Tuna Species Research Articles

Valuable Ca/P Sources Obtained from Tuna Species’ By-Products Derived from Industrial Processing: Physicochemical and Features of Skeleton Fractions

The global tuna canning industry generates substantial volumes of by-products, comprising 50% to 70% of the total processed material. Traditionally, these by-products have been utilized in low-value products such as fish oils and fishmeal. However, there is significant potential to extract high-value compounds from these by-products, such as calcium phosphates (CaP), which can have pharmaceutical, agricultural and biotechnological applications. This work explores the potential of tuna canning by-products, particularly mineral-rich fractions (central skeleton, head and fish bones) as sources of calcium phosphates (CaP), offering a sustainable alternative to conventional synthetic derivatives within a circular bioeconomy framework. By-products from two of the most exploited species (yellowfin and skipjack) were subjected to enzymatic hydrolysis and chemical extraction, followed by controlled calcination to obtain CaP. The content of organic matter, nitrogen, total proteins, lipids and amino acids in the cleaned bones, as well as the main chemical bonds, structure and elemental composition (FT-Raman, XRD, XRF) were evaluated. Results indicated that the highest recovery yield of wet bones was achieved using the chemical method, particularly from the dorsal and caudal fins of yellowfin tuna. The proximal composition, with ash content ranging from 52% to 66% and protein content varying between 30% and 53%, highlights the potential of tuna skeleton substrates for plant growth formulations. Furthermore, variations in crystalline structures of the substrates revealed significant differences depending on the by-product source and species. XRD and Raman results confirmed a monophase calcium phosphate composition in most samples from both species, primarily based on hydroxyapatite (central skeleton, caudal and dorsal fin) or whitlockite/β-tricalcium phosphate (viscera), whereas the heads exhibited a biphasic composition. Comparing the species, yellowfin tuna (YF) exhibited a hydroxyapatite structure in the branchial arch and scales, while skipjack (SKJ) had a biphasic composition in these same regions.

The Small-Scale Tuna Fishery in Leyte, Philippines: Fishing Gears, Practices, Catch Rate and Composition

The Philippines is a significant tuna producer globally and ranks among the major tuna-fishing nations. One of the various areas where tuna fishery occurs in the country is the province of Leyte in Eastern Visayas. However, available information on the fishery in the province is limited. Thus, this study aimed to provide comprehensive information on the current status of small-scale tuna fishery in selected municipalities in Leyte, particularly on the types of fishing gears used, practices employed by fishers, and the catch rate and composition of the gears. This study used a purposive sampling method, and data were gathered through face-to-face interviews with a total of 68 small-scale tuna fishers, and actual catch sampling. The respondents’ involvement in tuna fishing ranged from 3 to 60 years with a mean of 26±13 years. A total of three different types of hook and line gear used in the fishery were recorded, namely: 1) paired troll line, 2) single troll line, and 3) single hook and line with float. The paired troll line is the most commonly used gear among tuna fishers. The mean catch per unit effort varies depending on the fishing gear type. The catch composition of the three gears based on the actual catch sampling was comprised of four tuna species including longtail tuna Thunnus tonggol (50.48%), big-eye tuna T. obesus (21.90%), eastern little tuna Euthynnus affinis (18.10%), frigate tuna Auxis thazard (3.81%), and two other species including Megalapis cordyla (3.81%) and Scomberomorus commerson (1.90%). The current major issues in the fishery include catch seasonality, illegal fishing, and border restriction.

Analyses of Biometric Growth Parameters, Feeding Composition and Fisheries Aspects of Auxis thazard (Frigate Tuna) of the East, West and South Coasts of Sri Lanka

This study examines the biometric parameters of Auxis thazard, a commercially significant neritic tuna species in Sri Lanka, after primary and secondary data analyses. In secondary data analysis, data following the year 2017 were obtained from the Department of Fisheries and Aquatic Resources for a comparative study of Western, Southern and Eastern coasts. The Length-Weight Relationships (LWR) for Auxis thazard in West, South and East coasts were W= 0.0012TL^3.6586, W = 0.0026TL^3.4846 and W = 0.0147TL^2.951. The pooled regression coefficient (‘b’) values indicated positive allometric growth in West and South, and isometric growth in East. The condition factor showed relatively healthy conditions in fish for West and South and poor condition for East. The gillnets reported 98% of catches in West and ringnets reported. 68% and 67% of catches in South and East respectively. The primary data analysis was conducted in the West coast from November 2021 to February 2022. The LWR was W= 0.0114TL^3.0366 indicating isometric growth and fish were relatively healthy. Shrimps were the most preferred prey item at each stomach fullness level. The percentages below 29.5 (length at first maturity reports by FishBase) included 18.8, 39.2 and 34.0 for West, South and East suggesting continuous fish landing monitoring.

