Modelling European small pelagic fish distribution: Methodological insights

Simulating the changes of the habitats suitability of chub mackerel (Scomber japonicus) in the high seas of the North Pacific Ocean using ensemble models under medium to long-term future climate scenarios

Understanding and forecasting changes in marine habitats due to global climate warming is crucial for sustainable fisheries. Using future environmental data provided by Global Climate Models (GCMs) and occurrence records of Chub mackerel in the North Pacific Ocean (2014-2023), we built eight individual models and four ensemble models to simulate current habitat distribution and forecast changes under three future climate scenarios (SSP1-2.6, SSP2-4.5, SSP5-8.5) for the 2050s and 2100s. Ensemble models outperformed individual ones, with the weighted average algorithm model achieving the highest accuracy (AUC 0.994, TSS 0.929). Sea Surface Temperature (SST) and chlorophyll-a (Chla) significantly influenced habitat distribution. Predictions indicate current high suitability areas for Chub mackerel are concentrated beyond the 200-nautical-mile baseline. Under future climate scenarios, habitat suitability is expected to decline, with a shift towards higher latitudes and deeper waters. High suitability areas will be significantly reduced.

Potential impacts of climate change on cephalopods in a highly productive region (Northwest Pacific): Habitat suitability and management

Cephalopods occupy a mid-trophic level in marine ecosystems and are vital both ecologically and as fishery resources. However, under the pressure of climate change and fishing, the sustainability of cephalopod resources requires reasonable management. This study aims to study climate change and fishing impacts on the common economic cephalopod species habitats using species distribution models. We take the northwest Pacific Ocean region as an example, which stands out as a significant region for cephalopod production around the world. Results found that the habitats of cephalopods are moving to higher latitudes or deeper waters (Bohai Sea, mid-bottom Yellow Sea, and the Okinawa Trough waters) under climate change. Additionally, these regions are currently under lower fishing pressure, which suggests that species migration might mitigate the effects of warming and fishing. This study provides the large-scale assessment of the distribution range of cephalopods affected by climate change coping with fishing pressure in the northwest Pacific Ocean. By identifying climate refuges and key fishing grounds, we underscore the importance of this information for managing cephalopod resources in the context of climate adaptation and sustainable fishing practices.

Climate as a Predictive Factor for Invasion: Unravelling the Range Dynamics of Carpomya vesuviana Costa

Invasive alien species (IAS) significantly affect global native biodiversity, agriculture, industry, and human health. Carpomya vesuviana Costa, 1854 (Diptera: Tephritidae), a significant global IAS, affects various date species, leading to substantial economic losses and adverse effects on human health and the environment. This study employed biomod2 ensemble models, multivariate environmental similarity surface and most dissimilar variable analyses, and ecological niche dynamics based on environmental and species data to predict the potential distribution of C. vesuviana and explore the environmental variables affecting observed patterns and impacts. Compared to native ranges, ecological niche shifts at invaded sites increased the invasion risk of C. vesuviana globally. The potential geographical distribution was primarily in Asia, Africa, and Australia, with a gradual increase in suitability with time and radiation levels. The potential geographic distribution centre of C. vesuviana is likely to shift poleward between the present and the 2090s. We also show that precipitation is a key factor influencing the likely future distribution of this species. In conclusion, climate change has facilitated the expansion of the geographic range and ecological niche of C. vesuviana, requiring effective transnational management strategies to mitigate its impacts on the natural environment and public health during the Anthropocene. This study aims to assess the potential threat of C. vesuviana to date palms globally through quantitative analytical methods. By modelling and analysing its potential geographic distribution, ecological niche, and environmental similarities, this paper predicts the pest's dispersal potential and possible transfer trends in geographic centres of mass in order to provide prevention and control strategies for the global date palm industry.

