Tuna Caught Research Articles

The IUU Nature of FADs: Implications for Tuna Management and Markets

World tuna catches reached 5.2 million metric tons in 2018, more than doubling since the early 1990s, primarily due to the introduction of Fish Aggregating Devices (FADs). The widespread use of drifting FADs has increased the economic efficiency of the fleet by making it easier to aggregate and locate tuna schools, but at a high ecological cost, including: significant catches of juvenile tunas; bycatch of endangered, threatened and protected species; and “ghost fishing,” marine pollution, and sensitive habitat destruction by abandoned FADs. Recent analysis indicates that most deployed FADs are eventually lost, stolen, beached, or abandoned, continuing their destructive impacts. This paper examines the legal regime, market forces, and other factors that frame FAD use. We demonstrate that, because deployed FADs are legally considered to be fishing, when they drift into closed areas or otherwise contravene national or international agreements or regulations, they are Illegal, Unreported, and/or Unregulated (IUU); vessels using such FADs are therefore IUU. We suggest that introducing a transparent FAD ownership tracking system and requiring FAD owners to mitigate their impacts could substantially improve the effectiveness of tuna Regional Fisheries Management Organizations (RFMOs) and redirect market incentives to properly support tuna management.

PRODUKSI DAN PRODUKTIVITAS TUNA OLEH KAPAL TUNA LONGLINE YANG BERBASIS DI PPN PALABUHANRATU

Produktivitas penangkapan tuna dapat dilihat dari produksi penangkapan yang didaratkan di pelabuhan (landing) per upaya penangkapan (effort). Pelabuhan Perikanan Nusantara (PPN) Palabuhanratu menjadi salah satu pelabuhan perikanan yang aktivitas perikanannya tergolong aktif di wilayah pesisir selatan Pulau Jawa dan menjadi salah satu pusat kegiatan perikanan tangkap di wilayah Propinsi Jawa Barat. Produksi ikan tuna di PPN Palabuhanratu mengalami peningkatan yang cukup signifikan dari tahun 2010 sampai tahun 2019. Pada tahun 2014-2018 produksi ikan tuna di PPN Palabuhanratu mengalami penurunan yang cukup drastis. Pada tahun 2019, produksi kembali meningkat menjadi 1,091,612 ton. Landing Per Unit Effort (LPUE) digunakan dalam penelitian perikanan untuk mengindikasikan kelimpahan sumberdaya yang digunakan untuk melakukan stock assessment ketika mengestimasi kelimpahan relatif dari suatu spesies yang dieksploitasi. Komposisi hasil tangkapan tuna oleh kapal tuna longline terdiri atas ikan tuna sirip kuning (Thunnus albacores), tuna mata besar (Thunnus obesus), ikan tuna albakor (Thunnus alalunga). Produksi tuna yang didaratkan di PPN Palabuhanratu dari tahun 2010-2019 mengalami fluktuasi. Pada tahun 2010 produksi ikan tuna sirip kuning sebesar 444,952 ton, ikan tuna mata besar sebesar 979,189 ton, ikan tuna albakor sebesar 122,671 ton. Pada tahun 2019 produksi ikan tuna sirip kuning sebesar 617,992 ton, ikan tuna mata besar sebesar 240,487 ton, ikan tuna albakor sebesar 233,133 ton. Produktivitas tertinggi terjadi pada ikan tuna sirip kuning tahun 2014 dengan nilai LPUE sebesar 6,09 dengan produksi sebesar 2,448,171 ton dengan jumlah effort 402. Produktivitas mengalami fluktuasi setiap tahunnya.

