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A specimen of the smalleye squaretail, Tetragonurus cuvieri Risso, 1810, was caught on 16 February 2024 (TL = 37.2 cm, W = 277.56 g) by trawl net at approximately 100 m depth in the Mljet Channel, between the islands of Lopud and Šipan (Croatian coast). This represents the first well-documented record of T. cuvieri in the whole Adriatic Sea. Although the species has been mentioned in the checklist of Albanian fishes pertaining to Adriatic waters previously, no supporting data were provided to confirm its occurrence. The specimen was identified based on morphological characters supported by molecular analysis. Morphological and biological data are presented herein. As information on the biology, ecology, and distribution of this species in the Mediterranean Sea remains scarce, this finding extends its known range and contributes to the growing number of rare or poorly known species recently recorded in the Adriatic Sea.

It has been suggested that observed spatial variation in mackerel fisheries, extending over several hundreds of kilometers, is reflective of climate-driven changes in mackerel migration patterns. Previous studies have been unable to clearly demonstrate this link. In this paper we demonstrate correlation between temperature and mackerel migration/distribution as proxied by mackerel catch data from both scientific bottom trawl surveys and commercial fisheries. We show that mackerel aggregate and migrate distances of up to 500 km along the continental shelf edge from mid-November to early March. The path of this migration coincides with the location of the relatively warm shelf edge current and, as a consequence of this affinity, mackerel are guided towards the main spawning area in the south. Using a simulated time series of temperature of the shelf edge current we show that variations in the timing of the migration are significantly correlated to temperature fluctuations within the current. The proposed proxies for mackerel distribution were found to be significantly correlated. However, the correlations were weak and only significant during periods without substantial legislative or technical developments. Substantial caution should therefore be exercised when using such data as proxies for mackerel distribution. Our results include a new temperature record for the shelf edge current obtained by embedding the available hydrographic observations within a statistical model needed to understand the migration through large parts of the life of adult mackerel and for the management of this major international fishery.

Bottom trawl fishing has widespread impacts on benthic habitats and communities. The benthic response to trawling seems to be smaller or absent in areas exposed to high natural disturbance, leading to the hypothesis that natural and trawl disturbance affect benthic communities in a similar way. However, systematic tests of this hypothesis at large spatial scales and with data from sites spanning a large range of natural disturbance do not exist. Here, we examine the effects of trawl and natural (tidal-bed shear stress) disturbance on benthic communities over gradients of commercial bottom trawling effort in 8 areas in the North and Irish Seas. Using a trait-based approach, that classified species by life-history strategies or by characteristics that provide a proxy for their role in community function, we found support for the hypothesis that trawl and natural disturbance affect benthic communities in similar ways. Both sources of disturbance caused declines in long-living, hard-bodied (exoskeleton) and suspension-feeding organisms. Given these similar impacts, there was no detectable trawling effect on communities exposed to high natural disturbance. Conversely, in 3 out of 5 areas with low bed shear stress, responses to trawling were detected and resulted in community compositions comparable with those in areas subject to high natural disturbance, with communities being composed of either small-sized, deposit-feeding animals or mobile scavengers and predators. The findings highlight that knowledge of the interacting effects of trawl and natural disturbance will help to identify areas that are more or less resilient to trawling and support the development of management plans that account for the environmental effects of fishing.

The grey rockcod, Lepidonotothen squamifrons is an important prey species for seals, penguins and Patagonian toothfish (Dissostichus eleginoides) in the Southern Ocean. Across the Kerguelen Plateau, the species was fished to commercial extinction (ca. 152 000 tonnes between 1971 and 1978) prior to the declaration of the French Exclusive Economic Zone in 1979 and the Australian Fishing Zone in 1981. In this study we estimate; age, growth, maturity, sex ratio, body condition (weight-at-length), and population density of grey rockcod using data from 19 trawl surveys from 1990 to 2014. There appeared to be three distinct geographical populations, with differences in biological parameters within each population. This study has identified separate metapopulations within the southern region of the Kerguelen Plateau and we recommend that management should take into account the different characteristics of these populations, and that this meta-population structure may be a factor in why this species required several decades to show signs of recovery.

The brown comber (Serranus hepatus) is a small benthopelagic species with no commercial value, primarily caught by bottom trawls as a by-catch. In this work, we studied the feeding habits of this species. For this purpose, samples were obtained from the trawl fleet within the different editions of the ECOFISH project carried out between 2019 and 2022. A total of 1534 individuals were analyzed. In the diet analysis, various factors were considered, such as the season, the depth, and the time of day of the capture, as well as the size range of the individuals caught. For the feeding analysis, different indexes were calculated, such as the vacuity index (%Vi) and index of relative importance (%IRI). The size range of the specimens was between 3.2–16.3 cm, and the weight was between 1.02–39.73 g. Of the stomach content analyzed, 49.7% of the stomachs were found to be empty. The resources with the greatest importance in the diet of the brown comber were from the crustacean group, especially mysidaceans and decapods. There were differences in the diet according to season, depth, and size; however, there was no variation in diet by the time of day.

