Feeding ecology and trophic position of three sympatric demersal chondrichthyans in the northwestern Mediterranean

14 pages, 5 figures, 3 tables, supplementary material http://dx.doi.org/10.3354/meps11188Understanding how marine predators interact is a scientific challenge. In marine ecosystems, segregation in feeding habits has been largely described as a common mechanism to allow the coexistence of several competing marine predators. However, little is known about the feeding ecology of most species of chondrichthyans, which play a pivotal role in the structure of marine food webs worldwide. In this study, we examined the trophic ecology of 3 relatively abundant chondrichthyans coexisting in the Mediterranean Sea: the blackmouth catshark Galeus melastomus, the velvet belly lanternshark Etmopterus spinax and the rabbit fish Chimaera monstrosa. To examine their trophic ecology and interspecific differences in food habits, we combined the analysis of stomach content and stable isotopes. Our results highlighted a trophic segregation between C. monstrosa and the other 2 species. G. melastomus showed a diet composed mainly of cephalopods, while E. spinax preyed mainly on shrimps and C. monstrosa on crabs. Interspecific differences in the trophic niche were likely due to different feeding capabilities and body size. Each species showed different isotopic niche space and trophic level. Specifically, C. monstrosa showed a higher trophic level than E. spinax and G. melastomus. The high trophic levels of the 3 species highlighted their important role as predators in the marine food web. Our results illustrate the utility of using complementary approaches that provide information about the feeding behaviour at short (stomach content) and long-term scales (stable isotopes), which could allow more efficient monitoring of marine food-web changes in the study areaM.A.-P. was supported by a predoctoral fellowship of the FPI program (Spanish Ministry of Economy and Competitiveness). J.N. was supported by a research contract of the Marie Curie GIC project BioWeb. M.C. and J.A. are supported by a post-doctoral contract of the Ramon y Cajal Program (Spanish Ministry of Economy and Competiveness), and M.C. was also supported by BioWeb project. This study is a contribution to the project ECOTRANS (CTM2011-26333, Ministerio de Economía y Competitividad, Spain)Peer Reviewe

Eco-socio-economic vulnerability assessment of Portuguese fisheries to climate change

Understanding ecological, and socio-economical vulnerabilities is fundamental towards developing and implementing regional adaptation strategies to climate change. The Portuguese coast is situated in a transition zone between temperate ecosystems to the north, and subtropical with Mediterranean characteristics, to the south, with distinct oceanographic regions (north, centre, and south), fish assemblages and socioeconomic realities of fish communities across these regions. We develop a framework to assess fisheries climate vulnerability in each port. A total of 32 ecological and socio-economic indicators were used to measure exposure, sensitivity, and adaptive capacity of the fishing sector to climate change by combining i) environmental projections ii) information from fishing communities (surveys at ports) and iii) landings and socio-economic data from official statistics offices. The vulnerability to climate change across regions, and its expected impact on fishing fleets and local communities, was low-moderate. Such information will enable fishing communities and decision makers to respond to expected climate change effects and direct/indirect associated activities. This framework comprises background information for developing mandatory EU climate adaptation plans that aim to improve the resilience of fisheries socio-economic systemsFundação para a Ciência e a Tecnologia | Ref. UIDB/04326/2020Fundação para a Ciência e a Tecnologia | Ref. UIDP/04326/2020Fundação para a Ciência e a Tecnologia | Ref. LA/P/0101/2020Fundação para a Ciência e a Tecnologia | Ref. SFRH/BD/11426/2022Ministerio de Ciencia e Innovación | Ref. FJC2020–043449-IFundação para a Ciência e a Tecnologia | Ref. SFRH/BD/06336/202Fundação para a Ciência e a Tecnologia | Ref. DL57/2016/CP1361/CT0008Fundação para a Ciência e a Tecnologia | Ref. 2022.04803.CEECINDPortugal 2020 | Ref. SAICT-45-2017-02Portugal 2020 | Ref. ALG-01-0145-FEDER-028518Portugal 2020 | Ref. PTDC/ASP-PES/28518/2017MAR2020-FEAMP | Ref. MAR-01.03.02-FEAMP-005

Ecological sensitivity and vulnerability of fishing fleet landings to climate change across regions