Corythauma ayyari (Insecta, Heteroptera, Tingidae) depends on its host plant to spread in Europe

Biological invasions increase with the intensity of globalization, human activities, and climate change. Insects represent a high potential of invasive species due to their adaptability to new environment. We analysed here the potential of an Asian phytophagous bug, Corythauma ayyari (Heteroptera, Tingidae) to become widespread, recently recorded in Europe, and that depends on Jasminum spp., an ornamental plant widespread in Europe. We modelled its current distribution, projected it into the future and tested its niche overlap between native and invaded areas. When considering the host plants as environmental variables, the analysis shows that C. ayyari shifted to a new ecological niche but its distribution is restricted by its host plant distribution. Including or excluding the host plants as environmental variables has an impact on C. ayyari distribution. We recommend to consider host plant interactions when dealing with niche modelling of phytophagous species.

Decoding the spread of non-indigenous fishes in the Mediterranean Sea

The ocean is dynamically changing due to the influence of climate processes and human activities. The construction of the Suez Canal in the late nineteenth century opened the Pandora's box by facilitating the dispersal of Red Sea species in the Mediterranean Sea. In this study, we developed an open-source spatio-temporal numerical analysis framework to decodify the complex spread of Mediterranean non-indigenous fish species (NIS) that entered through the Suez Canal. We utilized 772 historical detection records of 130 NIS to disentangle their dynamic spread through space and time. The results indicated that species follow a north-westward trajectory with an average expansion time step of 2.5 years. Additionally, we estimated the overall time for a NIS to reach the Central Mediterranean Sea from the Suez Canal at approximately 22 years. Based on the analysis, more than half of the introduced fishes have been established in less than 10 years. Finally, we proceeded in the cross-validation of our results using actual spread patterns of invasive fishes of the Mediterranean Sea, resulting up to 90% of temporal and spatial agreement. The methodology and the findings presented herein may contribute to management initiatives in highly invaded regions around the globe.

Addressing ocean planning challenges in a highly crowded sea space: a case study for the regional sea of Catalonia (Western Mediterranean)

Background

This study performs an exploratory analysis of current-future sustainability challenges for ocean planning for the regional seas of Catalonia located in the Western Mediterranean (Spain).

Methods

To address the challenges we develop an Maritime Spatial Planning (MSP)-oriented geodatabase of maritime activities and deploy three spatial models: 1) an analysis of regional contribution to the 30% protection commitment with Biodiversity Strategy 2030; 2) a spatial Maritime Use Conflict (MUC) analysis to address current and future maritime activities interactions and 3) the StressorGenerator QGIS application to locate current and anticipate future sea areas of highest anthropogenic stress.

Results & Conclusions

Results show that the i) study area is one of the most protected sea areas in the Mediterranean (44-51% of sea space protected); ii) anthropogenic stressors are highest in 1-4 nautical miles coastal areas, where maritime activities agglomerate, in the Gulf of Roses and Gulf of Saint Jordi. iii) According to the available datasets commercial fishery is causing highest conflict score inside protected areas. Potential new aquaculture sites are causing highest conflict in Internal Waters and the high potential areas for energy cause comparably low to negligible spatial conflicts with other uses. We discuss the added value of performing regional MSP exercises and define five challenges for regional ocean sustainability, namely: Marine protection beyond percentage, offshore wind energy: a new space demand, crowded coastal areas, multi-level governance of the regional sea and MSP knowledge gaps.

Construction of chub mackerel (Scomber japonicus) fishing ground prediction model in the northwestern Pacific Ocean based on deep learning and marine environmental variables

Accurate prediction of the central fishing grounds of chub mackerel is substantial for assessing and managing marine fishery resources. Based on the high-seas chub mackerel fishery statistics and multi-factor ocean remote-sensing environmental data in the Northwest Pacific Ocean from 2014 to 2021, this article applied the gravity center of the fishing grounds, 2DCNN, and 3DCNN models to analyze the spatial and temporal variability of the chub mackerel catches and fishing grounds. Results:1) the primary fishing season of chub mackerel fishery was April-November which catches were mainly concentrated in 39°∼43°N, 149°∼154°E. 2) Since 2019, the annual gravity center of the fishing grounds has continued to move northeastward; the monthly gravity center has prominent seasonal migratory characteristics. 3) 3DCNN model was better than the 2DCNN model. 4) For 3DCNN, the model prioritized learning information on the most easily distinguishable ocean remote-sensing environmental variables in different classifications.

