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Atlantic sailfish - East Atlantic
Marine Resource  Fact Sheet
Stock status report 2016
Atlantic sailfish - East Atlantic
Fact Sheet Citation  
Owned byInternational Commission for the Conservation of Atlantic Tunas (ICCAT) – More
Related observationsLocate in inventorydisplay tree map
 
Species:
FAO Names: en - Atlantic sailfish, fr - Voilier de l'Atlantique, es - Pez vela del Atlántico, ru - Парусник атлантический
Geographic extent of Atlantic sailfish - East Atlantic
Main Descriptors
Considered a single stock: No        Spatial Scale: Sub-Regional
Management unit: Yes        Reference year: 2014
 
 
Biological State and Trend
State & Trend Descriptors
PartnerFIRMS
Exploitation rateF2014/FMSY = 0.33-2.85High fishing mortalityRed
Abundance levelB2014/MSY = 0.22-0.70Depleted
History
 

The most recent stock assessments for East and West sailfish were conducted in 2016 using catch data available to 2014, through a process that included meetings for data preparatory, and a catch rate standardization workshop in May. The previous sailfish stock assessments were conducted in 2009.
Habitat and Biology
Climatic zone: Temperate.   Horizontal distribution: Oceanic.   Vertical distribution: Pelagic.  


Sailfish is more coastally oriented than other billfish species. Conventional tagging data suggests they move shorter distances than the other billfish (Figure 1). Temperature preferences for adult sailfish appear to be in the range of 25-28°C. Sailfish generally seek out the warmest water available, and electronic tagging studies indicate that about 96% of darkness, 86% of twilight, and 82% of daylight hours are spent near the surface (Hoolihan et al. 2011). Vertical habitat use is more complex however, with frequent short duration excursions to deeper depths in excess of 100 m, with some dives as deep as 350 m.

Sailfish grow rapidly and reach a maximum size of 160 cm for males and 220 cm for females, with a mean maximum age of at least 12 years. A new length at 50% maturity (L50) has been estimated for West Atlantic female sailfish (146.12 cm LJFL); while the previous L50 value used for western sailfish males remains at 135.7 cm LJFL. No values are currently available for eastern Atlantic sailfish.

Sailfish spawn over a wide area and year around. For the western stock, evidence of spawning has been detected in the Straits of Florida, and off the Venezuelan, Guyanese and Surinamese coasts. In the southwestern Atlantic, spawning has been confirmed off the southern coast of Brazil between 20° and 27°S. Additional spawning areas occur in the eastern Atlantic off Senegal and Côte d’Ivoire. Timing of spawning can differ between regions; from the Florida Straits to the areas off Guyana western Atlantic sailfish spawn in the second and third quarter of the year, while in the southwestern Atlantic they spawn during the austral summer.


Figure 1. Conventional tag returns for Atlantic sailfish. Lines join the locations of release and recapture.
Geographical Distribution
Jurisdictional distribution: Highly migratory


Sailfish (Istiophorus albicans) has a pan-tropical distribution.
Water Area Overview
Spatial Scale: Sub-Regional

Geo References
Resource Structure
Considered a single stock: No


Based on life history information, migration rates and geographic distribution of catch, ICCAT has established two management units for sailfish, eastern and western Atlantic stocks (Figure 2). However, a recent preliminary study investigating genetic differentiation among groups of Atlantic sailfish suggests genetic stock structure between both the eastern and western Atlantic, and northern and southern hemispheres, suggesting the need for further investigations to elucidate and confirm the presence of additional stock structure that may influence future assessments.
Figure 2. Geographic distribution of sailfish total catches by decade (last decade only covers 5 years). The dark line denotes the separation between stocks.
Exploitation
 

Description of fisheries

Sailfish are targeted by coastal artisanal and recreational fleets and are captured to a lesser extent as by-catch in longline and purse seine fisheries. Historically, catches of sailfish were reported together with spearfish by many longline fleets. In 2009 these catches were separated by the Committee (Table 1). The eastern stock is exploited by surface fisheries, mainly artisanal gillnet and troll, and to a lesser degree by purse seine, as well as longline and recreational fisheries. The main surface fisheries are carried out by the artisanal fleets of Côte d’Ivoire, Ghana and Senegal followed by the EU mixed flags fleets (France and Spain) in the Gulf of Guinea and in the waters of the tropical eastern Atlantic. The main longline fleets are EU-Spain, Japan and Chinese Taipei fleets which operate in the central, eastern and western Atlantic. Total reported landings, increased abruptly after 1973, to peak above 5,000 t in 1975-1976, remaining relatively high (>2000 t), largely due to the incorporation of artisanal fishing effort by the traditional surface (gillnet and troll) fisheries (Figure 3). A generally decreasing trend of catch is apparent since 2008, mainly due to a decreased catch by the surface fisheries (gillnet and purse seine). The total catch in 2015 was 1,271 t, and the average catch in the last five years is about 1,350 t, close to 50% below the historical average of 2,302 t recorded in 1975-2009.
Figure 3. Task I catches of sailfish for the East Atlantic stock.
Assessment
 
Assessment Model

Several standardized CPUE data series were used in 2016 for the Atlantic sailfish stock assessment. For the eastern Atlantic stock, the eight indices of abundance used were: Côte d’Ivoire, Ghana, and Senegal artisanal, Chinese Taipei longline, Japan longline (early and late), EU-Portugal longline, and EU-Spain longline (Figure 4).
Figure 4. Relative abundance indices used in the assessment of the eastern Atlantic sailfish stocks. All indices were scaled to the mean of each series prior to graphing.