SPATIO-TEMPORAL VARIATIONS OF YELLOWFIN TUNA CAUGHT BY HANDLINE IN THE INDIAN OCEAN, SOUTH OF NUSA TENGGARA

One of the main targets from small-scale handline tuna fishery is yellowfin tuna (Thunnusalbacares), where most, if not all of its operation depended heavily on the installment of the fish aggregating device (FAD). The objective of the study was to investigate the spatial and temporal distribution of catch and size of yellowfin tuna from FAD-associated handline fishery. The study was conducted from January to December 2018 with main observation location was in Labuhan Lombok fishing port, West Nusa Tenggara. The results showed that the highest catch rate was obtained during April-June, followed by the frequent emergence of large yellowfin tuna (>100 cm FL). On the other hand, January-March was considered as a low season, where most of the catch was dominated by juvenile yellowfin tuna (<50 cmFL). The spatial distribution of yellowfin tuna abundance is closely related to the presence of FADs, where all fishing operations are carried out around FADs. Also, aggregation of fish was more likely influence by temporal variation rather than the quantity of FAD. More abundant yellowfin tuna were found during the east monsoon (April-June) compared to another season where less fish occurred.

SPATIOTEMPORAL VARIABILITY OF TARGET-SPECIES IN TUNA AND TUNA-LIKE FISHING IN BRAZIL

Knowing the history of fishing-target catches and identifying them is essential for fish species conservation, mainly for the conservation of migratory species, whose stock assessment data are often provided by commercial fleets. Data on the catch, effort, and geographic distribution of fishing operations found in Banco Nacional de Dados da Pesca de Atuns e Afins - BNDA (National Database of Tuna and Tuna-like Species Fishing) were herein analyzed. The ratios between catches of different Tuna and tuna-like species were calculated and the identified patterns were used to classify what would be the target-species of the Brazilian fleet in different periods between 1978 and 2018. Based on the current results, there are three different exploration phases marking the Brazilian longline fleet. The first phase (1978-1981) was featured by the prevalence of Japanese vessels, which recorded the highest presence of swordfish on catching quantity within that period (with mean target-species indicator of Dka = 0.30). The second phase took place between 1982 and 2001, and it was marked by an increased indicator for tuna species, mainly of albacore (with mean of Dka = 0.17). Finally, the third phase (2002-2018) stood out for the leasing of several vessels, increasing the effort and the volume of swordfish (with mean of Dka = 0.04), and blue shark catches (with mean of Dka = 0.19). Moreover, the recorded CPUE reflected variations in fleet targeting over the years, as well as the biomass of the analyzed species.

Reliability of the data on tuna catches obtained from the dockside in Indonesia: A study of stakeholders’ perceptions

This paper is a study of stakeholders’ perceptions of the reliability of landings data obtained by governments on fish stocks. The case studied is the tuna fishery in Indonesia, which is the country’s most important fisheries sector in terms of income and employment, but poses particular difficulties for landings data collection because Indonesia is an archipelago made up of 17,500 islands making data collection a very complex, time-consuming, and costly process because of the large number of ports and the need to employ a considerable team of enumerators to collect the data. This study is not an enquiry into whether the officially recorded data are reliable, but whether fishers and other stakeholders believe them to be reliable. We carried out a survey of 921 respondents (724 tuna fishers; 154 live-bait fishers; 16 policy makers; 16 public sectors and 11 private sectors) to investigate their perceptions of the way landings data on tuna are obtained and collated by Indonesian government officials. The results indicate there is considerable scepticism about the accuracy of these fisheries data. Respondents said there was inadequate funding for data collection; the enumerators were poorly trained; and there were few incentives for checking the results of surveys. These and other criticisms raise serious doubts about the efficacy of the management of the tuna fisheries in Indonesia. Stakeholders’ perceptions on how to improve their confidence in the data collected include greater involvement of individual fishers and the private sector.

