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Canadian fisheries management has embraced the precautionary approach and the incorporation of ecosystem information into decision-making processes. Accurate estimation of fish stock biomass is crucial for ensuring sustainable exploitation of marine resources. Spatio-temporal models can provide improved indices of biomass as they capture spatial and temporal correlations in data and can account for environmental factors influencing biomass distributions. In this study, we developed a spatio-temporal generalized additive model (st-GAM) to investigate the relationships between bottom temperature, depth, and the biomass of three key fished species on The Grand Banks: snow crab (Chionoecetes opilio), yellowtail flounder (Limanda ferruginea), and Atlantic cod (Gadus morhua). Our findings revealed changes in the centre of gravity of Atlantic cod that could be related to a northern shift of the species within the Grand Banks or to a faster recovery of the 2J3KL stock. Atlantic cod also displayed hyperaggregation behaviour with the species showing a continuous distribution over the Grand Banks when biomass is high. These findings suggest a joint stock assessment between the 2J3KL and 3NO stocks would be advisable. However, barriers may need to be addressed to achieve collaboration between the two distinct regulatory bodies (i.e., DFO and NAFO) in charge of managing the stocks. Snow crab and yellowtail flounder centres of gravity have remained relatively constant over time. We also estimated novel indices of biomass, informed by environmental factors. Our study represents a step towards ecosystem-based fisheries management for the highly dynamic Grand Banks.
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Ecosistema , Gadus morhua , Animales , Biomasa , Explotaciones Pesqueras , Terranova y Labrador , Canadá , Dinámica PoblacionalRESUMEN
Increasing impacts of both fisheries and climate change have resulted in shifts in the structure and functioning of marine communities. One recurrent observation is the rise of cephalopods as fish recede. This is generally attributed to the removal of main predators and competitors by fishing, while mechanistic evidence is still lacking. In addition, climate change may influence cephalopods due to their high environmental sensitivity. We aim to unveil the effects of different anthropogenic and environmental drivers at different scales focusing on the cephalopod community of the Western Mediterranean Sea. We investigate several ecological indicators offering a wide range of information about their ecology, and statistically relating them with environmental, biotic and fisheries drivers. Our results highlight non-linear changes of indicators along with spatial differences in their responses. Overall, the environment drivers have greater effects than biotic and local human impacts with contrasting effects of temperature across the geographic gradient. We conclude that cephalopods may be impacted by climate change in the future while not necessary through positive warming influence, which should make us cautious when referring to them as generalized winners of current changes.
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Cefalópodos , Ecosistema , Animales , Humanos , Cefalópodos/fisiología , Mar Mediterráneo , Cambio Climático , Explotaciones PesquerasRESUMEN
Fish body condition and growth are two interrelated traits closely associated with species life history and fitness, whose trade-off can ultimately impact population dynamics albeit seldom empirically demonstrated. They can intricately affect survival rates, which are particularly relevant for species under exploitation. Using individual spatiotemporal information in Northwestern Mediterranean, we document for the first time the existence of a trade-off between condition and growth in regulating survival dynamics in two important fish species for the Mediterranean fisheries that are characterized by contrasting life histories. For the European hake (Merluccius merluccius), a benthopelagic species, juveniles' body condition was detected to be positively linked to survival and negatively associated with the growth of this age group. For the red mullet (Mullus barbatus), the same pattern was observed for young adults. We also show that the observed patterns on a regional level have a clear spatial dependence as we found that observed body condition over a local scale had a broad effect on the population dynamics of the whole region, with the Ebro delta area emerging as the demographic engine of the two species. We discuss our results in the context of fisheries management and underline the importance of improving current stock assessment models and spatially based fishery management towards incorporating body condition and growth due to their influence on important parameters such as survival.
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Gadiformes , Perciformes , Animales , Mar Mediterráneo , Peces/fisiología , Dinámica Poblacional , Explotaciones PesquerasRESUMEN
By evaluating genetic variation across the entire genome, one can address existing questions in a novel way while raising new ones. The latter includes how different local environments influence adaptive and neutral genomic variation within and among populations, providing insights into local adaptation of natural populations and their responses to global change. Here, under a seascape genomic approach, ddRAD data of 4609 single nucleotide polymorphisms (SNPs) from 398 sardines (Sardina pilchardus) collected in 11 Mediterranean and one Atlantic site were generated. These were used along with oceanographic and ecological information to detect signals of adaptive divergence with gene flow across environmental gradients. The studied sardines constitute two clusters (FST = 0.07), a pattern attributed to outlier loci, highlighting putative local adaptation. The trend in the number of days with sea surface temperature above 19°C, a critical threshold for successful sardine spawning, was crucial at all levels of population structuring with implications on the species' key biological processes. Outliers link candidate SNPs to the region's environmental heterogeneity. Our findings provide evidence for a dynamic equilibrium in which population structure is maintained by physical and ecological factors under the opposing influences of migration and selection. This dynamic in a natural system warrants continuous monitoring under a seascape genomic approach that might benefit from a temporal and more detailed spatial dimension. Our results may contribute to complementary studies aimed at providing deeper insights into the mechanistic processes underlying population structuring. Those are key to understanding and predicting future changes and responses of this highly exploited species in the face of climate change.
