ABSTRACT Octopus americanus Froriep, is the most significant octopus species for industrial and artisanal fishing in the Western Atlantic. Redescribed in 2020, little is known about its ecology and behaviour in the natural environment, and available data for management plans largely derive from fleet fishing landings at depths ranging from 30 to 200 m. We employed three complementary methodologies to expand knowledge on the habitat use and distribution of this species in shallow water (up to 15 m) around coastal islands in South Brazil. These methods included: (1) longline pot fishing experiments (2014–2017), (2) scuba diving collections (2021–2023), and (3) interviews with artisanal fishermen in the region (2021–2022). We sampled octopus size, abundance, diet and habitat characteristics. Octopus americanus was found throughout the year around the islands, with large individuals prevalent in winter and smaller ones in autumn. Bivalves, especially Perna perna, along with crustaceans and gastropods, were the primary items identified in the octopus’ middens, while crustaceans, fish and polychaetes were present in the stomach contents. Octopus americanus was observed across various substrate and den types associated with the rocky coast, and frequently observed at the interface between rock and sand. The species utilised the study area for breeding, feeding and growth. Our results identify critical areas to sustain O. americanus’ population, contributing to the understanding of its ecological niche and conservation. Recommendations for fisheries management are provided.

Phytoplankton responses to marine heatwaves in the Kuroshio-Oyashio Extension region: Seasonal variations and potential drivers.

Moderate growth and limited movement of the prized golden sandfish sea cucumber, Holothuria lessoni

In the Amazon region, Arapaima gigas holds significant gastronomic and cultural value compared to other fish species due to its large size. This fish is home to various helminth species that parasitise primarily its gastrointestinal organs. During the 2023 dry season, a total of 60 gastrointestinal organs from A. gigas specimens were collected from a fisheries management program conducted by local residents within the Mamirauá Reserve. For gastric parasitological analysis, each organ was separated in containers, and the parasites were recovered, washed, and fixed in 70% alcohol for analysis by light and scanning electron microscopy. Additionally, stomach samples of the hosts infected with parasites were fixed in 10% formalin for histopathological examination. 16% of the parasitised fish presented ulcerative areas in the gastric mucosa of varying degrees. Microscopically, a severe inflammatory reaction with infiltration of eosinophils, lymphocytes, and macrophages was observed, associated with co-infection by Goezia spinulosa and Neoterranova serrata. Additionally, morphological and morphometric data aided by scanning electron microscopy for N. serrata were added.

ABSTRACT Fish farming is a part of the agricultural sector that provides economic, social, and ecosystem functions that are important for reducing food and nutrition insecurity for the poorest and most marginalized groups around the world and particularly crucial for poverty reduction in African countries. While many studies are preoccupied with developed countries, there is less research focusing on Sub‐Saharan Africa. In Ethiopia, research on the governance of fishing management is relatively scarce. Therefore, this study aimed to analyze the implications of environmental governance for fishing management. Purposive and convenience sampling were used to select respondents. Survey data were collected from 180 fishers, with three key informants. Principal component analysis (PCA) and factor analysis (FA) were used to analyze the quantitative data. The results show a low level of environmental governance practices in the two study areas, a lack of attention to the fishing sector, political instability being the major challenge in one of the study areas, top‐down governance approach, and fishing as a characteristic of poverty. We argue that strong political drive, capacity, and stability are crucial for effective environmental and governance. Interactive governance of natural resource systems, adaptive and collaborative environmental governance are needed to promote sustainable fishery management across Africa. Insights from this study can contribute to the implementation of a new framework for future sustainable fishing management. The proposed framework critically engages with the challenges and interventions that are needed to positively influence fishing management and can fill current geographical and topical research gaps.

