dynamics within fishing communities.

Czaja, Raymond; Biggs, Christopher; Fung, Mai; Grüss, Arnaud; Hu, Xinping; Jensen, Christine; Montagna, Paul A; Olsen, Zachary; Beseres Pollack, Jennifer; Quigg, Antonietta; Yang, Zong-Liang; Liu, Zhanfei

doi: 10.1093/icesjms/fsag014pmid: N/A

Climate change is exacerbating the frequency and intensity of severe weather conditions. The ecosystem approach to fisheries management (EAFM) may benefit from considering how severe weather conditions interplay with biotic relationships, including predator-prey relationships and density dependence, to predict spatiotemporal trends of relative abundance of fishery species. Dynamic structural equation modelling (DSEM) is used to assess the impact of severe drought, salinity, and biotic relationships in predicting abundances of select predator and prey species in two Gulf of Mexico estuaries: the Mission-Aransas Estuary and Trinity-San Jacinto Estuary. In the DSEM framework, models include lagged and non-lagged effects, as well as direct and indirect effects in two trophic systems: a sciaenid trophic system of Red Drum (predator), Spotted Seatrout (predator), Atlantic Croaker (prey), and Blue Crab (prey); and a keystone predator system of Bull Shark (predator), Alligator Gar (predator), Gulf Menhaden (prey), and Striped Mullet (prey). The most parsimonious models retained trophic (manifested through bottom-up and top-down effects) and density-dependent relationships in both trophic systems in the Trinity-San Jacinto Estuary, but the sciaenid trophic system in the Mission-Aransas Estuary did not retain trophic relationships. Tight predator-prey relationships (Red Drum-Atlantic Croaker and Bull Shark-Striped Mullet) helped produce high prediction skill for predators (e.g. >0.83 Spearman’s rho correlations for these predators). Drought impacts were often negative, but varied between and within estuaries. For example, Spotted Seatrout abundances were up to 55% lower in severely dry years in the most saline bay within the Mission-Aransas Estuary, but were up to 45% higher in severely dry years in fresher bays within the Trinity-San Jacinto Estuary. The DSEM approach allowed us to identify that drought can have lagged and indirect effects on predators through bottom-up and density-dependent effects, and that biotic lagged and indirect effects can offset immediate direct impacts of drought. Overall, the results indicate that accounting for trophodynamics, density dependence, and drought can lead to robust predictions of estuarine predators via DSEM, an EAFM tool that can enhance resource management. Additionally, management approaches should be locale-specific because baseline salinity conditions affect how different estuaries and bays respond to severe weather conditions.

Cubaynes, Hannah C; Vergara-Pena, Alejandra; Bowler, Ellen; Downie, Rod; Forcada, Jaume; Garde, Eva; Heide-Jørgensen, Mads Peter; Higdon, Jeff W; Ida, Emina; Kovacs, Kit M; Lancaster, Melanie L; Lapointe St-Pierre, Mathilde; Lydersen, Christian; Matthews, Cory J D; Spencer, Matt; Fretwell, Peter T

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Claver, Cristina; Sobradillo, Beatriz; Mendibil, Iñaki; Canals, Oriol; Boyra, Guillermo; Ibaibarriaga, Leire; Kelly, Ryan P; Rodríguez-Ezpeleta, Naiara

doi: 10.1093/icesjms/fsag005pmid: N/A

Accurate abundance estimates of fisheries resources are essential for sustainable fisheries management. In response to the growing need for developing more accurate and cost-effective biomass estimation methods, the analysis of environmental DNA (eDNA) has recently emerged as an alternative for fish abundance quantification. However, practical approaches for integrating eDNA data into fisheries assessment remain limited. Here, we introduce a Bayesian joint model that combines acoustic-trawl and eDNA data to estimate fish biomass. Utilizing 209 water eDNA samples and 196 acoustic transects, the model was applied to estimate the distribution and abundance of the European anchovy (Engraulis encrasicolus) in the Bay of Biscay. The joint model produced similar estimates to those derived from acoustic observations alone and consistent with known spatial patterns of anchovy, with eDNA data suggesting a broader distribution and potentially higher abundance. This research demonstrates the value of incorporating eDNA data as a complement to acoustic-trawl for stock assessment and illustrates the versatility of joint Bayesian models and their potential application to various species and datasets. Ultimately, our work opens new avenues for more holistic fisheries assessment, underscoring the growing role of eDNA in that context.

Vihtakari, Mikko; Aune, Magnus; Assmann, Karen M; Howell, Daniel; Hallfredsson, Elvar H; Ward, Eric J

doi: 10.1093/icesjms/fsag009pmid: N/A

Monitoring stock status using fisheries-independent methods is essential for sustainable marine resource management. These methods help identify biases in fisheries-dependent data but often require comprehensive, long-term surveys. Recent advancements in spatiotemporal models enable the integration of fisheries-independent data from multiple sources, enhancing stock status estimates. We compiled bottom trawl survey data (over 43 000 trawl hauls from 1981 to 2024) for beaked (Sebastes mentella) and golden redfish (Sebastes norvegicus) from the Institute of Marine Research databases. Using spatiotemporal generalized linear mixed-effects models, we estimated trends and spatial distributions of these species in the Barents and Norwegian Seas. Model selection, conducted through 10-fold cross-validation, highlighted depth, spatial, and spatiotemporal random fields as crucial components for estimating survey indices. Beaked redfish had the highest biomass densities in the Central Barents Sea, while golden redfish dominated along the Norwegian Coast. Nursery areas for both species were primarily located in the Barents Sea, with beaked redfish juveniles distributed further north. We also detected distribution shifts: the Central Barents Sea has gained beaked redfish biomass, while the Southern Barents Sea and the close shore Norwegian coast are increasingly important for golden redfish. Additionally, we observed reductions in golden redfish biomass on the large banks south of Lofoten and in the Western and Central Barents Sea. Biomass indices indicated a positive trend for beaked redfish and a stable trend for golden redfish. Biomass changes in beaked redfish were correlated with rising bottom temperatures; however, golden redfish were only weakly correlated. The survey indices for both species correlated with commercial catches and total stock biomass estimates from current assessments. This study demonstrates the capability to track changes in species distribution over time, improving stock assessments. The methodology presented here is applicable for monitoring and managing marine species globally.