Catch Losses Research Articles

A device that prevents the loss of catch from a trawl designed to work on a small vessel

A device that prevents the loss of catch from a trawl designed to work on a small vessel

A Study on the Catch Losses and Mesh Selectivity Related to the Attachment of Marine Mammal Bycatch Reduction Devices on Midwater Trawl Gear

The National Institute of Fisheries Science in Korea is developing marine mammal bycatch reduction devices (BRDs) for high-risk fishing gear, such as trawls. We experimented with two BRD types (guiding nets) attached in front of codend at 30° and 45° angles, and catch losses and mesh size selectivity were investigated. Experimental fishing operations were conducted along the East Coast of South Korea where whales and dolphins are commonly sighted. The catch was classified according to fishing location, BRD type, codend, and covernet, with measurements recorded for body length, maximum girth, and weight. The average selectivity for each haul was analyzed using the ‘selfisher’ package. The catch loss rates with the BRD attached at tilt angles of 30° and 45° were 11% and 29% for common flying squid, 6% and 28% for sailfin sandfish, and 5% and 8% for pearlside. While the mesh selectivity rates for common flying squid and pearlside remained at 0.2–0.5 across all lengths and tilt angles, the mesh selectivity curve for sailfin sandfish was estimated. There were significant differences in catch loss between 30° and 45° angles, with the 30° angle being more effective in catch loss. We observed a masking effect in the codend.

Vulnerability to Climate Change: Adaptation Costs of Artisanal Sea Fishing in Lima Region, Peru

Artisanal fishers and their livelihoods are vulnerable to variable catches caused mainly by climate change. The objective of this study is to assess vulnerability and estimate the costs of adaptation to climate change among artisanal fishers in the Lima region. The method consisted of generating catch loss indices and adaptation measures for artisanal marine fishing based on workshops with local fishers. According to the seawater surface temperature anomalies (SSTA) metric recorded by coastal laboratories of the Peruvian sea, the El Niño phenomenon in the summer of 2017 was classified as strong. We constructed five-catch variation indices (from ‘slight’ to ‘severe’ catch loss variation). The results indicate that in the artisanal fishery, despite there being no species subject to severe variation, there were some, such as flathead mullet (Mugil cephalus), mahi mahi (Coryphaena hippurus), and crab (Platyxanthus orbignyi), with a very high variation index, while the snakehead kingcroaker (Menticirrhus ophicephalus) exhibited moderate variation. We concluded that for the period 2017–2030, the adaptation costs (base year 2017) of accessible fishing credit and a bonus payment to artisanal fishers affected by El Niño events would be 3.9 million soles (US $ 1.2 million) in 2017 present value.

Molecular basis and cellular functions of vinculin-actin directional catch bonding

The ability of cells and tissues to respond differentially to mechanical forces applied in distinct directions is mediated by the ability of load-bearing proteins to preferentially maintain physical linkages in certain directions. However, the molecular basis and biological consequences of directional force-sensitive binding remain unclear. Vinculin (Vcn) is a load-bearing linker protein that exhibits directional catch bonding due to interactions between the Vcn tail domain (Vt) and filamentous (F)-actin. We developed a computational approach to predict Vcn residues involved in directional catch bonding and produced a set of associated Vcn variants with unaltered Vt structure, actin binding, or phospholipid interactions. Incorporation of the variants did not affect Vcn activation but reduced Vcn loading and altered exchange dynamics, consistent with the loss of directional catch bonding. Expression of Vcn variants perturbed the coordination of subcellular structures and cell migration, establishing key cellular functions for Vcn directional catch bonding.

