Fisheries ResearchPub Date : 2025-07-10DOI: 10.1016/j.fishres.2025.107458
Jessica Bonicelli , Constanza Sandoval , Naití Morales-Serrano , Francisca Osorio-Zúñiga , Carola Hernández-Santoro , Juan Carlos Saavedra-Nievas
{"title":"Spatiotemporal variation in the spawning strategy of the Peruvian anchovy Engraulis ringens in northern Chile: Is the Peruvian anchovy developing a new strategy for survival?","authors":"Jessica Bonicelli , Constanza Sandoval , Naití Morales-Serrano , Francisca Osorio-Zúñiga , Carola Hernández-Santoro , Juan Carlos Saavedra-Nievas","doi":"10.1016/j.fishres.2025.107458","DOIUrl":"10.1016/j.fishres.2025.107458","url":null,"abstract":"<div><div>This study analyzed the spatiotemporal differences in the spawning of <em>Engraulis ringens</em> in northern Chile. We used three monthly time series of anchovy egg abundance collected over 26 years at three coastal stations in northern Chile (Arica, Iquique, Mejillones) and assessed the relative effects of hydrographic factors (i.e., temperature, salinity) and female reproductive conditions (i.e., Gonadosomatic Index [GI]) on egg abundance before and after the delay in the reproductive peak observed after 2009. We found significantly higher egg abundances in Arica during the first period (1998–2009). In contrast, during the second period (2015–2023), there were no significant differences between sites, and the spawning season became shorter, concentrating reproductive activity between August and October. The GAM model showed significant differences between periods and sites. Only in Arica, GI have a significant non-linear effect, while temperature had a linear effect on egg abundance. During the second period, GI had a significant linear effect on egg abundance that was not observed during the first period. Additionally, a shorter spawning season, smaller females and a reduction of the spawning stock biomass during the second period suggest a decline in spawning activity. We conclude that anchovies may have concentrated their spawning activity to increase their survival rates during the second period, which could explain the relationship between egg abundance and GI during this time, as well as a more organized spawning activity modulated solely by GI. This study represents the first analysis of the spawning strategy on a local scale, highlighting the urgent need for more regional management plans, especially under a global warming scenario that is affecting the natural cycles of marine species.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"288 ","pages":"Article 107458"},"PeriodicalIF":2.2,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144597595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fisheries ResearchPub Date : 2025-07-10DOI: 10.1016/j.fishres.2025.107466
George A. Rose
{"title":"Comment on Hayes et al. (2025): 500 years of the once largest fishery in the world: A comprehensive catch reconstruction for the Newfoundland cod fishery (1508–2023)","authors":"George A. Rose","doi":"10.1016/j.fishres.2025.107466","DOIUrl":"10.1016/j.fishres.2025.107466","url":null,"abstract":"<div><div>No abstract needed.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"288 ","pages":"Article 107466"},"PeriodicalIF":2.2,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144595442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fisheries ResearchPub Date : 2025-07-09DOI: 10.1016/j.fishres.2025.107465
José L. Varela , Michael J. Dadswell , Laura Logan-Chesney , Colin Buhariwalla , Cornel Ceapa , Michael J.W. Stokesbury
{"title":"Diet and stable isotope signatures of Atlantic sturgeon (Acipenser oxyrinchus) caught in Minas Basin, Bay of Fundy, and the Saint John River, Canada","authors":"José L. Varela , Michael J. Dadswell , Laura Logan-Chesney , Colin Buhariwalla , Cornel Ceapa , Michael J.W. Stokesbury","doi":"10.1016/j.fishres.2025.107465","DOIUrl":"10.1016/j.fishres.2025.107465","url":null,"abstract":"<div><div>The feeding habits of Atlantic sturgeon <em>Acipenser oxyrinchus</em> (AS) juveniles and sub- adults from Minas Basin (MB), and adults taken during their spawning run in the Saint John River (SJR) were investigated by stomach content and stable isotope analysis. While the diet of AS from MB was mainly composed of <em>Corophium volutator</em> (% index of relative importance = 98.6 %), the stomachs collected from the specimens caught in the SJR were empty. In SJR AS, no correlation was found between <em>δ</em><sup>15</sup>N and C:N ratios suggesting that lipid reserves satisfy energy costs related to the spawning run. Trophic positions (TP) were estimated using isotopic data of <em>C. volutator</em> as the food web baseline for the region. Blood isotopic data indicated that SJR AS occupied a higher TP than MB AS (3.9 ± 0.3 and 3.7 ± 0.1, respectively), whereas the opposite was indicated by muscle data (4.0 ± 0.2 for SJR AS, and 4.5 ± 0.1 for MB AS). Isotopic niche areas estimated by standard ellipse areas and kernel utilization density analyses indicated that MB AS had a more diverse diet than SJR AS. There was no isotopic niche overlap between MB AS and SJR AS indicating that the two groups had distinct feeding grounds. These findings are directly relevant to the conservation and management of the AS, providing critical empirical data to support ecosystem-based models, particularly in the Bay of Fundy and Saint John River regions.