The degree of exposure of fishing communities to environmental changes can be partially determined by the vulnerability of the target species and the landings composition. Hence, identifying the species that ecologically most contribute to the vulnerability of the landings are key steps to evaluate the risk posed by climate change. We analyse the temporal variability in intrinsic sensitivity and the ecological vulnerability of the Portuguese fisheries landings, considering the species proportions derived both from the weights and revenues. To account for the diversification of species of each fleet, we explored the species dependence of the fishery in combination with the vulnerability of them. The analyses were carried out separately for three fleet typologies and three regions. Opposite to what has been observed at a global scale, the ecological sensitivity of the fisheries landings between 1989 and 2015 did not display a decline across areas or fishing fleets. Considering each fleet independently, for trawling, where average vulnerability was lower than in the other fleets, the sensitivity of the landings increased since the 2000s. On the other hand, the high vulnerability found in multi-gear fleets was compensated by diversification of the species caught, while purse-seine fleets targeted low vulnerability species but presented a high fishery dependence on few species. The results highlight the importance of combining information on ecological vulnerability and diversification of fishing resources at a regional scale while providing a measure of the ecological exposure to climate change.info:eu-repo/semantics/publishedVersio

Ecological sensitivity and vulnerability of fishing fleet landings to climate change across regions

The degree of exposure of fishing communities to environmental changes can be partially determined by the vulnerability of the target species and the landings composition. Hence, identifying the species that ecologically most contribute to the vulnerability of the landings are key steps to evaluate the risk posed by climate change. We analyse the temporal variability in intrinsic sensitivity and the ecological vulnerability of the Portuguese fisheries landings, considering the species proportions derived both from the weights and revenues. To account for the diversification of species of each fleet, we explored the species dependence of the fishery in combination with the vulnerability of them. The analyses were carried out separately for three fleet typologies and three regions. Opposite to what has been observed at a global scale, the ecological sensitivity of the fisheries landings between 1989 and 2015 did not display a decline across areas or fishing fleets. Considering each fleet independently, for trawling, where average vulnerability was lower than in the other fleets, the sensitivity of the landings increased since the 2000s. On the other hand, the high vulnerability found in multi-gear fleets was compensated by diversification of the species caught, while purse-seine fleets targeted low vulnerability species but presented a high fishery dependence on few species. The results highlight the importance of combining information on ecological vulnerability and diversification of fishing resources at a regional scale while providing a measure of the ecological exposure to climate change.Fundação para a Ciência e a Tecnologia | Ref. UIDB/04326/2020Fundação para a Ciência e a Tecnologia | Ref. SAICT-45-2017-02Fundação para a Ciência e a Tecnologia | Ref. ALG-01- 0145-FEDER-028518Fundação para a Ciência e a Tecnologia | Ref. PTDC/ASP-PES/28518/2017Fundação para a Ciência e a Tecnologia | Ref. MAR-01.03.02-FEAMP-0052Fundação para a Ciência e a Tecnologia | Ref. FCT DL57/2016/CP1361/CT000

The seasonal distribution of a highly commercial fish is related to ontogenetic changes in its feeding strategy

Improving the knowledge on the biology, ecology and distribution of marine resources exploited by fisheries is necessary to achieve population recovery and sustainable fisheries management. European hake (Merluccius merluccius) is one of the most important target species in the Mediterranean Sea and is largely overexploited by industrial fisheries. Here, we used two methodological approaches to further investigate the seasonal variation in the spatial distribution of European hake considering ontogenetic changes and trophic ecology in the western Mediterranean Sea. Our main aim was to explore if spatial changes in hake distribution were related to trophic behavior, in addition to key environmental factors. We employed a hierarchical Bayesian species distribution modeling approach (B-SDM), using spatial data from two oceanographic surveys conducted during winter and summer. We analyzed how the environmental variables, together with abundance and mean weight distribution of the main preys identified for European hake, affected the seasonal distribution of the species. Results revealed clear differences in the distribution of the European hake between seasons, which were indeed partially correlated to the distribution of their main preys, in addition to the environment. Stable isotope values and Bayesian isotopic mixing models (MixSIAR) revealed substantial seasonal and ontogenetic differences in trophic habits of European hake, partly matching the spatial distribution results. These findings could have implications for a future seasonal-based adaptive fisheries management, as local depletion of prey, or variation in size and condition may affect European hake presence in this area. Moreover, this study illustrates how the sequential application of methodologies provides a more holistic understanding of species seasonality, which is essential to understand the phenological processes of exploited species and their potential shifts due to environmental changes.Postprin