An argo‐based experiment providing near‐real‐time subsurface oceanic environmental information for fishery data

AbstractA better understanding of the relationships between oceanic environments and fishing conditions could make the utilization of fish more efficient, profitable, and sustainable. The current lack of high‐precision subsurface seawater information has long been a constraint on fishery research. Using near‐real‐time Argo observations, this paper presents a new approach called gradient‐dependent optimal interpolation. This approach provides daily subsurface oceanic environmental information according to fishery dates and locations. An experiment was conducted in the western and central Pacific Ocean using yellowfin tuna (YFT) catch data in August 2017. The results of seawater temperature and salinity represented differences of less than ±0.5°C and ±0.05, respectively, according to verification of error analysis and truth‐finding comparisons. After applying the constructed temperature and salinity profiles, we described the relationship between subsurface information and yellowfin tuna catch distribution. Statistical analysis revealed that yellowfin tuna were more adapted to warmer and saltier seawater. At the near‐surface (&lt;5 m), the most suitable temperature was 28–29°C, although yellowfin tuna can endure a temperature range from 11 to 12°C at a depth of 300 m. The corresponding upper boundary of the thermocline was approximately 75 m, with a mean strength of 0.074°C/m, and the most suitable salinity for yellowfin tuna was 34.5–36.0 at depths shallower than 300 m. These results indicated that the constructed subsurface information was very close to the true values and they had high spatial and temporal accuracy.

Catch per Unit Effort Dynamic of Yellowfin Tuna Related to Sea Surface Temperature and Chlorophyll in Southern Indonesia

Tuna fisheries are the most valuable fisheries in the world, with an estimated market value of at least US$42 billion in 2018. Indonesia plays an important role in the global tuna fisheries and has committed to improve its fisheries management; therefore, a pilot of long-term spatial-temporal data bases was developed in 2012, however none have utilized data to have better understanding for management improvement. In this study, the annual and seasonal variation of large (≥10 kg) Yellowfin Tuna (YFT) catch per unit effort (CPUE) have been investigated and the influence of sea surface temperature (SST) and chlorophyll-a on these variables examined. We used fish landing data from West Nusa Tenggara recorded every month between 2012 and 2017 and analyzed using generalized linear models and generalized additive models. We found a seasonal and annual pattern of tuna abundance affected by SST and chlorophyll-a (chl a) and related to upwelling and El Nino event. These results also suggest that a two-month closure to fishing in August and September in southern Lombok is worth considering by the Government to maximize conservation of stocks due to a high abundance of juveniles emerging during the upwelling months from June to August.

Relationship between chlorophyll-a and sea surface temperature to tuna catch in the Southern Water of Java

The Southern Waters of Java included in 573 WPP has high fishing activity, which the most important commodity is Tuna. The number of Tuna catch are fluctuated which influenced by oceanography factors in the waters. Some of the factors that affect the catch are sea surface temperature (SST) and chlorophyll-a, so this study aimed to determine the distribution, fluctuations in SST and chlorophyll-a, and its relationship to the Tuna catch. SST and chlorophyll-a data were downloaded from NASA, and Tuna catch data in 2017 was collected from Cilacap Fishing Port. The relationship between SST and chlorophyll-a with the catch was analyzed with cross correlation analysis. Distribution of SST and chlorophyll-a was higher in the east part and coastal areas compared to the western and offshore parts. SST and chlorophyll-a fluctuations are inversely proportional but have a very close relationship. SST in the western season and transition 1 an increase then a decline in the east season and transition II, while chlorophyll-a in the western season and transition I is lower than in the east season and transition II. The highest correlation between SST and catch in the time lag -3, while chlorophyll-a in the lag time -4.

Restricted vertical and cross-shelf movements of longtail tuna (Thunnus tonggol) as determined by pop-up satellite archival tags

The global catch of longtail tuna (Thunnus tonggol) has almost tripled over the past two decades, with recent stock assessments suggesting overexploited stocks. Nine longtail tuna were tracked for 2–115 days with pop-up satellite archival tags off eastern Australia (27.5°S 153.4°E to 27.5°S 153.4°E) to better understand their movements, habitat specificity, and post-capture mortality. Fish primarily utilised coastal waters of 0–25 m (maximum 90 m) and water temperatures of 23–28 °C (17.1–28.5 °C). All fish moved north for distances of up to 654 km, with three fish moving to a known spawning area where their vertical movement behaviour changed abruptly. Their occupation of shallow waters and a lack of diel vertical migrations differ markedly to the habits of oceanodromous Thunnus species. This may be due to the absence of a swim bladder and highly evolved heat exchanging vascular networks that may limit their niche breadth. The tagging data may help improve stock assessment model inputs and subsequent outcomes to guide the development of science-based conservation and management measures.

