ICES Journal of Marine Science: Journal du Conseil

Norderhaug, Kjell Magnus; Knutsen, Halvor; Filbee-Dexter, Karen; Sodeland, Marte; Jorde, Per Erik; Wernberg, Thomas; Oomen, Rebekah; Moland, Even

doi: 10.1093/icesjms/fsae039pmid: N/A

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.

Misund, Ole Arve

doi: 10.1093/icesjms/fsae045pmid: N/A

I recount my personal history, beginning as a young fisherman, becoming an academic fisheries biologist, and ultimately a leader of institutions dedicated to marine and polar research, higher education, and advising policymakers. After my dissertation in the early 1990s, I embarked on an active research career at the Institute of Marine Research (IMR) in Bergen, Norway, developing a sonar method to estimate the abundance of schooling, pelagic fish. My career then transitioned to middle leadership—15 years as Section Leader and Research Director at IMR—followed by >10 years as a top leader for The University Centre in Svalbard, the National Institute of Nutrition and Seafood Research, and finally the Norwegian Polar Institute. I describe the major challenges, opportunities, and processes these leadership roles have entailed. I hope to send a positive message about the influential role of science, and the necessity of clear communication of results and advice at a time when there is a sense of urgency.

Gammage, Louise C; Longo, Catherine S; van Putten, Ingrid; Bucio-Bustos, Edaysi; Gordon, Andrew Kenneth; Lejbowicz, Amanda; Vergara-Solana, Francisco J

doi: 10.1093/icesjms/fsae038pmid: N/A

Addressing diverse and complex socio-ecological challenges is crucial for achieving ocean sustainability. This is especially true for effective fishery management, which is vital for the sustainability of marine resources. One way of overcoming barriers to fisheries reform is through interdisciplinary collaboration and innovative management and policy approaches. One such approach is market incentives offered by eco-certification against sustainability standards, such as those set by the Marine Stewardship Council (MSC). Complementary interventions that support sustainability improvements are fishery improvement projects (FIPs) and MSC pathway projects. These interventions have clear intermediary and final objectives, and monitoring impact throughout the implementation process remains important. We interviewed participants of a pathway project from five fisheries in South Africa and Mexico using semistructured interviews designed to capture the nonmonetary impacts of these projects as they progress. Our results show that interventions can play a role in facilitating broader collaboration within a fishery and across stakeholder groups, increasing sustainability awareness. Emphasizing the importance of stakeholder engagement and collaboration, we highlight how the project implementation process can lead to communication changes that lead to improved understanding and collaboration. Importantly, we reflect on the suitability of the survey in monitoring progress in such projects.

Sobradillo, Beatriz; Boyra, Guillermo; Uranga, Jon; Moreno, Gala

doi: 10.1093/icesjms/fsae040pmid: N/A

Tropical tuna fisheries support some of the largest artisanal and industrial fisheries worldwide. Approximately 37% of the tropical tuna catch by industrial purse seiners is obtained from tuna associated with drifting fish aggregating devices (DFADs), where three tuna species coexist: skipjack (Katsuwonus pelamis), bigeye (Thunnus obesus), and yellowfin tuna (Thunnus albacares), with stocks subject to different health status. Purse seine fishers heavily rely on acoustic technology to detect and assess the quantity of tuna at DFADs. Yet, accurately distinguishing between species using solely acoustic methods is limited by insufficient knowledge about each species' acoustic response across frequencies. This study was carried out on six swimbladdered individuals belonging to two sets with mean lengths of 51.9 ± 9.5 and 52.9 ± 2 cm. It focuses on the frequency response obtained from ex situ measurements of yellowfin tuna recorded at 38, 70, 120, and 200 kHz, which revealed a flat response across frequencies, with b20 values of −72.4 ± 9, −73.2 ± 8, -72.3 ± 8, and −72.3 ± 9 dB, respectively. These results, contrast with previous findings on bigeye and skipjack, demonstrating the discrimination potential of acoustics in these three species. To harness this potential, a discrimination algorithm was developed.

