Total Allowable Catch Research Articles

Using Benford's Law to Detect Possible Biases in Reported Catches of Tropical Tuna From the Indian Ocean

ABSTRACTAccuracy of catch landing data reported by captains of commercial vessels is crucial in the assessment of marine species stocks and in fisheries policy and management. However, this data can be subject to estimation biases, such as a tendency to inflate some catches (to the detriment of others) and refusal to fill in logbooks. We assessed the accuracy of catch reports from the Spanish tropical tuna purse seine fleet (which accounts for 26% of catches in the Indian Ocean) using Benford's law, a mathematical principle effective for detecting irregularities across multiple datasets. During 2013–2020, including periods before and after the implementation of total allowable catch (TAC) limits in 2017, reported catches differed from Benford's expected distribution, especially for bigeye tuna, indicating potential inaccuracies in reported catches. Changes in data reporting after TAC limits were imposed in 2017 suggested modifications in fishing operations and reporting practices. Use of Benford's law highlighted its potential as an auditing tool in fisheries management and provided insights into data integrity that are crucial for sustainable fisheries governance.

The ecological and socioeconomic implications of future total allowable catch decisions and illegal fishing scenarios for South Africa’s West Coast rock lobster fishery

The West Coast rock lobster fishery, vital to South Africa, is in a critical state with only 1.1 % of its original exploitable biomass remaining. This study evaluates effects of various total allowable catch (TAC) decisions on biomass and economic performance, taking illegal fishing, currently a serious problem, into account. TAC options included two sustainable options and an option (1500 mt), which could only be feasible if illegal fishing is stopped. Biomass projections, from 2022 to 2050, are modelled from a length-based model incorporating a Beverton and Holt stock-recruit relationship. The impacts of different TAC decisions on biomass, net seasonal incomes (NSI) and net present value (NPV) are assessed. Sensitivity to different discount rates is also considered. Biomass projections suggest an imminent collapse if legal fishing limits are set too high or if IUU fishing is not substantially reduced. The NPVs for the entire sectors are found to be highest under a 1500 mt TAC but unless accompanied by a halt to IUU fishing, would result in unsustainable catch rates and rapidly declining NSI in areas where many quota holders are located. Under the 550 mt TAC scenario, there is less risk of biomass declines but the quotas for many stakeholders would be economically unviable. Lower TAC options are forecast to lead to the functional exclusion of many rights holders and reduction in employment. The most secure and economically successful strategy is considered to be adjusting annual TACs in response to the effectiveness of controlling IUU fishing and changes in biomass.

AI-RCAS: A Real-Time Artificial Intelligence Analysis System for Sustainable Fisheries Management

This study proposes an Artificial Intelligence-based Real-time Catch Analysis System (AI-RCAS) for sustainable fisheries management. The AI-RCAS, implemented on a Jetson board, consists of fish recognition using YOLOv10, tracking with a ByteTrack algorithm optimized for marine environments, and a counting module. Experiments in actual fishing environments showed significant improvements, with species recognition rates of 74–81%. The system supports the efficient operation of the total allowable catch (TAC) system through real-time analysis, addressing the limitations of the existing Electronic Monitoring (EM) systems. However, challenges remain, including object-tracking difficulties and performance issues in unstable marine environments. Future research should focus on optimizing the fishing process, improving video processing, and expanding the dataset for better generalization.

A Study on the Automation of Fish Species Recognition and Body Length Measurement System

The rapid depletion of fishery resources has led to the global implementation of Total Allowable Catch (TAC) systems. However, the current manual survey methods employed by land-based inspectors show limitations in accuracy and efficiency. This study proposes an automated system for fish species recognition and body length measurement, utilizing the RT-DETR (Real-Time Detection Transformer) model and ARCore technology to address these issues. The proposed system employs smartphone Time of Flight (ToF) functionality to measure object distance and automatically calculates the weight of 11 TAC-managed fish species by measuring their body length and height. Experimental results reveal that the RT-DETR-x model outperformed the YOLOv8x model by achieving an average mAP50 value 2.3% higher, with a mean recognition accuracy of 96.5% across the 11 species. Furthermore, the ARCore-based length measurement technique exhibited over 95% accuracy for all species. This system is expected to minimize data omissions and streamline labor-intensive processes, thereby contributing to the efficient operation of the TAC system and sustainable management of fishery resources. The study presents an innovative approach that significantly enhances the accuracy and efficiency of fishery resource management, providing a crucial technological foundation for the advancement of future fisheries management policies.

