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Graphical Abstract   Highlight Research Synthetic nets, widely used in aquaculture and marine fishing, experience reduced performance over time due to environmental exposure. The study analyzes the effectiveness of Toli shad gillnets based on their technical age using statistical and experimental methods. A strong negative correlation exists between technical age and both breaking strength (r = -0.972) and elongation (r = -0.92). Toli shad gillnets perform optimally within 2 to 3 years of use, with effectiveness declining by the fourth year as indicated by scores of 40–59, suggesting adequate performance but the need for targeted improvements. Medium-term maintenance should be performed annually throughout the net’s service life, up to a maximum of 7 years, while replacement is recommended starting in the 4 year to mitigate performance degradation.     Abstract Synthetic nets have high elasticity and are widely used for both aquaculture and marine fishing. However, as their technical age increases, their performance declines due to wear, reduced breaking strength, and decreased elongation caused by continuous exposure to the marine environment. Monitoring the technical age of nets is crucial to maintaining the effectiveness of Toli shad gillnets, minimizing losses, and ensuring optimal catch yields. This study aims to examine the physical degradation of synthetic gillnets used in Toli shad (Tenualosa macrura) fisheries based on their technical age. This study utilized gillnets targeting toli shad (Tenualosa macrura), with varying technical ages (control net, 1-year, 2-year, and 3-year nets), all made from polyamide (PA) monofilament. The differences in net dimensions were attributed to variations in their service life. The method used is purposive sampling, analyzed using descriptive statistics, correlation analysis, a Completely Randomized Design (CRD), and effectiveness evaluation. The results show that the structure of Toli shad gillnets consists of mesh sizes of 77.82–99.60 mm, thread diameters of 0.34–0.53 mm, and knot heights of 1.52–2.28 mm. The relationship between technical age and breaking strength has a correlation coefficient (r) of -0.972, an R² of 0.94, and a regression equation of y = 9.85 - 1.31x. The LSD test indicates a significant difference in breaking strength across treatments. The correlation between technical age and elongation has an r-value of -0.92, an R² of 0.86, with the equation y = 20.11 - 0.34x. The LSD test shows that the control net has significantly different elongation compared to others, but nets aged 1, 2, and 3 years show no significant differences. The study concludes that Toli shad gillnets remain effective for up to 3–4 years, with an effectiveness value of ≥50%. The implications of this study contribute to the efficient management of fishing nets by informing maintenance and replacement strategies based on the technical age and mechanical degradation of the gear. These findings suggest the importance of integrating net lifespan into gear management to enhance catch performance and sustainability in small-scale fisheries.

In the icy waters of the Pacific, a massive humpback whale unexpectedly finds herself tangled in a net abandoned by fishermen. When a rescue boat and a convoy of divers arrive to help the struggling humpback, a realistic and moving encounter bridges the human and aquatic worlds.

The xiphosurids are a typical chelicerae group with massive morphological, anatomical, biochemical, and ecological documentation. Despite this study, information about extant horseshoe crab abnormalities is underexplored, especially in the Indonesian region. Thus, this study aims to investigate the abnormal horseshoe crab in Subang, West Java. This research was conducted from January until February 2020 in Legon Wetan, Subang, West Java. Here, we only documented abnormalities of extant xiphosurids namely Tachypleus gigas . During the study, we greatly found extant abnormal xiphosurids by identifying 45 specimens with a wide range of abnormalities on the cephalothorax (prosoma), thoracetron (opisthosoma), telson, and appendages. The abnormal coastal horseshoe crab found also included adults (male and female) and juveniles ranging from 11.6 cm to 21 cm of carapace width. We note that the most common abnormal body parts are the cephalothorax and the thoracetron. Although the original cause may be unknown, the three main causes of the abnormality-inducing which are injuries such as self-injuries or fishing net injuries, physiologic developmental abnormalities or teratologies, and pathologies.

Plastic waste from end-of-life (EOL) fishing nets is a significant contributor to marine pollution. Recycling these nets has attracted increasing attention, particularly in coastal countries such as Vietnam. However, recycled materials often exhibit reduced properties compared to virgin materials due to degradation. Blending recycled and virgin polymers provides a simple solution to obtain materials with properties close to virgin ones, thereby reducing the demand for natural resource extraction. In this study, EOL trawling nets were collected, cleaned, shredded, and extruded into recycled granulates (RGs), which were compared with virgin granulates (VGs) and a 1:1 blend (R-VGs). Characterization was performed using FTIR, DSC, MFI, and tensile testing. Results confirm that the nets are made of high-density polyethylene (HDPE). RGs showed slightly lower yield stress (20.94 MPa) than VGs (21.59 MPa), while R-VGs reached 21.50 MPa, closely matching virgin properties. The mechanical performance of RGs was sufficient for filament production in 3D printing, demonstrating a feasible approach toward sustainable circular economy applications.