Time to Step Up Conservation: Climate Change Will Further Reduce the Suitable Habitats for the Vulnerable Species Marbled Polecat (Vormela peregusna)

Habitat loss and human threats are putting the marbled polecat (Vormela peregusna) on the brink of extinction. Numerous recent studies have found that climate change will further deteriorate the living environment of endangered species, leading to their eventual extinction. In this study, we used the results of infrared camera surveys in China and worldwide distribution data to construct an ensemble model consisting of 10 commonly used ecological niche models to specify potential suitable habitat areas for V. peregusna under current conditions with similar environments to the sighting record sites. Changes in the suitable habitat for V. peregusna under future climate change scenarios were simulated using mid-century (2050s) and the end of the century (2090s) climate scenarios provided by the Coupled Model Intercomparison Project Phase 6 (CMIP6). We evaluated the accuracy of the model to obtain the environmental probability values (cutoff) of the V. peregusna distribution, the current distribution of suitable habitats, and future changes in moderately and highly suitable habitat areas. The results showed that the general linear model (GLM) was the best single model for predicting suitable habitats for V. peregusna, and the kappa coefficient, area under the curve (AUC), and true skill statistic (TSS) of the ensemble model all exceeded 0.9, reflecting greater accuracy and stability than single models. Under the current conditions, the area of suitable habitat for V. peregusna reached 3935.92 × 10⁴ km², suggesting a wide distribution range. In the future, climate change is predicted to severely affect the distribution of V. peregusna and substantially reduce the area of suitable habitats for the species, with 11.91 to 33.55% of moderately and highly suitable habitat areas no longer suitable for the survival of V. peregusna. This shift poses an extremely serious challenge to the conservation of this species. We suggest that attention be given to this problem in Europe, especially the countries surrounding the Black Sea, Asia, China, and Mongolia, and that measures be taken, such as regular monitoring and designating protected areas for the conservation of vulnerable animals.

Redistribution of fisheries catch potential in Mediterranean and North European waters under climate change scenarios

The Mediterranean Sea is a hotspot of global warming where key commercial species, such as demersal and pelagic fishes, and cephalopods, could experience abrupt distribution shifts in the near future. However, the extent to which these range shifts may impact fisheries catch potential remains poorly understood at the scale of Exclusive Economic Zones (EEZs). Here, we evaluated the projected changes in Mediterranean fisheries catches potential, by target fishing gears, under different climate scenarios throughout the 21st century. We show that the future Mediterranean maximum catch potential may decrease considerably by the end of the century under high emission scenarios in South Eastern Mediterranean countries. These projected decreases range between -20 to -75 % for catch by pelagic trawl and seine, -50 to -75 % for fixed nets and traps and exceed -75 % for benthic trawl. In contrast, fixed nets and traps, and benthic trawl fisheries may experience an increase in their catch potential in the North and Celtic seas, while future catches by pelagic trawl and seine may decrease in the same areas. We show that a high emission scenario may considerably amplify the future redistribution of fisheries catch potential across European Seas, thus highlighting the need to limit global warming. Our projections at the manageable scale of EEZ and the quantification of climate-induced impacts on a large part of the Mediterranean and European fisheries is therefore a first, and considerable step toward the development of climate mitigation and adaptations strategies for the fisheries sector.

