Fish Aggregating Devices Research Articles

Are tuna always hungry? A deep dive into stomach-fullness measures in the western and central Pacific Ocean

Context Understanding tuna diet and its drivers can provide valuable insights into the dynamics of pelagic ecosystems and their capacity to adapt to environmental and human-induced stressors. Aims To reconstruct tropical tuna dietary histories by using different metrics of stomach fullness and to assess their association with fisheries-related, environmental and biological covariates. Methods We examined stomachs from 8229 skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares) and bigeye tuna (T. obesus) captured in the western and central Pacific Ocean between 2001 and 2021, classified each on the basis of categorical and continuous fullness metrics, then built statistical models to gauge covariate effects. Key results Only models for the binary fullness metric (i.e. empty or non-empty) performed well. Tuna with empty stomachs were more likely to be caught on active gear (e.g. purse seine) and earlier in the day. Skipjack and bigeye tuna with empty stomachs were more likely to be associated with floating objects (e.g. fish-aggregating devices). Conclusions Our results add to the evidence that tropical tunas forage more effectively during the day and more actively when not associated with floating objects. At the individual level, tuna stomach fullness is highly variable. Implications Further research is needed to understand the factors governing this promising indicator of ecosystem change.

Technical review of encircling ringed gillnet for gillnet standardization in Indonesia

Abstract A technical review of encircling ringed gill nets for gillnet standardization in Indonesia is necessary to determine the design and construction by the waters and their fish target. The aim of this study was to describe the characteristics and design of fishing gear, including dimension, shape, and construction. The result of the identification of encircling ringed gillnet belonging to the local fishermen associated with the size of black pomfret (Parastromateus niger) as the fished target is used for the preparation of fishing gear standardization materials for the concerned by adjusting the size of fish target by measuring a fish length of about 150 up to 250 mm or a fish body circumference of about 300 up to 400 mm. As a result, the encircling ringed gillnet is made of nylon monofilament diameter 0.35 mm, and PE 380 d/6 mesh size 76,2 mm, ML = 2879 mesh, and MD = 218 mesh with an upper rope length of 120.65 m shorter than the lower rope 142,6 m. This Gillnet has a buoyancy of 173.6 grf/m and a sinking power of 124,7 grf/m or a buoyancy ratio of 1,39 sinking power. The gillnet is trapezoidal-shaped, operated by making the circumference of the net to fish closed around FAD (Fish Aggregating Device) near waters of more than 20 m depth with an attached net height of 13,30 m.

Numerical Investigation into the Hydrodynamic Performance of a Biodegradable Drifting Fish Aggregating Device

Drifting fish aggregating devices (DFADs) can significantly enhance fishing efficiency and capability. Conventional drifting devices are prone to degradation in harsh marine environments, leading to marine waste or pollution. In this study, we develop a biodegradable DFAD (Bio-DFAD) to minimise negative impacts on marine ecology. To investigate the hydrodynamic performance of the proposed device, numerical modelling involving the unsteady Reynolds-averaged Navier–Stokes equation has been conducted, in which a realisable k–ε model is applied to consider the turbulence effect. The response amplitude operators, which are key parameters for design, are obtained for heave and pitch motions. The hydrodynamic performance is found to be sensitive to the relative length, relative diameter, and wave steepness, but they are less sensitive to the relative current velocity. This work provides some scientific insights for practical applications.

Numerical Modelling of the Hydrodynamic Performance of Biodegradable Drifting Fish Aggregating Devices in Currents

Fish Aggregating Devices (FADs) are essential supplementary structures used in tropical tuna purse-seine fishing. They are strategically placed to attract tuna species and enhance fishing productivity. The hydrodynamic performance of FADs has a direct effect on their structural and environmental safety in the harsh marine environment. Conventional FADs are composed of materials that do not break down naturally, leading to the accumulation of waste in the ocean and potential negative effects on marine ecosystems. Therefore, this work aimed to examine the hydrodynamic performance of biodegradable drifting FADs (Bio-DFADs) in oceanic currents by numerical modelling. The Reynolds-averaged Navier–Stokes equation was used to solve the flow field and discretized based on the realizable k-ε turbulence model, employing the finite volume method. A set of Bio-DFADs was developed to assess the hydrodynamic performance under varying current velocities and attack angles, as well as different balsa wood diameters and sinker weights. The results indicated that the relative current velocity significantly affected the relative velocity of Bio-DFADs. The relative length of the raft significantly affected both the relative velocity and the relative wetted area in a pure stream. Finally, the diameter of the balsa wood affected the drift velocity, and the sinker’s relative weight affected the hydrodynamic performance of the Bio-DFADs.