Population structure of longtail tuna (Thunnus tonggol) within and across Indonesia’s fisheries management areas (FMAs) and neighboring countries based on mitochondrial control region

Longtail tuna (Thunnus tonggol), one of the neritic tuna species commonly found in the coastal areas of the Indo-Pacific region, is known to be in an overfishing state in certain areas, including in Indonesia. Understanding the condition of the T. tonggol population within Indonesia is very important in managing its fisheries policy. This research aims to understand the population genetic structure of T. tonggol across Indonesia's Fisheries Management Areas (FMAs), as well as to investigate the phylogeography of T. tonggol within the Indo-Pacific region. A total of 586 samples were collected from 18 locations within Indonesia’s six FMAs, and two locations from Malaysian waters. A 520 bp portion of mtDNA control region was amplified and sequenced. Data analysis was conducted using 586 total sequences generated from this study, and 336 sequences retrieved from GenBank, as well as provided by the author of previous study. Population structure analysis indicated a panmictic population of T. tonggol within six Indonesian FMAs and within the neighboring countries (Malaysia, Andaman Sea, Vietnam, Philippines, and India), with an indication of population expansion. These data do, however, reveal two potentially distinctive clades, one showing an affinity among samples from certain parts of Indonesia (East Aceh, West Aceh, Medan - FMA571 & FMA572) and India. Based on this finding, the T. tonggol fisheries should be managed as a single management unit both within Indonesia’s FMA and within neighboring countries, while also emphasizing localized genetic diversity to protect the sustainability of the species and its fishery.

Exploring structural and computational contrasts in Myoglobins: Implications for thermal treatment-induced Sulfmyoglobin formation

Greening of tuna metmyoglobin (MetMb) by thermal treatment (TT) and free cysteine is associated with sulfmyoglobin (SulfMb) production. This greening reaction (GR) was once thought to occur only in tuna species. However, recent research has revealed that not all tuna species exhibit this behavior, and it can also occur in horse MetMb. Thus, the present study aimed to compare the GR-reactive (Katsuwonus pelamis and Equus caballus) and GR-unreactive (Sarda chiliensis and Euthynnus lineatus) MetMb using UV–vis spectrometry during TT (60 °C/30 min and free cysteine) to monitor the GR. We used molecular dynamics (MD) simulation to assess the stability of the heme group during TT. We discovered that using GR-unreactive MetMb resulted in an incomplete GR without producing SulfMb. Additionally, our MD simulations indicated that Met85 presence in the heme cavity from GR-unreactive is responsible for the heme group instability and displacement of distal His during TT.

Pacific tuna update: 20th Meeting of the Western and Central Pacific Fisheries Commission

The Western and Central Pacific Fisheries Commission (WCPFC), the governing body for the world’s largest tuna fishery, held its 20th annual Commission meeting in Rarotonga, Cook Islands, in December 2023. This commentary provides an overview of the meeting and its outcomes. Revisions to the tropical tuna measure were the main focus of member states’ attention, alongside the determination of an interim Target Reference Point for South Pacific albacore, compliance monitoring reporting, and updates to measures and harvest strategies for Northern Stocks. The members were able to comprehensively address the management of the tropical tuna species and made progress on harvest strategies. Harvest strategies are pre-determined management actions that would reduce the reliance on short-term management decisions and achieve a long-term management framework. However, other important issues, such as developing an allocation framework, remained unresolved despite the member's commitment to start developing such a framework at this year’s meeting. Emerging shifts in meeting dynamics were observed and may signal changes in how the WCPFC operates moving forward.

