ICES Journal of Marine Science

Silvar-Viladomiu, Paula; Cavan, Emma L; Martin, Angela H; Bentley, Jacob W; Hill, Simeon L; Reid, David G

doi: 10.1093/icesjms/fsag095pmid: N/A

The marine biological carbon cycle plays a crucial role in the sinking and sequestration of atmospheric carbon and in regulating the global climate. Most existing research on biological carbon sequestration has focused on the role of oceanic (off-shelf) species and processes. We know little about how species living on continental shelves contribute to and influence carbon sinks due to the complex dynamics of biological and physical transport processes. However, continental shelves often have high levels of carbon productivity and a high potential for disturbance from human activities such as fishing, which strongly impact fish communities. Fish are important components of ecosystems that interact with the biological carbon cycle. Here, we used an Ecopath with Ecosim food web model of the Irish Sea coupled with biogeochemical equations to provide a novel quantitative assessment of the contribution of the fish community to the annual carbon reaching the continental-shelf seafloor over a four-decade simulation (1973–2016). Similar to the open ocean, faecal pellets dominated estimates of fish-mediated carbon flux in the Irish Sea. Our simulations imply that pelagic fish contribute more than half of the fish-mediated carbon, equivalent to approximately 2% of the plankton-mediated carbon deposited on the seafloor. Our results provide the first quantitative assessment and early insights into the relationship between fish species and the biological carbon sink in a shelf ecosystem.

Asche, Frank; Smith, Martin D

doi: 10.1093/icesjms/fsag092pmid: N/A

Many studies in fisheries and aquaculture begin with the premise that small is beautiful, while large is problematic. That is, large fishing vessels, large aquaculture farms, and large seafood companies as well as global markets undermine environmental, economic, and social sustainability in the seafood sector. However, there is limited evidence to support this sweeping generalization. In this paper, we look closer at the thesis that small is beautiful (and the complementary claim that large is not) using literature on economic and social status of fisheries and aquaculture primarily from the last three decades. We find that healthy fish stocks and environmental sustainability in general are independent of scale but highly dependent on governance. Our findings are similar with respect to economic and social sustainability, as different opportunities and resources are best utilized using suitable approaches with varying scales, and poor outcomes are associated with small as well as large sizes. As such, studies that start with a preference for any size are likely to overlook valuable perspectives and solutions.

Ingram, Evan C; Dunton, Keith J; Frisk, Michael G; Butler, Liam

doi: 10.1093/icesjms/fsag091pmid: N/A

(1) The rapid expansion of offshore wind energy raises concerns about potential impacts on marine wildlife, yet development often outpaces the capacity for ecological assessment. Data-limited species in offshore environments are particularly challenging to monitor, constraining the ability to evaluate potential risks and design evidence-based management strategies across large marine areas. (2) We present a novel, scalable framework based on ensemble machine learning methods, including shallow neural networks, to predict species distribution across extensive, data-limited marine systems. By combining multiple algorithms with high-resolution environmental predictors, the framework reduces model-specific bias, improves predictive reliability, and generates transparent, reproducible spatial predictions of species occurrence. This integrative approach demonstrates how heterogeneous and non-traditional data streams can be formally combined to inform applied ecological decisions. (3) We demonstrate the framework using Atlantic Sturgeon (Acipenser oxyrinchus), a long-lived, highly migratory species of conservation concern, by leveraging cooperative acoustic telemetry detections to predict distributions at ∼1 km² resolution across more than 620 000 km² of northwest Atlantic continental shelf waters. The approach explicitly accounts for dynamic habitat use and seasonal movements, providing a realistic representation of the species’ spatial ecology in areas of limited observational coverage. (4) In the context of expanding offshore development and other emerging ocean uses, map outputs from these models function as ecological triage tools, providing early, defensible predictions to prioritize monitoring and help to allocate survey resources across areas of varying predicted risk. Importantly, the approach avoids the longstanding tendency to interpret data gaps as evidence of negligible risk, supporting precautionary and adaptive decision-making to better inform management under constrained conservation resources. (5) Synthesis and applications. The framework is modular and broadly transferable, applicable to other taxa, regions, and regulatory contexts, and readily accommodates new data as monitoring coverage grows. Embedding ensemble-based predictions within existing regulatory processes enhances transparency, defensibility, and ecological realism of offshore impact assessments. By linking predictive models directly to monitoring and management decisions, this approach supports adaptive, evidence-based stewardship of marine resources in an era of rapid offshore development, increasing human ocean use, and escalating conservation pressures.