Regional oceanography affects humpback whale entanglements in set fishing gear

AbstractHumpback whales Megaptera novaengliae undertake annual migrations along eastern Australia, where they can be susceptible to entanglement in set fishing gear. This can potentially result in both sublethal and fatal outcomes for the whales, and financial losses for the fishing industry, including loss of gear and catch. Interannual fluctuations in entanglement records suggest that dynamic oceanographic features may be associated with the whales' migration path, and therefore, risk of entanglement. Using records of demersal fish traps off the coast of New South Wales (NSW), we identify two areas of high fishing pressure and entanglement risk overlap. Within each area, we combine entanglement observations with metrics associated with the East Australian Current (EAC) and climate (i.e., southern oscillation index). We show that the strength and position of the EAC was associated with the likelihood of entanglement in set fishing gear. In northern NSW (30.3° S), entanglement risk was highest between July and October when the EAC is relatively close to the coast. In contrast, there was no evidence suggesting that oceanography further south in the separation zone of the EAC (33.8° S) was associated with risk of entanglement. In the years following a strongly negative SOI (i.e., El Niño events), entanglement risk was also reduced. While we provide clear linkages with regional oceanographic dynamics and entanglement risk off NSW, if a dynamic ocean management approach to reducing entanglements is to be realized, further research into the fine‐scale movements of humpback whales is needed.

STATUS OF INSURANCE IN THE FISHERIES SECTOR OF INDIA

Indias fisheries sector has grown rapidly during the last six decades. Risks associated with capture fisheries include trawler damage or destruction, equipment and gear failure, catch loss, and maritime casualties. With the exception of a few tiny local public sector insurers and cooperatives, neither the federal nor state governments have paid attention to this industry. Since the Insurance Regulation and Development Authority liberalised the insurance industry, about 35 private enterprises have been registered (IRDA). A range of obstacles and concerns usually arise as a result of the adoption of fisheries insurance. Combined with governance reforms, technology has the potential to significantly improve efficiency, transparency, and moral hazard in fisheries insurance.

Fault Diagnosis of Train Body Sign Abnormal Pattern with Deep Learning Based Target Detection

<p>With the development of high-speed trains in recent years, security issues have received more attention. Automatic visual inspection of the train operation system for detecting abnormalities has become a fundamental element to guarantee the safety of the train operation. Train body sign patterns like the loss and fracture of signs and lock catch (SLC) on the electrical box cover (EBC) affect the regular operation of the train electrical system. In this paper, to ensure the safe operation of the train, a novel method combining a faster region-based convolutional neural network (Faster R-CNN) and similarity metrics is proposed to detect the abnormality of SLCs on train EBC. First, the positions of body train signs of multiple sizes are located by Faster R-CNN. Then, the regions of interest (ROI) are cut out and resized to the same size as the corresponding template images. Finally, by similarity measures, the status of the train body sign pattern is judged by comparing with the given threshold similarity value between ROIs and the template images. It is worth noting that the combination of Faster R-CNN and cosine similarity renders high accuracy in small target detection and strong robustness in image similarity comparison. The effectiveness of the proposed fault detection method and its superiority over the other types of combined methods are verified by actual experiments on the train of Guangzhou Metro Line 2.</p> <p> </p>

Collaborative Seismic Environment Plan (CSEP) project – a long-term, consistent, consortium-based approach to environmental approvals

The Collaborative Seismic Environment Plan (CSEP) project was formed in 2018 by NERA (National Energy Resources Australia) and an industry consortium of marine seismic acquisition operators and exploration titleholders. Using a collaborative approach, the vision of the CSEP project was to streamline seismic survey environment plan preparation, submission and assessment by the regulator (National Offshore Petroleum Environmental and Safety Authority, NOPSEMA), with an emphasis on mutually agreed protocols with commercial fishers operating within the CSEP Operational Area. Stakeholder consultation undertaken during Environmental Plan (EP) preparation was identified by the consortium as a principal cause for concern and a common reason for unsuccessful EP submissions. The CSEP project has achieved the project’s vision through: A Commercial Fishing Industry Adjustment Protocol to provide a standardised, evidence-based process to assess and provide monetary adjustment to commercial fishers for loss of catch, displacement and gear loss/damage; an Operational Protocol to provide guidance regarding improved communications with commercial fishers, including the spatial and temporal repetition and advanced notifications of seismic activities; a single overarching approvals framework for seismic activities within the CSEP Operational Area; a consistent assessment of environmental receptors, potential impacts, and management controls for seismic activities; and Improved understanding of potential cumulative impacts of seismic activities across the CSEP Operational Area. The CSEP project is an example of best practice stakeholder consultation that can be applied to offshore oil and gas and renewable energy activities.