The habitat preference of commercial tuna species based on a daily environmental database approach in the tropical region of the Eastern Indian Ocean off Java-Bali waters

This paper explores the habitat characteristics of commercial tuna species based on daily oceanography parameters in the Eastern Indian Ocean Off Java-Bali Waters. Moreover, more research is needed combining the daily spatial distribution of oceanographic variables of surface and sub-surface data to analyse the habitat characteristics of large pelagic fish, including tuna species. In this study, we used five main daily oceanography parameters: sea surface temperature (SST), sea surface chlorophyll (CHLa), sea surface height (SSH), dissolved oxygen at 100m (DO100), the temperature at 100m (temp100) and the combination of the catch of yellowfin (YFT), albacore (ALT) and bigeye (BET) tuna that use long lines. To analyse the relationship between the environmental database and tuna catch, we utilized Generalized Additive Models (GAMs) from univariate variables until the combination of all variables. The result stated that all the variables influence the existence of all tuna species with P-values <0.001. Temperature is the most critical predictor variable, SST is the most vital predictor for BET and YFT tuna, and temp100 is the most critical for ALT. The second most essential variables were DO100 for BET, Temp 100 for YFT, and SSH for ALT. Moreover, BET and YFT prefer to stay at a lower temp100, and ALT tuna remains at a higher temp100. However, all of them avoid an SST higher than 29 °C. Further assessment of the long-term SST trend specific to tuna species is required to fully account for the effects of global warming on the oceans.

First evidences in the Gulf of Cádiz (northeastern Atlantic Ocean) as a spawning area of bullet tuna species (Auxis rochei)

The bullet tuna, Auxis rochei, is a commercially significant scombrid in small-scale inshore fisheries in the northeastern Atlantic and western Mediterranean. We hypothesized that the Gulf of Cádiz could serve as a spawning area of bullet tuna. We analysed the gonads and GSI of 428 individuals (23.9–48.7 cm SFL) caught by Portuguese and Spanish traps along the south Atlantic Iberian Peninsula, as well as by Spanish recreational fishery between 2004 and 2021. Larvae of bullet tuna were collected during surveys conducted on the northern shelf of the Gulf of Cádiz in June and August. Bullet tuna landings exhibited high seasonality in the Gulf of Cádiz, peaking during the warmest months, notably from August to October. Analysis of maturity data, monthly GSI variations, larvae distribution, and landings indicate that bullet tuna is reproductively active in the Gulf of Cádiz, particularly in July and August. A more comprehensive understanding of the reproductive behaviour of bullet tuna in this region is essential to confirm its reproductive success and to study recruitment mechanisms further.

Adaptive spatiotemporal management to reduce shark bycatch in tuna fisheries.

Purse-seine tropical tuna fishing in the eastern tropical Pacific Ocean (EPO) results in the bycatch of several sensitive species groups, including elasmobranchs. Effective ecosystem management balances conservation and resource use and requires considering trade-offs and synergies. Seasonal and adaptive spatial measures can reduce fisheries impacts on nontarget species while maintaining or increasing target catches. Identifying persistently high-risk areas in the open ocean, where dynamic environmental conditions drive changes in species' distributions, is essential for exploring the impact of fisheries closures. We used fisheries observer data collected from 1995 to 2021 to explore the spatiotemporal persistence of areas of high bycatch risk for 2 species of oceanic sharks, silky shark (Carcharhinus falciformis) and oceanic whitetip shark (Carcharhinus longimanus), and of low tuna catch rates. We analyzed data collected by fisheries scientific observers onboard approximately 200 large purse-seine vessels operating in the EPO under 10 different flags. Fishing effort, catch, and bycatch data were aggregated spatially and temporally at 1°×1° cells and monthly, respectively. When areas of high fishing inefficiency were closed the entire study period and effort was reallocated proportionally to reflect historical effort patterns, yearly tuna catch appeared to increase by 1-11%, whereas bycatch of silky and oceanic whitetip sharks decreased by 10-19% and 9%, respectively. Prior to fishing effort redistribution, bycatch reductions accrued to 21-41% and 14% for silky and oceanic whitetip sharks, respectively. Our results are consistent with previous findings and demonstrate the high potential for reducing elasmobranch bycatch in the EPO without compromising catch rates of target tuna species. They also highlight the need to consider new dynamic and adaptive management measures to more efficiently fulfill conservation and sustainability objectives for exploited resources in the EPO.

