Proceedings, Volume 146, 2026

The Twaite shad (Alosa fallax Lacépède, 1800) is an endangered anadromous fish listed as Vulnerable on the IUCN Red List. In northern Catalonia (NE Iberian Peninsula), the species maintains a small reproducing population in the Fluvi&ag...

Ocean deoxygenation is intensifying globally, and hypoxia is increasingly documented on tropical coral reefs; yet, its consequences for the physiology and social functioning of reef fishes remain poorly understood. Here, we experimentally exposed the...

Introduction: The Strait of Gibraltar, a narrow gateway between the Atlantic Ocean and the Mediterranean Sea, concentrates intense biotic exchange and functions as a global “ecological gate” for marine species. Despite its ecological rele...

Diadromous fish provide key ecological and socio-economic services in European Atlantic catchments, yet their marine phase remains poorly understood and weakly integrated into management. Involving nine partners from Portugal, Spain, France and Irela...

Introduction: As apex and mesopredators, elasmobranchs help maintain marine ecosystem balance by shaping food-web structure and habitat connectivity, yet more than one-third of species are threatened with extinction. Identifying where and when they a...

Introduction: Mediterranean coastal wetlands are highly dynamic ecosystems that support diverse fish communities and are often of high conservation value. The Ebro Delta is one of the most important coastal wetlands in the Western Mediterranean, and...

Introduction: The aglomerular kidney, characterised by the absence of functional glomeruli and reliance on tubular secretion alone, has evolved independently across multiple teleost lineages occupying diverse environments, including notothenioids of...

Small pelagic fishes are essential for artisanal fisheries and food security in São Tomé and Príncipe, yet biological information required for stock assessment remains scarce. This study examined the population dynamics and life-...

Currently, more than half of Pyrenean high mountain lakes are occupied by fish as a result of historical introductions that date back centuries and which have accelerated during the last 70 years. In the southern slope of these mountains, the main fi...

Transitional waters—such as estuaries, lagoons, deltas, and coastal wetlands—are dynamic environments where freshwater and seawater interact, forming highly productive and biologically diverse ecosystems. Shaped by temperature and salinit...

Fish are continuously exposed to stress factors throughout their life cycle, making the use of anaesthetics essential for a wide range of experimental procedures. Currently, the most commonly used and FDA approved anaesthetic for fish research is Tri...

Introduction: Elasmobranchs play a crucial role in ecosystem regulation, but they are highly vulnerable to rapid environmental changes, particularly those driven by anthropogenic activities. Therefore, elasmobranchs are among the most threatened vert...

Introduction: Understanding population structure is essential for effective fishery management, and otolith shape analysis provides a robust framework for detecting spatial variation in marine fish populations. The bluefish (Pomatomus saltatrix), a c...

Introduction: Biological invasions constitute one of the main threats to freshwater ecosystems, causing significant ecological changes through the introduction of exotic species that compete with or prey upon native species. In Portugal, the introduc...

Introduction: River connectivity is a fundamental component of lotic ecosystems, frequently disrupted by anthropogenic barriers. Fishways are critical mitigation tools for restoring this connectivity; however, their temporal use by fish is often assu...

Introduction: Long-term ecological changes in estuarine communities are primarily driven by anthropogenic and environmental pressures. While abundance-based indicators are commonly used to assess these shifts, they often mask underlying ecological as...

Diadromous fishes support culturally important small-scale fisheries in Galicia (NW Spain), but their assessment is constrained by scarce biological and effort data. We evaluated nine data-poor fishery units using first-sale records for Alosa alosa,...

Introduction: Marine recreational fishing (MRF) is a socially, economically, and ecologically important activity. However, the absence of systematic monitoring and research in Portugal has limited a comprehensive understanding of the sector and its b...

Introduction: Longlines are traditional fishing gear and are widely used in marine systems for both quantitative and qualitative sampling of large predators like tuna, swordfish, sailfish, marlin or sharks. This highly selective method has been appli...

Introduction: Knowledge of Iberian freshwater fish fauna among the general public is scarce and generally limited to a handful of species. Moreover, this knowledge gap increases as time goes by, particularly in younger generations, due to the lack of...

Brown trout (Salmo trutta L.) is a bioindicator species of ecological integrity in mountain rivers of northern Portugal. Habitat loss and recreational fishing justify sustainable management to balance the conservation and exploitation of these fish p...

Introduction: The circum-Mediterranean region is a global biodiversity hotspot, hosting a highly distinctive freshwater fauna with a high degree of endemism and conservation concern. However, these ecosystems are increasingly threatened by biological...

Currently, in Catalonia, Spanish toothcarp (Apricaphanius iberus) has a discontinuous distribution, with its main populations located in the Ebro Delta and the Empordà wetlands. Along the Catalan coast, there are some small, isolated populatio...

Introduction: Understanding population structure is essential for the effective management of marine resources. The bluefish (Pomatomus saltatrix) is a widely distributed and commercially important species along the Brazilian coast, yet its populatio...

Introduction: The global ornamental fish trade is a rapidly expanding sector and a major pathway for the introduction of non-native species, particularly in freshwater ecosystems in developed countries. The introduction of non-native species can resu...