Interactions between common bottlenose dolphins (Tursiops truncatus) and the artisanal fishery in Asinara Island National Park (Sardinia): assessment of catch damage and economic loss

In 1999, the Italian Central Institute for Applied Marine Research (ICRAM), in response to reports made by local fisheries, began a study into the interactions between common bottlenose dolphins (Tursiops truncatus) and the artisanal fishery in the Asinara Island National Park (Sardinia). Using onboard observers, fishing boat surveys were carried out to determine the frequency of interactions, variations in the catch of target species and damage to two different types of trammel net caused by dolphins. Interactions occurred primarily with trammel nets targetting striped red mullet (Mullus surmuletus; the less valuable peacock wrasse, Simphodus tinca, was also caught). Interactions also occurred with trammel nets set for lobster (Palinurus elephas), cuttlefish (Sepia spp.) and scorpionfish (Scorpaena spp.), but these were considered negligible. The target species, catch and damage inflicted on the catch was recorded, both in the presence and absence of dolphins, in an effort to ascertain associated damage and economic cost. Loss of catch was found to be significant only in the case of nets deployed during the red striped mullet fishing season. Although the level of interaction was high relative to the narrow red striped mullet fishery season, the overall economic impact on the fishing community was found to be modest. The presence and regulations of the national park area may provide an opportunity for investigating mitigation activities compatible with both cetacean conservation and the maintenance of the traditional fisheries.

High‐frequency pingers do not increase catch loss owing to seals in the Baltic Sea

Abstract The Baltic Proper harbour porpoise population is listed as Critically Endangered by IUCN, and only a few hundred animals remain. One of the most serious threats to this population is bycatch in static net fisheries. To minimize bycatch, ICES has proposed that acoustic deterrent devices, pingers, should be used on static nets within the population’s range. However, there have previously been indications that grey seals learn to associate the pinger sounds with the presence of nets with easily accessible prey, and that pinger use therefore can increase the risk of seal depredation in static net fisheries. In recent years, pingers operating at higher frequencies have been made commercially available, the idea being that harbour porpoises will still be able to hear the sound at 50–120 kHz while this will be above or at the limit of seal hearing. This would mean that such high‐frequency pingers would not induce this so‐called dinner‐bell effect. In this study, data were collected from active commercial static net fisheries in the Baltic Proper, using two types of high‐frequency pingers operating at 50–120 and 70 kHz, respectively. Pingers were attached to nets in accordance with manufacturers’ guidelines, and fishers were asked to estimate the catch loss owing to seals in nets with and without pingers. Data were received from 646 deployments made between May 2019 and September 2020. Four generalized mixed effect models were developed with relevant variables. The results suggest using high‐frequency pingers does not increase seal depredation on static nets. It is concluded that pingers could be used as an interim measure to minimize bycatch of the Critically Endangered Baltic Proper harbour porpoise population.

No free lunch: estimating the biomass and ex-vessel value of target catch lost to depredation by odontocetes in the Hawai‘i longline tuna fishery

Depredation by marine predators causes economic losses and impacts depredating species and fish stocks. To understand these impacts, it is important to accurately estimate catch losses from depredation. Pelagic longline fisheries are susceptible to depredation, and depredation is difficult to quantify, because gear is suspended in the water column away from the vessel for extended periods. In the present study, we used fisheries data and a novel modeling approach to estimate catch removal by odontocetes in the Hawai‘i deep-set longline fishery. We estimated annual biomass and economic value lost to depredation of three of the most commonly landed species as approximately 100 t and 1 million USD, respectively, during 2012–2018. The median cost on sets when depredation occurred was $600 USD, with the worst 10% of sets experiencing losses exceeding $2300 USD. We also identified broad-scale spatiotemporal patterns and hotspots of depredation across the range of the fishery. Our findings quantify the ecological and economic implications of this interaction, and our methods can be applied in similar fisheries elsewhere to assess the impacts of depredation.