Assessment on demersal fisheries status in the FMA 573 under data-limited situation: A combination of statistic and CPUE data as inputs for bayesian surplus production model

Abstract Demersal stock potential, total allowable catch (TAC), and exploitation level status in the FMA 573 were assessed and determined by the National Commission of Stock Assessment (KOMNASKAJISKAN) through Ministerial Decree No. 19/2022. However, the fisheries status, i.e., the biomass level concerning the BMSY and the effort level compared to FMSY, was not completely determined. This study demonstrated the alternative approach to determining fisheries status under limited data. Statistical time series production and existing CPUE data were used to perform the Bayesian Surplus Production Model (cMSY). Based on the results, the stock of demersal fisheries in FMA 573 is overexploited, whereas the F/FMSY and B/BMSY are>1 and <1, respectively. The situation needs concern from all stakeholders. Rebuilding the stock formulation scheme through harvest strategy development for demersal fisheries in FMA 573 must be prioritized to ensure the sustainability of the stock and the fisheries business.

Acoustic Target Strengths and Swimbladder Morphology of Chub Mackerel Scomber japonicus in the Northwest Pacific Ocean

The Northwest Pacific chub mackerel (Scomber japonicus) is one of the most productive, economically important fishery resources worldwide. Accurately assessing this species and ensuring adherence to total allowable catch limits are crucial owing to fluctuations in their abundance and distribution. Acoustic target strength measurements of S. japonicus were conducted at 38, 70, and 120 kHz using a split-beam echosounder of individuals from nine size groups (mean fork length, 10.8–28.3 cm) swimming freely in a net cage within a seawater tank. An underwater camera was utilized to simultaneously measure swimming angle. Least-squares regression analysis revealed that when the slope was constrained to 20, as per the generally applicable morphometric equation, the resulting values for the constant term (b20) were −67.7, −66.6, and −67.3 dB at 38, 70, and 120 kHz, respectively. S. japonicus mean swimming angle across the groups was −10.5–9.6° (standard deviation [SD], 16.3–33.3°). Furthermore, the ratio of swimbladder height to swimbladder length, the ratio of swimbladder length to fork length, and the tilt angle of the swimbladder (mean ± SD) were 0.191 ± 0.060, 0.245 ± 0.055, and 9.6 ± 3.0°, respectively. These results can be used for the acoustic stock assessment of S. japonicus in the Northwest Pacific Ocean.

Towards sustainable exploitation of European pilchard (Sardina pilchardus) stocks off West African waters

European pilchard (Sardina pilchardus), herein referred to as “sardine” or “European sardine”, is the most productive and economically important small pelagic fish in the Northwest African waters. Thus far, very little is known about its stock status in the West African region despite the rapid decadal increase in its catch production. The present study provides avenues vital to improving guidance for sustainable species management. In this region, sardine is divided administratively into three stocks (northern: stock N, central: stock A + B, and southern: stock C). Thus, the present study used two Surplus Production Models (SPM) to evaluate sardine's stock status. Sardine's catch and scientific survey biomass data obtained from FAO-CECAF's (Fishery Committee for the Eastern Central Atlantic (CECAF)) latest reports were used in this analysis to fit the SPMs and investigate the effectiveness of the available catch-per-unit-effort (CPUE) trends in setting the total allowable catch (TAC) for sustaining the different sardine stocks in the region. Results from the SPMs indicate that the sardine stock in the north is fished at optimum levels. Meanwhile, the SPMs output based on the scientific survey biomass indices indicated a healthy state for the central and southern sardine stocks. Similarly, the fishery CPUE indices for the central and southern stocks showed similar biomass trends compared to the survey biomass index, indicating healthy stock status. Therefore, in cases where survey biomass index data is unavailable to run stock assessments, this study suggests that sardine fishery CPUEs could be used in SPMs to monitor biomass trends over time and may also provide stock status proxies. Additionally, with rapid climate and other environmental changes, sardine stocks must be regularly monitored with consistent and comparable scientific methodologies and updated fisheries time series data.