The functioning of the trophic cascade in fishponds determines the ecosystem stability and breeding success. We investigated the trophic and competitive relationships in the meta-network of carp ponds. We hypothesised that small taxa of the zooplankton consumer level would play a dominant role in the community. The importance of taxa for biomass flux and the strength of interspecific relations were assessed using network graph modelling. Critical to the coherence of the meta-network were positive associations initiated by species that exploit different feeding niches and tolerate high cyanobacterial biomass, such as small cladocerans Bosmina longirostris and Chydorus sphaericus, and the rotifers Polyarthra longiremis. Negative associations, potentially reflecting predation and competitive exclusion, were less important. The observed characteristics of dominant species and their relationships made it possible to identify trophic pathways and their potential consequences for common carp culture. This study presents a new approach to understanding the functioning of the pond food web in aquaculture and may contribute to sustainable fisheries management.

Paralabrax albomaculatus, known as the camotillo or white-spotted sand bass, is a finfish endemic to the Galápagos Islands. An important species in the artisanal fishery, P. albomaculatus has undergone heavy population declines in recent decades, and is categorised as Endangered by the IUCN. Despite its socio-economic importance and endemic status, nothing is currently known about the population structure of the species, impeding evidence-based fisheries management. In this study, we use microsatellite markers to investigate its population structure and genetic diversity over the east, south and west of the Galápagos archipelago. We found evidence of high connectivity across the archipelago, with the species constituting a single population. We also found that genetic diversity was high, despite fishing pressure and recorded ongoing population declines. Our results suggest that P. albomaculatus should be managed as a single fishery stock across the Galápagos. As a single-population species and fishery, managers should also be aware that P. albomaculatus is inherently vulnerable to perturbation as recruitment from other populations is not possible in the event of population decline. However, high genetic diversity gives cause for cautious optimism regarding the genetic capacity for resilience of the population to novel environmental stressors. These results should aid in the implementation of a species-specific management plan for this Galápagos endemic.

Abstract The United Nations Fish Stocks Agreement is mandated to ensure the long-term conservation and sustainable use of straddling and highly migratory fish stocks through the effective implementation of the relevant provisions of the UNCLOS. However, the Agreement can only achieve its intended outcomes if all relevant States become parties to it, implement its provisions, and comply with its obligations. A key focus of the Agreement has been the longstanding emphasis on the duties of flag States to exercise effective control over vessels flying their flags. This study examines the legislative frameworks governing flag State duties under UNFSA in selected South Asian countries, including Bangladesh, India, Maldives, and Sri Lanka, within the Bay of Bengal region. Furthermore, the study proposes strategies to enhance the effective implementation of flag State duties for achieving sustainable fisheries management.

ABSTRACT The New Zealand black-footed abalone, Haliotis iris, holds significant ecological, economic, and cultural value. Abalone from the Chatham Islands fisheries contribute substantially to the national catch, yet populations show marked variability in growth rates. To investigate whether this variability relates to the gut microbiome, sub-adult and adult abalone from four sites were assessed using morphometrics and 16S rRNA gene Illumina MiSeq sequencing. Adult abalone collected from Ascots Beach and Wharekauri were heavier, longer and had larger tissue areas than those from Owenga Harbour and Point Durham, whereas sub-adults showed no size differences. Gut content analysis revealed that fast-growing populations consumed more red algae and less green algae, while brown algae dominated digestion across all sites. Although alpha-diversity did not differ significantly among sites or ages (except at Point Durham), microbial beta-diversity varied significantly by both factors. Core taxa included Psychrilyobacter, Mycoplasma, Vibrio, Propionigenium, unassigned Bacilli, and Blastopirellula. Site- and age-associated microbiome differences may reflect seaweed availability and nutritional quality, warranting further investigation through targeted feeding trials. This study provides a reference baseline for future gut microbiota research on wild H. iris and highlights how algal nutrients and gut-bacteria-mediated digestion may contribute to population-level growth patterns, supporting sustainable fishery management.