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Genética de Población , Genómica , Mar Mediterráneo , Genoma , Adaptación Fisiológica/genética , Polimorfismo de Nucleótido Simple/genéticaRESUMEN
Seabirds are bioindicators of marine ecosystems health and one of the world's most endangered avian groups. The creation of marine protected areas plays an important role in the conservation of marine environment and its biodiversity. The distributions of top predators, as seabirds, have been commonly used for the management and creation of these figures of protection. The main objective of this study is to investigate seabirds biodiversity distribution in the Mediterranean Sea through the use of Bayesian spatial Beta regression models. We used an extensive historical database of at-sea locations of 19 different seabird species as well as geophysical, climatology variables and cumulative anthropogenic threats to model species biodiversity. We found negative associations between seabirds biodiversity and distance to the coast as well as concavity of the seabed, and positive with chlorophyll and slope. Further, a positive association was found between seabirds biodiversity and coastal impact. In this study we define as hot spot of seabird biodiversity those areas with a posterior predictive mean over 0.50. We found potential hot spots in the Mediterranean Sea which do not overlap with the existing MPASs and marine IBAs. Specifically, our hot spots areas do not overlap with the 52.04% and 16.87% of the current MPAs and marine IBAs, respectively. Overall, our study highlights the need for the extension of spatial prioritization of conservation areas to seabirds biodiversity, addressing the challenges of establishing transboundary governance.
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Biodiversidad , Ecosistema , Animales , Mar Mediterráneo , Teorema de Bayes , Aves , Conservación de los Recursos NaturalesRESUMEN
Fishing is one of the most widespread and important human activities in coastal ecosystems and it plays a fundamental role in employment and the economy of coastal communities. However, in the period 2020-2021, the global outbreak of COVID-19 negatively affected fishing economic activity. Against this background, Andalusia (South of Spain) is an important region in which the resilience of different fishing exploitation systems can be studied, but within the same social and economic framework. Therefore, the main study aim was to investigate the resilience of fishing activity to the COVID-19 pandemic in two Andalusian fishing grounds (i.e. Atlantic and Mediterranean). We analysed daily landings and the first-sale prices of fresh fish of the most caught species in both fishing grounds, while taking into account the different seasonal behaviour of the fisheries. Generalised Linear Models were used to compare the data, which were obtained during periods in which the COVID-19 severity levels differed. These levels were implemented according to political measures. The final objective was to understand how the degree of industrialisation in the fleets can hinder or help maintain the economic activity of fisheries during major crises.
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Although there is a great knowledge about individual anthropogenic threats to different fish species in the Mediterranean Sea, little is known about how these threats accumulate and interact to affect fish species richness in conjunction with environmental dynamics. This study assesses the role of these threats in the fish richness component and identifies the main areas where the interaction between fish species richness and threats is highest. Our results show that fish richness seems to be higher in saltier and colder areas where the chlorophyll-a and phosphate concentrations are lower. Among the anthropogenic threats analyzed, the costal impact and the fishing effort seems to be the more relevant ones. Overall areas with high fish richness are mainly located along the western and northern shores, with lower values in the south-eastern regions. Areas of potential high cumulative threats are widespread in both the western and eastern basins, with fewer areas located in the south-eastern region. By describing the spatial patterns of the fish richness and which drivers explain these patterns we can also identify which anthropogenic activities can be managed more effectively to maintain and restore marine fish biodiversity in the basin.