When economy meets ecology, is it truly conflicted? A dashboard approach to assess the sustainability performance of European tropical tuna purse seine fisheries

The development of an ecosystem approach to fisheries management makes the assessment of the sustainability performance of fisheries a priority. This study examines European tropical tuna purse seine fleets as a case study, employing a multidisciplinary dashboard approach to evaluate historical and current sustainability performances. The aim is to enhance comprehension of the interconnected dimensions of sustainability and pinpoint management policy priorities.Using 18 indicators, we assessed the environmental, economic and social sustainability performances of European tropical tuna purse seine fleets, comparing them with other industrial tropical tuna fishing fleets in the Atlantic and Indian Oceans. The analysis also explored the temporal trend of sustainability performance for European tuna purse seiners from 2009 to 2019.Our results suggest that, compared with gillnetters and longliners, purse seiners and baitboats have a greater species-based selectivity, thereby catching fewer endangered, threatened or protected species, but a lower mature tuna catch rate, thus capturing more juveniles. We identify likely gaps in bycatch data reported by fishing on fish aggregating devices (FADs), due to results regarding selectivity and discard rates that appear inconsistent in the light of the scientific literature.The greater use of FADs, likely caused by the global tuna market, by purse seiner seems result in decreased ecological performances, as suggested by an increased carbon footprint per tonne landed. At the same time, it implies a better economic performance on the short-term, with higher net profit, energy efficiency (fuel consumed relative to monetary value created) and catch. For our case study, Ecology and Economy might seem to be in conflict for short-term perspective. However, consideration of the long-term impacts of FAD fishing and market incentives for fishing on free schools should lead purse seiner fleets to reduce drifting FAD fishing and promote more sustainable fishing practices.

Implementation of an Enhanced Crayfish Optimization Algorithm.

This paper presents an enhanced crayfish optimization algorithm (ECOA). The ECOA includes four improvement strategies. Firstly, the Halton sequence was used to improve the population initialization of the crayfish optimization algorithm. Furthermore, the quasi opposition-based learning strategy is introduced to generate the opposite solution of the population, increasing the algorithm's searching ability. Thirdly, the elite factor guides the predation stage to avoid blindness in this stage. Finally, the fish aggregation device effect is introduced to increase the ability of the algorithm to jump out of the local optimal. This paper performed tests on the widely used IEEE CEC2019 test function set to verify the validity of the proposed ECOA method. The experimental results show that the proposed ECOA has a faster convergence speed, greater performance stability, and a stronger ability to jump out of local optimal compared with other popular algorithms. Finally, the ECOA was applied to two real-world engineering optimization problems, verifying its ability to solve practical optimization problems and its superiority compared to other algorithms.

The aggregation effect of offshore mussel farming on pelagic fishes

AbstractThe increase in hard artificial structures in the marine environment is contributing to ocean sprawl. As well as adding hard structure to the seabed, mussel aquaculture adds rope droppers and anchor lines to the water column, where such structure would otherwise be absent. This paper aims to monitor the effects of mussel headlines on the pelagic fish community over time, as well as to investigate whether there is an interaction between the age of cultivated mussels with the number of epibiota species and the abundance of pelagic fishes. Two surveys were carried out: a time series monitoring survey to assess whether the mussel headlines change the surrounding fish species relative to control areas over time, and a fish aggregation device effect survey to investigate whether older and larger mussels support greater abundances of pelagic fishes and epibiota. The most abundant fish species was Atlantic horse mackerel, Trachurus trachurus, with significantly greater numbers recorded around ropes growing older mussels. Results from the surveys show that the physical farm infrastructure has provided a substrate for colonisation by a variety of epibiota: A total of 21 species were recorded growing on the mussel ropes. Furthermore, the older and larger the mussels become, the greater the numbers of epibiota taxa that can colonise, coupled with a greater abundance of pelagic fish recorded around the ropes. The sustainable development of offshore Blue Industries is essential to produce renewable resources. This study brings essential evidence for marine managers and regulators that offshore mussel farming can provide benefits for pelagic and benthic species of both conservation and commercial importance while producing sustainable protein to feed a growing population.

