Search Results (23)

Fish year-class strength (YCS) has been estimated via longitudinal analysis of catch-at-age data and via catch-curve regression, but no study has compared the two approaches. The objective of this study was to compare YCS estimates between the two approaches with application to the lake trout (Salvelinus namaycush) population in the main basin of Lake Huron, one of the Laurentian Great Lakes of North America. YCSs were reconstructed for both hatchery-stocked and wild lake trout. Akaike information criterion (AIC) and Bayesian information criterion (BIC) were used to compare 14 linear mixed-effects models for longitudinal analysis of catch-at-age data, and three linear mixed-effects models for catch-curve regression. From the best models based on AIC or BIC comparisons, YCS estimates with year-class as a fixed effect were consistent with those estimated with year-class as a random effect. Estimated YCS patterns and trends were the same or similar between the longitudinal analysis and the catch-curve regression, indicating that both approaches provide robust estimates of YCS. Potential bias in using the approach of catch-curve regression could be caused by abrupt changes in adult mortality. It is also critical to recognize multiple recruitment origins for using the approach of longitudinal analysis of catch-at-age data. Full article

Accurate catch data are essential for effective fisheries management. This study reconstructs the historical recreational catch of hairtail (Trichiurus lepturus) in Korean waters by incorporating unreported catches to improve stock assessment accuracy. Using a Bayesian state-space surplus production model, we conducted a multi-fishery stock assessment by integrating abundance indices from eight major fisheries. The multigear mean standardization (MGMS) method was applied to derive standardized CPUE indices for each fishery, providing a more comprehensive evaluation of stock trends. The results indicate that excluding recreational catches and multiple CPUE indices may lead to biased stock assessments of hairtail in Korean waters. Models using an integrated CPUE index (SMSC) yielded higher MSY and biomass estimates, suggesting a more optimistic stock condition, whereas fishery-specific CPUE models (MSC) provided more precautionary estimates. The Kobe plot analysis indicates recent stock recovery, but continued monitoring and adaptive management are required to ensure long-term sustainability. This study highlights the importance of integrating recreational catch data and multi-fishery approaches in stock assessments, particularly under data-limited conditions, to enhance resource management and policy decision-making. Full article

Background: The development of microsurgical techniques has enabled reconstructive versatility in various clinical scenarios. Supermicrosurgery is an advanced microsurgical technique ensuring precise reconstructions by operating on small-caliber vessels and nerves, with applications in reconstructive surgeries. Objectives: This study aims to compare the effectiveness of four low-cost training models, thereby improving surgical precision and reducing the learning curve for novice surgeons. Materials and Methods: We conducted a prospective non-randomized study comparing the classic anastomosis technique, the intravascular stenting (IVaS) technique, the color contrast (CC) technique, and our newly introduced double-contrast (DC) technique, which combines IVaS with CC. We used a non-living experimental model represented by chicken wings, analyzing the vessel preparation and anastomosis time, anastomosis patency, and back wall biting through a standardized protocol. We performed 120 end-to-end anastomoses in total, with vessel diameters ranging from 0.5 to 0.8 mm. Results: CC demonstrated superior time efficiency and success rates, reaffirming it as a reliable option in supermicrosurgery, while DC showed slightly better time efficiency and patency compared to both IVaS alone and the classic method. CC outperformed the others in anastomosis time, patency, and back wall catching, reaffirming its reliability in supermicrosurgery. Conclusions: Although DC did not significantly improve patency, it reduced back wall engagement. This makes the DC technique beneficial for trainees working on vessels under 0.5 mm in diameter, where stenting is often required, improving surgical precision and reducing the learning curve, leading to better outcomes in supermicrosurgery. Full article

Endangered sharks and rays usually often lack basic information specific to conservation, such as population size. Previous studies have reconstructed shark and ray catch statistics between 1950 and 2019 for the southeast = south of Brazil, but lacking detail at the species level, because the catches were grouped by family, genus or even common name (e.g., skates and rays, Dasyatidae, Rhinobatos, Sphyrnidae, Squatinidae). In this study, we used proportions between species from scientific observer fishing trips and Dirichlet regression modelling to reclassify these categories. This model is a multivariate extension of beta regression and enables the modeling of asymmetric and heteroscedastic compositional data, allowing multinomial data to be obtained in a more informative way. The reconstruction of catches for unclassified data showed a massive dominance of the Squatinidae family until the late 1970s, when catches showed signs of decline. At the same time, the rays of the “emplastro” family showed a progressive increase from 2006 onwards. However, this scenario changed after the reclassification. The category Squatinidae was maintained almost exclusively by S. guggenheim, while 16 categories of species were observed within “emplastro” rays, many of which fall into “endangered”, “vulnerable” and “critically endangered” criteria. These reconstructed series provide a more reliable scenario of the catches of thirty elasmobranch species in the southeast and south of Brazil and serve as baseline information for understanding the conservation status of these species. Full article