Dietary plasticity and broad North Atlantic origins inferred from bulk and amino acid-specific δ15N and δ13C favour killer whale range expansions into Arctic waters.

Killer whales (Orcinus orca) occur seasonally in the eastern Canadian Arctic (ECA), where their range expansion associated with declining sea ice have raised questions about the impacts of increasing killer whale predation pressure on Arctic-endemic prey. We assessed diet and distribution of ECA killer whales using bulk and compound-specific stable isotope analysis (CSIA) of amino acids (AA) of 54 skin biopsies collected from 2009 to 2020 around Baffin Island, Canada. Bulk ECA killer whale skin δ15N and δ13C values did not overlap with potential Arctic prey after adjustment for trophic discrimination, and instead reflected foraging history in the North Atlantic prior to their arrival in the ECA. Adjusted killer whale stable isotope (SI) values primarily overlapped with several species of North Atlantic baleen whales or tuna. Amino acid (AA)-specific δ15N values indicated the ECA killer whales fed primarily on marine mammals, having similar glutamic acid δ15N-phenylalanine δ15N (δ15NGlx-Phe) and threonine δ15N (δ15NThr) as mammal-eating killer whales from the eastern North Pacific (ENP) that served as a comparative framework. However, one ECA whale grouped with the fish-eating ENP ecotype based δ15NThr. Distinctive essential AA δ13C of ECA killer whale groups, along with bulk SI similarity to killer whales from different regions of the North Atlantic, indicates different populations converge in Arctic waters from a broad source area. Generalist diet and long-distance dispersal capacity favour range expansions, and integration of these insights will be critical for assessing ecological impacts of increasing killer whale predation pressure on Arctic-endemic species.

Leader material and bait effects on target and bycatch species caught in an Atlantic Ocean pelagic longline fishery

The influence of bait type and leader material on target and bycatch species was assessed through fishing experiments in the Portuguese shallow pelagic longline fishery in the Atlantic Ocean. Wire leaders were found to decrease catch rates of commercially valuable species such as bigeye tuna and yellowfin tuna, while increasing catch rates of elasmobranchs, including the blue shark and shortfin mako. The odds ratios of capture swordfish and tunas also decrease when using wire leaders, while elasmobranchs have higher odds ratios of capture and at-haulback mortality when using wire leaders. Squid bait led to higher catches of targeted tuna species, however it also resulted in higher catches of marine turtles. For most of the taxa caught at-haulback mortality risk was found to be higher on squid bait, which may be related with increased deep-hooking events. While bait type and leader material did not significantly affect size selectivity for most species, wire leaders were found to retain larger blue sharks and fish bait attracted smaller-sized swordfish. This study showed that banning wire leaders on pelagic longline fisheries is an effective measure for reducing the retention of pelagic shark species, particularly of large size blue sharks.

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.

Age validation of yellowfin and bigeye tuna using post-peak bomb radiocarbon dating confirms long lifespans in the western and central Pacific Ocean

Abstract Age-reading protocols for tuna species using annual growth zones in thin-cut transverse otolith sections have produced greater age estimates than previous methods. Lifespan estimates for yellowfin (YFT) and bigeye (BET) tuna (Thunnus albacares and T. obesus) were validated up to 16–18 years in the western North Atlantic Ocean using bomb 14C dating and the current study extends the approach to YFT and BET of the western and central Pacific Ocean (WCPO). Archived otoliths from young-of-the-year (YOY) tuna caught in the WCPO were analysed for 14C to establish a reference chronology covering 30 years (1989–2019). This YOY 14C time series exhibited strong concordance with existing coral-otolith 14C references for the tropical-subtropical Pacific Ocean and was combined as a single chronology. Otolith cores from YFT aged 1–14 years and BET aged 1–13 years from presumed annual counts were analysed for 14C. These measurements aligned with the reference chronology for the calculated hatch years for both species. These findings provide strong evidence that growth zones in thin-sectioned otoliths are deposited annually for YFT and BET of the WCPO and that age interpretation is correct using the current age reading protocol with little to no bias.