Acoustic detection of bottlenose dolphin depredation on nets and implications for conservation

Abstract Understanding the depredation process is pivotal to the management of conflicts between wildlife and human activities. Depredation by marine mammals on fisheries occurs when animals ‘steal’ fish from the fishing gear, causing catch loss and damage to gear and catches. The common bottlenose dolphin is a vulnerable species and is the main depredator of coastal static net fisheries in the Mediterranean Sea. The nature and extent of the phenomenon is still poorly understood since evidence is often incomplete or inconsistent mostly due to the different methods used to measure depredation. Here, passive acoustic monitoring devices were used to estimate the consistency between dolphin acoustic detection in proximity to the net and direct dolphin observations and catch measurements at different sites in Sardinia (north‐western Mediterranean Sea). Further, some factors influencing depredation (fishing duration and fishing net length) and changes in catch amount and composition were evaluated. The frequency of dolphin detection based on direct dolphin observations was significantly lower than that based on acoustic monitoring; the latter was related to the amount of catch. Thus, the measurement of catch was more realistically related to depredation than direct dolphin observations. Further, dolphin depredation was related to the duration of the fishing operation. The measure of depredation and catch loss provided here can be used to realistically estimate the damage suffered by fishers and provide preliminary insights to guide the development of an approach for sustainable coexistence between dolphins and fisheries.

Questionnaire and experimental surveys show that dolphins cause substantial losses to a gillnet fishery in the eastern Mediterranean Sea

AbstractCommon bottlenose dolphins (Tursiops truncatus) are known to depredate fishing gear, resulting in damage to the catch and/or the gear itself. The extent of this damage and estimated financial loss varies between areas, métiers, and survey methods. We quantified losses due to bottlenose dolphin depredation in a coastal gillnet fishery in the Thermaikos Gulf, Greece, in terms of CPUE reduction, catch damage, and gear damage. Experimental fishing effort was carried out over two seasons (2020 and 2021), along with concurrent questionnaire surveys over the second season (2021). Depredation frequency (∼35%) and CPUE changes due to depredation (a significant decrease of 45–50%) were similar for both sampling schemes. The number of damaged fish in experimental hauls increased significantly with dolphin depredation, but did not fully account for the sizeable loss in marketable catch, indicating that large numbers of fish were removed from the nets entirely. Damage to experimental nets increased with dolphin presence and group size, with an average of 0.59% of net surface area damaged per depredation event. Both datasets point to annual economic losses of over €5000 per vessel in this fishery, while the similarity between direct observations and self-reported losses highlights the usefulness of frequent questionnaire surveys.

Concurrent 15. Presentation for: INPEX-led Ichthys Joint Venture – developing a dynamic adjustment area to identify, time, duration and potential exposure periods related to a 2D seismic survey offshore Western Australia

Presented on Wednesday 18 May: Session 15 The oil and gas industry is striving for effective consultation between titleholders and commercial fishing stakeholders. Recent developments in cross-industry consultation have resulted in frameworks to provide an adjustment (compensation) claim process, where short-term displacement of fishers and reduction of catch coincident and following marine seismic survey activities may occur. 3D seismic surveys are undertaken more intensively, in geographically smaller areas and shorter time periods. This allows for discreet areas and periods to be defined for the applicability of a claim when fishing catch rates or displacement may occur. By contrast, 2D seismic surveys can be undertaken at regional scales with long sail line transects. These result in a survey vessel being active in an area of potential acoustic influence for infrequent and short periods of time, thus making justification for claims, for loss of catch or displacement, over the full survey area and full acquisition period challenging. To address this challenge a novel approach was developed to determine a dynamic area, based on where and when a survey vessel was operating the seismic source. INPEX utilised the 10 nautical miles (nm) × 10 nm geospatial grid data set provided by Department of Primary Industries Resources and Development, for commercial fishers to report catch effort. The methodology used modified navigation files, to determine the frequency, duration and number of times a fishing block was intersected during the survey. The resulting data provided an ‘adjustment area’ and ‘exposure date’ which could then be referred to as a basis for claim. To access the presentation click the link on the right. To read the full paper click here