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"288 ","pages":"Article 107465"},"PeriodicalIF":2.2,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144595586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fisheries ResearchPub Date : 2025-07-09DOI: 10.1016/j.fishres.2025.107464
Carissa L. Gervasi , Matthew McPherson , Mandy Karnauskas
{"title":"Using participatory conceptual modeling to integrate ecosystem and socioeconomic information into the fisheries stock assessment process: A Gulf of America red snapper case study","authors":"Carissa L. Gervasi , Matthew McPherson , Mandy Karnauskas","doi":"10.1016/j.fishres.2025.107464","DOIUrl":"10.1016/j.fishres.2025.107464","url":null,"abstract":"<div><div>Fisheries stock assessments are the backbone of fisheries management in the United States. While a stock assessment model provides scientific estimates of stock status and overfishing limits, the broader process involves decisions about which data are collected, how the model is structured, and the social and economic effects of implementing the quota advice. Despite growing recognition that ecosystem and socioeconomic factors strongly influence fish stocks and fisheries, these drivers remain underrepresented in the assessment process. In the current period of rapid global change, environmental disturbances and anthropogenic impacts are increasing in frequency and intensity, escalating the need for stock assessments to explore and account for the complex dynamics among fish stocks, fisheries, and social systems. In our research, we illustrate how participatory conceptual modeling can improve the entire stock assessment to management process by identifying data gaps, elucidating changes in fishing activity and human behavior over time, providing context to help explain model uncertainty and improve model parameterization, and describing feedback loops and unintended consequences of management actions. A case study from the Gulf of America red snapper (<em>Lutjanus campechanus</em>) fishery is used to illustrate the benefits of this methodology. Encouraging participatory conceptual modeling alongside future stock assessments would greatly increase our understanding of the socio-ecological feedbacks that are often critical to management success, and help determine how best to manage fisheries through an ever changing environmental and human landscape.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"288 ","pages":"Article 107464"},"PeriodicalIF":2.2,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fisheries ResearchPub Date : 2025-07-08DOI: 10.1016/j.fishres.2025.107460
Xuan Dong Nguyen , Xuan Quang Ngo , Thi My Yen Nguyen , Thanh Thai Tran , Thi Hoang Yen Tran , Thi Minh Trang Thai , Thanh Luu Pham
{"title":"Fish biodiversity and its current status in the Mekong river as evidence for developing conservation measures: A case study of the Ba Lai River estuary, Vietnam","authors":"Xuan Dong Nguyen , Xuan Quang Ngo , Thi My Yen Nguyen , Thanh Thai Tran , Thi Hoang Yen Tran , Thi Minh Trang Thai , Thanh Luu Pham","doi":"10.1016/j.fishres.2025.107460","DOIUrl":"10.1016/j.fishres.2025.107460","url":null,"abstract":"<div><div>The Mekong delta boasts a remarkable fish biodiversity, hosting over 500 recorded species. Among these, the Ba Lai River estuary (BLRE) stands out as one of the most diverse areas in the Mekong delta. This study explored the biodiversity of the fish community in the BLRE, and it assessed its current status. A thorough collection and identification effort conducted from April 2022 to April 2024, encompassing seven sampling sites, resulted in the documentation of 8134 fish individuals representing 188 species, 126 genera, 69 families, and 24 orders. Six species, accounting for 3.19 % of the total, were classified as vulnerable, and one species (0.53 %) was listed as endangered according to the <em>Vietnam Red Data Book</em> and the <em>IUCN Red List</em>; four species (2.13 %) were vulnerable; three species (1.60 %) were near threatened; 18 species (9.57 %) were data deficient, and 125 species (66.49 %) were of least concern. Furthermore, 99 species were migratory fishes (52.66 %); 38 species were endemic to the Mekong River (17.43 %), and 70 species were considered to have local economic value (37.23 %). The Ba Lai River estuary (BLRE) serves as the primary migration route for fish traveling upstream from the sea. However, the area’s fish population has been threatened, leading to a decline in fish biodiversity and stock. Numerous species that were once economically significant now find themselves under threat. Some other species were identified as endemic fishes of the Mekong River, including <em>Pangasianodon hypophthalmus</em>, <em>Pangasius krempfi</em>, <em>Cyclocheilichthys enoplos</em>, and <em>Hemibagrus spilopterus</em>. They have a limited distribution range and are facing threats globally. This study strengthened the protection and conservation of fish fauna in the Mekong estuary and contributed to a deeper understanding of its biodiversity.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"288 ","pages":"Article 107460"},"PeriodicalIF":2.2,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Microsatellite analysis reveals strong genetic connectivity in Scomber colias along the Northwest coast of Africa","authors":"Salah Eddine Sbiba , María Quintela , Geir Dahle , Hocein Bazairi , Nikolaos Nikolioudakis , Oussama Rbiai , Ismaïla Ndour , Malika Chlaida","doi":"10.1016/j.fishres.2025.107452","DOIUrl":"10.1016/j.fishres.2025.107452","url":null,"abstract":"<div><div>Understanding the population structure of wild marine species is essential for sustainable management, particularly in environments with high gene flow where it can be difficult to identify genetic differentiation. Climate change adds further complexity to population dynamics by altering habitats, necessitating a clear definition of stock boundaries and accurate identification of harvested species. This study uses nine microsatellites to examine the population structure and connectivity of <em>Scomber colias</em> along the northwest African coast from Larache (Morocco, 34°N) to Senegal (13°N). The genotyping of 266 individuals across nine sampling areas revealed significant genetic diversity (PIC = 0.86, <em>H</em><sub>E</sub> = 0.859, <em>H</em><sub>O</sub> = 0.805), but a deficiency in heterozygosity indicates non-random mating and suggests Wahlund effects. Despite the high polymorphism of the nine neutral markers, we observed significant deviation from panmixia (<em>F</em><sub>ST</sub> = 0.0047, <em>P</em>-val < 0.0001), subtle yet biologically significant genetic structuring. These findings provide valuable insights and baseline information that can enhance the design of management strategies to maintain genetic connectivity and consider potential subpopulation structures. This study emphasizes the need to integrate genetic insights into the management of <em>S. colias</em> stocks in the Northwest Atlantic to promote sustainable harvesting and ensure the resilience of marine resources.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"288 ","pages":"Article 107452"},"PeriodicalIF":2.2,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144570662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fisheries ResearchPub Date : 2025-07-07DOI: 10.1016/j.fishres.2025.107456
Margit R. Wilhelm , Arariky S. Shikongo , Angelika M. Veii , Ralf Schwamborn
{"title":"Extremely slow somatic growth and intermittent recruitment of west coast steenbras Lithognathus aureti, an over-exploited, longevous Sparid, analysed with novel bootstrapped methods","authors":"Margit R. Wilhelm , Arariky S. Shikongo , Angelika M. Veii , Ralf Schwamborn","doi":"10.1016/j.fishres.2025.107456","DOIUrl":"10.1016/j.fishres.2025.107456","url":null,"abstract":"<div><div>West coast steenbras <em>Lithognathus aureti</em> is an overexploited coastal Sparid in the northern Benguela ecosystem, Namibia. They are believed to consist of two genetically distinct highly resident stocks, one in northern Namibia (17–24°S) and one in southern Namibia (24–26°S). Here, Von Bertalanffy growth function (VBGF) parameters were obtained and compared using bootstrapped length-frequency-analysis, LFA (ELEFAN_GA_boot, n = 29 monthly length-frequency-distributions of 20,090 individuals), tag-and-recapture (grotag_boot, n = 80 growth increments) and length-at-age, LAA (grolenage_boot, based on n = 104 otoliths northern stock and n = 155 southern stock) methods in the “fishboot” R package. For the first time, these three methods were combined and compared within a standardized, robust bootstrap framework. The results