ICES Journal of Marine Science: Journal du Conseil

Burgess, M G; Becker, S L; Langendorf, R E; Fredston, A; Brooks, C M

doi: 10.1093/icesjms/fsad045pmid: N/A

Scenarios are central to fisheries and aquatic conservation research on climate change. Scenarios project future greenhouse-gas emissions, which climate models translate into warming projections. Recent climate research and global development trends have significantly changed our understanding of plausible emissions pathways to 2100 and climate sensitivities to emissions. Here, we review these developments and make recommendations for scenario use in fisheries and aquatic conservation research. Although emissions pathways are uncertain, recent research suggests that scenarios producing ∼3.4–4.5 W/m2 radiative forcing by 2100 (e.g. scenarios SSP2-3.4 and SSP2-4.5/RCP4.5) might be most plausible. This corresponds to ∼2–3 degrees C global warming by 2100 with median climate sensitivities, or 1.5–4 degrees C considering climate-system uncertainties. Higher- and lower-emissions scenarios (e.g. RCP2.6 and RCP6.0) might be plausible and should be explored in research. However, high-emission scenarios (RCP8.5/SSP5-8.5, SSP3-7.0) seem implausible and should be used with clear rationales and caveats to ensure results are not misinterpreted by scholars, policymakers, and media. We analyse fisheries and aquatic conservation papers published from 2015 to 2022 in major journals, and find that RCP8.5/SSP5-8.5 are the most commonly used scenarios, though RCP4.5/SSP2-4.5 use has increased since 2020. Studies predominantly project quantitative rather than qualitative differences between these scenarios’ impacts.

Kjesbu, O S; Tiedemann, I; Alix, M; Thorsen, A; Sundby, S

doi: 10.1093/icesjms/fsad073pmid: N/A

Predicting recruitment in a reliable fashion is a great challenge within operational fisheries advice. Here, we consulted the unique but undercommunicated IMR Cod Larva Project (1975–1990), its spin-offs, placed in an international era of advancements over the last 50 years to glance into the future. Few initiatives of this kind have applied such extensive research approaches, spanning from laboratory, mesocosm, tank, and field studies to process modelling. The “critical period” concept appeared misleading, covering months rather than days of the early life history stages (ELHS) of Northeast Arctic cod. Larval feeding success was strongly modified by improved encounter rates from wind-induced turbulence. In addition, the following maternal effect studies evidenced that the dynamics of stock demography prior to spawning should be upheld to promote recruitment success. Although we now have lower-trophic level models as well as ELHS individual-based models, such models are still insufficiently reflecting the needed spatiotemporal resolution. The same problem applies to climate/circulation models. Nevertheless, this long-lasting research has significantly improved the mechanistic understanding of ELHS dynamics but also of the more predictable adult reproductive parameters. Based on a “to-list list,” we suggest research avenues that should be pursued to further improve our ability predicting recruitment strength in marine fish stocks.

Murillas-Maza, A; Mugerza, E; Bachiller, E; Errazkin, L A; Louzao, M

doi: 10.1093/icesjms/fsad075pmid: N/A

The main goal of this paper is to improve the understanding of the spatial distribution of small-scale inshore fisheries (SSF) in coastal waters of the Bay of Biscay. The study used a participatory process, in which fishers, regional administration, and researchers were involved in supplying the data. Displayed on a 1-km2 grid, the data for effort and catch composition, variable costs, revenue, and profits at each site show the spatial patterns of the main SSF metier activities. This information indicates the economic value of the fishing grounds and the cost of reaching those areas, which can reveal possible trade-offs for more distant fishing grounds. Trammelnet vessels are widely dispersed, following economic incentives, while longliners also demonstrate high mobility, using many fishing sites, though the economic incentive does not always lead to high benefits. A narrow expansion range with activity close to the coastal area (trap, gillnet, and trammelnet users) suggests that the target-species stocks maintain their economic profitability even though it is lower than that in other coastal fleets. Such information helps develop a holistic approach to SSF management in this multi-use region by increasing the availability of high-quality multidisciplinary geospatial data, currently in short supply for this fleet.