Monitoring of Spanish flagged purse seine fishery targeting tropical tuna in the Indian ocean: Timeline and history

The Spanish tuna purse seine freezer fleet targeting tropical tuna in the Indian Ocean is one of the most important fleets in the world. The present study firstly describes the history and evolution of this fishery (including its current status, following the economic crisis and the upsurge of Somali piracy of this last decade), and secondly describes the effort of Spanish scientific institutions to collect data (including estimates of catch, effort, and length-frequency distributions by species) from distant fisheries. This monitoring has been carried out in collaboration with stakeholders and other regional scientific organizations since its origins in the early 1980s. During this period the monitoring have been adapted to the change in the fishery, improving both the scientific estimates of the exploited species, as well as our knowledge of the impact of the fishery on the ecosystem, which in turn has served to improve the management and sustainability of the fishery. Although, in general, data quality has improved over time, there are periods with poor data quality. Currently, the priority is to eliminate possible biases from sampling at port. Finally, our general assessment of the adequacy of past and present monitoring systems, is that the current estimation system (called T3) is an important tool throughout the historical series to provide total tropical tuna catches, but in the new context of the TAC proposed for the yellowfin tuna, it is necessary to separate this scientific tool from others used for the flag state authorities to manage the TAC.

Machine learning for characterizing tropical tuna aggregations under Drifting Fish Aggregating Devices (DFADs) from commercial echosounder buoys data

The use of echosounder buoys deployed in conjunction with Drifting Fish Aggregating Devices (DFADs) has progressively increased in the tropical tuna purse seine fishery since 2010 as a means of improving fishing efficiency. Given the broad distribution of DFADs, the acoustic data provided by echosounder buoys can provide an alternative to the conventional CPUE index for deriving trends on tropical tuna stocks. This study aims to derive reliable indices of presence of tunas (and abundance) using echosounder buoy data. A novel methodology is presented which utilizes random forest classification to translate the acoustic backscatter from the buoys into metrics of tuna presence and abundance. Training datasets were constructed by cross-referencing acoustic data with logbook and observer data which reported activities on DFADs (tuna catches, new deployments and visits of DFADs) in the Atlantic and Indian Oceans from 2013 to 2018. The analysis showed accuracies of 75 and 85 % for the recognition of the presence/absence of tuna aggregations under DFADs in the Atlantic and Indian Oceans, respectively. The acoustic data recorded at ocean-specific depths (6–45 m in the Atlantic and 30–150 m in the Indian Ocean) and periods (4 a.m.–4 p.m.) were identified by the algorithm as the most important explanatory variables for detecting the presence of tuna. The classification of size categories of tuna aggregations showed a global accuracy of nearly 50 % for both oceans. This study constitutes a milestone towards the use of echosounder buoys data for scientific purposes, including the development of promising fisheries-independent indices of abundance for tropical tunas.

Quantifying the distribution of swordfish (Xiphias gladius) density in the Hawaii-based longline fishery

The Hawaii-based longline fishery targeting bigeye tuna and swordfish is the most economically important fishery in Hawaii. An improved understanding of the distribution of swordfish within this fishery and how it changes in response to environmental conditions is critical for predicting potential climate change impacts to the fishery. The multi-species Vector-Autoregressive Spatio-Temporal (VAST) model was used to estimate abundance and density of swordfish within the Hawaii-based longline fishing grounds. Swordfish and bigeye tuna catch per unit effort were used in a spatial dynamics factor analysis to help estimate swordfish density in time periods when the swordfish fishery was closed. Although the model was unable to account fully for the significant changes in fishery regulations in 2000, it provided quantified estimates of swordfish density and distribution and information on how those distributions may change in response to environmental variables. Swordfish density center of gravity was found to correlate with the Southern Oscillation Index (SOI) averaged during the swordfish spawning season (April – July), with densities centered further north and east during positive SOI (cooler sea temperatures) and further south and west during negative SOI (warmer sea temperatures).