indicated an extremely slow body growth, with similar median “optimum” results for K and L∞ , but smaller median Φ′ for LAA (otolith readings) than from other methods. LAA was the most precise method, especially when large-sized individuals were captured (northern stock). No differences in growth between stocks or sexes (males, females, hermaphrodites) were detected. The bootstrapped VBGF model that best explained the data, combining results from different methods (southern stock), had extremely slow growth with intermittent recruitment occurring every 4 years (in 2000, 2004, and 2008), with the following median values: K = 0.066 y<sup>−1</sup> (from otoliths, 95 % CI: 0.0067–0.12 y<sup>−1</sup>), L∞ = 77.29 cm (from otoliths, 95 % CI: 55.48–400.26 cm), Φ′ = 2.62 (95 % CI: 2.52 –2.74), t<sub>anchor</sub>= 0.50 (95 % CI: 0.18–0.87), C = 0.53 (95 %CI: 0.19–0.87), and t<sub>s</sub> = 0.47 (95 %CI: 0.14–0.88) from LFA. This makes <em>L. aureti</em> even more vulnerable to overfishing as well as climate change. There is an urgent need for the development and application of new management strategies for this endangered, longevous species (maximum age from otolith readings: 38 years), considering its irregular reproduction, recruitment, and extremely slow growth. Also, our study evidences the need to develop new software tools for LFA, that should be able to explicitly consider intermittent recruitment.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"288 ","pages":"Article 107456"},"PeriodicalIF":2.2,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144569821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fisheries ResearchPub Date : 2025-07-04DOI: 10.1016/j.fishres.2025.107459
Olivia T. Dinkelacker , Grace A. Casselberry , Lucas P. Griffin , Sascha Clark Danylchuk , Steven J. Cooke , Andy J. Danylchuk
{"title":"Effects of capture and handling on striped bass (Morone saxatilis) in the recreational fishery of coastal Massachusetts","authors":"Olivia T. Dinkelacker , Grace A. Casselberry , Lucas P. Griffin , Sascha Clark Danylchuk , Steven J. Cooke , Andy J. Danylchuk","doi":"10.1016/j.fishres.2025.107459","DOIUrl":"10.1016/j.fishres.2025.107459","url":null,"abstract":"<div><div>Striped bass (<em>Morone saxatilis</em>) are a highly valued recreational fishery along the eastern coast of North America, with most hooked fish released voluntarily or due to regulations. Understanding how striped bass respond to capture and handling, particularly air exposure, is crucial for improving management and angler practices to maximize post-release survival. This study evaluated the physical and physiological condition of 521 striped bass subjected to catch-and-release angling across different gear and tackle types and five air exposure treatments using reflex action mortality predictors. A subset of striped bass (n = 37) caught on conventional gear and double treble hook lures were fitted with triaxial accelerometer biologgers to assess short-term post-release activity across three air exposure treatments. Reflex impairment increased with higher water temperatures, longer fight and handling times, increased air exposure, and hooking in locations other than the jaw. Physical injury from foul hooking was more frequent with conventional gear, while deep hooking occurred more often with fly gear. Post-release activity was influenced by time following release, with higher activity observed in striped bass not air exposed compared to those exposed for 30 s and 120 s. Within 20 min of release, all fish survived, demonstrating resilience to the tested conditions. Our findings suggest that anglers can minimize their impact by using single hooks, reducing fight and handling times, limiting air exposure, and avoiding high water temperatures, especially for striped bass larger than 65.4 cm. These findings can inform management decisions and hone best practices for catch-and-release of striped bass.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"288 ","pages":"Article 107459"},"PeriodicalIF":2.2,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fisheries ResearchPub Date : 2025-07-04DOI: 10.1016/j.fishres.2025.107454
Will Rempel , Chase C. Lamborn , Zachary D. Miller , Jordan W. Smith