INPEX-led Ichthys Joint Venture – developing a dynamic adjustment area to identify, time, duration and potential exposure periods related to a 2D seismic survey offshore Western Australia

The oil and gas industry is striving for effective consultation between titleholders and commercial fishing stakeholders. Recent developments in cross-industry consultation have resulted in frameworks to provide an adjustment (compensation) claim process, where short-term displacement of fishers and reduction of catch coincident and following marine seismic survey activities may occur. 3D seismic surveys are undertaken more intensively, in geographically smaller areas and shorter time periods. This allows for discreet areas and periods to be defined for the applicability of a claim when fishing catch rates or displacement may occur. By contrast, 2D seismic surveys can be undertaken at regional scales with long sail line transects. These result in a survey vessel being active in an area of potential acoustic influence for infrequent and short periods of time, thus making justification for claims, for loss of catch or displacement, over the full survey area and full acquisition period challenging. To address this challenge a novel approach was developed to determine a dynamic area, based on where and when a survey vessel was operating the seismic source. INPEX utilised the 10 nautical miles (nm) × 10 nm geospatial grid data set provided by Department of Primary Industries Resources and Development, for commercial fishers to report catch effort. The methodology used modified navigation files, to determine the frequency, duration and number of times a fishing block was intersected during the survey. The resulting data provided an ‘adjustment area’ and ‘exposure date’ which could then be referred to as a basis for claim.

Feasibility and effectiveness of seal deterrent in coastal trap-net fishing – development of a novel mobile deterrent

With the rapid growth of grey seal (Halichoerus grypus) population in the Baltic Sea, seal-induced catch losses have increased dramatically in coastal fisheries. There have been various attempts to mitigate these damages, such as modification of fishing gear, but solutions have proven inadequate. Promising research results have recently been obtained by using acoustic deterrent devices (ADDs) to keep seals away from the immediate vicinity of the gear. We tested the feasibility and effectiveness of a raft-mounted and a novel mobile ADD in Baltic salmon (Salmo salar) trap-net fisheries along the Finnish coast in collaboration with 13 commercial fishers. Fishers operated trap-nets (pontoon traps) that were equipped with and without an ADD. Our results indicate that a fisher with a trap-net equipped with an ADD can expect to catch on average 3.4 salmon per day whereas in trap-net without an ADD a fisher can expect on average 2.1 salmon per day. The deployment of ADDs over the two years testing period indicated an average increase of 64% in salmon catches. Our study suggests that in salmon trap-net fisheries an ADD is a useful and economically viable (given that the investment is subsided) mitigation tool for reducing seal-induced catch losses. Furthermore, the mobile ADD developed in this study provides unique practical opportunities and notable potential for a wider use of an ADD.

Effect of ground gear modification on bycatch of rays in mediterranean bottom trawl fishery

Bycatch of rays and skates in towed fishing gears represents one of the major threats to these relatively slow-growing marine species. The objective of this study was to modify ground gear in a bottom trawl fishery to increase the escape of these species during towing without associated loss of target catch. Sea trials were carried out with a research vessel in Mersin Bay, North-eastern Mediterranean. Experimental ground gear was modified by cutting the rigging twine between the fishing line and the footrope in the central part of the ground gear. Capture of three unwanted bycatch species were estimated. The probability of capture of guitarfish (Rhinobatos sp.) and common stingray (Dasyatis pastinaca) was significantly reduced to 8% and 20% for guitarfish and stingray, respectively compared to standard ground gear. The results for spiny butterfly ray (Gymnura altavela) were inconclusive due to the wide confidence intervals. Further, the catch comparison results for five out of six target species investigated did not show significant reduction in catch efficiency when using experimental gear compared to the standard trawl. Only for common sole (Solea solea) the modified trawl had significantly lower catch efficiency than the standard trawl. We believe that this technical measure for reducing unwanted bycatch in bottom trawls has a potential to be adopted by the fishery due to being an efficient, low-cost measure which does not create additional challenges during handling of the gear.