Addressing the dichotomy of fishing and climate in fishery management with the FishClim model

The relative influence of fishing and Climate-Induced Environmental Change (CIEC) on long-term fluctuations in exploited fish stocks has been controversial1–3 because separating their contributions is difficult for two reasons. Firstly, there is in general, no estimation of CIEC for a pre-fishing period and secondly, the assessment of the effects of fishing on stocks has taken place at the same time as CIEC4. Here, we describe a new model we have called FishClim that we apply to North Sea cod from 1963 to 2019 to estimate how fishing and CIEC interact and how they both may affect stocks in the future (2020-2100) using CMIP6 scenarios5. The FishClim model shows that both fishing and CIEC are intertwined and can either act synergistically (e.g. the 2000-2007 collapse) or antagonistically (e.g. second phase of the gadoid outburst). Failure to monitor CIEC, so that fisheries management immediately adjusts fishing effort in response to environmentally-driven shifts in stock productivity, will therefore create a deleterious response lag that may cause the stock to collapse. We found that during 1963-2019, although the effect of fishing and CIEC drivers fluctuated annually, the pooled influence of fishing and CIEC on the North Sea cod stock was nearly equal at ~55 and ~45%, respectively. Consequently, the application of FishClim, which quantifies precisely the respective influence of fishing and climate, will help to develop better strategies for sustainable, long-term, fish stock management.

Expected contraction in the distribution ranges of demersal fish of high economic value in the Mediterranean and European Seas

Fisheries and aquaculture are facing many challenges worldwide, especially adaptation to climate change. Investigating future distributional changes of largely harvested species has become an extensive research topic, aiming at providing realistic ecological scenarios on which to build management measures, to help fisheries and aquaculture adapt to future climate-driven changes. Here, we use an ensemble modelling approach to estimate the contemporary and future distributional range of eight demersal fish species of high economic value in the Mediterranean Sea. We identify a cardinal influence of (i) temperature on fish species distributions, all being shaped by yearly mean and seasonality in sea bottom temperature, and (ii) the primary production. By assessing the effects of changes in future climate conditions under three Representative Concentration Pathway (RCP2.6, RCP4.5 and RCP8.5) scenarios over three periods of the twenty-first century, we project a contraction of the distributional range of the eight species in the Mediterranean Sea, with a general biogeographical displacement towards the North European coasts. This will help anticipating changes in future catch potential in a warmer world, which is expected to have substantial economic consequences for Mediterranean fisheries.

Improving predictions of invasive fish ranges combining functional and ecological traits with environmental suitability under climate change scenarios

Biological invasions represent one of the main threats to marine biodiversity. From a conservation perspective, especially in the context of increasing sea warming, it is critical to examine the suitability potential of geographical areas for the arrival of Range-Expanding Introduced and Native Species (REINS), and hence anticipate the risk of such species to become invasive in their new distribution areas. Here, we developed an empirical index, based on functional and bio-ecological traits, that estimates the Invasive Potential (IP; i.e. the potential success in transport, introduction and population establishment) for a set of 13 fishes that are expanding their distributional range into the Mediterranean Sea, the most invaded sea in the world. The IP index showed significant correlation with the observed spreading of REINS. For the six species characterized by the highest IP, we calculated contemporary and future projections of their Environmental Suitability Index (ESI). By using an ensemble modelling approach, we estimated the geographical areas that are likely to be the most impacted by REINS spreading under climate change. Our results demonstrated the importance of functional traits related to reproduction for determining high invasion potential. For most species, we found high contemporary ESI values in the South-eastern Mediterranean Sea and low to intermediate contemporary ESI values in the Adriatic Sea and North-western Mediterranean sector. Moreover, we highlighted a major potential future expansion of high ESI values, and thus REINS IP, towards the northern Mediterranean, especially in the northern Adriatic Sea. This potential future northward expansion highlights the risk associated with climate-induced impacts on ecosystem conservation and fish stock management throughout the entire Mediterranean Sea.