Important progress was made on the integration of new data sources, in particular standardized catch rate data, size data, and modeling approaches, in the 2016 assessment of the status of the stocks of Atlantic sailfish. For both stocks (East and West), uncertainty in data inputs and model configuration was explored through sensitivity analysis. They revealed that results were sensitive to structural assumptions of the models. The production model formulations and the Stock Synthesis model (applied for the western stock) had varying degrees of difficulty fitting the decreasing or increasing trends in the CPUE series. Overall, assessment results were uncertain and should be interpreted with caution.

The Bayesian surplus production model, the ASPIC and the Stock Reduction Analysis models showed similar trends in biomass trajectories and fishing mortality levels; trends in abundance suggest that the stock suffered their greatest declines in abundance prior to 1990. Different model runs indicate a declining/increasing trend in recent years depending on the CPUE series selected. All the scenarios considered for advice using the surplus production models indicated that the stock is overfished (0.27-0.71 BMSY), but overfishing status is uncertain (0.33-2.85 FMSY) (Figure 5).
Figure 5. Phase plot summarizing scenario outputs for the current (2014) stock status of Sailfish east (SAI_east). SRA is Stock Reduction Analysis; E-up-equal wt to E-up-low process are BSMP-JAGS model runs, E1 GH1&GH2 is ASPIC base case model run.
Overall Assessment Results
Projection

Outlook

The eastern and western sailfish stocks may have been reduced to stock sizes below BMSY. There is considerable uncertainty on the level of reduction. The results for the eastern stock were more pessimistic than those for the western stock in that more of the results indicated recent stock biomass below BMSY. Therefore, there is particular concern over the outlook for the eastern stock.

Due to the difficulty of determining current status for both the eastern and western Atlantic stocks, the Committee considered that it was not appropriate to conduct quantitative projections of future stock condition based on the range of scenarios considered at the stock assessment meeting
Management
Management unit: Yes


Effects of current regulations

No ICCAT regulations for sailfish are in effect, however, some countries have established domestic regulations to limit the catch of sailfish. Among these regulations are: requirement of releasing all billfish from longline vessels, minimum size restrictions, use of circle hooks and catch and release strategies in sport fisheries.

Currently, four ICCAT Contracting Parties (Brazil, Canada, Mexico, and the United States) mandate or encourage the use of circle hooks on their pelagic longline fleets. Recent research has demonstrated that in some longline fisheries the use of non-offset circle hooks resulted in a reduction of billfish mortality, while the catch rates of several of the target species remained the same or were greater than the catch rates observed with the use of conventional J hooks or offset circle hooks.
Management Advice

Considerable uncertainty still remains in the assessments of both the eastern and western stocks. Available abundance indices demonstrate conflicting trends for both stocks, and there are concerns that reported catches, including dead discards, may be incomplete. Nevertheless, it should be noted that there have been significant improvements since the last assessment. There were more abundance indices available, and the standardizations have seen general improvement, fostered in part by the CPUE workshop held in advance of this meeting. As was the case during the 2009 Sailfish Stock Assessment Session, the results for the eastern stock were more pessimistic than the western stock in that more of the results indicated recent stock biomass below BMSY.

The eastern Atlantic sailfish stock appears to have declined markedly since the 1970s, reaching a low in the early 1990s. There is broad agreement across model results that the stock is currently overfished. Since 2010, catches appear to have declined substantially. However, models disagree whether overfishing is occurring and whether the stock is recovering. Based on the assessment results, and considering the associated uncertainties, the Committee recommends at a minimum that catches should not exceed current levels. Furthermore, taking into account that overfishing may be occurring, the Commission may consider reductions in catch levels.
EASTERN ATLANTIC SAILFISH  SUMMARY
Maximum Sustainable Yield (MSY) 1,635-2,157 t 1
Current Yield (2015) 1,271 t
B2014/BMSY 0.22-0.70 1
F2014/FMSY 0.33-2.85 1
Overfished Yes
Overfishing Possibly
Management Measures in Effect None

1Range obtained of plausible estimates from bootstrapped ASPIC, BSP-JAGS, and SRA models.
Source of information
 
Standing Committee on Research and Statistics (SCRS). “Atlantic Sailfish, Executive Summary.” Madrid, Spain October 3 - 7 2016. ICCAT Click to openhttp://www.iccat.int/Documents/Meetings/Docs/2016_SCRS_ENG.pdf
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