The Chilean jack mackerel (Trachurus murphyi) is an economically important pelagic fish widely distributed across the South Pacific Ocean. Due to intense fishing pressure and the lack of high-quality genomic resources, the development of sustainable fisheries management strategies has been hindered. Here, we present a highly contiguous chromosome-level genome assembly of T. murphyi using PacBio and Hi-C sequencing data. The assembled genome spans 818.31 Mb, with a contig N50 length of 24.89 Mb and a scaffold N50 length of 34.34 Mb. The assembly is anchored on 24 pseudo-chromosomes, covering 95.80% of the genome. BUSCO analysis indicates a high level of completeness at 99.0%. Telomeric repeat motifs were detected at 12 single chromosome ends, whereas putative centromeric regions were identified on 12 chromosomes. Repetitive sequences account for 23.86% of the total genome, and 47,734 protein-coding genes were annotated, 90.98% of them with assigned function. This high-quality genome assembly serves as a valuable resource for studying the genetic diversity and population structure of the Chilean jack mackerel and provides a solid foundation for future management and conservation efforts.

ENSO-driven distribution shifts in the critically endangered Mustelus whitneyi along the Northern Peruvian Coast.

Declining response rates coupled with increasing non-response bias to recreational surveys pose challenges for accurately estimating participation and associated economic metrics. This study investigates the presence of “avidity bias,” defined as the disproportionate representation of anglers with higher fishing participation frequencies and examines its implications for fisheries management surveys. Using data from two recent studies of recreational anglers conducted in Ohio (2021 and 2024), and other historical datasets this study identify significant overrepresentation of avid anglers in surveys. This study demonstrates a post-hoc weighting technique based upon years of fishing license-purchase history, as an indicator, to account for the influence of avidity bias. Results indicate that unadjusted estimates overrepresented fishing effort by roughly 31%, while the post-hoc weighting substantially reduced the measured overrepresentation. These findings highlight the importance of addressing avidity bias in recreational survey design to improve the reliability of estimates.

ABSTRACTHorse mackerel (Trachurus trachurus, Linnaeus, 1758) is an epipelagic fish commonly found in Moroccan Mediterranean waters. This study was aimed at studying the ecology by monitoring gonadal development and reproductive indices of T. trachurus populations along the eastern Moroccan Mediterranean coast over a 12‐month period. For that, a total of 390 specimens were sampled, with total lengths ranging from 7.8 to 33.8 cm and weights from 3.78 to 310.52 g. Several reproductive indices were analyzed. Monthly monitoring of the gonado‐somatic index (GSI) identified two spawning periods for T. trachurus: the first in late winter‐early spring (February–April), and the second in summer (July–September), confirming that this species is a fractional spawner fish. The hepato‐somatic index (HSI) followed a similar trend to GSI, reflecting the energy allocation for reproduction. The size at first sexual maturity (L50) was estimated at 23.5 cm for females and 22.5 cm for males, representing critical metrics for fisheries management, as they help set regulatory guidelines, such as minimum landing sizes, and are also a prerequisite for estimating spawning stock biomass. The overall sex ratio showed a predominance in favor of males (62%) over females (38%). These results represent a valuable contribution to a better understanding of the biology of T. trachurus, and to the implementation of stock assessment to ensure the sustainability of catches.

Persistent taxonomic uncertainty has plagued the Trichiuridae family (hairtails), a group of ecologically and commercially significant fishes, a result of conflicting morphological criteria and historical misclassifications. While molecular approaches have advanced understanding their taxonomy, mitochondrial-based analyses and misapplied nomenclature have obscured species boundaries and population dynamics. Here, we integrate a chromosome-level genome assembly of Trichiurus japonicus with whole-genome resequencing of congeneric species to resolve the taxonomic ambiguity in Trichiurus. Combining phylogenomic, demographic, and population genetic analyses, we resolve taxonomic uncertainties by redefining species boundaries, reconstructing population dynamics, and identifying genomic divergence between populations. Our analyses suggest that T. japonicus and T. nanhaiensis are distinct species. Crucially, we identify a cryptic, genetically distinct lineage putatively derived from the Indian Ocean, misclassified as T. lepturus in previous studies, underscoring the impact of commercial trade on taxonomic confusion. Our analyses reveal low spatial genetic differentiation in T. japonicus across the sampled Northwest Pacific localities, consistent with weak population structure within our sampling frame. This study establishes a genomic framework of Trichiurus to resolve taxonomic conflicts in morphologically cryptic taxa and advances strategies for sustainable fisheries management under climate change.