Defining the stock structures of key commercial tunas in the Pacific Ocean II: Sampling considerations and future directions

Delineating the stock structure of highly-mobile, wide-ranging fishes subject to exploitation is a challenging task, yet one that is fundamental to optimal fisheries management. A case in point are stocks of skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus) and albacore tuna (Thunnus alalunga) in the Pacific Ocean, which support important commercial, artisanal, subsistence, and recreational fisheries, and contribute roughly 70 % of global commercial tuna catches. Although some spatial and temporal structuring is recognised within these stocks, growing evidence from a range of approaches suggests that the stock structure of each tuna species is more complex than is currently assumed in both stock assessment and climate change models, and in management regimes. In a move towards improving understanding of the stock structure of skipjack, yellowfin, bigeye and South Pacific albacore tunas in the Pacific Ocean, an international workshop was held in Nouméa, New Caledonia, in October 2018 to review knowledge about their movement and stock structure in the region, define and discuss the main knowledge gaps and uncertainties concerning their stock structure, and develop biological sampling approaches to support the provision of this information. Here, we synthesise the discussions of this latter component. For each tuna species, we identify several general sampling considerations needed to reduce uncertainty, including i) the need for broadscale sampling in space, ideally covering each species’ distribution, targeting adults in spawning condition and adopting a phased approach; ii) the need for temporally-repeated sampling of the same geographical areas to assess stability in observed patterns over time; iii) the need to resolve patterns in spatial dynamics, such as those resulting from movements associated with the seasonal extensions of poleward flowing currents, from underlying stock structure, iv) the importance of adopting a multidisciplinary approach to stock identification, and v) the need for careful planning of logistics and coordination of sampling efforts across agencies. Finally, we present potential sampling designs that could be adopted to help overcome uncertainties around the initial identification of stocks and the provenance, mixing and proportional contributions of individuals in harvested assemblages, as well as how these uncertainties could be accounted for in fisheries management via the use of management strategy evaluation.

Defining the stock structures of key commercial tunas in the Pacific Ocean I: Current knowledge and main uncertainties

Tunas are the focus of significant fisheries in the Pacific Ocean, where landings of four species – skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus) and albacore tuna (Thunnus alalunga) – constitute approximately 70 % of the global tuna catch. Stock assessments for skipjack, yellowfin and bigeye tunas in the Pacific Ocean currently assume eastern and western stocks. For albacore tuna, separate North Pacific Ocean and South Pacific Ocean stocks are currently assumed. In each case, these geographic definitions reflect the historical development of fisheries management across the Pacific rather than biological considerations. There is widespread agreement that uncertainties surrounding the stock structures of these four tuna species could have important impacts on the population dynamics models used to assess their status and inform management options. Knowledge of stock structure is also essential for improved modelling of the effects of climate change on tuna distribution and abundance and associated implications for fisheries. This paper reviews current knowledge and understanding of the stock structures of skipjack, yellowfin, bigeye and South Pacific albacore tunas in the Pacific Ocean, by exploring available literature relating to their biology, movement and spatial dynamics. As a guide for future research in this area, we identify the main uncertainties in defining the stock structure of these four tunas in the Pacific, including i) spawning dynamics; ii) the degree of spawning area fidelity and localised residency; iii) the provenance of individuals in, and proportional contributions of self-replenishing populations to, fishery catches within the Pacific Ocean; iv) linkages with adjacent ‘stocks’; v) the effects of climate change on stock structure and proportional contributions of self-replenishing populations to fisheries; and vi) the implications of improved knowledge of tuna stock structure for stock assessment and climate change model assumptions and fisheries management. We also briefly propose some approaches that future studies could use to address these uncertainties.