ANALISIS HASIL TANGKAPAN IKAN TONGKOL YANG DIDARATKAN DI PELABUHAN PERIKANAN NUSANTARA AMBON

This research aims to analyze the catches of tuna landed at the Ambon Nusantara Fisheries Port. The research was conducted for two months, from January to February 2023, using descriptive methods. Primary data was collected through direct observation and interviews with fishermen and port officers, while secondary data was obtained from PPN Ambon. The results of this research show that the catch was landed by four fishing fleets, namely purse seines, gill nets, fish trawls and lines fishing. The total catch landed during the 2012-2021 period was 510,203 tons, which was dominated by Auxis thazard. Purse seines are the most dominant fishing gear used, contributing 52.1% of the total catch with a total fishing effort of 597 trips. The productivity of the fishing fleet fluctuates from year to year, the lowest productivity for Euthynnus affinis occurred in 2018 and the highest in 2013, while the lowest productivity forl Auxis thazard occurred in 2017 and the highest in 2018. Fluctuating and low productivity indicates the existence of potential for overfishing. This research suggests the need for further analysis regarding the potential and level of utilization of the two species of frigate tuna landed in PPN Ambon

Differentiation of three commercial tuna species through GC-Q-TOF and UPLC-Q/Orbitrap mass spectrometry-based metabolomics and chemometrics

Food fraud is common in the tuna industry because of the economic benefits involved. Ensuring the authenticity of tuna species is crucial for protecting both consumers and tuna stocks. In this study, GC-Q-TOF and UPLC-Q/Orbitrap mass spectrometry-based metabolomics were used to investigate the metabolite profiles of three commercial tuna species (skipjack tuna, bigeye tuna and yellowfin tuna). A total of 22 and 77 metabolites were identified with high confidence using GC-Q-TOF and UPLC-Q/Orbitrap mass spectrometry, respectively. Further screening via chemometrics revealed that 38 metabolites could potentially serve as potential biomarkers. Hierarchical cluster analysis showed that the screened metabolite biomarkers successfully distinguished the three tested tuna species. Furthermore, a total of 27 metabolic pathways were identified through enrichment analysis based on the Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathways.

Lower thermal tolerance restricts vertical distributions for juvenile albacore tuna (Thunnus alalunga) in the northern limit of their habitats

IntroductionEvaluating the thermal tolerance of commercially valuable tuna species and their behavioral responses to the limits of this tolerance is essential for evaluating the effects of changes in water temperature driven by global climate change on their distribution and fisheries. We aimed to identify the lower thermal tolerance (Tmin) of juvenile albacore tuna (ALB) and evaluate their behavioral response to Tmin by focusing on wild behavior in the northern distributional limit. Additionally, we investigated how vertical behavior is linked to the vulnerability of ALB to Japanese longline (LL) and pole-and-line (PL) fisheries.MethodsWe explored the swimming depths and water temperatures of four previously reported tagged individuals migrating from subtropical to temperate areas and identified Tmin and its depths in the water column as unfavorable depths (DTmin). To investigate the spatial patterns of ALB fishery grounds for LL and PL fisheries, we analyzed hotspots specific to each type of gear using the historical Japanese fishery logbook for both fisheries.ResultsComparisons of the fishery grounds between the two fisheries revealed that PL hotspots appeared in the northern areas, while LL hotspots were in the southern regions. We also discovered that the vertical distribution of ALB became shallow in high-latitude areas, which were strongly affected by DTmin shallowing at high latitudes.DiscussionThese results provide evidence of a behavioral response among juvenile ALB that avoids Tmin by remaining at the surface. We discuss the implications of the results for latitudinal changes in the vulnerability of ALB to fisheries in terms of the overlapping depth between ALB vertical habitats and the gear-setting depth for each fishery.

Spatial distribution models for the four commercial tuna in the sea of maritime continent using multi-sensor remote sensing and maximum entropy

