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| Fact Sheet Title Fact Sheet |
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| Bigeye tuna - Indian Ocean |
| | Data Ownership | | This document provided, maintained and owned by Indian Ocean Tuna Commission (IOTC) , is part of IOTC Stock Status Reports data collection. |
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| ident Block | ident Block | | | | Species List: | | Species Ref: en - Bigeye tuna, fr - Thon obèse(=Patudo), es - Patudo, ru - Тунец большеглазый |
Species Ref Type: Measure |
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| ident Block Bigeye tuna - Indian Ocean Aq Res Ident Aq Res Ident Aq Res Ident | fao Major |
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| 51 | Indian Ocean, Western |
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| 57 | Indian Ocean, Eastern |
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| Aq Res | Biological Stock: Biological Stock Management Unit: Management Unit
Reference Year: 2018 |
| Considered a management unit: An aquatic resource or fishery is declared as [Fishery] Management Unit if it is effectively the focus for the application of selected management methods and measures, within the broader framework of a management system. According to the FAO Glossary for Responsible Fishing, "a Fishery Management Unit (FMU) is a fishery or a portion of a fishery identified in a Fishery Management Plan (FMP) relevant to the FMP's management objectives." FMU's may be organised around fisheries biological, geographic, economic, technical, social or ecological dimensions , and the makeup and attribute of a fishery management unit depends mainly on the FMP's management objectives. |
| Jurisdictional distribution: Jurisdictional qualifier (e.g. "shared", "shared - highly migratory") of the aquatic resource related with its spatial distribution. |
| Environmental group: Classification of the aquatic resource according to the environmental group (e.g. pelagic invertebrate, or demersal fish) to which the species belong. |
| | | | | | Habitat Bio Climatic Zone: Temperate; Tropical. Horizontal Dist: Oceanic. Vertical Dist: Pelagic. Geo Dist Geo Dist: Highly migratory Geo Dist  | | Geo Dist Bigeye tuna - Indian Ocean
| fao Major | 51: Indian Ocean, Western | | 57: Indian Ocean, Eastern |
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Geo DistBigeye tuna - Indian Ocean | fao Major | 51: Indian Ocean, Western | | 57: Indian Ocean, Eastern | | lme | 30: Agulhas Current | | 31: Somali Coastal Current | | 32: Arabian Sea | | 33: Red Sea | | 34: Bay of Bengal | | 38: Indonesian Sea | | 39: North Australian Shelf | | 42: Southeast Australian Shelf | | 43: Southwest Australian Shelf | | 44: West-Central Australian Shelf | | 45: Northwest Australian Shelf |
Aq Res Struct Biological Stock: Biological Stock The tag recoveries from the RTTP-IO [Regional Tuna Tagging Project-Indian Ocean] provide evidence of rapid and large scale movements of juvenile bigeye tuna in the Indian Ocean, thus supporting the current assumption of a single stock for the Indian Ocean. Exploit Fishery Indicator | Fishery Indicator | Fishery Indicator | Fishery Indicator | Fishery Indicator | Fishery Indicator |
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| Type | Measure | 6589 | tonnes | Average 1950 - 1959 | | Measure | 22269 | tonnes | Average 1960 - 1969 | | Measure | 31720 | tonnes | Average 1970 - 1979 | | Measure | 58117 | tonnes | Average 1980 - 1989 | | Measure | 120031 | tonnes | Average 1990 - 1999 | | Measure | 136178 | tonnes | Average 2000 - 2009 | | Measure | 95805 | tonnes | Average 2010 - 2019 | | Measure | 94374 | tonnes | 2011 | | Measure | 124759 | tonnes | 2012 | | Measure | 113193 | tonnes | 2013 | | Measure | 93056 | tonnes | 2014 | | Measure | 96396 | tonnes | 2015 | | Measure | 86849 | tonnes | 2016 | | Measure | 90862 | tonnes | 2017 | | Measure | 94750 | tonnes | 2018 | | Measure | 78441 | tonnes | 2019 | | Measure | 83449 | tonnes | 2020 |
Bio Assess In 2019 a new stock assessment was carried out for bigeye tuna in the IOTC area of competence to update the stock status undertaken in 2016. Two models were applied to the bigeye stock (JABBA and Stock Synthesis (SS3)).The reported stock status is based on the SS3 model formulation using a grid of 18 model configurations designed to capture the uncertainty on stock recruitment relationship, the influence of tagging information and selectivity of longline fleets. On the weight-of-evidence available in 2019, the bigeye tuna stock is determined to be not overfished but subject to overfishing. Assess Models Type: Age-structured Stock Synthesis III (SS3) Sci Advice The stock status determination changed qualitatively in 2019 to not overfished but subject to overfishing. If catches remain at 2018 levels there is a risk of breaching MSY reference points with 58.9% and 60.8% probability in 2021 and 2028. Maintaining catches of at least 10% below 2018 levels will likely reduce the probabilities of breaching reference levels to 49.1% in 2028. Continued monitoring and improvement in data collection, reporting and analyses is required to reduce the uncertainty in assessments. Management Management: Management Sources IOTC–SC23 2020. Report of the 23rd Session of the IOTC Scientific Committee. Seychelles, 7 – 11 December 2020. IOTC–2020–SC23–R[E]: 211ppp.  https://www.iotc.org/sites/default/files/documents/2021/06/IOTC-2020-SC23-RE_Rev1.pdf Bibliography All references to figures, tables and bibliography in the text are found within the source of information. |
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