Gillespie, Douglas; Harris, Robert N; Sparling, Carol

doi: 10.1093/icesjms/fsag098pmid: N/A

Reducing pinniped predation on salmonid fish in river environments is an important conservation priority in rivers globally. In UK rivers, predation by seals on endangered Atlantic salmon is considered to be an important factor in their continuing poor conservation status. Acoustic deterrent devices (ADDs) have often been considered a useful tool in preventing seals from entering rivers, but continuous operation raises concerns about impacts on non-target wildlife and the potential for seal habituation. We developed an automated system that uses multibeam imaging sonar to detect seals in real time and triggers an ADD only when a seal is present. This targeted approach reduces the likelihood of harm to other animals and reduces the likelihood that seals will habituate to deterrent signals. The system was deployed for four months on a Scottish river, during which it successfully detected and triggered on 71 seals travelling upstream. Comparison with historical control data from previous years and from the pre-deployment period suggests an approximate 90% reduction in upstream seal movements during operation. Although river conditions occasionally resulted in elevated false-trigger rates, on most days the deterrent was only active on average for 65 s (<0.1% of each day). These results indicate that automated, event-triggered, acoustic deterrence can substantially reduce seal incursions while minimizing acoustic exposure to other sensitive wildlife.

Karang, I Wayan Gede Astawa; Basheer Ahammed, K K

doi: 10.1093/icesjms/fsag093pmid: N/A

Spatiotemporal changes in mangrove health within urbanized estuaries are indicators of coastal resilience under increasing anthropogenic and climatic pressures. This study analyzes species-level mangrove health dynamics in Benoa Bay, Bali, an area experiencing significant hydrological alteration due to reclamation and infrastructure development. We used a multiscale, multisensor remote sensing approach (PlanetScope SuperDove, Sentinel-2 MSI, and Landsat 8/9 TIRS,) spanning the period from 2018–2025, to separate the spectral-physiological responses of six dominant mangrove species, namely, Sonneratia alba Sm., Rhizophora apiculata Blume, Rhizophora mucronata Poir., Bruguiera gymnorhiza (L.) Lam, Ceriops tagal (Perr.) C.B. Robinson, and Avicennia spp. We used a random forest classification model, which achieved a validation accuracy of 0.82, to stratify the study area. We subsequently analyzed a suite of 10 vegetation indices (VIs), prioritizing red-edge indices (IRECI, SeLI, and NDCI) alongside traditional broadband indices (NDVI and EVI) and thermal metrics (Tc), to distinguish structural biomass signals from physiological indicators of chlorophyll content and stress. We validated our statistics using one-way analysis of variance, Tukey’s Honestly Significant Difference post hoc analysis, and spatial autocorrelation metrics. Our results indicate that red-edge-based indices, particularly the inverted red-edge chlorophyll index and Sentinel-2 LAI Green Index (SeLI), significantly outperform traditional indices in discriminating species-specific health status, revealing gradual degradation in stands where the broadband NDVI indicates stability. We observed different health trajectories, while C. tagal exhibited a positive trend in physiological vigor, S. alba, the pioneer species most susceptible to hydrodynamic alteration, displayed signs of stagnation and decline in specific zones, which were correlated with sedimentation-induced pneumatophore stress. Cluster analysis (K-means) and Moran’s I revealed highly clustered spatial degradation patterns linked to proximity to reclamation infrastructure. Our results show that the red-edge region detects early physiological stress in mangrove ecosystems before structural canopy loss occurs and provides spatial data for the management of Ngurah Rai Forest Park.

Jónsdóttir, Ingibjörg G; Karpouzoglou, Theodoros; Singh, Warsha; Sólmundsson, Jón

doi: 10.1093/icesjms/fsag099pmid: N/A

Understanding the long-term stability and plasticity of marine migrations is essential for predicting species’ responses to environmental changes. In this study, we analysed 75 years (1951–2025) of tagging data from two spawning areas to characterize the feeding migrations of Atlantic cod in Icelandic waters, evaluating the influence of decadal-scale temperature shifts and prey availability. While overall cod migrations exhibited considerable stability from 1951 to 2025, two distinct periods of alteration emerged in recent decades. During the 1990s and 2000s, the primary migration routes from the southwest spawning regions diverged from the northwest, shifting instead towards the south and southeast. A more recent shift in the 2020s saw cod from both spawning areas moving extensively north of Iceland and towards the Dohrn Bank. Substantial changes were observed in water temperature over the Icelandic shelf, with a 1.6°C warming of near-bottom waters between 1993 and 2003. Cod responses to this warming are primarily indirect, apparently driven by the spatial redistribution of their principal prey, capelin, and the periodic availability of blue whiting. By comparing recent observations with historical records (1950s–2000s), we show that the shift towards the Dohrn Bank represents a recurrent migration pattern that had been absent for several decades. This study highlights the importance of long-term monitoring for understanding species' responses to hydrographic and biological changes and improving predictions of future outcomes.