PKM PENGEMBANGAN USAHA PENGOLAHAN PRODUK IKAN TONGKOL, SEBAGAI UPAYA MENINGKATKAN PENDAPATAN ISTRI NELAYAN DI DESA KATIALADA, KECAMATAN KWANDANG, KABUPATEN GORONTALO UTARA, PROVINSI GORONTALO

Katialada Village is located in Kwandang sub-district, North Gorontalo District, Gorontalo Province. One of the dominant marine potentials in Katialada is Tuna. Based on the report from the North Gorontalo District Fisheries Service in 2016, the average catch of Tuna each month reached 300 tons. Bolowa and Cakalang SMEs (Small and Medium Enterprise) are a community business group consisting of fishermen's wives in Katialada Village established since 2014. Bolowa SMEs produce pickled products, while UKM Cakalang produces abon and panada tore cakes. Based on the information compiled from the Bolowa and Cakalang SME groups, there are several problems and obstacles that hamper the development of SME groups. These constraints and problems are limited equipment used, there is no taste diversification, unattractive product packaging, bad business management, and a marketing system that has not been maximized. To overcome those problems, the solution agreed with partners is the procurement of tools to drain the oil contained in the product, procurement of vacuum sealer tools to package the product, there are 5 variations of flavors which are divided based on the level of spiciness, the creation and design of products that are good and attractive, giving business management training to be better, finding partners to sell products, creating accounts on online buying and selling sites and social media as a marketing medium. The method used in the activity is lecture, discussion and practicum. In addition, the facilities support from the Gorontalo Polytechnic Machine and Agricultural Equipment Study Program in the form of workshops and food microbiology laboratories in the Agricultural Product Technology Study Program will support the implementation and success of the service program.

CPUE STANDARDIZATION OF FRIGATE TUNA (Auxis thazard) CAUGHT BY PURSE SEINE OFF THE COAST OF WESTERN SUMATERA (FMA 572)

Frigate tuna (Auxis thazard) is one of the major commercial tuna species, both in industrial and small scale fisheries, particularly in the waters off Western Sumatera. In Indonesia, A. thazard is a group of locally called “tongkol” together with A. rochei, Thunnus tonggol, and Euthynnus affinis. This study describes a preliminary examination of frigate tuna catch from purse seine off the coast of western Sumatera (FMA 572). The data were collected daily by an enumerator on the fish landing site from 2013 to 2017, including fishing gear, number of days at sea, catch, length, and weight of frigate tuna. The fishing ground coordinate data provided by the observer on board the vessel. General Linear Model (GLM) with gamma was applied in this study to standardize the CPUE by year, quarter, season, and GT as fixed variables. The results showed that the variation of CPUE was mostly influenced by year and quarter, while season and fleet size (GT) showed less impact on the catch. In general, even though the catch trend declines during the observation years, the population of frigate tuna off the coast of western Sumatera (FMA 572) were considered sustainable.

Sea surface temperature and chlorophyll-a condition of skipjack tuna (Katsuwonus Pelamis) catching area in Ternate Island marine waters

Skipjack tuna is one pelagic fish that always migrates for a condition with relevant oceanographic factors for their survival, particularly for optimum sea surface temperature and chlorophyll-a. This study conducted with the experimental fishing method from June - November 2018 in the waters of Ternate Island in observation of the optimal condition of oceanographic factors, mainly SST and Chlorophyll-a in the distribution of skipjack tuna. Employing a polynomial regression analysis, the research results show that the sea surface temperature and chlorophyll-a parameters are strictly related to the distribution of the amount of skipjack tuna caught with correlation coefficient value (r) respectively of 0.646 for sea surface temperature and 0.565 for chlorophyll-a. The optimum temperature for the skipjack tuna in the waters of Ternate Island according to the research results ranges from 27.0°C - 30.9°C, while the optimum condition of chlorophyll-a is higher than 0.2 mg/m3-0.35mg/m3, and it seems that every increment of chlorophyll-a content in water indicates an increase of the amount of skipjack tuna catch.