ABSTRACT This study examined the capture dynamics of mantis shrimp (Squilla mantis) in the small-scale fisheries of Thermaikos Gulf (N. Aegean, Greece) by using commercial catch data and video recordings during net hauling. Mantis shrimp was a major bycatch species in the trammel-net fishery targeting the common sole Solea solea, accounting for 11% of total biomass. Notably, 54.9% of mantis shrimp catches were commercialized, 42.1% were retained by fishermen and only 2.2% discarded, primarily owing to damaged individuals. Their abundance was strongly associated with to muddy substrates and positively correlated with teleost fishes, particularly flatfishes like common sole and spotted flounder Citharus linguatula. Observations provided direct evidence of mantis shrimp actively preying on fish trapped in nets, with nearly one out of every five mantis shrimp preying on different species and establishing predatory groups of 2–11 individuals per prey item. Mantis shrimp occurred both individually and in clusters, the latter usually linked to feeding activity. The reported dual role of mantis shrimp as a large local economic asset and an active predator of valuable commercial flatfish within nets should aid in fisheries management, market exploitation and ecological knowledge of this important benthic predator.

Achieving sustainable management of marine resources and implementing biologically realistic assessment depend on accurate identification of stock structure. Most harvested marine species are currently assessed under the common and long-standing assumption of "stock unit" within designated spatiotemporally invariant polygons known as assessment units, despite evidence of passive and/or active dispersal across multiple scales. Our objective here is to investigate the connectivity and spatial structure of red mullet (Mullus barbatus) metapopulation system in the Northwestern Mediterranean Sea and compare the delineation of assessment units with biological units. To achieve this, we integrate simulated larval dispersal modelling with tissue stable isotope analysis, encompassing the entire life cycle. We observe misalignment between the present "closed" assessment units and the identified biologically informed units. The identified metapopulation system comprises northern and southern subpopulations with dissimilar demographic roles. This principally stems from the Northern Current mediated larval transport from high-density persistent spawning grounds and, secondarily, likely from the regional differences in the isotopic baseline associated with different productivity regimes. Such an interdisciplinary approach is of elevated importance for species with stark differences across their life history, such as red mullet. Moreover, larval connectivity diagnostics successfully capture the interannual variability of recruitment dynamics of this complex stock, evidencing the capacity of biophysical models to inform fisheries assessment and management. This study highlights the importance of implementing spatial stock assessment frameworks that rely on critical, yet still largely disregarded, ecological information.

Accurate, gear-specific data is essential for fisheries management to quantify fishing pressure and ecosystem impacts, particularly in multi-gear fleets. In this study, we used electronic logbooks and sales notes from 2014 to 2023 to analyze the Portuguese multi-gear coastal fleet, obtaining information at a haul level. The objective was to identify and validate métiers down to level 6 according to the European Commission’s definition (a combination of gear specifications, target species, fishing area, and season). This fleet comprises approximately 500 vessels using various types of traps, nets, and longlines to catch around 200 species of fish and invertebrates. We identified 28 métiers across six main gear types. The most representative métier is the octopus (Octopus vulgaris) trap fishery, followed by the European hake (Merluccius merluccius) gillnet and the black scabbardfish (Aphanopus carbo) longline fisheries. A strong association was found between most métiers and variables such as fishing season, fishing area, depth, and sediment type. Traps and nets were mostly used in the northwest area, in mixed sediments or sand, whereas longlines were mostly operated in the central west area, in steeper slopes on sandy and rocky bottoms. The study highlights the complexity of quantifying gear-specific fishing effort in multi-gear fisheries, where technical interactions occur, and competitive relationships exist between different fishing fleets and gears that exploit the same fish stocks.