The dynamic of marine environmental parameters affects the distribution of commercial tuna in the sea of the maritime continent. Hence, the objectives of this study are to develop spatial distribution models for the four main tuna species in the Maritime continent's sea with reasonable accuracy, identify their correlation with marine environmental parameters, and investigate areas of interaction between those tuna species. The study develops the distribution models for albacore (Thunnus alalunga), bigeye (Thunnus obesus), yellowfin (Thunnus albacares), and skipjack (Katsuwonus pelamis) tuna species, utilizing multi-sensor satellite remote sensing and maximum entropy. The results show models have good performance, focusing on environmental factors such as sea surface temperature (SST), chlorophyll-a (CHL), and sea surface height anomalies (SSHA), combined with eddy kinetic energy (EKE). Seasonal variations in potential tuna habitats are revealed, emphasizing the influence of those marine environmental conditions. From December to May, the four commercial tuna species were distributed in conditions characterized by SST of 26–31.5 °C, CHL levels of 0–3 mg/l, SSHA of −0.3 to 0.2 m, and EKE of 0–1 m2/s2, while from June to November, they experienced SST of 23–31 °C, CHL levels of 0–4 mg/l, SSHA of −0.5 to 0.3 m, and EKE of 0–1.1 m2/s2. The spatial persistence of the four tuna species emerged mainly around the south sea of Java, with skipjack being the most common species found in the sea of the maritime continent. With sufficient and evenly distributed tuna presence records, the results indicate the potential for extrapolation beyond the training data to estimate habitat suitability for the four commercial tuna distributions. The results also suggest potential competition between tuna species sharing ecological niches and highlight possible overlapping areas where different tuna species interact with the same fishing gear.

Discrimination of three commercial tuna species through species-specific peptides: From high-resolution mass spectrometry discovery to MRM validation

The risk of tuna adulteration is high driven by economic benefits. The authenticity of tuna is required to protect both consumers and tuna stocks. Given this, the study is designed to identify species-specific peptides for distinguishing three commercial tropical tuna species. The peptides derived from trypsin digestion were separated and detected using ultrahigh-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF/MS) in data-dependent acquisition (DDA) mode. Venn analysis showed that there were differences in peptide composition among the three tested tuna species. The biological specificity screening through the National Center for Biotechnology Information’s Basic Local Alignment Search Tool (NCBI BLAST) revealed that 93 peptides could serve as potential species-specific peptides. Finally, the detection specificity of species-specific peptides of raw meats and processed products was carried out by multiple reaction monitoring (MRM) mode based on a Q-Trap mass spectrometer. The results showed that three, one and two peptides of Katsuwonus pelamis, Thunnus obesus and Thunnus albacores, respectively could serve as species-specific peptides.

Time-varying effects of crude oil price fluctuations on tuna fish prices

This research presents an investigation of the time-varying effects of crude oil on the price of three tuna species, namely skipjack, albacore, and yellow fin. The investigation analyses the impact coefficient of oil price fluctuation on tuna species over time with specific phases related to time points when crude oil prices fall, including December 2008 (due to the impact of the Financial Crisis), February 2016 (due to the impact of the US shale oil and gas revolution), and April 2020 (due to the impact of the global COVID-19). The analysis shows that the price of yellow fin and skipjack shows sensitivity to these phased oil price shocks but stays consistent after recovery. This research finds that the relationship between oil price and tuna price depends on specific phases of oil price fluctuations and that global crude oil price shocks could have immediate and short-term impacts on fish markets, especially during a period of financial crisis.

Target strength measurements of yellowfin tuna (Thunnus albacares) and acoustic discrimination of three tropical tuna species

Abstract Tropical tuna fisheries support some of the largest artisanal and industrial fisheries worldwide. Approximately 37% of the tropical tuna catch by industrial purse seiners is obtained from tuna associated with drifting fish aggregating devices (DFADs), where three tuna species coexist: skipjack (Katsuwonus pelamis), bigeye (Thunnus obesus), and yellowfin tuna (Thunnus albacares), with stocks subject to different health status. Purse seine fishers heavily rely on acoustic technology to detect and assess the quantity of tuna at DFADs. Yet, accurately distinguishing between species using solely acoustic methods is limited by insufficient knowledge about each species' acoustic response across frequencies. This study was carried out on six swimbladdered individuals belonging to two sets with mean lengths of 51.9 ± 9.5 and 52.9 ± 2 cm. It focuses on the frequency response obtained from ex situ measurements of yellowfin tuna recorded at 38, 70, 120, and 200 kHz, which revealed a flat response across frequencies, with b20 values of −72.4 ± 9, −73.2 ± 8, -72.3 ± 8, and −72.3 ± 9 dB, respectively. These results, contrast with previous findings on bigeye and skipjack, demonstrating the discrimination potential of acoustics in these three species. To harness this potential, a discrimination algorithm was developed.