On-orbit autonomous relative navigation performance strongly depends on both sensor suite and state reconstruction selection. Whenever that suite relies on image-based sensors working in the visible spectral band, the illumination conditions strongly affect the accuracy and robustness of the state reconstruction outputs. To cope with that limitation, we investigate the effectiveness of exploiting image sensors active in the IR spectral band, not limited by the lighting conditions. To run effective and comprehensive testing and validation campaigns on navigation algorithms, a large dataset of images is required, either available or easy to obtain in the visible band, not trivial and not accessible for the thermal band. The paper presents an open-source tool that exploits accurate finite volume thermal models of celestial objects and artificial satellites to create thermal images based on the camera dynamic. The thermal model relies on open CFD code (OpenFOAM), pushed to catch the finest details of the terrain or of the target geometries, and then the temperature field is processed to compute the view factors between the camera and each face of the mesh; thus, the radiative flux emitted by each face is extracted. Such data feed the rendering engine (Blender) that, together with the camera position and attitude, outputs the thermal image. The complete pipeline, fed by the orbiting target and the imaging sensor kinematic, outputs a proper synthetic thermal image dataset, exploitable either by a relative navigation block or any other scope of research. Furthermore, in the same framework, the article proposes two different thermal sensor models but any sensor model can be applied, providing full customization of the output. The tool performance is critically discussed and applied for two typical proximity scenarios, asteroid and artificial satellite; for both cases, the challenges and capabilities of the implemented tool for synthetic thermal images are highlighted. In the end, the tool is applied in a phase B mission design sponsored by ESA and in related research works; for such cases, the results are reported in the article. Full article

This paper presents a baseline-free damage imaging technique using a parallel array of piezoelectric sensors and a control board that facilitates custom combinations of sensor selection. This technique incorporates an imaging algorithm that uses parallel beams for generation and reception of ultrasonic guided waves in a pitch–catch configuration. A baseline-free reconstruction algorithm for probabilistic inspection of defects (RAPID) algorithm is adopted. The proposed RAPID method replaces the conventional approach of using signal difference coefficients with the maximum signal envelope as a damage index, ensuring independence from baseline data. Additionally, conversely to the conventional RAPID algorithm which uses all possible sensor combinations, an innovative selection of combinations is proposed to mitigate attenuation effects. The proposed method is designed for the inspection of lap joints. Experimental measurements were carried out on a composite lap joint, which featured two dissimilar-sized disbonds positioned at the lap joint’s borderline. A 2D correlation coefficient was used to quantitatively determine the similarity between the obtained images and a reference image with correct defect shapes and locations. The results demonstrate the effectiveness of the proposed damage imaging method in detecting both defects. Additionally, parametric studies were conducted to illustrate how various parameters influence the accuracy of the obtained imaging results. Full article

In the context of global warming, climate change in river headwater regions and its drivers have attracted increasing attention. In this study, tree-ring width (TRW) chronology was constructed using tree-ring samples of fir (Abies faxoniana) in Dadu River Basin in the central part of the western Sichuan Plateau, China. Correlation analysis with climatic factors implies that the radial growth of trees in the region is mainly limited by temperature and has the highest correlation with the mean minimum temperature in summer (June and July) (R = 0.602, p < 0.001). On this basis, the TRW chronology was adopted to reconstruct variations in the mean minimum temperatures in summer from 1733 to 2010 in the upper reaches of Dadu River. The reconstruction equation was stable and reliable and offered a variance explanation rate of 36.2% in the observed period (1962~2010). In the past 278 years, the region experienced nine warm periods and ten cold periods. The warmest and coldest years occurred in 2010 and 1798, respectively, with values of 13.6 °C and 11.0 °C. The reconstruction was highly spatiotemporally representative and verified by temperatures reconstructed using other tree-ring data in surrounding areas. A significant warming trend was found in the last few decades. Moreover, the multi-taper method (MTM) analysis indicated significant periodic changes in quasi-2-year and 21–35-year periods, for which the El Niño Southern Oscillation (ENSO) and the Pacific decadal oscillation (PDO) could be the key controlling factors. Full article

With the rapid development of ubiquitous data collection and data analysis, data privacy in a recommended system is facing more and more challenges. Differential privacy technology can provide strict privacy protection while reducing the risk of privacy leakage, but it also introduces unwanted noise, which makes the performance of the recommender system worsen. Among different users, the degree of their sensitivity to privacy is usually different. Thus, through considering the impact of users’ personalized requirements, the collaborative filtering algorithm can be designed to reduce the amount of unwanted noise. Taking the above assertions into account, we propose a collaborative filtering algorithm based on personalized privacy protection. First, it locally classifies ratings by privacy sensitivity on the user side, then utilizes the random flip mechanism to protect the privacy-sensitive ratings. Then, after the server catches the perturbed rating data, we reconstruct the joint item-item distribution through the Bayesian estimation method. Experimental results show that our proposed algorithm can significantly improve the recommendation performance of recommendation systems while protecting users’ privacy. Full article