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Efectos Antropogénicos , Biodiversidad , Animales , Ecosistema , Peces , Mar MediterráneoRESUMEN
The northward expansion of round sardinella (Sardinella aurita) in the Mediterranean Sea, together with declines and fluctuations in biomass and landings of European sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) observed in recent decades, may suggest potential inter-specific competition in the pelagic domain. The coexistence of sympatric zooplanktivorous fish species might therefore be exposed in part to trophic niche overlap and competition for food. Combining visual diet characterization under the microscope with DNA metabarcoding from stomach contents of fish collected in spring results show that predation on relatively large krill is equally important for sardinella than for the other two niche overlapping species. Furthermore, an important overlap is found in their isotopic niche, especially with anchovy, using nitrogen (δ15N) and carbon (δ13C) stable isotopes in muscle tissue. In fact, the three fish species are able to feed effectively in the whole prey size spectrum available during the sampled season, from the smallest diatoms and copepods to the larger prey (i.e., decapods and euphausiids), including fish larvae. Moreover, effective predation upon other large prey like siphonophores, which is observed only when multi-proxy analyses in stomach contents are applied, might also be relevant in the diet of sardinella. The overlapping diet composition in spring, together with the effective use of food resource by sardinella, can be of special interest in potential future scenarios with warmer water temperature leading to lower zooplankton and/or higher jellyfish availability, where sardinella may take advantage over other species due to its feeding plasticity.
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Marine Ecosystem Models (MEMs) provide a deeper understanding of marine ecosystem dynamics. The United Nations Decade of Ocean Science for Sustainable Development has highlighted the need to deploy these complex mechanistic spatial-temporal models to engage policy makers and society into dialogues towards sustainably managed oceans. From our shared perspective, MEMs remain underutilized because they still lack formal validation, calibration, and uncertainty quantifications that undermines their credibility and uptake in policy arenas. We explore why these shortcomings exist and how to enable the global modelling community to increase MEMs' usefulness. We identify a clear gap between proposed solutions to assess model skills, uncertainty, and confidence and their actual systematic deployment. We attribute this gap to an underlying factor that the ecosystem modelling literature largely ignores: technical issues. We conclude by proposing a conceptual solution that is cost-effective, scalable and simple, because complex spatial-temporal marine ecosystem modelling is already complicated enough.
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European anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) are crucial species for the marine ecosystem of the Northwestern Mediterranean Sea. They account for a high percentage of fish landings and they represent an important economic income for the fishery sector. Concerns over their stock status are rising in recent years as biomass, growth, reproductive capacity, and body condition of both species are declining, with latitudinal variations. Therefore, there is an urgent need for a body condition monitoring scheme. Energy storage variability has important implications for both fish recruitment and population structure. Direct condition indices, such as energy density (ED) with bomb calorimetry, are highly reliable for measuring the energy content, but time-consuming. Alternatively, fatmeter analysis and relative condition index (Kn) have been proposed as effective indirect methods. The aim of this study is to test the application of fatmeter as a surrogate of bomb calorimetry to infer the energy content of sardine and anchovy. To validate its use, fatmeter values were compared with both ED and Kn values. Individuals of both species were sampled monthly for a year in order to assess seasonal variations in energy content. Our results highlight that fatmeter measurements are strongly correlated with calorimetry ED for sardine, while a weaker but significant correlation was found for anchovy. The observed differences between the two species are related to their breeding strategies. Based on this study, Kn cannot be considered a good proxy of the energy density of sardine, in particular during the resting period. By contrast, fatmeter analysis appears to be a faster and suitable method to evaluate the energy content of both species routinely. In addition, we provide a linear model to infer ED from fatmeter values for both small pelagic fish. Eventually, these findings could be used to implement body condition monitoring protocols and boost continuous large-scale monitoring.
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Ecosistema , Peces , Animales , Calorimetría , Explotaciones Pesqueras , Humanos , Alimentos MarinosRESUMEN
We propose 'triple-blind review' for peer-reviewed journals - a process that keeps author identities and affiliations blind to manuscript editors until after first appraisal. Blinded appraisal will help to reduce the biases that negatively affect under-represented and minority scientists, ultimately better supporting equity in scientific publishing.
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Edición , HumanosRESUMEN
Global climate change is a major threat to reefs by increasing the frequency and severity of coral bleaching events over time, reducing coral cover and diversity. Ocean warming may cause shifts in coral communities by increasing temperatures above coral's upper thermal limits in tropical regions, and by making extratropical regions (marginal reefs) more suitable and potential refugia. We used Bayesian models to project coral occurrence, cover and bleaching probabilities in Southwestern Atlantic and predicted how these probabilities will change under a high-emission scenario (RCP8.5). By overlapping these projections, we categorized areas that combine high probabilities of coral occurrence, cover and bleaching as vulnerability-hotspots. Current coral occurrence and cover probabilities were higher in the tropics (1°S-20°S) but both will decrease and shift to new suitable extratropical reefs (20°S-27°S; tropicalization) with ocean warming. Over 90% of the area present low and mild vulnerability, while the vulnerability-hotspots represent ~ 3% under current and future scenarios, but include the most biodiverse reef complex in South Atlantic (13°S-18°S; Abrolhos Bank). As bleaching probabilities increase with warming, the least vulnerable areas that could act as potential refugia are predicted to reduce by 50%. Predicting potential refugia and highly vulnerable areas can inform conservation actions to face climate change.