Perricone, V; Mutalipassi, M; Mele, A; Buono, M; Vicinanza, D; Contestabile, P

doi: 10.1093/icesjms/fsad080pmid: N/A

Coastal erosion is occurring at a faster rate than in the past. The adverse impacts are not negligible at environmental, economic, and socio-cultural levels. Hence, coastal protection is currently seen as an emerging need to counteract erosion impacts and their many negative effects on worldwide ecosystems. In this regard, natural systems and their organisms represent a complex system of solutions that can efficiently create and/or inspire the development of natural, sustainable, and cutting-edge coastal barriers. Coastal ecosystems, such as coral reefs, oyster reefs, mangroves, saltmarshes, seagrasses, and polychaete reefs, act as a natural barrier for destructive waves and wind forces. Moreover, living organisms have evolved unique strategies to withstand their environmental hydrodynamic loadings. This review intends to provide an overview regarding natural systems and related nature-based and bioinspired strategies in the specific field of coastal protection, describing the state of the art, methods, processes, and tools, as well as delineating a promising pathway for new functional and sustainable designs.

Souza Jr, P M; Olsen, Z; Brandl, S J

doi: 10.1093/icesjms/fsad085pmid: N/A

Estuaries worldwide provide critical habitat to many ecologically and socioeconomically important fish species. However, the high turbidity and strong environmental gradients inherent to many estuaries make the monitoring of fish populations a challenging task. To assess the health and diversity of local fish populations, resource managers often employ fisheries-independent sampling methods, which result in valuable population assessments, but suffer from low-temporal resolution and high rates of mortality. Passive acoustic monitoring (PAM) provides a near-continuous, non-invasive means for monitoring soniferous fish activity over extended periods, but its utility for quantifying entire fish communities is largely untested, especially in turbid estuaries. Here, we use synchronized acoustic and gillnet sampling at 51 locations in the Mission-Aransas Estuary (TX), across two sampling seasons to test correlations between acoustic indices and gillnet catch. Positive correlations were observed between gillnet catch and sound pressure levels in both broadband (50–22050 Hz) and low-frequency (50–2500 Hz) bands. Additionally, sciaenid calling activity was positively correlated with sciaenid catch during the spring, when most spawning activity occurs. Our results indicate that PAM can be used to monitor the relative abundances of fish in Gulf of Mexico estuaries and beyond, although this is subject to species identity and seasonal dynamics.

Zhou, Z; Yang, X; Ji, H; Zhu, Z

doi: 10.1093/icesjms/fsad041pmid: N/A

The visibility of fishes and invertebrates is highly impacted by the complexity of the environment. Images acquired in underwater environments suffer from blurriness and low contrast. This results in a low classification accuracy. To address this problem, this study uses a pre-trained Resnet50 neural network as the feature extractor, which avoids over-fitting and accuracy saturation while realizing improved feature extraction capabilities. It also proposes an enhancement of the error-minimized random vector functional link (EEMRVFL) neural network, which is used as the classifier in the convolutional neural network (CNN) model instead of the original softmax classifier. EEMRVFL reduces the maximum residual error in each incremental process. The selected hidden nodes are added to the network, which improves the compactness of its structure. The proposed residual CNNs model exhibits improved classification accuracy for underwater image classification compared to existing methods. This is demonstrated experimentally on available datasets such as URPC, LifeCLEF 2015, and Fish4Knowledge with accuracy rates reaching 99.68%, 97.34%, and 99.77%, respectively.

McCormick, M I; Fakan, E P; Vamvounis, G; Bosshard, S; Moad, C; Smyth, E; Gatenby, P; Edmiston, J; Patel, K; Allan, B J M

doi: 10.1093/icesjms/fsad049pmid: N/A

This study experimentally explored the influence of periodic consumption of polystyrene (PS) microplastic fragments on the body condition and fitness of a tropical marine fish. Adult damselfish, Acanthochromis polyacanthus, were pulse fed microplastic fragments bound with one of two different common plasticizers [di-2-ethylhexyl phthalate (DEHP), di-2-ethylhexyl terephthalate (DEHT)] together with virgin-plastic and no-plastic controls. Ingestion of plastic over a 150d period had no detectable effect on growth, indices of body condition, or gonadosomatic indices. Histology of the liver showed no detrimental effects of ingesting any of the plastic treatments on hepatocyte density or vacuolation. Plastic consumption had no effect on the number of clutches produced over the breeding period, the number of eggs, or the survival of embryos. It is believed that the relatively inert nature of PS, the low amount of plasticizers leached from the fragments and fast gut through-put times meant fish were exposed to low levels of toxic compounds.

