Atlantic bluefin tuna (ABFT) stocks have been considered overfished over the last decades, especially the western stock, whose main spawning grounds are in the Gulf of Mexico (GoM). Despite the ...current measures implemented, spawner bycatch by the longline fleet targeting yellowfin tuna (YFT) may explain the lack of recovery of local stocks. This situation demands the implementation of appropriate spatiotemporal management strategies to minimize bluefin bycatch in the GoM, which involves knowledge in depth of its distribution and environmental forcing. Using catch and effort data from the Mexican commercial longline fleet with 100% scientific observer coverage from 1999 to 2012 and satellite derived environmental data, this study investigated the influence of environmental conditions on catch per unit effort (CPUE) of ABFT and YFT. General additive models (GAMs) were fitted using a negative binomial distribution and applying Akaike information criterion (AIC) to select the best model. Bluefin CPUE exhibited a marked seasonality, reaching higher values in February and March while YFT catches occurred throughout the year. Two main locations were identified with higher ABFT bycatch rates, Campeche Bay and the western‐central area of the GoM. Higher ABFT CPUE was significantly associated with areas with negative sea level anomalies and low sea surface temperatures, characteristic of cyclonic eddies. Instead, YFT CPUE showed a lesser environmental influence in its distribution. To our knowledge, the patterns shown in this study provide the first in‐depth approach to understand ABFT bycatch in Mexican waters, which will help in further development of adequate management strategies.
This study presents a novel approach to high-resolution density distribution mapping of two key species of the 1170 "Reefs" habitat,
and
, in the Bay of Biscay using deep learning models. The main ...objective of this study was to establish a pipeline based on deep learning models to extract species density data from raw images obtained by a remotely operated towed vehicle (ROTV). Different object detection models were evaluated and compared in various shelf zones at the head of submarine canyon systems using metrics such as precision, recall, and F1 score. The best-performing model, YOLOv8, was selected for generating density maps of the two species at a high spatial resolution. The study also generated synthetic images to augment the training data and assess the generalization capacity of the models. The proposed approach provides a cost-effective and non-invasive method for monitoring and assessing the status of these important reef-building species and their habitats. The results have important implications for the management and protection of the 1170 habitat in Spain and other marine ecosystems worldwide. These results highlight the potential of deep learning to improve efficiency and accuracy in monitoring vulnerable marine ecosystems, allowing informed decisions to be made that can have a positive impact on marine conservation.
Data from the Mexican longline fishery in the Gulf of Mexico (GoM) between 1994 and 2012 were analyzed to identify the spatio-temporal behavior of fishing effort and catch per unit effort of ...yellowfin (YFT) and Atlantic bluefin tuna (BFT), focused on habitat overlap. The applied fishing effort showed significant seasonal differences, being greater and spatially concentrated during summer months (May to August), decreasing by around 30% during the winter period (December to April), when its spatial distribution covers a larger area, probably targeting a higher number of species. The spatio-temporal distribution of YFT showed a recurrent pattern throughout the study period, with two relative abundance peaks: one in June, related to a strong aggregation process along the coast of Veracruz, and the other in November, associated with a broader distribution along the Mexican GoM. BFT occurs mainly during the winter, reaching its highest relative abundance in March, at the beginning of the spawning season. A substantial overlap between the distributions of both species was observed, warranting further oceanographic habitat characterization to be supported. The results, consistent with those obtained in U.S. waters, provide the basis for the development of specific management measures to reduce BFT bycatch in the GoM.
Gorgonians play a fundamental role in the deep sea (below 200 m depth), composing three-dimensional habitats that are characterized by a high associated biodiversity and playing an important part in ...biogeochemical cycles. Here we describe the use of a benthic lander to monitoring polyps activity, used as a proxy of gorgonian feeding activity of three colonies of Placogorgia sp. Images cover a period of 22 days with a temporal resolution of 30 min. In addition, this seafloor observatory is instrumented with oceanographic sensors that allows continuous monitoring of the hydrographic conditions in the site. Deep-learning is used for automatic detection of the state of the polyps registered in the images. More than 1000 images of 3 large specimens of gorgonians are analyzed, annotating polyps as extended or retracted, using the semantic segmentation algorithm ConvNeXt. The segmentation results are used to describe the feeding patterns of this species. Placogorgia sp. shows a daily pattern of feeding conduct, depending on the hours of day and night. Using a Singular Spectrum Analysis approach, feeding activity is related to currents dynamics and Acoustic Doppler Current Profile (ADCP) return signal intensity, as proxy of suspended matter, achieving a linear correlation of 0.35 and 0.11 respectively. This is the first time that the behavior of the Placogorgia polyps, directly related to their feeding process, is described.