Crab Harvesting, Sustainability Issues, and International Trade: Insights from Russia

This article aims to analyze Russia’s efforts, both domestically and internationally, to combat illicit crab harvesting and safeguard its marine resources. A comparison of total crab imports and allowable catch in Russian waters from 1990 to 2022 indicates a peak in shadow activities during the mid-2000s, with a cessation of large-scale illegal fishing observed since 2013. A narrative analysis of institutional shifts reveals that the bolstering of internal oversight, heightened accountability for harvesters, and enhanced global cooperation have been pivotal in fostering these positive dynamics. Concerning trends, however, emerged towards the beginning of the current decade, indicating potential instability within the legal framework of the crab industry. Persistent statistical discrepancies in trade with South Korea, diminishing institutional capacities within Russia to combat shadow activities, and heightened media scrutiny of illicit crab harvesting underscore the need for sustained vigilance in addressing both internal and external dimensions of this multifaceted problem.

Toward Sustainable Fishing Practices in Indonesia: Defining a Catch Quota Allocation for Saddletail Snapper (Lutjanus Malabaricus) in the Arafura Sea

The Arafura Sea hosts the commercially significant fish species, Lutjanus malabaricus, commonly known as the saddletail snapper. We devised a quota allocation approach for sustainably capturing this species. This approach involved estimating the species’ life history parameters through calculations of the size at 50% maturity, as well as life history ratios (M/K and Lm/L∞) to figure out the Total Allowable Catch (TAC). We based our calculations on the Maximum Sustainable Yield (MSY) that came from the catch and landing data from Probolinggo Port. This helped us set a fishing quota that fits the situation in Indonesia. Our analysis revealed that the size at 50% maturity was 52 cm, slightly lower compared to the neighborhood waters. Using the Length Based-Spawning Potential Ratio (LB-SPR) model, we determined the stock’s SPR to be approximately 17%, which falls below the targeted healthy fish stock SPR reference of 40%. The estimated MSY stood at 2,307 tons, and the TAC calculation slightly exceeded the approach based on time series fitting. Given the notably low SPR estimate, we suggest a cautious approach, recommending an MSY of 2,307 tons per year for Probolinggo Port, emphasizing the importance of maintaining the fishing mortality rate within the sustainable threshold.

Economic gains from individual fishing quotas: The Norwegian coastal groundfish fisheries

AbstractMany rights‐based systems in fisheries use individual fishing quotas (IFQs) that allocate shares of total allowable catch to individual fishers, vessels, or groups of fishers. We analyze the performance of IFQs in the Norwegian coastal groundfish fisheries that substantially limit transferability. We use data from two similar fishing groups that were treated with different management. Difference‐in‐differences results show that IFQs increase productivity and prices for some of the main groundfish species. Results suggest that expected productivity gains and price gains from first‐best rights‐based policies that create highly transferable IFQs can result from second‐best policies that substantially limit transferability.