Statistical population reconstruction models based on maximum likelihood and minimum chi-square objective functions provide a robust and versatile approach to estimating the demographic dynamics of harvested populations of wildlife. These models employ numerical optimization techniques to determine which set of model parameters best describes observed age-at-harvest, catch-effort, and other auxiliary field data. Although numerous optimization methods have been used in the past, the benefits of using particle swarm optimization (PSO) have yet to be explored. Using a harvested population of North American river otter (Lontra canadensis) in Indiana as a case study, we investigated the performance of population reconstruction using particle swarm optimization, spectral projected gradient (SPG), Nelder–Mead, and Broyden–Fletcher–Goldfarb–Shanno (BFGS) methods. We used Monte Carlo studies to simulate populations under a wide range of conditions to compare the relative performance of population reconstruction models using each of the four optimization methods. We found that using particle swarm optimization consistently and significantly improved model stability and precision when compared with other numerical optimization methods that may be used in statistical population reconstruction. Given that these models are frequently used to guide management decisions and set harvest limits, we encourage management agencies to adopt this more precise method of estimating model parameters and corresponding population abundance. These results illustrate the benefits of using particle swarm optimization, caution against relying on the results of population reconstruction based on optimization methods that are highly dependent on initial conditions, and reinforce the need to ensure model convergence to a global rather than a local maximum. Full article

While numerous Marine Protected Areas (MPA) have been created in the last decades, their effectiveness must be assessed in the context of the country’s biodiversity conservation policies and must be verified by local observations. Currently, the observations of local stakeholders, such as those from non-governmental organizations (NGOs), academics, government civil servants, journalists, and fishers, are not considered in any MPA database. The Sea Around Us has added observations from local stakeholders to address this gap, adding their perspectives to its reconstructed fisheries catch database, and to at least one MPA in each country’s Exclusive Economic Zone. It is important to pursue and incentivize stakeholder knowledge sharing to achieve a better understanding of the current level of marine protection, as this information is a valuable addition to the existing MPA databases. To address this gap, we demonstrated that personal emails containing a one-question questionnaire about the fishing levels in an MPA are an excellent way to gather data from local stakeholders, and that this works especially well for respondents in NGOs, academia, and governments. Of the stakeholders who replied to our personalized email, 66% provided us with the fishing level of the MPA that we asked for. The paper also presents how to access this information through the Sea Around Us website, which details in anonymized form the most common fishing levels for each selected MPA, as perceived or observed by different local stakeholder groups. This information is a unique and novel addition to a website that is concerned with marine conservation and contributes to a more accurate and inclusive discourse around MPAs. This information also helps to identify the gaps that need to be addressed to turn ‘paper parks’ (i.e., MPAs that are legally designated but not effective) into effective MPAs, which can contribute to climate-resilient ‘blue economies’. Full article

Pagellus acarne, Pagellus bellottii, Pagellus bogaraveo and Pagellus erythrinus are sparids distributed throughout Large Marine Ecosystems (LMEs), the Iberian Coastal region (25) and Canary Current region (27). They are target species due to their important commercial value to local and international fleets from three different continents: Africa, Asia and Europe. Given the high exploitation interest of these species, sustainable management of the resource is essential. For this reason, a key element for its implementation is the knowledge of the historical behaviour of catches by geolocalised areas. To this end, marine catches reconstructed in total wet-weight tonnes from 1950 to 2014 from the Sea Around Us database were analysed. A total of 2,058,172.60 tn of species of the Pagellus genus were caught for the entire region, of which 83.20% (1,712,552.21 tn) corresponded to the Canary Current area and the remaining 16.79% (345,620.38 tn) to the Coastal Iberian area. The dominant area was Canary Current; its catches were higher than those of the Coastal Iberian area, with an annual average percentage of 78.21%. Overall, the fishery showed a negative trend of −511.37 tn/year. In terms of species, 61.52% of the catches were of Pagellus bellottii (1,266,219.36 tn), 20.04% of Pagellus sp (not identified at species level, only to genus) (412,482.53 tn), 8.91% of Pagellus erythrinus (183,434.67 tn), 6.74% of Pagellus bogaraveo (138,717.29 tn) and the remaining 2.78% of Pagellus acarne (57,318.74 tn). Our results suggest the existence of important variations in the reconstructed catches of the four species analysed in two large marine ecosystems, showing an overall decreasing behaviour. Canary Current was undoubtedly the region with the highest fishing pressure during the 65 years analysed and Pagellus bellotii was the dominant species in the Current Canary region and in the whole region. This multispecies analysis presented could help the development of sustainable management protocols by providing insight into the historical evolution and status of the reconstructed catches for large marine ecosystems. Full article