Reducing cod bycatch in flatfish fisheries

Management measures to facilitate the recovery of fish stocks can lead to shifts in traditional fishing patterns and target species. In the Baltic Sea, drastic reductions in catch quota for cod (Gadus morhua) force mixed demersal trawl fisheries to avoid cod bycatch and focus on flatfish species. This study developed and tested a simple selection concept that aims to avoid cod bycatch in flatfish-directed trawl fisheries by removing a section of the top panel from the extension piece of the trawl (roofless concept). Sea trials testing the performance of a baseline roofless design, and two designs intended to enhance escape reactions of cod were conducted during two sea cruises. Analysis of the resulting catch data revealed that applying the baseline roofless design consistently reduced cod bycatch by ∼75%. Catches of the target species plaice (Pleuronectes platessa) and flounder (Platichthys flesus) were reduced by less than 15%; however, we estimated that catch losses of the two flatfish species could be balanced by increasing fishing effort to ∼8% and ∼12%, respectively. None of the two roofless designs, intended to enhance escape reactions on cod, improved the performance of the baseline design. Under the scenario of fishery choke caused by limited cod quotas, we estimated that the use of the baseline roofless concept could increase fishing possibilities for flatfish by more than 300%.

Trade-offs between bycatch and target catches in static versus dynamic fishery closures

While there have been recent improvements in reducing bycatch in many fisheries, bycatch remains a threat for numerous species around the globe. Static spatial and temporal closures are used in many places as a tool to reduce bycatch. However, their effectiveness in achieving this goal is uncertain, particularly for highly mobile species. We evaluated evidence for the effects of temporal, static, and dynamic area closures on the bycatch and target catch of 15 fisheries around the world. Assuming perfect knowledge of where the catch and bycatch occurs and a closure of 30% of the fishing area, we found that dynamic area closures could reduce bycatch by an average of 57% without sacrificing catch of target species, compared to 16% reductions in bycatch achievable by static closures. The degree of bycatch reduction achievable for a certain quantity of target catch was related to the correlation in space and time between target and bycatch species. If the correlation was high, it was harder to find an area to reduce bycatch without sacrificing catch of target species. If the goal of spatial closures is to reduce bycatch, our results suggest that dynamic management provides substantially better outcomes than classic static marine area closures. The use of dynamic ocean management might be difficult to implement and enforce in many regions. Nevertheless, dynamic approaches will be increasingly valuable as climate change drives species and fisheries into new habitats or extended ranges, altering species-fishery interactions and underscoring the need for more responsive and flexible regulatory mechanisms.

Characteristics of catch losses in stow nets with finless porpoise excluder devices and a strategy to reduce them

Finless porpoise excluder devices have been developed to prevent bycatch of finless porpoise by stow net in Korea; however, fishermen are hesitant to use them owing to concerns of associated catch losses. To promote their use, we aimed to identify the characteristics of catch losses associated with finless porpoise excluder devices used along the Korean west coast and suggest a strategy to reduce these losses. Therefore, we analyzed the selectivity of the separator net in excluder devices, the catch loss rates in stow net with upward- or downward-facing exit holes, and the size distribution between the lost and caught fish for significant species of stow net. As a result, it was confirmed that the selectivity of the separator was best expressed by the bi-normal function for Japanese anchovies (L50 = 8.1 to 10.9 cm) and golden cuttlefish (L50 = 6.7 to 8.7 cm) and by the constant function for hair tails and swimming crabs. In addition, the size distribution between lost and caught fish species was not significantly different except for Japanese anchovies. Analysis results of the catch loss rate by the position of exit of the excluder devices were as follows. Upward-facing exit holes showed relatively high losses of Japanese anchovies (upward exit 14.40 vs. downward exit 1.11%) and hair tails (3.38 vs. 0.26%). In contrast, downward-facing exit holes showed high losses of golden cuttlefish (3.58 vs. 7.55%) and swimming crabs (0% vs. 15.72%). However, these losses significantly decreased when the exit hole direction was reversed, suggesting that changing the exit hole direction depending on the species could reduce catch losses, increasing fishermen’s willingness to use finless porpoise excluder devices and reducing bycatch.