The hexactinellid sponge Asconema setubalenseKent, 1870 is a deep-sea species characterized by its expansive cup-shaped morphology, which contributes significantly to the three-dimensional complexity ...of the marine ecosystems. This sponge forms grounds that offer protection to pelagic organisms and juvenile stages. Despite its ecological relevance, there is a lack of information on the ecology, behavior and population structure of this species. The research aimed to conduct a multitemporal analysis of this sponge in the Aviles Canyon System over a ten-year period, focusing on spatial distribution and abundance. Changes in fishing pressure were estimated using the presence of fishing gears as a proxy. Additionally, the study sought to provide a detailed morphometric description through 3D photogrammetric reconstructions based on the latest data. The multi-temporal analysis revealed a subtle increase in sponge density, particularly at depths ranging from 320 to 390 m, exhibiting an irregular spatial distribution in 2022, with maximal values of 0.08 individuals/m2. Despite a small decrease on the loss of fishing gears in the overlapping area between samplings in 2012 and 2022, there was not a clear indication of a decline in fishing pressure over the years. Notably, more sightings of fishing gears were found in transect IC222TV_16 (0.07 gears/m2) than in IC222_TV02 (0.04 gears/m2) in 2022, suggesting potential spatial preferences for fishing activities. Visual analysis of temporal populations revealed an increase of 7% in specimen perturbations over ten years, with the population in IC222_TV16 being healthier (9% of the individuals presenting severe deformations) than in IC222_TV02 (40%). High-density fishing gear locations coincided with areas inhabited by sponges displaying the highest perturbation levels in both transects. Morphometric analysis using data from 2022 indicated a prevalence of individuals with heights concentrated between 0.18 and 0.38 m, osculum and flounce diameters reaching 0.4 and 0.56 m and osculum and flounce surfaces of 0.02–0.04 and 0.06–0.19 m2 respectively. Over 80% of measured specimens exhibited a high degree of asymmetry. Strong correlations were observed between heights and osculum and flounce surfaces, but external factors may be included for explaining wall deformities. These findings contribute valuable insights into the characterization of A. setubalense, serving as a foundation for future research in the area. Moreover, this work highlights the promising potential of photogrammetry as an efficient tool for monitoring of vulnerable marine ecosystems (VME) and marine protected areas.
•Photogrammetry effectively studies benthic communities without disturbance.•The Asconema setubalense population modestly increased from 2012 to 2022.•This rise may be attributed to protective policies, demonstrating their efficacy in preserving biodiversity.•Our current research has significantly expanded our understanding of the morphometric parameters associated with this species.
The Bay of Biscay is a structurally complex region, exhibiting high biodiversity and productivity and hosting a wide variety of benthic habitats. Unfortunately, current scientific knowledge of ...deep-sea ecosystems is limited. Our investigation provides an updated vision of the existing knowledge on key aspects of the deep-sea ecosystem and identifies research priorities for the definition of a research roadmap in support of sustainable management, including the protection and conservation of deep-sea ecosystem of the Bay of Biscay. To achieve this, firstly a revision of projects, surveys and studies conducted in the region, was carried out resulting in the identification of 62 publicly available scientific documents. Secondly, an online survey was carried out, receiving 51 responses from 24 research institutions in 9 countries. Finally, a workshop was attended by 39 scientists to identify and discuss ways forward on deep-sea research in the Bay of Biscay. Results indicate that knowledge of benthic habitats, and vulnerable and sensitive habitats/species is good or very good for 45% of the respondents, while limited knowledge was reported for deep pelagic habitats. Almost 75% of the scientists agreed that deep-sea processes affect shallower areas. Funding (71%) and research vessel availability (57%) were considered the most constraining aspects limiting deep-sea research. More than 50% of the scientists perceived a short- or medium-term threat from human activities and pressures, while over than 40% of the respondents considered that there are no, or limited, data available to assess the environmental status. Regarding climate change, 55% of scientists partially or fully agreed with the existence of evidence of climate change effects, but 47% of them totally or partially considered that climate change monitoring is insufficient to assess eventual changes and effects. Most respondents (63%) considered that deep-sea ecosystems are not properly represented in the current Marine Protected Areas network. In terms of future needs, the development of monitoring strategies to reduce costs and guarantee an optimal design, data sharing and an increase in transnational collaboration are most cited. Finally, a proposal for a roadmap to fill in knowledge gaps for a better understating of the ecosystem processes of the deep sea of the Bay of Biscay is delivered.
