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Albacore - South Atlantic
Marine Resource  Fact Sheet
Stock status report 2016
Albacore - South Atlantic
Fact Sheet Citation  
Albacore in the South Atlantic
Owned byInternational Commission for the Conservation of Atlantic Tunas (ICCAT) – More
Related observationsLocate in inventorydisplay tree map
 
Species:
FAO Names: en - Albacore, fr - Germon, es - Atún blanco, ru - Тунец длинноперый
Geographic extent of Albacore - South Atlantic
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Sub-Regional
Management unit: Yes        Reference year: 2014
 
 
Biological State and Trend
State & Trend Descriptors
PartnerFIRMS
Exploitation rateF2014/FMSY = 0.54 range (0.31-0.87)Moderate fishing mortalityGreen
Abundance levelB2015/BMSY = 1.10 range (0.51-1.80)Intermediate abundance
History
 

The status of the South Atlantic albacore stocks is based on the most recent analyses conducted in May 2016 by means of using the available data up to 2014. Complete information on the assessment can be found in the Report of the 2016 ICCAT North and South Atlantic Albacore Stock Assessment Meeting.
Habitat and Biology
Climatic zone: Temperate.   Horizontal distribution: Oceanic.   Vertical distribution: Pelagic.  


Albacore is a temperate tuna widely distributed throughout the Atlantic Ocean and Mediterranean Sea. On the basis of the biological information available for assessment purposes, the existence of three stocks is assumed: northern and southern Atlantic stocks (separated at 5ºN) and a Mediterranean stock (Figure 1). However, some studies support the hypothesis that various sub populations of albacore exist in the North Atlantic and Mediterranean. Likewise, there is likely intermingling of Indian Ocean and South Atlantic immature albacore which needs further research.

Scientific studies on albacore stocks, in the North Atlantic, North Pacific and the Mediterranean, suggest that environmental variability may have a serious potential impact on albacore stocks, affecting fisheries by changing the fishing grounds, as well as productivity levels and potential MSY of the stocks. Those yet sufficiently unexplored aspects might explain recently observed changes in fisheries, such as the lack of availability of the resource in the Bay of Biscay in some years, or the apparent decline in the estimated recruitment which are demanding focussed research.

The expected life-span for albacore is around 15 years. While albacore is a temperate species, spawning in the Atlantic occurs in tropical waters. Present available knowledge on habitat, distribution, spawning areas and maturity of Atlantic albacore is based on limited studies, mostly from past decades. In the Mediterranean, there is a need to integrate different available studies so as to better characterize growth of Mediterranean albacore. Besides some additional recent studies on maturity, in general, there is poor knowledge about Mediterranean albacore biology and ecology.

More information on albacore biology and ecology is published in the ICCAT Manual.
Geographical Distribution
Jurisdictional distribution: Highly migratory


Albacore is a temperate tuna widely distributed throughout the Atlantic Ocean and Mediterranean Sea.
Water Area Overview
Spatial Scale: Sub-Regional

Geo References
Resource Structure
Considered a single stock: Yes


On the basis of the biological information available for assessment purposes, the existence of three stocks is assumed: northern and southern Atlantic stocks (separated at 5ºN) and Mediterranean stock (Figure 1).
Figure 1 Geographic distribution of albacore accumulated catch by major gears and decade (1960-2014). Baitboat and troll catches prior to the 1990s, these catches were assigned to only one 5ºx5º stratum in the Bay of Biscay. Plots are scaled to the maximum catch observed from 1960 to 2014 (last decade only covers 5 years).
Exploitation
 

Description of fisheries

South Atlantic

The recent total annual South Atlantic albacore landings were largely attributed to four fisheries, namely the surface baitboat fleets of South Africa and Namibia, and the longline fleets of Brazil and Chinese Taipei (Table 1; Figure 2). The surface fleets are entirely albacore directed and mainly catch sub-adult fish (70 cm to 90 cm FL). These surface fisheries operate seasonally, from October to May, when albacore are available in coastal waters. Brazilian longliners target albacore during the first and fourth quarters of the year, when an important concentration of adult fish (>90 cm) is observed off the northeast coast off Brazil, between 5ºS and 20ºS, being likely related to favorable environmental conditions for spawning, particularly of sea surface temperature. The longline Chinese Taipei fleet operates over a larger area and throughout the year, and consists of vessels that target albacore and vessels that take albacore as by-catch, in bigeye directed fishing operations. On average, the longline vessels catch larger albacore (60 cm to 120 cm FL) than the surface fleets.