Numerical Study of the Hydrodynamic Response of Biodegradable Drifting Fish Aggregating Devices in Regular Waves

Fish-aggregating devices play a significant role in tuna purse fisheries. The severe marine environment and the large number of non-biodegradable fish-aggregating devices impact structural safety and cause marine litter. Therefore, hydrodynamic performance and the use of biodegradable materials are crucial issues for ensuring the sustainability of fish-aggregating devices. In this study, a type of virtual biodegradable drifting fish-aggregating device (Bio-DFAD) was designed. Numerical simulations were conducted to investigate the motion responses and relative velocities of Bio-DFADs in regular waves (first- and fifth-order waves). The numerical model was applied based on unsteady Reynolds-averaged Navier–Stokes equations with the realizable k–ε model. For different scenarios of modeling, various conditions were modeled, including the relative length, wave steepness, and diameter of the balsa wood, to analyze their effects on the hydrodynamic response of the Bio-DFADs. The results indicated that the increased relative length, wave steepness, and diameter of balsa wood had a significant influence on the motion response amplitude operators (RAOs) and relative velocity of Bio-DFADs. The results suggested that a relative length (LF/B = 1.5) and smaller diameter (DF = 30 mm) were recommended for fewer motion responses and relative velocity. The obtained results provide insight for practical engineering applications of the hydrodynamic design of Bio-DFADs.

Disentangling the dynamic of the Moored Fish-Aggregating Devices (MFADs) fleet in Guadeloupe using a stock-flow analysis

Fish-aggregating devices (FADs) have been used in centuries to attract fish and facilitate their captures. Drifting FADs developed at a large and industrial scale, but moored fish-aggregating devices (MFADs) are mostly used by artisanal fishers and often implemented to shift the pressure away from depleted coastal fish stocks and toward large migratory pelagic fish populations. Indeed, as pelagic fish aggregate around the devices, MFADs allow small-scale fishers to access this resource and improve their income. If there are many studies on the development of MFADs, the underlying assumption that the development of the MFAD fishery leads to the redeployment of the coastal fleet toward large pelagic species remains unproven. In the French archipelago of Guadeloupe, Lesser Antilles (FAO area 31), an important small-scale MFADs fleet targeting dolphinfish and tuna species developed since the end of the 80s. Available data on vessels, fishers and fishing effort permitted to develop a stock-flow framework and to analyse allocation of fishing effort between coastal and MFADs fisheries over the 2008–2019 period as well as the fleet and sub-fleet dynamics. The framework showed that the redeployment of fishing effort towards pelagic species thanks to MFADs was not straight forward. Pelagic vessels were more likely to become coastal than the opposite, and there was no influence of MFADs on the likelihood of pelagic vessels to quit their coastal activity. Instead, vessels fishing both on MFADs and coastal stocks were the dominant sub-fleet in the pelagic fleet in 2019. Nevertheless, pelagic vessels fished less and less on coastal stocks during the period, which was correlated with an increased use of MFAD. It also showed that the MFAD fishery remained more attractive for younger fishers but, as for the coastal fishery, MFADs failed to attract enough newcomers to compensate the outflows of ageing fishers as working conditions and barriers to enter the fishery remain key issues.