Estimating the impact of climate change on the potential distribution of Indo-Pacific humpback dolphins with species distribution model

As IUCN critically vulnerable species,the Indo-Pacific humpback dolphins (Sousa chinensis) have attracted great public attention in recent years. The threats of human disturbance and environmental pollution to this population have been documented extensively. However, research on the sensitivity of this species to climate change is lacking. To understand the effect of climate change on the potential distribution of Sousa chinensis, we developed a weighted ensemble model based on 82 occurrence records and six predictor variables (e.g., ocean depth, distance to shore, mean temperature, salinity, ice thickness, and current velocity). According to the true skill statistic (TSS) and the area under the receiver operating characteristic curve (AUC), our ensemble model presented higher prediction precision than most of the single-algorithm models. It also indicated that ocean depth and distance to shore were the most important predictors in shaping the distribution patterns. The projections for the 2050s and 2100s from our ensemble model indicated a severe adverse impact of climate change on the Sousa chinensis habitat. Over 75% and 80% of the suitable habitat in the present day will be lost in all representative concentration pathway emission scenarios (RCPS) in the 2050s and 2100s, respectively. With the increased numbers of records of stranding and deaths of Sousa chinensis in recent years, strict management regulations and conservation plans are urgent to safeguard the current suitable habitats. Due to habitat contraction and poleward shift in the future, adaptive management strategies, including designing new reserves and adjusting the location and range of reserves according to the geographical distribution of Sousa chinensis, should be formulated to minimize the impacts of climate change on this species.

European cephalopods distribution under climate-change scenarios

In a context of increasing anthropogenic pressure, projecting species potential distributional shifts is of major importance for the sustainable exploitation of marine species. Despite their major economical (i.e. important fisheries) and ecological (i.e. central position in food-webs) importance, cephalopods literature rarely addresses an explicit understanding of their current distribution and the potential effect that climate change may induce in the following decades. In this study, we focus on three largely harvested and common cephalopod species in Europe: Octopus vulgaris, Sepia officinalis and Loligo vulgaris. Using a recently improved species ensemble modelling framework coupled with five atmosphere-ocean general circulation models, we modelled their contemporary and potential future distributional range over the twenty-first century. Independently of global warming scenarios, we observed a decreasing in the suitability of environmental conditions in the Mediterranean Sea and the Bay of Biscay. Conversely, we projected a rapidly increasing environmental suitability in the North, Norwegian and Baltic Seas for all species. This study is a first broad scale assessment and identification of the geographical areas, fisheries and ecosystems impacted by climate-induced changes in cephalopods distributional range.

Predicting seasonal movements and distribution of the sperm whale using machine learning algorithms

Implementation of effective conservation planning relies on a robust understanding of the spatiotemporal distribution of the target species. In the marine realm, this is even more challenging for species rarely seen at the sea surface due to their extreme diving behavior like the sperm whales. Our study aims at (a) investigating the seasonal movements, (b) predicting the potential distribution, and (c) assessing the diel vertical behavior of this species in the Mascarene Archipelago in the south-west Indian Ocean. Using 21 satellite tracks of sperm whales and eight environmental predictors, 14 supervised machine learning algorithms were tested and compared to predict the whales' potential distribution during the wet and dry season, separately. Fourteen of the whales remained in close proximity to Mauritius, while a migratory pattern was evidenced with a synchronized departure for eight females that headed towards Rodrigues Island. The best performing algorithm was the random forest, showing a strong affinity of the whales for sea surface height during the wet season and for bottom temperature during the dry season. A more dispersed distribution was predicted during the wet season, whereas a more restricted distribution to Mauritius and Reunion waters was found during the dry season, probably related to the breeding period. A diel pattern was observed in the diving behavior, likely following the vertical migration of squids. The results of our study fill a knowledge gap regarding seasonal movements and habitat affinities of this vulnerable species, for which a regional IUCN assessment is still missing in the Indian Ocean. Our findings also confirm the great potential of machine learning algorithms in conservation planning and provide highly reproductible tools to support dynamic ocean management.