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Marine Resource Fact Sheet |
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Blue marlin - 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 - Blue marlin, fr - Makaire bleu, es - Aguja azul, ar - مقير أزرق أطلسيّ ، مكيرأزرق أطلسيّ, zh - 蓝枪鱼, ru - Марлин синий |
Fishery IndicatorsProduction: Catch |
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| Geographic extent of Blue marlin - 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: 2017 |
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 Blue marlin - 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 Blue marlin - 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 No information on stock structure is currently available in the Indian Ocean; thus for the purposes of assessment, one pan-ocean stock is assumed. However, spatial heterogeneity in stock indicators (catch–per–unit–effort trends) for other billfish species indicates that there is potential for localised depletion. Exploitation Fishery Indicators Type | Measure | Value | Unit | Time period |
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Production | Catch | 2574 | tonnes | Average 1950 - 1959 | Catch | 3546 | tonnes | Average 1960 - 1969 | Catch | 3550 | tonnes | Average 1970 - 1979 | Catch | 5113 | tonnes | Average 1980 - 1989 | Catch | 7629 | tonnes | Average 1990 - 1999 | Catch | 8696 | tonnes | Average 2000 - 2009 | Catch | 8987 | tonnes | Average 2010 - 2019 | Catch | 9018 | tonnes | 2011 | Catch | 11965 | tonnes | 2012 | Catch | 8577 | tonnes | 2013 | Catch | 6955 | tonnes | 2014 | Catch | 8506 | tonnes | 2015 | Catch | 9701 | tonnes | 2016 | Catch | 9889 | tonnes | 2017 | Catch | 8536 | tonnes | 2018 | Catch | 8424 | tonnes | 2019 | Catch | 6956 | tonnes | 2020 |
Assessment No new stock assessment for blue marlin was carried out in 2021 so the stock status is based on the 2019 assessment conducted using the Bayesian State-Space Surplus Production model JABBA which suggests that there is an 87% probability that the Indian Ocean blue marlin stock in 2017 is in the red zone of the Kobe plot, indicating the stock is overfished and subject to overfishing (B2017/BMSY=0.82 and F2017/FMSY=1.47) as shown in Table 1 and Fig. 2. The most recent catch is lower than the estimate of MSY (Catch2019 = 8,486 t; MSY = 9,984 t). The previous assessment of blue marlin concluded that in 2015 the stock was subject to overfishing but not overfished. The change in stock status can be attributed to increased catches for the period 2015-2017 as well as improved standardisation of CPUE indices, which includes the area disaggregation of JPN and TWN indices to account for fleet dynamics. Assessment Model Type: Biomass-aggregated Scientific Advice The current catches of blue marlin (average of 8,701 t in the last 5 years, 2016-2020) are lower than MSY (9,984 t). The assessment conducted in 2017 indicated that the stock was overfished and subject to overfishing. In order to achieve the Commission objectives of being in the green zone of the Kobe Plot by 2027 (F2027 < FMSY and B2027 > BMSY) with at least a 60% chance, the catches of blue marlin would have to be reduced by 35% compared to the average of the last 3 years, to a maximum value of approximately 7,800 t. 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.pdf Bibliography All references to figures, tables and bibliography in the text are found within the source of information. |
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