A spatially explicit model for predicting the probability of occurrence of zero-catch quadrants in the tuna purse seine fishery of the Eastern Tropical Pacific Ocean

Null purse seine sets (those in which the catch is zero) are common in every tuna fishery in the world. Current evidence suggests that different environmental factors can influence the occurrence of null sets. In this study, we used a long-term (2003–2015) database from the tuna purse seine fishery in the eastern Pacific Ocean to analyze the temporal and spatial variability of the occurrence of 1º × 1º quadrants where the retained tuna catch was zero (“null cells”). We fitted a logistic generalized additive model to predict the occurrence of null cells as a function of environmental and operational covariates. Results of the modeling process suggested that high probabilities of null cell occurrence exist mainly in 2 environmentally different zones: the entrance to the Gulf of California, Mexico, and off the coast of Central America. The final statistical model suggested that operational variables (number of sets, type of fishing indicator) are more important to null cell occurrence than environmental factors (sea surface temperature, chlorophyll concentration, sea level anomaly, and El Niño events).

Tuna trade‐offs: Balancing profit and social benefits in one of the world’s largest fisheries

AbstractThe western and central Pacific Ocean (WCPO) tuna fishery is one of the world's largest in terms of both catch volume and value, providing over half of global tuna catch with a landed value of US $5.84 billion in 2017. Fishing is conducted by both large‐ and small‐scale fleets, with fisheries subsidies disproportionately benefiting the former. The primary objective of this study was to determine the optimal distribution of effort between two large‐scale fisheries (LSF) and two small‐scale fisheries (SSF) in the WCPO under three scenarios: to maximize industry benefits, minimize subsidization or maximize food supply. The objective was approached using a bioeconomic game‐theoretic model. Results indicate opposite distributions of effort to maximize industry benefits (all fishing conducted by LSF) or to minimize subsidization (all fishing by SSF), with more balanced effort distributions to maximize food supply. Total value of capacity‐enhancing subsidies in optimal scenarios ranged from $1.4 billion when industry benefits were maximized to $0.2 billion when subsidization was minimized. Investigation of suboptimal scenarios reveals the flexibility of these results, with wide ranges in outputted state variables for a given goal. Difficulty was encountered in modelling the SSF sector due to data deficiencies, a well‐recognized issue in managing SSF. Investments towards “data equity” to help ensure that management decision‐making can properly account for the SSF sector would be useful. This study has implications for the objectives we set in fisheries management, and the potential trade‐offs, often value‐driven in nature, that we must make explicit in that management.

Potential predictability of skipjack tuna (Katsuwonus pelamis) catches in the Western Central Pacific

The Pacific Island countries have a substantial socio-economic dependency on fisheries. Skipjack tuna is one of the most important species in the Western Central Pacific (WCP) and its catches in this region exhibit a spatio-temporal variability influenced by ocean conditions, mainly the El Niño-Southern Oscillation (ENSO). This study investigates the relationship between skipjack tuna catch amounts and environmental variables in the equatorial Pacific during 1990–2014, and evaluates the potential predictability of the catches based on their statistical relationship. A series of regressed and reconstructed spatial patterns of upper-ocean temperature, salinity, currents and precipitation represent ENSO-like variability, and their principal component time series are used to estimate the predictability of skipjack tuna catches in the Federated States of Micronesia (FSM). ENSO-like variability depicted from 100 m temperature and 5 m salinity in the equatorial Pacific exhibit a significant predictability for the annual catch amount in the FSM for several years with a training period of > 20 years. This suggests that the subsurface temperature or near surface salinity can be a better predictor of ecosystem variability than widely used sea surface temperature. Applications of this result to other species could have broad implications for the fishery industry in the WCP.