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Antozoos/crecimiento & desarrollo , Cambio Climático , Ecosistema , Calentamiento Global , Animales , Océano Atlántico , Arrecifes de Coral , Agua de Mar , TemperaturaRESUMEN
We investigated the main drivers of eggs and larvae distributions of European sardine and anchovy from the NW Mediterranean Sea. We used Generalized Additive Models and satellite environmental data. Mainly sea surface temperature, but also currents, surface height, and primary production were significantly correlated with both species' early stages distributions. Anchovy optimal temperature upper limit was not detected, but sardine eggs and larvae presented a small-ranged bell-shape curve relationship to SST with an upper SST threshold around 13 °C. Sardine spawning during winter appeared to be dependant not only on in-situ environmental conditions but also on summer conditions prior to the spawning event. Model predictions of the larval and spawning habitat distribution showed clear differences between developmental stages and between species, confirming a worsening of the sardine habitat with time. Considering the further increase of surface temperature predicted in the years to come, the survival of the sardine in the region could be compromised.
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Ecosistema , Peces , Animales , Larva , Mar Mediterráneo , Alimentos MarinosRESUMEN
There is a general lack of information related to the spatial structure and functioning of marine ecosystems considering seasonality. Here, we modeled the biomass distribution of eight commercial marine species in the northwestern Mediterranean Sea during winter and summer. We hypothesised that the seasonal differences of the water column and the spatial heterogeneity of oceanographic conditions in the study area could result in seasonal variations on the species biomass distributions. We employed a Bayesian hierarchical species distribution modelling approach (B-SDM) with data from two experimental trawl surveys to analyse which are the significant drivers in each season. Our results showed that bathymetry, temperature and fishing patterns are important variables explaining the species spatial biomass distributions. Furthermore, we found seasonal differentiation in the spatial distribution of biomass for all the studied species. Our results provide essential knowledge about the seasonal distributions of key species in the Mediterranean Sea, with important management implications.
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Ecosistema , Teorema de Bayes , Biomasa , Mar Mediterráneo , Estaciones del AñoRESUMEN
Sustainable fishing practices must ensure human wellbeing by safeguarding the integrity of marine life-supporting systems. Unfortunately, a significant challenge to fisheries management is that sustainable fishing levels can decline, often synergistically, by co-occurring with climate-driven environmental stressors. Within one of the most impacted marine areas in the world, and encompassing a number of highly targeted commercial species, the small pelagic fish community of the western Mediterranean Sea has recently shown signs of collapse. In this study, we identify a worrying coincidence where fishing hotspots for the commercially valuable European sardine Sardina pilchardus and anchovy Engraulis encrasicolus occur in marine areas mostly affected by climate change. To identify these areas, we overlayed detailed, spatially explicit measurements of fishing pressure with the finest-scale maps of cumulative climate change impacts onto these species. According to our results, doubly impacted marine areas largely occur in the north-western Mediterranean Sea, with climate and fisheries mostly affecting European sardine. Reducing local stressors (i.e., fishing pressure) in highly impacted areas may contribute to maintain these communities within a "safe operating space" (SOS), where they remain resilient to climate change. Accordingly, the redistribution and/or reduction of fishing intensity may alleviate pressure in those areas already affected by climate change. Sustainable fishing strategies may benefit, therefore, from the SOS concept and the spatial assessments provided in this study.
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Ecosistema , Explotaciones Pesqueras , Animales , Cambio Climático , Peces , Humanos , Mar Mediterráneo , Alimentos MarinosRESUMEN
To protect the most vulnerable marine species it is essential to have an understanding of their spatiotemporal distributions. In recent decades, Bayesian statistics have been successfully used to quantify uncertainty surrounding identified areas of interest for bycatch species. However, conventional simulation-based approaches are often computationally intensive. To address this issue, in this study, an alternative Bayesian approach (Integrated Nested Laplace Approximation with Stochastic Partial Differential Equation, INLA-SPDE) is used to predict the occurrence of Mobula mobular species in the eastern Pacific Ocean (EPO). Specifically, a Generalized Additive Model is implemented to analyze data from the Inter-American Tropical Tuna Commission's (IATTC) tropical tuna purse-seine fishery observer bycatch database (2005-2015). The INLA-SPDE approach had the potential to predict both the areas of importance in the EPO, that are already known for this species, and the more marginal hotspots, such as the Gulf of California and the Equatorial area which are not identified using other habitat models. Some drawbacks were identified with the INLA-SPDE database, including the difficulties of dealing with categorical variables and triangulating effectively to analyze spatial data. Despite these challenges, we conclude that INLA approach method is an useful complementary and/or alternative approach to traditional ones when modeling bycatch data to inform accurately management decisions.
