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| Marine Resource Fact Sheet |
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| Skipjack tuna - Indian Ocean |
 | Skipjack 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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| Related observations | Locate in inventory | | | | Species: | | FAO Names: en - Skipjack tuna, fr - Listao, es - Listado, zh - 鲣, ru - Тунец полосатый (=скипджек) |
Fishery IndicatorsProduction: Catch |
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| Geographic extent of Skipjack tuna - Indian Ocean
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| FAO Major Fishing Areas |
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| 51 | Indian Ocean, Western |
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| 57 | Indian Ocean, Eastern |
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| Main Descriptors | Considered a single stock: Yes
Management unit: Yes
Reference year: 2019 |
| Considered a single stock: A group of individuals in a species occupying a well defined spatial range independent of other stocks of the same species. It can be affected by random dispersal movements and directed migrations due to seasonal or reproductive activity. |
| Spatial Scale: Spatial scale contains a standard term such as Global, Regional (e.g. for the whole Atlantic), sub-regional (e.g. for a part of the Atlantic), national, local (for sub-national levels). |
| 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. |
| Reference Year: The Reference Year is the last year considered in the stock assessment and/or fishery status. |
| | | | | | Biological State and Trend Habitat and Biology Climatic zone: Temperate; Tropical. Horizontal distribution: Oceanic. Vertical distribution: Pelagic. Geographical Distribution Jurisdictional distribution: Highly migratory Geo References  | | Geographic extent of Skipjack tuna - Indian Ocean
| FAO Major Fishing Areas | 51: Indian Ocean, Western | | 57: Indian Ocean, Eastern |
| | | | | | Intersecting Major FAO areas and LME areas |
The following area codes have been found as intersecting the distribution of Skipjack tuna - Indian Ocean | FAO Major Fishing Areas | 51:
Indian Ocean, Western | | 57:
Indian Ocean, Eastern | | Large Marine Ecosystem Areas (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 |
Resource Structure Considered a single stock: Yes The tag recoveries from the RTTP-IO [Regional Tuna Tagging Project-Indian Ocean] provide evidence of rapid, large scale movements of skipjack tuna in the Indian Ocean, thus supporting the current assumption of a single stock for the Indian Ocean. Skipjack tuna in the Indian Ocean are considered a single stock for assessment purposes. Exploitation Fishery Indicators | Type | Measure | Value | Unit | Time period |
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| Production | Catch | 15013 | tonnes | Average 1950 - 1959 | | Catch | 26864 | tonnes | Average 1960 - 1969 | | Catch | 46918 | tonnes | Average 1970 - 1979 | | Catch | 130121 | tonnes | Average 1980 - 1989 | | Catch | 319130 | tonnes | Average 1990 - 1999 | | Catch | 472982 | tonnes | Average 2000 - 2009 | | Catch | 457382 | tonnes | Average 2010 - 2019 | | Catch | 378438 | tonnes | 2011 | | Catch | 340919 | tonnes | 2012 | | Catch | 433829 | tonnes | 2013 | | Catch | 424037 | tonnes | 2014 | | Catch | 400642 | tonnes | 2015 | | Catch | 470148 | tonnes | 2016 | | Catch | 505486 | tonnes | 2017 | | Catch | 609178 | tonnes | 2018 | | Catch | 590450 | tonnes | 2019 | | Catch | 555240 | tonnes | 2020 |
Assessment A new stock assessment was carried out for skipjack tuna in 2020 using Stock Synthesis with data up to 2019. The outcome of the 2020 stock assessment model does not differ substantially from the previous assessment (2017) despite the large catches recorded in the period 2018-2019, which exceeded the catch limits established in 2017 for this period. The final overall estimate of stock status indicates that the stock is above the adopted target for this stock and that the current exploitation rate is just below the target. Assessment Model Type: Age-structured Stock Synthesis III (SS3) Scientific Advice The catch limit calculated applying the HCR specified in Resolution 16/02 is 513,572 t for the period 2021-2023. The SC noted that this catch limit is higher than for the previous period. This is attributed to the new stock assessment which estimates a higher productivity of the stock and a higher stock level relative to the target reference point, possibly due to skipjack life history characteristics and favourable environmental conditions. Thus, it is likely that the recent catches that have exceeded the limits established for the period 2018-2020 have been sustained by favourable environmental conditions. Therefore, the Commission needs to ensure that catches of skipjack tuna during this period do not exceed the agreed limit. Management Management unit: Yes Source of information IOTC–SC23 2020. Report of the 23rd Session of the IOTC Scientific Committee. Seychelles, 7 – 11 December 2020. IOTC–2020–SC23–R[E]: 211pp.  https://www.iotc.org/sites/default/files/documents/2021/06/IOTC-2020-SC23-RE_Rev1.pdfBibliography All references to figures, tables and bibliography in the text are found within the source of information. |
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