•Scientific knowledge of the deep-sea ecosystem in the Bay of Biscay is limited.•An updated vision of current knowledge on key aspects of the deep-sea ecosystem is provided.•Research priorities for the definition of a research roadmap are identified.•Intended to support sustainable management, protection and conservation.
Macro and megafauna were studied in the Avilés Canyon System (ACS), southern Bay of Biscay (Cantabrian Sea), during several oceanographic cruises carried out from 2009 to 2017. The biodiversity of ...ACS is summarized and its description is herein updated after sampling surveys of several programmes (ECOMARG, INDEMARES, SponGES, INTEMARES) conducted by the Spanish Institute of Oceanography (IEO).
This study has updated previous knowledge in the canyon area from past national and international projects, their reports and publications as well as data collected in the context of regional projects designed to gain new insight into the diversity of marine invertebrates and fishes from the ACS. Samples were taken using a range of sampling gears (Rock dredge, Beam trawl, Trawl gear GOC-73, Suprabenthic sledge, Box corer and Remoted operated vehicle), from 55 to 2291 m in depth. A total of 1015 species were identified at the ACS: 98 Porifera, 153 Cnidaria, 14 Brachiopoda, 22 Bryozoa, 97 Mollusca, 151 Annelida, 315 Arthropoda, 74 Echinodermata and 91 Chordata. New records for the Bay of Biscay fauna include 13 Porifera species, 17 Cnidaria, 7 Mollusca, 8 Arthopoda, 3 Echinodermata and 4 Chordata. Also the bathymetric range of some species has been extended. As a result of the research projects carried out in the area in the last fifteen years, important information is now available which suggests that the ACS houses a large number of species with a high ecological value, that it represents a biodiversity hotspot in terms of the presence of sponge aggregations and coral reefs in certain regions, and that it sustains important fisheries due to the abundance of comercial species. Given the relevance of the species and habitats occurring in the ACS, there is a need to implement a conservation and management plan of the area in order to maintain habitats in good state of preservation.
•A list of 1015 identified species in the ACS is completed with indication of depth range.•52 are new record for ACS.
Gorgonians play a fundamental role in the deep sea (below 200 m depth), composing three-dimensional habitats that are characterized by a high associated biodiversity and playing an important part in ...biogeochemical cycles. Here we describe the use of a benthic lander to monitoring polyps activity, used as a proxy of gorgonian feeding activity of three colonies of Placogorgia sp. Images cover a period of 22 days with a temporal resolution of 30 min. In addition, this seafloor observatory is instrumented with oceanographic sensors that allows continuous monitoring of the hydrographic conditions in the site. Deep-learning is used for automatic detection of the state of the polyps registered in the images. More than 1000 images of 3 large specimens of gorgonians are analyzed, annotating polyps as extended or retracted, using the semantic segmentation algorithm ConvNeXt. The segmentation results are used to describe the feeding patterns of this species. Placogorgia sp. shows a daily pattern of feeding conduct, depending on the hours of day and night. Using a Singular Spectrum Analysis approach, feeding activity is related to currents dynamics and Acoustic Doppler Current Profile (ADCP) return signal intensity, as proxy of suspended matter, achieving a linear correlation of 0.35 and 0.11 respectively. This is the first time that the behavior of the Placogorgia polyps, directly related to their feeding process, is described.
Ovaries of bluefin tuna, Thunnus thynnus, from organisms measuring 247.62 ± 3.54 cm fork length collected within the Mexican Exclusive Economic Zone in the Gulf of Mexico, were examined. The highest ...gonadosomatic index was recorded in April (1.6 ± 0.28), coinciding with the presence of oocytes with a migratory nucleus (oocyte diameter 439 ± 32.84 µm); fully developed gonads were also observed in two females and two males (ovaries or testes, respectively) caught in late April when sea surface waters exceeded 26 °C. The microscopic examination of the gonads sampled showed structures that evidenced spawning in females measuring 280 cm FL.
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BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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