The impact of marine protected area taman wisata perairan timur pulau bintan (TWP-TB) on the fishermen’s catch in mapur village bintan regency

Bintan Island is designated as a marine protected area through the Decree of the Minister of Maritime Affairs and Fisheries of the Republic of Indonesia Number 18 of 2022 called Taman Wisata Perairan Timur Pulau Bintan (TWP-TB) which consists of three areas: Teluk Sebong, Gunung Kijang, Bintan Pesisir. Mapur Village is one of the villages in Bintan Pesisir Regency, which includes the area. The research aimed the impact of the establishment of marine protected area on the fishing grounds and catches of Mapur Village fishermen. The research was conducted in July 2024 in Mapur Village, Bintan Regency, Riau Islands Province. The descriptive and quantitative research method used questionnaires and FGD (Focus Group Discussion). Marine protected area has no impact on fishing catches. Most fishermen catch pelagic fish, and most fishing gear is handline. Fishermen do not change their fishing grounds even though there is a marine protected area because in general the fishing grounds are 1-17 miles from Mapur Village. Fishermen who make changes to the fishing area are the majority of fishermen who do not use fish aggregating devices (FADs).

Colonization, diversity, and seasonality of fishes at pelagic fish aggregating devices.

The pelagic zone of the ocean can be a challenging environment in which to conduct research and as a result we lack the robust baseline abundance and diversity data, compared to what is available in more accessible coastal habitats, to be able to track changes or stressors to the biota in this environment. Many large-scale fisheries target pelagic fish, and much of the information available on these species is based on fisheries-dependent data that may be biased towards hotspots and commercially valuable fishes. Here, a long-term video and visual fish survey was conducted on two subsurface moored fish aggregating devices (FADs) in the pelagic waters of the central Bahamas to determine the feasibility of using moored pelagic FADs as tools for collecting fish abundance and diversity data. A wide range of species was documented, including large migratory fish that are the focus of commercial and recreational fisheries, and smaller often overlooked species on which little abundance or seasonality information exists. We found that FADs colonize quickly and reach a peak stable (albeit seasonally cyclical) abundance and diversity within the first several months after deployment. Species richness was higher in video surveys, but abundance was higher in visual surveys, except for sharks. Our results highlight the need to tailor survey methods to fit the context and study objective, and provide further evidence for the importance of fisheries-independent data in monitoring pelagic species.

Evaluation of Marine Predator Algorithm by Using Engineering Optimisation Problems

This paper provides a real application of a popular swarm-intelligence optimisation method. The aim is to analyse the efficiency of various settings of the marine predator algorithm (MPA). Four crucial numerical parameters of the MPA are statistically analysed to propose the most efficient setting for solving engineering problems. Besides population size, particle velocity parameter P, Lévy flight parameter β, and fish aggregating device (FAD) probabilities are studied. Finally, 193 various settings, including fixed values and dynamic changes of the MPA parameters, are experimentally compared when solving 13 engineering problems. Standard statistical approaches are employed to highlight significant differences in various MPA settings. The setting of two MPA parameters (P, FADs) significantly influences MPA performance. Three newly proposed MPA settings outperform the original variant significantly. The best results provide the MPA variant with the dynamic linear change of P from 0.5 to 0. These parameters influence the velocity of prey and predator individuals in all three stages of the MPA search process. Decreasing the value of P showed that decreasing the velocity of individuals during the search provides good performance. Further, lower efficiency of the MPA with higher FAD values was detected. It means that more occasional use of fish aggregating devices (FADs) can increase the solvability of engineering problems. Regarding population size, lower values (N=10) provided significantly better results compared with the higher values (N=500).

Fish aggregating devices could enhance the effectiveness of blue water marine protected areas

AbstractIn the past two decades, drifting fish aggregation devices (FADs) have revolutionized pelagic fisheries, and are now responsible for the majority of tuna purse seine catches. Here, we argue that by taking advantage of the same proven aggregative properties, FADs could be used to enhance the benefits provided by blue water marine protected areas (MPAs). Using models of commercially targeted fish populations, we explore the potential benefits that could be achieved if unfished conservation FADs—designed as self‐powered devices capable of remaining semi‐stationary—were deployed within blue water MPAs. By increasing the residence time of exploited species in MPAs, conservation FADs will reduce average mortality rates. By increasing the local density of exploited species, they may also improve the function of ecosystems in blue water MPAs. Conservation FADs could, therefore, amplify the benefits of blue water MPAs. We find this amplification is largest in those contexts where blue water MPAs have attracted the most criticism—when their area is small compared to both the open ocean and the distribution of fish stocks that move through them.