The dynamics of fishing nets can be estimated by modeling and numerically computing the forces acting on them. However, the dynamic models of fishing nets are highly nonlinear owing to the significant influence of hydrodynamic forces acting on the net. Therefore, if there are unknown parameters that define the state of motion in the model, it is often difficult to achieve high accuracy in the numerical simulations of fishing gear and evaluate its dynamics. To address this issue, a method is proposed for estimating these unknown parameters by integrating a nonlinear Kalman filter into a fishing net dynamics model. This study aimed to estimate the hauling velocity of large- and medium-sized purse seine fishing nets, which can be a challenging parameter to measure. The calculations are based on the data obtained from a research operation conducted by the Marine Fisheries Research and Development Center in 2019 using the purse seine fishing vessel “Taikei Maru No. 1”. The time series of the hauling-net velocity was estimated based on the results of the estimation experiment. These results allowed the estimation of the hauling velocity and calculation of the net dynamics during the hauling process. This shows that net dynamics simulation is possible even with unknown parameters.

The development and utilization of biodegradable plastics is an effective way to overcome environmental pollution caused by the disposal of non‐degradable plastics. Recently, polybutylene succinate co‐butylene adipate co‐ethylene succinate co‐ethylene adipate, (PBEAS) a biodegradable polymer with excellent strength and elongation, was developed to replace conventional nylon‐based non‐degradable fishing nets. The biodegradable fishing gear developed in this way can greatly contribute to inhibiting ghost fishing that may occur at the fishing site. In addition, by collecting the products after use and disposing of them in composting conditions, the environmental problem such as the leakage of microplastics strongly can be prevented. In this study, the aerobic biodegradation of PBEAS fishing nets under composting conditions is evaluated and the resulting changes in physicochemical properties are analyzed. The PBEAS fishing gear exhibits a mineralization rate of 82% in a compost environment for 45 days. As a result of physicochemical analysis, PBEAS fibers show a representative decrease in molecular weight and mechanical properties under composting conditions. PBEAS fibers can be used as eco‐friendly biodegradable fishing gear that can replace existing non‐degradable nylon fibers, and in particular, fishing gear collected after use can be returned to nature through biodegradation under composting conditions. Under aerobic degradation conditions, nylon 6,6 fibers is non‐degradable, whereas PBEAS fishing nets show 81% degradation in 45 days. As the biodegradation proceeded, the PBEAS fiber show a clear decrease in molecular weight and mechanical properties. The carbonyl group of PBEAS fibers is discovered to be the primary site of degradation.

In coastal stow net fishing, the heavy weight of a typical anchor (750–1000 kg) can increase the risk of capsizing the boat and crew member injury during hoisting operations. Thus, to prevent these accidents, a reduction in the anchor weight is required. One strategy to achieve this is to reduce the resistance force of the fishing gear used, which would allow lighter anchors to be employed. This requires the accurate estimation of the resistance force for various gear designs. Therefore, the resistance force and shape during the operation of two representative types of coastal stow nets currently employed in the Korean coastal stow net fishing industry were investigated using simulations and modeling experiments. The modeled fishing gear was divided into four sections according to the mesh size. Based on the results, the twine thickness was reduced in order to target areas of the gear where the greatest resistance was observed, while the front part of the gear was redesigned to prevent the front of the net from being pushed back into a suboptimal shape. The proposed low-resistance fishing gear has the potential to improve occupational safety in the coastal stow net fishing industry.

Abstract Inspired by the energy absorption of fishing nets during fishing in daily life and combined with the excellent energy absorption characteristics of double thin-walled tubes and reticular multicellular tubes, a structure of fishing net-shaped double tube (FNSDT) is designed by using circular arc arrays. Finite element analysis shows that, under equal mass, the FNSDT achieves up to 30% higher energy absorption and 8.3%−11.6% lower initial peak crushing force than conventional circular tubes due to its shorter folding wavelength and increased fold number. Parametric studies reveal that excessive unit numbers (>30) or wall thicknesses (>2 mm) induce local buckling or global instability, reducing crashworthiness. Finally, a deformation mode map is also established for design guidance.

Fishing net cleanliness plays a critical role for aquaculture industry as bio-fouled nets restrict the flow of water through the net leading to a build-up of toxins and reduced oxygen levels within the pen, thereby putting the fish under increased stress. In this paper, we proposed an underwater fishing Net Health State Estimation (NHSE) method, which can automatically analyze the degree of fouling on the net through underwater image analysis using remotely operated vehicles (ROV) images, and calculate a blocking percentage metric of each net opening. The level of fouling estimated through this method help the operators decide on the need of cleaning or maintenance schedule. There are mainly six modules in the proposed NHSE method, namely user interaction, distortion correction, underwater image dehazing, marine growth segmentation, net-opening structure analysis, and blocked percentage estimation. To evaluate the proposed NHSE method, we collected and labeled several underwater images in Mulroy Bay, Ireland with pixel-wise annotations. In order to verify the universality and robustness of the algorithm, we simulated and built a virtual fishing farm, and, on this basis, collected and labeled fishing net images under different environmental conditions. Seven evaluation metrics are introduced to demonstrate the effectiveness and advantages of the proposed method.