The Tropical Eastern Pacific Ecosystem off Peru sustains important fisheries that contribute 12% of the annual fisheries landings of Peru, the world's third-largest marine fisheries producer by catch volume. Although climate change is anticipated to negatively affect fish production in this region, species-specific vulnerability to climate change remains unclear. We implemented a trait-based Climate Vulnerability Assessment using expert elicitation to estimate the relative vulnerability of 35 fishery resources (benthic, demersal, and pelagic) to the impacts of climate change by 2055. Ten exposure factors (e.g., temperature, salinity, pH, chlorophyll) and 12 sensitivity attributes (biological and population-level traits) were used. No species were assessed as having "very high" vulnerability, five species were ranked with "high" vulnerability, 17 species with "medium" vulnerability, and 13 species with "low" vulnerability. The benthic group, particularly bivalves, were ranked the most vulnerable. The pelagic group was the second most vulnerable, with sharks amongst the most vulnerable. The demersal group was estimated with the lowest vulnerability. Temperature, primary productivity, salinity, pH, and chlorophyll were the principal drivers of exposure. This study allowed estimation of the most vulnerable fishery resources and the main exposure factors driving vulnerability, and detection of research and monitoring priorities in the region, which may be helpful to fisheries managers in developing climate change adaptation options and mitigation alternatives in the Tropical Eastern Pacific Ecosystem off Peru.

Organism movement is a key process in the transfer of individuals, genes, functional traits, matter, and energy among habitat patches, at sea and across the land-sea interface. The resulting fluxes, collectively termed marine functional connectivity (MFC), underpin planetary health and an array of ecosystem services. The ecological and economic impacts of rapid environmental change, including climate change, overexploitation, habitat loss and fragmentation, and the global transport of nonindigenous species make accurate estimation and prediction of MFC patterns paramount. However, estimating MFC is challenging given the relative inaccessibility of the oceans and the small size of many of the organisms and life stages with the highest dispersal potential. Here, we provide a methodological roadmap to help researchers and stakeholders understand, use, and integrate different tools to estimate organism movement and connectivity, focusing on (1) tagging and telemetry, (2) analysis of chemical markers in body tissues and structures, (3) genetics, and (4) numerical modeling. We describe method strengths and weaknesses, and the spatiotemporal resolution and scale of resulting connectivity estimates. Ancillary and emerging methods to estimate MFC are also reviewed. We then present case studies that have successfully applied or integrated different methods, particularly to support (1) marine protected area design, (2) global change predictions, focusing on climate change and bioinvasions, and (3) fisheries management. Finally, we highlight methodological innovations and concepts that promise to transform MFC research in the future.

Ecosystem dynamics can lead to trade‐offs between reaching harvest targets and protecting vulnerable species across fisheries management decisions. However, in the context of rebuilding overfished populations, considering predator–prey interactions might provide opportunities to minimize or reverse these trade‐offs if overfished prey can recover when predators in shared habitat are harvested. To understand whether and under what conditions such opportunities might arise, we explore the effect of predator harvest on the rebuilding outcomes of a recovering prey that experiences bycatch mortality. We developed an age‐structured model with predation and harvest to evaluate changes in the population dynamics of prey at steady state and in their rebuilding time under increasing harvest of predators. We parameterized our models based on yelloweye rockfish (Sebastes ruberrimus), a U.S. West Coast Groundfish stock under a rebuilding plan, and one of their known predators, lingcod (Ophiodon elongatus). We found that lingcod harvest reduced the long‐term spawning biomass and increased the rebuilding time of yelloweye rockfish regardless of their prey specialization; these negative effects were due to yelloweye rockfish bycatch in the lingcod fishery. However, the degree to which predator harvest affects prey rebuilding depends on prey specialization, where the steady‐state dynamics of yelloweye rockfish were less affected by lingcod harvest and rebuilding occurred more rapidly when lingcod acted as a specialist compared to a generalist predator. As efforts to leverage ecosystem attributes in fisheries management are applied to recovery strategies, we highlight the role that the nature and strength of biological interactions can play in shaping outcomes of recovery.