Is FAD fishing an economic trap? Effects of seasonal closures and other management measures on a purse‐seine tuna fleet

AbstractThe management of fish aggregating devices (FAD) creates heated debates in tuna fishery management organizations striving to reduce the number of deployed floating objects. Through several econometric models and a machine learning approach, we evaluate the consequences of three management scenarios on the catch and profit of the French purse‐seine fleet operating in the Indian Ocean: (1) a half reduction in the number of authorized buoys per vessel, (2) a 72‐day closure of FAD fishing with and (3) without re‐allocation of effort on free schools. The results show a significant decrease of fleet profits by 7%, 10% and 18% respectively. We hypothesize an “economic trap” of FAD fishing caused by the far greater efficiency of this harvesting technique for larger vessels searching for economies of scale, and by the overfished status and catch limitation of yellowfin (Thunnus albacares) and bigeye (Thunnus obesus) tunas in the Indian Ocean. The results are compared with other studies looking at the impact of FAD management measures in other oceans.

How technical change has boosted fish aggregation device productivity in the Indian Ocean tuna fishery

Excess harvesting power can threaten the long-term sustainability of fisheries. Indicators of excess harvesting capacity must include input–output-based estimates of economic production efficiency. The increasing use of drifting Fish-Aggregating-Devices (DFADs) has boosted fishing productivity in high-seas tuna fisheries, perhaps beyond the biological capacity of the stocks, and is an object of global debate. We carried out a Data Envelopment Analysis (DEA) of relative changes in production efficiencies of the French purse-seine fleet targeting tropical tuna in the western Indian Ocean using two fishing strategies: (1) on floating objects (FOB) and (2) free swimming schools (FSC) using tuna catch and effort data spanning 1992–2019. We show that FOB fishing evolved dramatically through time with an estimated change of 3.6%yr−1 (8.0%yr−1 2007–2019), in contrast to 2.1%yr−1 for FSC. While the efficiency level in combining and using inputs has barely changed for FOB fishing, it means that all the growth in productivity comes from technical change for this strategy. The dynamics is different for the FSC with a mixture of innovation and higher efficiency. Immediate plans to improve input-based management in this region are needed to prevent further risks of overfishing to yellowfin (Thunnus albacares) and skipjack (Katsuwonus pelamis) tunas.

Present Status and Future Developmental Perspectives of Pole and Line Fishery in Sri Lanka

Present Status and Future Developmental Perspectives of Pole and Line Fishery in Sri Lanka

Ameliorative effect of natural floating island as fish aggregating devices on heavy metals distribution in a freshwater wetland

Growing human population and climate change are leading reasons for water quality deterioration globally; and ecologically important waterbodies including freshwater wetlands are in a vulnerable state due to increasing concentrations of pollutants like heavy metals. Given the declining health of these valuable resources, the present study was conducted to evaluate the effect of natural floating island in the form of fish aggregating devices (FADs) made of native weed mass on the distribution of heavy metals in the abiotic and bio compartments of a freshwater wetland. Lower concentrations of surface water heavy metals were observed inside the FADs with a reduction of 73.91%, 65.22% and 40.57–49.16% for Cd, Pb and other metals (viz. Co, Cr, Cu, Ni and Zn), respectively as compared to outside FAD. These led to 14.72–55.39% reduction in the heavy metal pollution indices inside the FAD surface water. The fish species inside the FADs were also found less contaminated (24.07–25.07% reduction) with lower health risk indices. The study signifies the valuable contribution of natural floating island as FADs in ameliorating the effect of heavy metals pollution emphasizing the tremendous role of the natural floating islands in sustainable maintenance of freshwater wetlands for better human health and livelihood.

First Record of Cetacean Killed in an Artisanal Fish Aggregating Device in the Mediterranean Sea.