Batoids play key roles in marine ecosystems, yet their slow life history traits make them particularly vulnerable to overexploitation. The Balearic Islands remain a hotspot of batoid diversity, although multiple species could face conservation concerns. We combine genetic analyses based on mitochondrial COI genetic diversity with data-poor stock assessment methodologies to assess the conservation and exploitation status of the most abundant Rajidae species in the area. A total of 181 sequences of five wide distributed species and two Mediterranean endemic species (Raja radula and Raja polystigma), were analysed and compared against a Mediterranean-Atlantic Rajidae genetic diversity framework. We also assessed the stocks of Dipturus oxyrinchus and Raja clavata, using the Bayesian state-space implementation of the Schaefer production model, as well as R. polystigma, using a length-based Bayesian biomass estimation method. The nucleotide diversity of most species was below the lower confidence interval of the median of the comparative framework. Despite this, the assessed species showed signs of recovery and sustainable exploitation. The biomass of R. clavata and D. oxyrinchus showed an important increase in recent years following reductions in fishing effort, while R. polystigma showed stability and sustainable exploitation. Raja brachyura, R. radula and Leucoraja naevus, with low overlap between their bathymetric distribution and the bottoms most intensively exploited by the bottom trawl fleet, showed the highest genetic diversities. Similarly, the low overlap of this fishery, at least with important fractions of the populations of R. clavata, R. polystigma and D. oxyrinchus, is in coincidence with their resilience to fishing exploitation. These findings highlight the importance of depth distribution in shaping resilience, emphasizing the need for species- and region-specific conservation strategies for these vulnerable species. In this sense, the integration of genetic monitoring with stock assessments is gaining relevance for detecting hidden vulnerabilities on threatened species such as batoids.

Demersal fishing is a major anthropogenic disturbance to marine sediments, with global implications for benthic carbon cycling and greenhouse gas emissions. Resuspension of sediment organic matter during bottom trawling enhances oxic mineralisation, converting stored organic carbon into aqueous CO.sub.2 and reducing the long-term carbon storage potential of the seafloor. Sediment heterogeneity likely plays a role in the vulnerability of sedimentary organic carbon to resuspension, but spatial estimates CO.sub.2 release from resuspended sediment rarely accounts for this heterogeneity. We conducted a large-scale survey in the Hauraki Gulf, New Zealand, to assess how sediment characteristics affect resuspension-induced CO.sub.2 production (RCO.sub.2 P). Using a resuspension assay at 57 sites, we quantified RCO.sub.2 P accompanied by measurements of sediment grain size, organic matter content and quality, and phytopigments. Boosted regression tree analysis revealed that organic matter content has the strongest influence on RCO.sub.2 P variability, followed by coarse grained sand content and water depth. Non-linear relationships with RCO.sub.2 P further indicate context-dependent mechanisms controlling RCO.sub.2 P and allowed for the identification of three clusters with differing levels of vulnerability to resuspension impacts and different environmental influences. Overall, risk of resuspension-induced CO.sub.2 release was moderate to very high in sediments with 3 % organic matter, 8 % coarse grained sand, and at depths 56 m, comprising 73 % of our sampling sites. Multiple \"hotspot\" locations were found in the Hauraki Gulf, likely driven by an interplay of organic matter bioavailability and hydrodynamic conditions. Our results demonstrate that accounting for sediment heterogeneity in resuspension impact assessments will create more realistic and ecologically relevant estimates of C vulnerability over regional scales to inform spatial fisheries management.

The Arctic Barents Sea is experiencing a record temperature increase, a poleward shift in the distributions of commercial fish stocks, and invasion by the snow crab, a new predator. To evaluate benthic community vulnerability when exposed to seawater warming, bottom trawling, and predation from a new predator, we used a trait-based approach and applied this to an extensive dataset of >450 megabenthic taxa, from a 1.5 million km2 area. Taxon rank values were obtained after sorting the taxa by temperature median and temperature range, i.e. the temperature sensitivity trait, and by body height, mean weight, and mobility, i.e. the trawl vulnerability trait, and were given as a size-based prey classification, i.e. the predation trait. The taxon rank values were then used to calculate the mean community sensitivity. Our study showed a recent significant increase in community mean temperature ranks, indicating an increased importance of species with affinity for warmer waters and a reduced importance of coldwater species. Commercial fish stocks and snow crabs are expanding into the western part of the Barents Sea, thereby simultaneously increasing the exposure of large immobile species to trawling and of small prey species to crab predation. Overall, we found a high level of vulnerability to the 3 investigated stressors in the northwestern Barents Sea, which may lead to alterations in community structure and diversity. Mapping vulnerability to multiple stressors enables authorities managing human activities to identify vulnerable areas that warrant special measures, including protection from trawling and reduction of the snow crab stock.

In order to improve the size selectivity and exploitation pattern for cocktail shrimp (Trachypenaeus curvirostris) in shrimp trawl fishery of the South China Sea (SCS), selective properties of four codends were tested and compared. These experimental codends involved two mesh sizes, 30 and 35 mm, and two mesh shapes, diamond-mesh (T0) and diamond-mesh turned by 90 degree (T90), respectively. Our results demonstrated that increasing the mesh sizes in T0 codends or/and applying T90 codends would improve the selective properties for cocktail shrimp in the SCS. By comparing selectivity parameters, delta selectivity and exploitation pattern indicators, the T90 codend with 35-mm mesh size (T90_35) presented the best selective properties for cocktail shrimp in the studied areas. It will be a potential choice to substitute the currently legal codend in fisheries management to mitigate the bycatch of undersized cocktail shrimp in shrimp trawl fisheries of the SCS.