Tanner crab at southwestern Kamchatka: fishing, stock condition and specifics of the assessment

Results of the current stage of research on tanner crab at the southwestern coast of Kamchatka, harvested in the Kamchatka-Kuril fishing subzone are presented. The stock dynamics since 2001 is analyzed, with special attention to its assessing and forecasting. Features of the crab biology associated with terminal molting are described. The algorithm for separation of the tanner crab recruits into morphometrically mature and immature males is developed that allows to calculate probability for a particular size group of morphometrically immature males to undergo the terminal molt and join to the commercial stock. This algorithm is applied for the data collected at southwestern Kamchatka since 2010. Two peaks in total male abundance of tanner crab were observed in 2005–2006 and 2020–2022. Landing of this species was banned in the Kamchatka-Kuril fishing subzone in 2019–2020, as the result of the local population abundance drop in the previous two years, but was resumed in 2021 after its full restoration. Possible reasons for underestimation of the crab recruitment are discussed, related both with features of the species biology and methodological problems. The population in the Kamchatka-Kuril fishing subzone is currently the most abundant for tanner crab, and this stock in 2020–2022 has reached the historical peak. The fishing of tanner crab in the last three years is distinguished by high catches and high rate of the total allowable catch (TAC) utilization.

POTENTIAL AND LEVEL UTILIZATION OF SKIPJACK (Katsuwonus pelamis) IN THE BUNGUS OCEAN FISHING PORT WEST SUMATERA PROVINCE

The skipjack (Katsuwonus pelamis) in Bungus Ocean Fishing Port has been evaluated for its sustainable potential using the surplus production approach method. The findings indicate a strong alignment with the Fox approach model. The estimated sustainable potential for skipjack is 471 tonnes per year, with an ideal effort of 45 trips annually. The analysis indicates a moderate utilization status, with an average skipjack utilization rate of 62.76%. It is evident that around 37.24% of its maximum sustainable potential, equivalent to 154.74 tonnes per year, is still unexplored. In addition, the catch rate of skipjack is relatively high at 96.14%, indicating that there is still some untapped potential, with 3.86% of the optimal fishing effort or two trips per year remaining unused. As a result, it is recommended that a total allowable catch of 341 tons be set in order to ensure the long-term sustainability of skipjack harvesting in the area.

Spanish fishing industry within the common fishery policy

The main objective of this article is to study the evolution of the Spanish fishing industry, with a specific focus on examining the correlation between actual catches by Spanish vessels and recorded landings against national Total Allowable Catches, which may contribute to improving the current state of the Common Fisheries Policy. Firstly, we offer an overview of the geographical, economic, and legal factors surrounding Spanish fisheries, along with an examination of the Common Fisheries Policy and relevant international agreements impacting these fisheries. Subsequently, we analyze three species, namely hake, anchovy, and cod as they are the most traded fish in the Spanish markets. Thirdly, we conduct an examination to provide information regarding the role of Common Fishery Policy quotas and to explore potential reasons behind the observed results. The main findings reveal the identification of a significant lack of alignment between the Common Fishery Policy and its resulting implementation through the Total Allowable Catches over the last decade.

한국과 미국간의 총허용어획량 제도 비교 분석

Topshell catch by Haenyeo (women divers) has been one of Jeju's economically significant harvests of marine living resources. Total allowable catch (TAC) has been introduced to restore the topshell stock. This paper examines the impacts of the TAC regulation on topshells in Jeju through a comparative study with the red snapper TAC in the Gulf of Mexico in the United States. The results showed that topshell production has not been restored since the TAC was introduced in 2001. The red snapper in the United States is a case of successfully restoring fishing stocks by introducing TAC. It will only be possible to increase topshell production by restoring the marine ecosystems off Jeju. The efforts to increase cultural activities, and to host various festivals have been irrelevant to the restoration of the stock. Without efforts to enhance the habitat quality, the decreasing topshell stocks will threaten the economic sustainability of Haenyeo. The continued expansion of municipal wastewater treatment facilities, the tightened regulation on effluents in the flounder aquaculture facilities, and reduced inputs of chemicals related to farming activities are expected to enhance the habitat quality of village fishing grounds. I hope that more women divers will increase their harvests while following their traditionally inherited community culture in their restored fishing grounds in the near future.

