Fisheries and Resources Monitoring System

Black marlin - Indian Ocean
Marine Resource  Fact Sheet
Stock status report 2021
Black marlin - Indian Ocean
Fact Sheet Citation  
Black marlin Indian Ocean
Owned byIndian Ocean Tuna Commission (IOTC) – More
Related observationsLocate in inventorydisplay tree map
FAO Names: en - Black marlin, fr - Makaire noir, es - Aguja negra

Fishery Indicators
Production: Catch
Geographic extent of Black marlin - Indian Ocean
Main Descriptors
Considered a single stock: Yes        Management unit: Yes
Reference year: 2019
Biological State and Trend
State & Trend Descriptors
Exploitation rateNot assessed/Uncertain (F2019/FMSY (95% CI) = 0.53 (0.22 – 1.05)Uncertain/Not assessed
Abundance levelNot assessed/Uncertain (B2019/BMSY (95% CI) = 1.98 (1.42 – 2.57)Uncertain/Not assessed
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

No information on stock structure is currently available in the Indian Ocean; thus for the purposes of assessment, one pan-ocean stock is assumed.
Fishery Indicators
TypeMeasureValueUnitTime period
ProductionCatch 912tonnesAverage 1950 - 1959
Catch 1719tonnesAverage 1960 - 1969
Catch 1483tonnesAverage 1970 - 1979
Catch 2667tonnesAverage 1980 - 1989
Catch 4891tonnesAverage 1990 - 1999
Catch 10325tonnesAverage 2000 - 2009
Catch 16320tonnesAverage 2010 - 2019
Catch 13370tonnes2011
Catch 12902tonnes2012
Catch 14813tonnes2013
Catch 18276tonnes2014
Catch 19122tonnes2015
Catch 22397tonnes2016
Catch 15215tonnes2017
Catch 18786tonnes2018
Catch 18068tonnes2019
Catch 16974tonnes2020
Level of uncertainty: High

A stock assessment based on JABBA, a Bayesian state-space production model (age-aggregated) was conducted in 2021 for black marlin. The Kobe plot from the JABBA model indicated that the stock is not subject to overfishing and is currently not overfished, however these status estimates are subject to a high degree of uncertainty. Since 2018, there has been no discernible improvement in the data available for black marlin and the subsequent assessment outputs remain uncertain and should be interpreted with caution. As such, there is no reasonable justification to change the stock status from “Not assessed/Uncertain”. 
Assessment Model
Type:  Biomass-aggregated
Scientific Advice

The 2020 catches (16,977 t) (Fig. 1) were substantially higher than the MSY limits stipulated in Res (18/05) which is 9,932 t. The Commission should provide mechanisms to ensure that catch limits are not exceeded by all concerned fisheries. Projections were not carried out due to the poor predictive capabilities identified in the assessment diagnostics.
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.  Click to open
All references to figures, tables and bibliography in the text are found within the source of information.
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