Vadrot, Alice B M; Wanneau, Krystel

doi: 10.1093/icesjms/fsae041pmid: N/A

Marine biodiversity monitoring is a complex task given the vast ocean areas to be covered, the types of data to be integrated, and the large number of possible parameters to consider when measuring biodiversity change. International agreements, such as the Convention on Biological Diversity (CBD) or the recently adopted ‘BBNJ treaty’protecting biodiversity beyond national jurisdiction (BBNJ), encourage states to monitor marine life both within and beyond their national waters to foster marine biodiversity conservation and sustainable use. While oceanographers in general, and marine biologists in particular, are aware of the challenges and complexities of measuring biodiversity in the ocean, the politics of marine biodiversity monitoring and the added value of social science perspectives tend to be neglected. This story from the frontline describes our experiences with turning marine biodiversity monitoring into an object of social science inquiry. The MARIPOLDATA project developed an innovative multi-sited approach to capture both the politics and practices of monitoring marine life. During our research, we were confronted with a diversity of perspectives and expectations of what monitoring is, how it works, why it should be done, and whom it should serve. By adopting a mixed-method approach and collecting data at different epistemic sites (negotiation rooms, scientific fields, laboratories, and conferences), we tried to cut through some of the observed ambiguities and trends. We conclude that studying monitoring necessitates a multidisciplinary approach and a sensitivity for the regional, institutional, and cultural specificities and inequalities that shape how we know and govern the ocean.

Hansen, Cecilie; Hjøllo, Solfrid Sætre; Skogen, Morten D; Mousing, Erik Askov; Skern-Mauritzen, Mette; Howell, Daniel; Ottersen, Geir; Browman, Howard I

doi: 10.1093/icesjms/fsae042pmid: N/A

With a biomass of ∼4 million tonnes, and annual catches of 900 000 tonnes, the northeast Atlantic (NEA) cod stock in the Barents Sea is the world’s largest. Scientists have been trying to explain the variability in recruitment of this stock for over 100 years, in particular connecting it to spawning stock biomass and environmental factors such as temperature. It has been suggested that the combination of ocean acidification and global warming will lead to a significant decrease in the spawning stock biomass and an eventual (end of this century) collapse of the NEA cod stock in the Barents Sea. We show that a temperature- and OA-driven decline in recruits will likely lead to a smaller cod stock, but not to a collapse. Instead, the level of fishing pressure and, not least, the choice of the recruitment function applied in simulations and how it relates to temperature, is extremely important when making such forecasts. Applying a non-linear relationship between temperature and spawning stock biomass—as has been done in studies that predict a collapse of the NEA cod stock—does not improve accuracy and, in addition, adds a large decrease in number of recruits that is not biologically supported.

Dumont, Agathe; Duparc, Antoine; Sabarros, Philippe S; Kaplan, David M

doi: 10.1093/icesjms/fsae043pmid: N/A

Bycatch rates are essential to estimating fishery impacts and making management decisions, but data on bycatch are often limited. Tropical tuna purse seine (PS) fisheries catch numerous bycatch species, including vulnerable silky sharks. Even if bycatch proportion is relatively low, impacts on pelagic ecosystems may be important due to the large size of these fisheries. Partial observer coverage of bycatch is a major impediment to assessing impacts. Here we develop a generic Δ modeling approach for predicting catch of four major bycatch species, including silky sharks, in floating object-associated fishing sets of the French Indian Ocean PS fleet from 2011 to 2018 based on logbook and observer data. Cross-validation and variable selection are used to identify optimal models consisting of a random forest model for presence–absence and a negative binomial general-additive model for abundance when present. Though models explain small to moderate amounts of variance (5–15%), they outperform a simpler approach commonly used for reporting, and they allow us to estimate total annual bycatch for the four species with robust estimates of uncertainty. Interestingly, uncertainty relative to mean catch is lower for top predators than forage species, consistent with these species having similar behavior and ecological niches to tunas.