CMSY++, an improved version of the CMSY approach developed from Catch-MSY which uses a Bayesian implementation of a modified Schaefer model and can predict stock status and exploitation, was used in the present study. Evaluating relative performance is vital in situations when dealing with fisheries with different catch time series start years and biological prior information. To identify the influences of data inputs on CMSY++ outputs, this paper evaluated the use of a nominal reported catch and a reconstructed catch dataset of the South Atlantic blue shark alongside different priors of the blue shark’s productivity/resilience (r) coupled with different indices of abundance. Results from the present study showed that different catch time series start years did not have a significant influence on the estimation of the biomass and fishing reference points reported by CMSY++. However, uninformative priors of r affected the output results of the model. The developed model runs with varying and joint abundance indices showed conflicting results, as classification rates in the final year changed with respect to the type of index used. However, the model runs indicated that South Atlantic blue shark stock could be overfished (B2020/Bmsy = 0.623 to 1.15) and that overfishing could be occurring (F2020/Fmsy = 0.818 to 1.78). This result is consistent with the results from a previous assessment using a state-space surplus production model applied for the same stock in 2015. Though some potential could be observed when using CMSY++, the results from this model ought to be taken with caution. Additionally, the continuous development of prior information useful for this model would help strengthen its performance. Full article

Guided waves are a potent tool in structural health monitoring, with promising machine learning algorithm applications due to the complexity of their signals. However, these algorithms usually require copious amounts of data to be trained. Collecting the correct amount and distribution of data is costly and time-consuming, and sometimes even borderline impossible due to the necessity of introducing damage to vital machinery to collect signals for various damaged scenarios. This data scarcity problem is not unique to guided waves or structural health monitoring, and has been partly addressed in the field of computer vision using generative adversarial neural networks. These networks generate synthetic data samples based on the distribution of the data they were trained on. Though there are multiple researched methods for simulating guided wave signals, the problem is not yet solved. This work presents a generative adversarial network architecture for guided waves generation and showcases its capabilities when working with a series of pitch-catch experiments from the OpenGuidedWaves database. The network correctly generates random signals and can accurately reconstruct signals it has not seen during training. The potential of synthetic data to be used for training other algorithms was confirmed in a simple damage detection scenario, with the classifiers trained exclusively on synthetic data and evaluated on real signals. As a side effect of the signal reconstruction process, the network can also compress the signals by 98.44% while retaining the damage index information they carry. Full article

Migrations of large pelagic fishes across the Pacific are usually inferred from tagging or genetic studies. Even though these techniques have improved over time, they still fail to demonstrate large transoceanic migrations, usually proposing ‘routes’ that do not cycle seasonally. The current study uses the concept of ‘philopatry’ in 11 large pelagic fish species, i.e., the tendency for animals to return to their natal site to reproduce. Tentative migration routes and maps emerge by applying this concept to the movements extracted through a comprehensive review of the literature on satellite and conventional tagging, and population and subpopulation linkages inferred from genetic and/or genomic studies. Moreover, when comparing these proposed migration routes and the mapped reconstructed catch (1950–2016, Sea Around Us) of each species in the Pacific, similarities emerge, reinforcing the accuracy of these migration cycles informed by philopatry. Finally, by superposing the migration routes of our 11 species, we identified areas of the Pacific that are part of the inferred migration routes of multiple species, leading to a discussion of possible ‘blue corridors’ that would protect the studied species’ key migration routes and stocks, which are important for the fisheries, culture and nutrition of Pacific islanders. Full article

Following a brief review of their biology, this contribution is an attempt to provide a global overview of the catches of mesopelagic fishes (of which 2.68 million tonnes were officially reported to the FAO) throughout the world ocean from 1950 to 2018, to serve as a baseline to a future development of these fisheries. The overview is based on a thorough scanning of the literature dealing with commercial or experimental fisheries for mesopelagics and their catches, and/or the mesopelagic bycatch of other fisheries. All commercial (industrial and artisanal) fisheries for mesopelagic fishes were included, as well as experimental fisheries of which we were aware, while catches performed only to obtain scientific samples were omitted. The processes of generating bycatch and causing discards are discussed, with emphasis on Russian fisheries. From peer-reviewed and gray literature, we lifted information on mesopelagic fisheries and assembled it into one document, which we then summarized into two text tables with catch data, one by country/region, the other by species or species groups. Full article