Introduction: Fish skin is the first line of defense against the aquatic environment, acting as a physical, chemical, and immunological barrier. In addition to preventing pathogen entry, the skin and its mucus contribute to osmoregulation, innate imm...

Fish Aggregating Devices (FADs), traditionally used to attract and concentrate fish, can also serve as effective environmental enrichment tools in reservoirs, particularly in those with homogeneous characteristics and scarce refuge habitat, enhancing...

Introduction: Squalius palaciosi (Doadrio, 1980; Leuciscidae) is a highly threatened freshwater fish species with an extremely restricted distribution, currently confined to a few tributaries on the right bank of the Guadalquivir River basin. During...

Introduction: Aquatic contaminants can alter fish behavior before overt toxicity becomes evident, making neurobehavioral endpoints relevant for ecosystem protection and for hazard prioritization within a One Health framework. We recently developed a...

Introduction: Marine heatwaves are increasing in frequency and intensity, posing major challenges for fishes inhabiting shallow coastal ecosystems. Short-term exposure to extreme warming can alter metabolic performance and thermal tolerance, with pot...

Introduction: The tub gurnard (Trigla lyra) is a demersal species of commercial interest whose long-term distributional dynamics remain poorly understood. Understanding spatial and temporal changes is essential for fisheries management and for assess...

Introduction: The Iberian killifish (Apricaphanius iberus), an endemic cyprinodontid of the Spanish Mediterranean coast, is a key conservation species due to its restricted distribution, high sensitivity to habitat alteration and invasive fish, and e...

The Iberian barbel (Luciobarbus bocagei Steindachner, 1864) is a potamodromous species that displays migratory movements, with adults moving upstream during spring to spawn, followed by downstream migration in autumn by both adults and juveniles to f...

Introduction: Artificial infrastructure interrupts river longitudinal connectivity, preventing the free flow of water, matter, energy, and organisms through the system, altering the habitat and impacting freshwater biodiversity. Freshwater fishes are...

Introduction: Freshwater fish communities in Mediterranean basins have undergone profound changes over recent decades due to biological invasions, habitat alteration, and hydrological regulation. The Segura River basin (SE Spain), particularly in the...

Introduction: The discharge of treated wastewater into coastal and marine environments represents a continuous source of pollutants, including pharmaceuticals and plastic additives with endocrine-disrupting (ED) potential. These compounds are of incr...

Introduction: Establishing baseline descriptions of inorganic elements in the early life stages of sharks and in their respective nursery areas is essential for assessing anthropogenic impacts and supporting conservation strategies. Objectives: This...

Introduction: Brown trout (Salmo trutta L.) is a salmonid fish considered a genetically and geographically highly structured species. The species is catalogued as vulnerable in the Spanish Red List since 1992. Based on morphological differentiation,...

Introduction: Elasmobranchs play a vital role in marine food webs through top-down control and the structuring of ecosystem stability, yet more than one-third of species face extinction. The Maldives, a recognised Indian Ocean hotspot for shark and b...

Introduction: Aquatic chemical pollution is among the most worrying threats to ecosystem health. There is an ever-increasing variety of pollutant substances detected across the source-to-sea continuum, causing loss of biodiversity and ecological dise...

Introduction: Restoring riverine connectivity is a cornerstone of ecological restoration for migratory fish populations. When physical barriers like dams lack effective fishways, translocation to more suitable sites becomes an alternative. Objectives...

Introduction: The genus Thorichthys comprises nine species of Central American freshwater cichlids, which are distributed along the eastern slopes of Mexico and Honduras. These species are grouped into two subgroups: “helleri” and “...

The Tua River is a tributary of the Douro River in the North of Portugal used as a spawning ground for potamodromous fish, namely the Iberian barbel (Luciobarbus bocagei, Steindachner, 1864). Although access to this tributary became severely constrai...

Introduction: Freshwater habitats underpin global biodiversity and provide an array of essential ecosystem services to humans. However, threat hotspots like the Iberian Peninsula combine severe anthropogenic impacts (habitat degradation, climate chan...

In the Iberian Peninsula, the rapid expansion of the invasive species Alburnus alburnus (bleak) has intensified its contact with several endemic cyprinid species, raising concerns about hybridization, introgression, and the loss of genetic diversity....

Introduction: The fish fauna in the Yucatan Peninsula exhibit a unique composition, shaped by the region’s complex geological and hydrological history. Thorichthys meeki is a widely distributed cichlid species that has been the subject of morph...

Introduction: Climate change is reducing freshwater availability worldwide, making it essential to understand how freshwater inflow influences estuarine ecosystem functioning and marine fisheries productivity. In the Gulf of Cádiz (SW Spain),...

Introduction: Skates (Rajidae) are cornerstone elasmobranchs, yet their intrinsic biological constraints, like slow growth, late maturation, and low fecundity, render them exceptionally susceptible to anthropogenic pressure. Despite their ecological...

Elopomorpha is one of the most primitive teleost lineages and is characterised by a unique trait, the leptocephalus larva. Its leaf-like and transparent body is largely composed of glycosaminoglycan (GAG), which makes it distinctive from other fish l...

Introduction: The Guadiana basin harbours one of the most threatened freshwater fish faunas in Europe, concentrating a high number of Iberian endemisms and species of high conservation interest. Among these, the Iberian minnowcarp (Anaecypris hispani...