Comparisons of landings to scientific advice indicate overshooting within the common TAC for skates and rays in the Northeast Atlantic

Abstract The International Council for the Exploration of the Sea (ICES) typically provides advice on fishing opportunities on a stock-by-stock basis. Nevertheless, levels of total allowable catch (TAC) are sometimes set for a collection of stocks and species (i.e. a common TAC). An explicit expectation of these is that landings will scale with ICES advice, especially when ICES advice is used to calculate the common TAC. This expectation is tested for skates and rays in the Northeast Atlantic, spanning 26 stocks, 8 species, and 3 ecoregions. Using ICES landings and ICES advice data from 2016 to 2022, we show that landings of several stocks and species have overshot their respective ICES advice, whereas others have undershot. Specifically, some stocks of blonde ray (Raja brachyura) in North Sea and Celtic Seas ecoregions are being landed at a rate that often exceeds double its ICES advice. By collating species based on their ICES assessment category and life-history traits, we find that those considered data-poor and potentially most vulnerable to fishing are consistently landed at higher-than-expected rates in the Celtic Seas. This study questions the appropriateness of a common TAC for skates and rays and calls for shifts towards the use of single-stock catch allocations and the application of advanced stock assessment methodologies.

A comparative economic analysis of industrial fisheries targeting small pelagic fish in Mauritanian waters: Free license versus charter regime

AbstractIndustrial fisheries targeting small pelagic fish have significant socio‐economic implications for North West African countries. This study examines the economic performance of fleets operating in Mauritania's exclusive economic zone under the free license and chartering systems. Using national production data from 1989 to 2010 and economic indicator ratios from European pelagic fishing vessels, we assess the economic performance of pelagic fisheries over one decade. Our findings show that vessel characteristics have rapidly evolved, with free‐licenced vessels having a higher average fishing capacity than chartered vessels. The nominal number of free licenses increased from under 8% in 1995; the year of free licencing began in Mauritania, to over 80% in 2010. The estimated average economic output for 2000–2010 was US$ 231 million, with free licenses contributing over 80% of the total turnover (US$ 187 million). Vessels operating under free licenses made a greater contribution to wealth creation than the chartering regime. Foreign ship owners generated US$ 40.7 million (22%) in income, while chartering yielded US$ 3.6 million (8%). However, the chartering regime was more fiscally advantageous, contributing over 68% of pelagic fisheries tax revenues (estimated at over US$ 29 million). The small pelagic fishery has been subject to a system of total allowable catches and fishing quotas since 2015. This study provides insights into the economic dynamics of the small pelagic fishery, informing decision‐making and potential strategies to enhance the sector's performance and overall economic impact.

A new approach to assessing and forecasting the stock of sprat in the Baltic Sea in modern conditions

The aim of this article: analysis of information and software for forecasting of the Baltic Sea sprat stock Sprattus sprattus balticus at 22–32 ICES subdivisions in the context of the suspension of Russia’s activities in the International Council for the Exploration of the Sea (ICES).Methods used: The data of estimates of sprat abundance and biomass by hydroacoustic methods, commercial and biostatistical characteristics of the species were used to assess the stock and predict its catch in the Baltic Sea. Estimation of the sprat stock was carried out using the traditional method of virtual population analysis (VPA) adjusted according to the method of extended survival analysis (XSA) using the internationally approved VPA module software within the framework of ICES and the R software environment. The recruitment calibration program RCT3 (Recruitment calibration) was used for the abundance of recruitment (age 1 year) according to XSA and forecast. A multivariate short-term forecast was carried out at different levels of development of the total allowable catch (TAC) under the MFDP program (Multi Fleet Deterministic Projection). As an alternative, the domestic software «KAFKA» was tested.Novelty: for the first time, estimates of the sprat stock were made in the conditions of limited access of Russian specialists to primary data in ICES in full.Result: modern methodological and informational support of scientific research in the Baltic Sea in the conditions of the suspension of the activities of Russian experts in ICES makes it possible to obtain information in the minimum necessary amount for assessing the stock of sprat and predicting its catch. Modeling with the «KAFKA» software showed satisfactory results.Practical significance: The current level of information support for forecasting the state of the stock and catch of sprat in the Baltic Sea will allow solving a complex of problems of managing this resource in modern conditions.