Skolgund, Helge; Kambestad, Marius; Normann, Eirik Straume; Wiers, Tore; Lehmann, Gunnar Bekke; Urdal, Kurt; Barlaup, Bjørn Torgeir; Vollset, Knut Wiik

doi: 10.1093/icesjms/fsae047pmid: N/A

Farmed salmon escaping from aquaculture and interbreeding with wild conspecifics pose a significant threat to the genetic integrity of natural salmon populations. Despite advancements in aquaculture security, escape incidents persist, prompting the need for effective mitigation strategies. This study summarizes experiences from efforts to remove escaped farmed salmon over a 12-year period in 63 western Norwegian rivers, using either (1) spearfishing during snorkelling by trained personnel or (2) traditional fishing methods employed by local groups. Recaptured farmed salmon ranged widely in size and included both spawners as well as immature fish, demonstrating that farmed fish entering rivers comprise fish of different ages and escape histories. Traditional fishing by locals recaptured the highest number of farmed fish, while removal during snorkelling in general captured larger and mature fish. On average, 53% of the farmed salmon observed during snorkelling were recaptured. This efficacy was influenced by the number of farmed fish present and the size of the farmed fish. In addition, efficacy increased over time, indicating that the removal team became more efficient. The study underscores that active removal, when executed judiciously, contributes to reducing the ecological risks associated with escaped farmed fish, complementing broader strategies for sustainable aquaculture.

Carloni, Joshua T; Wahle, Richard A; Fields, David M; Geoghegan, Paul; Shank, Burton

doi: 10.1093/icesjms/fsae051pmid: N/A

We build on previous research describing correlative links between changes in the abundance of the copepod Calanus finmarchicus, a foundational zooplankton species of the pelagic food web, and diminishing recruitment of young-of-year American lobster (Homarus americanus) to benthic nurseries in the Gulf of Maine. Using parallel 31-year time series of lobster larvae and zooplankton collected on the New Hampshire coast between 1988 and 2018, we investigated how changes in phenology of stage I larval lobster and their putative copepod prey, C. finmarchicus, affect their temporal overlap and potential to interact during the larval season. We found that over the time series both the lobster egg hatch and first appearance of larvae began earlier in the season, a trend significantly correlated with ocean warming. The last appearance of larvae in late summer has been delayed, however, thereby extending the larval season. Even with the longer larval lobster season, the C. finmarchicus season has increasingly been ending before the peak abundance of stage I lobster larvae. The net effect is a widening mismatch in phenology of the two species, an outcome consistent with the hypothesis that changes in abundance and phenology of C. finmarchicus have contributed to recent declines in lobster recruitment.

Wang, Terrance; Szuwalski, Cody S; Punt, André E; Hilborn, Ray

doi: 10.1093/icesjms/fsae052pmid: N/A

Fishing behavior is an important link between management decisions and bioeconomic outcomes. The diversity in fishers’ behavior, motivations, and abilities should inform incentive structures if management aims to consider heterogeneous impacts on and by communities. Modeling human behavior in resource management is important for successful fisheries, especially for fisheries undergoing rapid transformation, such as the Alaskan snow crab fishery. This study modeled how snow crabbers choose where to fish in the eastern Bering Sea and examined the diversity of strategies among individuals by fitting a random utility model to data on fishing locations using a variety of potential drivers of behavior as covariates. The overall fishing strategy of the snow crab fleet prioritizes revenue and shared information, while avoiding risk, poor weather, and cost. Diversity of fishing strategies was driven by differences in spatial footprint, vessel size, and ports of landing. Larger vessels ventured farther north, where weather conditions are more extreme. Despite differences in vessel size, crabbers were spatially adaptive and switched fishing regions depending on the abundance and distribution of crab. These findings on the patterns of fishing strategies can inform better management of the Alaskan snow crab fishery as it undergoes rebuilding.