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Teorema de Bayes , Conservación de los Recursos Naturales/métodos , Ecosistema , Especies en Peligro de Extinción , Explotaciones Pesqueras/estadística & datos numéricos , Rajidae , Animales , Océano PacíficoRESUMEN
Marine protected areas (MPAs) are a primary strategy for marine conservation worldwide, having as a common goal the protection of essential habitats to enhance fish population recovery. However, MPAs alone may not be effective because species are not isolated from critical impacts occurring outside their boundaries. We evaluated how protecting critical nursery habitats affect the population of an important fishing target, using a 6-year database to predict juvenile hotspots and estimate population trends of the endemic and endangered parrotfish Scarus trispinosus within a mosaic of MPAs at the Abrolhos Bank, NE Brazil. We found that important nursery habitats are within no-take areas, but both juvenile and adult populations still show a declining trend over time. MPAs failed to ensure population maintenance and recovery likely due to overfishing in adjacent areas and the lack of compliance to management rules within multiple-use and within no-take MPAs. MPAs alone are not enough to protect ecologically important endangered species, but is still one of the only conservation strategies, particularly in developing countries. Our results shed light on the need for a wider adoption of more effective conservation policies in addition to MPAs, both in Brazil and in countries with similar governance contexts.
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Especies en Peligro de Extinción , Explotaciones Pesqueras/normas , Peces/fisiología , Animales , Océano Atlántico , Biomasa , ReproducciónRESUMEN
This work combines state-of-the-art methods (DNA metabarcoding) with classic approaches (visual stomach content characterization and stable isotope analyses of nitrogen (δ15N) and carbon (δ13C)) to investigate the trophic ecology of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) at high taxonomic and spatial resolution in the Western Mediterranean Sea. Gut contents observed are in accordance with the dietary plasticity generally described for anchovy and sardine, suggesting a diet related to the opportunistic ingestion of available prey in a certain area and/or time. Genetic tools also showed modest inter-specific differences regarding ingested species. However, inter-specific and intra-specific differences in ingested prey frequencies and prey biomass reflected a latitudinal signal that could indicate a more effective predation on large prey like krill by anchovy versus sardine, as well as a generalized higher large prey ingestion by both species southwards. In fact, both species presented lower δ15N in the northernmost area. This latitudinal gradient indicates changes in the trophic ecology of anchovy and sardine that coincide with previously described better biological conditions for fish in the southern part of the study area as well as higher landings of both species in recent years.
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Código de Barras del ADN Taxonómico , Dieta , Peces/genética , Conducta Predatoria/fisiología , Animales , Ecosistema , Contenido Digestivo , Mar Mediterráneo , Alimentos Marinos , Estaciones del AñoRESUMEN
Interactions among species are likely to change geographically due to climate-driven species range shifts and in intensity due to physiological responses to increasing temperatures. Marine ectotherms experience temperatures closer to their upper thermal limits due to the paucity of temporary thermal refugia compared to those available to terrestrial organisms. Thermal limits of marine ectotherms also vary among species and trophic levels, making their trophic interactions more prone to changes as oceans warm. We assessed how temperature affects reef fish trophic interactions in the Western Atlantic and modeled projections of changes in fish occurrence, biomass, and feeding intensity across latitudes due to climate change. Under ocean warming, tropical reefs will experience diminished trophic interactions, particularly herbivory and invertivory, potentially reinforcing algal dominance in this region. Tropicalization events are more likely to occur in the northern hemisphere, where feeding by tropical herbivores is predicted to expand from the northern Caribbean to extratropical reefs. Conversely, feeding by omnivores is predicted to decrease in this area with minor increases in the Caribbean and southern Brazil. Feeding by invertivores declines across all latitudes in future predictions, jeopardizing a critical trophic link. Most changes are predicted to occur by 2050 and can significantly affect ecosystem functioning, causing dominance shifts and the rise of novel ecosystems.