Estimating of the maximum life expectancy and natural mortality of the red king crab on the example of the Barents Sea population

The purpose of the study is to establish the maximum life span (tmax) and natural mortality (M) in commercial Lithodidae using the example of the red king crab Paralithodes camtschaticus.Material and methods — after the introduction of P. camtschaticus into the Barents Sea in 1969, the dynamics of the maximum carapace width (CWmax) from the first crab catches in 1974 to 2022 was considered. The data of the authors’ own observations and the results of studies from the open press were used.Results. The retrospective dynamics of the maximum size of crabs for older ages for 1974–2022 is presented. The maximum sizes were established: in males CWmax 280–312 and 298 mm was in 2002 and 2003, and in females CWmax 210–220 mm in 1995, 1998 and in a later period.New data. Based on the fifty-year dynamics of CWmax, it was suggested that after the end of the acclimatization of P. camtschaticus in 1969, the first generation of local juveniles appeared in the area of introduction in the early 1970s; in the absence of fishing, these juveniles were able to freely reach the maximum historical size and maximum age. Males caught in 2002–2003 with CWmax 280–312 mm, could have been 30–33 years old (mean 31 years), and the age of females in 1995 with CWmax 210 mm was 20–25 years (mean 23 years). This age limit of crabs allows us to establish a natural mortality according to the formula М=3/tmax for crabs with CW ≥70–90 mm, when their natural elimination is minimal. In this case, the decrease in M in males will be 10% per year, and in females 13%.Practical significance. To estimate the commercial stock of P. camtschaticus, the values of natural mortality used today are 1.8–2.3 times higher than M established by tmax for this species in the Barents Sea. The use of a double overestimated value of M in model calculations leads to a decrease in the commercial stock of crab and, as a consequence, to a decrease in its total allowable catch.

Balancing environmental concerns and efficiency in Mediterranean fisheries: Economics of production with a look at market trends

The fishing sector in the Adriatic Sea is exposed to stricter regulations due to the negative ecological impact of large-scale fisheries, while increasing socio-economic challenges threaten the profitability of the industry. We apply Stochastic frontier and Price formation analysis to the rapido fishery of Chioggia (Italy) in order to investigate potential strategies to enhance the economic performance of the fishery, considering both effort restrictions and market trends. The use of two different methodological approaches emphasizes the need for a comprehensive and flexible approach to fisheries management, taking into account seasonal fluctuations in efficiency and average prices. The results reveal that efficiency variations are significantly influenced by seasonal factors and stock availability, thus indicating a limited capacity of fishers to adapt to changing market conditions. We emphasize the importance of flexible scheduling of fishing days and discuss the opportunity for implementing mixed management systems incorporating a Total Allowable Catch or quotas.

Quota use in mixed‐stock fisheries

AbstractAlthough most fisheries assessment and management focuses on the status of individual stocks, and regulations are commonly established as single‐species total allowable catch limits (TACs), much of the catch from global fisheries comes from mixed‐stock fisheries where species cannot be harvested separately. We show that in some fisheries where TAC and catch of demersal fish stocks are tracked, the average fraction of TAC harvested ranges from 21% to 68% overall and is declining. This is, in part, related to efforts to protect all species from overfishing, leading to ‘choke species’, which limit fishing pressure on other target species. While some choke species arise from a mix of low and high‐productivity species, others result from allocation processes, which can be aggravated by shifting distributions due to climate change. Underutilization of TACs can also result from market limitations, low value of individual species, undercapacity or management measures. Proposed methods for increasing long‐term yield require species to be managed in stock groups, or allowing the abundance of some stocks to fall below target reference points. We suggest that the observed low and declining aggregate harvests are due, primarily, to the focus on single‐stock sustainability measures, rather than performance of the fisheries in relation to potential overall yield. While there is a growing consensus that single‐species management should be replaced by an ecosystem‐based approach, this will require clear legislative directives regarding management of the trade‐offs involved. Time series considered in this analysis do not extend beyond 2019.