Changes in Life History Traits of Small Pelagic Fish in the Western Mediterranean Sea

21 pages, 8 figures, 3 tables, supplementary material https://www.frontiersin.org/articles/10.3389/fmars.2021.570354/full#supplementary-material.-- Data Availability Statement: The datasets presented in this article are not readily available because the dataset is available by request to the Spanish Institute of Oceanography. Requests to access the datasets should be directed to [email protected] pelagic fish (SPF) in the western Mediterranean Sea are key elements of the marine food web and are important in terms of biomass and fisheries catches. Significant declines in biomass, landings, and changes in the age/size structure of sardine Sardina pilchardus and anchovy Engraulis encrasicolus have been observed in recent decades, particularly in the northern area of the western Mediterranean Sea. To understand the different patterns observed in SPF populations, we analyzed key life history traits [total length at age, length at maturity, gonadosomatic index (GSI), and body condition (Kn)] of sardine and anchovy collected between 2003 and 2017, from different fishing harbors distributed along a latitudinal gradient from northern to southern Spain. We used Generalized Linear Models (GLM) to estimate the length at maturity and Generalized Additive Models (GAMs) to test the relationship with environmental variables (seawater temperature, water currents, and net primary productivity). The life history traits of both species presented seasonal, interannual and latitudinal differences with a clear decline in length at age, length at first maturity, and body condition, for both species in the northern part of the study area. In the southern part, on the contrary, life history traits did not present a clear temporal trend. The environmental conditions partially explained the long-term changes in life history traits, but the selected variables differed between areas, highlighting the importance of regional oceanographic conditions to understand the dynamics of small pelagic fish. The truncated length-at-age pattern for both species with the disappearance of the larger individuals of the population could have contributed to the poor condition of small pelagic fish populations in the northern part of the western Mediterranean Sea in recent years. In the south area, recent declines in body condition for sardine and anchovy were observed and could be a possible first sign for future population declines. This study highlights the importance of understanding the trade-off between the energy invested in reproduction, maintenance and growth at seasonal and interannual level to advance our knowledge on how environmental and human pressures influence population dynamics of small pelagic fish at local and regional scalesThis study was carried out within the Spanish Research project PELWEB (CTM2017-88939-R) funded by Spanish Ministry of Science, Innovation and Universities and the European Research Contract SPELMED (SC NR 02-TENDER EASME/EMFF/2016/032XXX) funded by EC EASME. Fisheries data collection has been co-funded by the EU through the European Maritime and Fisheries Fund (EMFF) within the National Program of collection, management and use of data in the fisheries sector and support for scientific advice regarding the Common Fisheries Policy (Regulation, EU 2017/1004)With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)Peer reviewe

Climate change and seasonal dynamics of bottom-trawl fisheries landings in the western Mediterranean

Comunicación presentada al Forum on Fisheries Science in the Mediterranean and The Black Sea (FishForum 2024), 19-23 Febrero 2024, celebrado en Antalya (Turquía)The Mediterranean Sea stands out as one of the most vulnerable ecosystems on global scale, facing an array of cumulative impacts, including high climate risks. Climate velocity drives species shifts and redistributions, which has led to changes at different ecosystem levels. However, it is necessary to examine how commercial marine species respond at regional and seasonal levels, which is often the optimal management scale. Here, we analyzed time series data on bottom-trawl fisheries landings (2007 to 2021) and explored seasonal variations using climate velocity and relative climate exposure as metrics of potential range shifts (1987 to 2021) in the Western Mediterranean Sea. Additionally, we examined the impact of climate connectivity, using climate velocity trajectories and temperature preferences, along with life-history traits of commercial species. The outcomes of our study showed fluctuations in climate velocity across diverse spatial and seasonal scales. We identified a relationship between the abundance of most captured commercial species and seasonal climate velocity. These variations were also influenced by the temperature preferences and the life-history traits of these species and, play a key role in the climate connectivity between the network of Marine Protected Areas. We conclude that climate velocity metrics are valuable to comprehend how economically important marine species respond in the Western Mediterranean Sea at regional and seasonal levels. Using this knowledge, we can develop climate-smart management strategies, contributing to biodiversity conservation and the preservation of crucial ecosystem services, while mitigating the risks associated with future maladaptation

. A trophic latitudinal gradient revealed in anchovy and sardine from the Western Mediterranean Sea using a multi-proxy approach

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.En prensa2,92