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Swordfish - Indian Ocean
Marine Resource  Fact Sheet
Stock status report 2021
Swordfish - Indian Ocean
Fact Sheet Citation  
Swordfish Indian Ocean
Owned byIndian Ocean Tuna Commission (IOTC) – More
Related observationsLocate in inventorydisplay tree map
 
Species:
FAO Names: en - Swordfish, fr - Espadon, es - Pez espada, ru - Меч-рыба

Fishery Indicators
Production: Catch
Geographic extent of Swordfish - Indian Ocean
Main Descriptors
Considered a single stock: Yes        Management unit: Yes
Reference year: 2018
 
 
Biological State and Trend
State & Trend Descriptors
PartnerFIRMS
Exploitation rateNot subject to overfishing (F2018/FMSY (80% CI) = 0.60 (0.40–0.83))No or low fishing mortality
Abundance levelNot overfished (SB2018/SBMSY (80% CI) = 1.75 (1.28–2.35))Pre-exploitation biomass or high 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


A recent genetic study did not reveal any structure within the Indian Ocean with the markers used, however the hypothesis of a population structuring at the regional level cannot be discarded and needs to be investigated using different markers or approaches. Results obtained from the markers used may simply be a matter of the resolving power of the markers used, which may simply have been insufficient for detecting population subdivision. Spatial heterogeneity in stock indicators (catch–per–unit–effort trends) indicates the potential for localised depletion of swordfish in the Indian Ocean.
Exploitation
 
Fishery Indicators
TypeMeasureValueUnitTime period
ProductionCatch 297tonnesAverage 1950 - 1959
Catch 1340tonnesAverage 1960 - 1969
Catch 2106tonnesAverage 1970 - 1979
Catch 5093tonnesAverage 1980 - 1989
Catch 26011tonnesAverage 1990 - 1999
Catch 32292tonnesAverage 2000 - 2009
Catch 28935tonnesAverage 2010 - 2019
Catch 21320tonnes2011
Catch 26785tonnes2012
Catch 30091tonnes2013
Catch 27270tonnes2014
Catch 31362tonnes2015
Catch 30743tonnes2016
Catch 32937tonnes2017
Catch 31017tonnes2018
Catch 33589tonnes2019
Catch 25913tonnes2020
Assessment
 

A new assessment was undertaken in 2020 using stock synthesis with fisheries data up to 2018. The assessment uses a spatially disaggregated, sex explicit and age structured model. The SS3 model, used for stock status advice, indicated that MSY-based reference points were not exceeded for the Indian Ocean population as a whole (F2018/FMSY< 1; SB2018/SBMSY> 1). The two alternative models (ASPIC and JABBA) applied to swordfish also indicated that the stock was above a biomass level that would produce MSY. Spawning biomass in 2018 was estimated to be 40-83% of the unfished levels. Most recent catches of 33,590 t in 2019 are approximately at the MSY level (33,000 t). On the weight-of-evidence available in 2020, the stock is determined to be not overfished and not subject to overfishing (Table 1, Fig. 2).
Assessment Model
Type:  Age-structured
Stock Synthesis III (SS3)
Scientific Advice

The most recent catches (33,590 t in 2019) are at approximately the MSY level (33,000 t). Under the current levels of catches, the spawning biomass is projected to remain relatively stable, with a high probability of maintaining at or above the SBMSY for the longer term. Nevertheless, the Commission should consider limiting the catches so as not to exceed the 2018 catch level (30,847 t at the time of the assessment) to ensure that the probability of exceeding the SBMSY target reference points in the long term remains minimal (2%). Projections indicate that an increase of 40% or more from 2018 catch levels will likely result in the biomass dropping below the SBMSY level for the longer term (>75% probability). Taking into account the updated information regarding swordfish stock structure (IOTC-2020-WPB18-09), as well as the differential CPUE and biomass trends between regions, the WPB should continue to discuss the swordfish stock assessment model specifications and consider the feasibility of including a multi-stock assessment in 2023. Recognising that there is recurring evidence for localised depletion in the southern regions (particularly the South West) the WPB expresses concern and suggests this should be further monitored.
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.  Click to openhttps://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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