{"title":"Exploring angler participation: The role of constraints, negotiation strategies, and crowding responses","authors":"Will Rempel , Chase C. Lamborn , Zachary D. Miller , Jordan W. Smith","doi":"10.1016/j.fishres.2025.107454","DOIUrl":"10.1016/j.fishres.2025.107454","url":null,"abstract":"<div><div>This study explores how angler characteristics, perceived constraints, use of negotiations, and responses to crowding differ between lapsed, recruited, re-activated, and retained anglers. Using Utah’s fishing license database, we surveyed a stratified random sample of anglers from various stages of angling participation, which resulted in 5421 responses. Exploratory factor analysis was used to reduce constraint and negotiation scale items into underlying constructs, then ANOVA and multinomial logistic regression were used to identify differences between angler classifications. Although anglers reported mild constraints to angling overall, retained anglers were significantly more likely to experience constraints related to <em>fishing quality</em> and significantly less likely to experience <em>lack of interest</em> and <em>structural</em> constraints (i.e., money, transportation, access, facilities, knowledge, and information). The analysis also revealed planning negotiations (i.e., planning and setting aside time for fishing, encouraging friends and family to join, and searching for high quality fishing spots) as well as taking one’s own children fishing were significantly stronger for more persistent angler classifications (re-activated and retained) relative to those who have lapsed. Also, results show crowding negatively impacts retained anglers’ experience and alters their behavior more than other angler groups, but crowding does not seem to be a reason for lapsing. Given retained anglers prioritize angling (i.e., they effectively use planning negotiation strategies) and are more likely to take others fishing (especially their own children), we suggest management and research focus on ways to cultivate retained anglers’ role in engaging new and less active anglers.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"288 ","pages":"Article 107454"},"PeriodicalIF":2.2,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fisheries ResearchPub Date : 2025-07-01DOI: 10.1016/j.fishres.2025.107448
William A.J. Connor , Cara Masere , Peter G. Coulson , Alyssa Marshell
{"title":"Quantifying distinctions in the otolith shape of morphologically similar Sub-Antarctic grenadier species (Macrourus) to assess fishery observer identifications.","authors":"William A.J. Connor , Cara Masere , Peter G. Coulson , Alyssa Marshell","doi":"10.1016/j.fishres.2025.107448","DOIUrl":"10.1016/j.fishres.2025.107448","url":null,"abstract":"<div><div>Accurate bycatch species identification is crucial in commercial fisheries, as species vary in vulnerability to fishing pressure. Fishery observer experience also varies, which can form inaccurate commercial fishing datasets and compromise species-level identifications. At the sub-Antarctic Heard Island and McDonald Islands (HIMI), four grenadier (<em>Macrourus</em>) species represent a high bycatch percentage in the Patagonian toothfish (<em>Dissostichus eleginoides</em>) demersal longline fishery. Current fisheries bycatch limits for <em>Macrourus</em> species are categorised into two species pair groups: shallow-water living (<em>Macrourus caml</em>, <em>M. whitsoni</em>) and deep-water living (<em>M. holotrachys, M. carinatus</em>). However, misidentification by fishery observers due to similar characteristics limits high taxonomic resolution within catch records. Therefore, improving observer accuracy of bycatch stock identification from pooled <em>Macrourus</em> Genus level to species level is required within HIMI fisheries. We photographed 800 otoliths across the four <em>Macrourus</em> species collected from HIMI’s longline fishery bycatch (2015–2021). <em>Macrourus</em> otolith shape and outline analysis was conducted using <em>shapeR</em>, while random forest models (RFM) coupled initial observer identifications with otolith morphometrics to predict species identification within each bycatch pair. RFM prediction accuracy varied from > 95 % for <em>M. holotrachys</em> and <em>M. caml</em> to 70 % and 60 % for <em>M. carinatus</em> and <em>M. whitsoni</em> respectively, highlighting otolith width, perimeter, and length as important predictor morphometrics. Otolith elliptical Fourier constructions of <em>M. whitsoni</em> and <em>M. carinatus</em> displayed dorsal margins with prominent outward shifts, which can visually assist onboard identification of these species. Overall, our research establishes baseline otolith morphometric data for four <em>Macrourus</em> species, supporting the refinement of historical Genus-level bycatch identifications to each species pair group at HIMI’s commercial fishery.</div></div>","PeriodicalId":50443,"journal":{"name":"Fisheries Research","volume":"288 ","pages":"Article 107448"},"PeriodicalIF":2.2,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144523009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}