Fisheries and Resources Monitoring System

Yellowfin tuna - Indian Ocean
Marine Resource  Fact Sheet
Stock status report 2016
Yellowfin tuna - Indian Ocean
Fact Sheet Citation  
Yellowfin tuna Indian Ocean
Owned byIndian Ocean Tuna Commission (IOTC) – More
Related observationsLocate in inventorydisplay tree map
FAO Names: en - Yellowfin tuna, fr - Albacore, es - Rabil, ru - Тунец желтоперый

Fishery Indicators
Production: Catch
Geographic extent of Yellowfin tuna - Indian Ocean
Main Descriptors
Considered a single stock: Yes        Management unit: Yes
Reference year: 2015
Biological State and Trend
State & Trend Descriptors
Exploitation rateSubject to overfishing (F2015/FMSY (plausible range) = 1.11 (0.86–1.36))High fishing mortality
Abundance levelOverfished (SB2015/SBMSY (plausible range) = 0.89 (0.79–0.99))Low abundance
Habitat and Biology
Climatic zone: Temperate; Tropical.   Horizontal distribution: Oceanic.   Vertical distribution: Pelagic.  

Geographical Distribution
Jurisdictional distribution: Highly migratory

Water Area Overview
Geo References
Resource Structure
Considered a single stock: Yes

The tag recoveries of the RTTP-IO [Regional Tuna Tagging Project-Indian Ocean] provide evidence of large movements of yellowfin tuna, thus supporting the assumption of a single stock for the Indian Ocean.
Fishery Indicators
TypeMeasureValueUnitTime period
ProductionCatch 27539tonnesAverage 1950 - 1959
Catch 51698tonnesAverage 1960 - 1969
Catch 53345tonnesAverage 1970 - 1979
Catch 127960tonnesAverage 1980 - 1989
Catch 333524tonnesAverage 1990 - 1999
Catch 385292tonnesAverage 2000 - 2009
Catch 425942tonnes2006
Catch 324577tonnes2007
Catch 321258tonnes2008
Catch 266935tonnes2009
Catch 301738tonnes2010
Catch 329305tonnes2011
Catch 400501tonnes2012
Catch 405050tonnes2013
Catch 408511tonnes2014
Catch 407573tonnes2015

In 2016, two models were applied to the update of the 2015 yellowfin tuna stock assessment, both of which give qualitatively similar results. Stock status is based on the Stock Synthesis III model formulation. On the weight-of-evidence available in 2016, the yellowfin tuna stock is determined to be overfished and subject to overfishing.
Assessment Model
Type:  Biomass-aggregated
Biomass Dynamic Model (BDM)

The WPTT [Working Party on Tropical Tunas of the IOTC] agreed that the base case model run from the SS3 stock assessment would be used for development of management advice for the Scientific Committee’s consideration. The other models (Bayesian biomass production model (BBPM) and Statistical-Catch-At-Age (SCAA)) should be discussed as supporting evidence.
Assessment Model
Type:  Age-structured
Stock Synthesis III (SS3)
Scientific Advice

The stock status determination did not change in 2016, but does give a somewhat more optimistic estimate of stock status than the 2015 assessment as a direct result of the use of more reliable information on catch rates of longline fisheries and updated catch up to 2015. The stock status is driven by unsustainable catches of yellowfin tuna taken over the last four (4) years, and the relatively low recruitment levels estimated by the model in recent years. The Commission has an interim plan for the rebuilding of this stock (Resolution 16/01, which is yet to be evaluated) to achieve the recovery of yellowfin stock, with catch limitations beginning January 1 2017. The projections produced to advise on future catches are, in the short term, driven by the below average recruitment estimated for in recent years since these year classes have yet to reach maturity and contribute to the spawning biomass (see Table 2).

Management unit: Yes
Source of information
IOTC–WPTT18 2016. Report of the 18th Session of the IOTC Working Party on Tropical Tunas. Seychelles, 5-10 November 2016. IOTC–2016–WPTT18– R[E]: 126 pp.  Click to open
Yellowfin tuna supporting information for the 17th Session of the IOTC Working Party on Tropical Tunas. 2016.  Click to open
All references to figures, tables and bibliography in the text are found within the source of information.
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