Fish Aggregating Devices (FADs) are anchored floating structures often made with cheap scrapped materials and used to aggregate pelagic fish species under their artificial shadows. Globally, the dangerous impact of FADs is well known. They pose a severe threat as a source of bycatch, as a danger to navigation, and with their high potential to become marine litter. Unintended entanglement and consequent mortality in FADs of vulnerable (e.g., sharks, sea turtles, and cetaceans) and commercial species is a serious concern for several international inter-governmental bodies (e.g., EU, GFCM, and IWC). This work describes the first case of a cetacean, a striped dolphin (Stenella coeruleoalba), entangled in a FAD in the Mediterranean Sea. A young male of striped dolphins was found dead along the coast of Lazio (central Tyrrhenian Sea) with its peduncle entangled in typical debris from illegal/artisanal FADs (i.e., a nylon rope, teared gardening plastic sheets, bush branches, and scrapped empty plastic bottles). Although this is the first confirmed case of a cetacean entangled in a FAD in Mediterranean waters, given the extent of the deployment of anchored FADs, the scale of this type of interaction with protected species might be seriously underestimated. Therefore, actions and monitoring need to be implemented urgently to effectively protect and conserve marine biodiversity.

Benefits, concerns, and solutions of fishing for tunas with drifting fish aggregation devices

AbstractDrifting fish aggregating devices (dFADs) are human‐made floating objects widely used by tropical tuna purse seine (PS) fisheries to increase catch of target species. However, dFAD use has several negative impacts, including increased potential for overfishing, higher juvenile tuna catch, higher bycatch compared to other PS fishing modes, ghost‐fishing, and generation of marine litter. Based on these impacts, some stakeholders, especially environmental non‐governmental organizations and other competing fishing industries, suggest that dFADs should be completely banned. We list the pros and cons of dFAD fishing; address how to improve current management; and suggest solutions for the sustainability of dFAD fishing in the long term. A dFAD ban would lead to major changes in the availability and sourcing of tuna for human consumption and decrease the licensing revenue received by many developing states. Most importantly, we argue that tools exist today to manage for, reduce or eliminate most of the negative impacts of dFADs (e.g., bans on discards, limits on active dFADs, biodegradable non‐entangling constructions, time‐area deployment closures, recovery programs, and full data transparency, among others). Management decisions based on sound scientific reasoning are needed to address the legitimate concerns surrounding dFAD use and ensure the sustainability of both pelagic and coastal ecosystems and tropical tuna PS fisheries.

Zoo-holoplankton assemblages in the surrounding waters of Kamal Western Part of Seram Island Maluku Indonesia

Zoo-holoplankton dynamic between the sites are useful to knowledge with the regard to the characteristic of the areas and in relative to the community structure of zoo-holoplankton.The research conducted in the surrounding waters of Kamal village, the western part of Seram Island, Maluku Province. Zoo-holoplankton organisms collected from six-fixed Research stations consisted of different characteristics, namely stations 1 and 2 are Fish Aggregation Device placement areas, station 3 is the area for setting the lift nets, stations 4 and 6 are in front of the river mouth and station 5 is in the coral reef area. Sampling done every two weeks by using zooplankton net (diameter of 45 cm) sled with a 200 µm meshed. The result showed that the composition of zoo-holoplankton consisted of 37 genera from 8 phylum, 9 classes, and 28 families. There were about 9 genera (Calanus sp, Calocalanus sp, Acartia sp, Centropages sp, Oithona sp, Onceae sp, Corycaeus sp and Copilia sp), which found in all stations and periods. While some genera are only present at certain stations or periods (Eucalanus sp, Labidocera sp, Sapphirina sp, and Evadne sp). The abundance of zoo-holoplankton peaked at station 5 (16,332 ind/m−3) in the third period, while the lowest was at station 1 (809 ind/m−3) in the second period. Similarities indices was high between station 1 and 2 during the whole period (91%, 82% and 78%) and was low between station 1 and 6 (In the first period) and station 3 and 5. We noticed that differences characteristic of sampling areas leading to the abundance and the genera numbers of zoo-holoplankton. .