Chen, Yuwen; Zhu, Guoping

doi: 10.1093/icesjms/fsad052pmid: N/A

Species identification by fish otoliths is an effective and appropriate approach. However, the allometric growth of otoliths can cause discrimination confusion, particularly in juvenile otolith classification. In the Southern Ocean, Chionodraco rastrospinosus,Krefftichthys anderssoni,Electrona carlsbergi, andPleuragramma antarcticum are frequently caught together in krill fishery as bycatch species. Furthermore, the otolith shape of these four species is relatively similar in juvenile fish, making the identification of fish species difficult. In this study, we tried and evaluated many commonly used machine learning techniques to solve this problem. Eventually, by introducing a triplet loss function (function used to reduce intraspecific variation and increase inter-specific variation), the discrimination confusion caused by the allometric growth of otoliths was reduced. The classification results show that the neural network model with the triplet loss function achieves the best classification accuracy of 96%. The proposed method can help improve otolith classification performance, especially under the context of limited sampling effort, which is of great importance for trophic ecology and the study of fish life history.

Clare, D S; Martinez, R; Goodsir, F; Spence, M A; Tyllianakis, E; Ware, S; Schratzberger, M

doi: 10.1093/icesjms/fsad053pmid: N/A

Spatial restrictions to human activities such as bottom trawling are increasingly used to improve the ecological condition of disturbed habitats. Such management interventions typically have socio-economic consequences, which creates a challenge for those making decisions about which activities should be restricted and where restrictions should apply. We present an approach for predicting the effects of fisheries management scenarios in spatially delimited marine areas and ranking them—using a loss function—according to how well they achieve desired outcomes across a set of ecological and socio-economic indicators. This approach is demonstrated by simulating alternative fishing gear restrictions and zoning options within a hypothetical marine protected area (MPA). Relative benthic status (RBS; an indicator of ecological condition) and relative catch value (RCV; an indicator of potential economic cost) were estimated for the baseline environment and 21 potential management scenarios. The rank order depended on which indicator was prioritized (i.e. whether RBS or RCV was given greater weighting in the loss function), with the top-ranked scenarios in each case involving considerably different management measures. The methods presented can be applied anywhere using locally or strategically relevant indicators to help identify spatial fisheries management measures that minimize ecological and socio-economic trade-offs.

Li, C; Liu, H

doi: 10.1093/icesjms/fsad056pmid: N/A

Human intervention and climate change jointly influence the functions and dynamics of marine ecosystems. Studying the impacts of human and climate on ecosystem dynamics is challenging. Unlike experimental studies, research on natural systems is not amendable at the scale of time, space, and biology. With confounding factors well balanced for two adjacent subtropical estuaries except urbanized disturbances, we conducted ecosystem modelling using indirect reasoning by exclusion to quantify the relative impacts of human disruption on estuarine ecosystems under climate variability. One major finding of this study is that the human intervention tends to magnify species fluctuations, complicate the species interaction network, and enhance species interaction strength combined with disclosed downscaling climate effects (indexed as North Atlantic Oscillation and Atlantic Multi-decadal Oscillation) on estuarine hydrology and biological communities. In addition, functional groups appeared to respond more diversely to external forcing in company with human interventions. While human perturbation was shown to destabilize the estuarine ecosystems, making them vulnerable to environmental variability under climate change, buffering effects of species diversity and trophic interaction tend to underpin the ecosystem functions. The findings of this study contribute to the holistic assessment and strategic management of estuarine ecosystems subjected to human and natural disturbances in the face of climate change.