Albacore landings increased sharply since the mid-1950s to reach values oscillating around 25,000 t between mid-1960s and the 1980, 35,000 t until the last decade were they oscillated around 20,000 t. Total reported albacore landings for 2012 were 24,726 t, higher than the last five year average. The Chinese Taipei catch in 2012 was slightly above the last five year average. However, the Chinese Taipei catch in the last years has decreased compared to historical catches, mainly due to a decrease in fishing effort targeting albacore. Chinese Taipei longliners (including boats flagged in Belize and St. Vincent and the Grenadines) stopped fishing for Brazil in 2003, which resulted in albacore only being caught as by-catch in tropical tuna-directed longline fisheries. The 2012 catch for Brazil is higher than catches in the recent past. However, albacore is only caught as by-catch in Brazilian tropical tuna-directed longline and baitboat fisheries. The significantly higher average catch of about 4,287 t during the period 2000-2003 was obtained by the Brazilian longline fleet when albacore was a target species.

In 2015, the estimated South African and Namibian catch (mainly baitboat), was similar to the average of the last five years. During the last decades, Japan took albacore as by-catch using longline gear, but recently Japan is again targeting albacore and increased the fishing effort in waters off South Africa and Namibia (20-40˚S). Thus, catches during the last five years double those in the last few decades.

The trend in mean weight from 1975 to 2014 is shown in ALB-Figure 3b. Surface fleets showed a stable trend from 1981 onwards with an average of 13 kg and a maximum and minimum average weight of 17 kg and 10 kg, respectively. Longline fleets showed a relatively stable trend for the mean weight around 17 kg until 1996 where the average weight increased to about 20 kg, oscillating between 16 and 26 kg.
Figure 2 Total albacore catches reported to ICCAT (Task I) by gear for the southern Atlantic stock including TAC.


Figure 3 Mean weight trend by surface and longline fisheries in South Atlantic stock.
Assessment
 
Assessment Model

In 2016, a stock assessment of South Atlantic albacore was conducted including catch, effort and size data up until 2014, and considering similar methods as in the previous assessment.

The southern standardized CPUE trends are mainly for longline fisheries, which harvest mostly adult albacore. The longest time series of Chinese Taipei, showed a strong declining trend in the early part of the time series, and less steep decline over the last three decades, similar to the Japanese longline index. However, the Uruguayan longline CPUE series showed significant decreases since the 1980s (Figure 4).

In the 2016 assessment, the same eight scenarios as in 2013 were considered, but after screening during the assessment meeting, the early Japanese CPUE series was not used to fit the models. Stock status results varied significantly among scenarios (Figure 5a). Two different production model forms were considered, each with four scenarios. One showed more optimistic results than the other. However, the Committee lacked enough objective information to identify the most plausible scenarios and considered them equally likely. Six of eight scenarios indicated that the stock is not overfished and not undergoing overfishing, and two other scenarios indicated that the stock is overfished but not undergoing overfishing. Six scenarios estimated a higher B/BMSY than in the last stock assessment, and seven scenarios estimated a lower F/FMSY than in the previous assessment. This indicated that current stock status has improved since the last assessment. Considering the whole range of scenarios, the median MSY value was 25,901 t (ranging between 15,270 t and 31,768 t), the median estimate of current B/BMSY was 1.10 (ranging between 0.51 and 1.80 t) and the median estimate of current F/FMSY was 0.54 (ranging between 0.31 and 0.87). The wide confidence intervals reflect the large uncertainty around the estimates of stock status. Considering all scenarios, there is 3% probability for the stock to be both overfished and experiencing overfishing, 31% probability for the stock to be either overfished or experiencing overfishing but not both, and 66% probability that biomass is above and fishing mortality is below the Convention objectives (Figure 5b).
Figure 4 Standardized catch rates used in the 2013 southern albacore stock assessment.


Figure 5 South Atlantic albacore. a) Stock status trajectories of B/BMSY and F/FMSY, as well as uncertainty around the current estimate (Kobe plots) for the base case ASPIC models (upper row) alongside those from the base case BSP runs (bottom row). From left to right, boxes indicate the following scenarios: Equal weight, Schaefer; Equal weight, Fox; Catch weight, Schaefer; Catch weight, Fox. (b) Combined probability of being overfished and overfishing (red, 3%), of being neither overfished nor overfishing (green (66%), and of being overfished or overfishing, but not both (yellow, 31%).


Overall Assessment Results
Projection

The projection results differ between the base case scenarios. Since there is not objective information with which to select which scenario is most plausible, the Committee considered the entire range of scenarios, thus characterizing the range of possible responses to the distinct catch levels projected, as done in 2013. The Kobe matrix indicates that, depending on the scenario, catches which enable the stock to be in the Kobe green zone in 2020 with at least a 60% probability ranged from 18,000 to 34,000 t, with an average of 25,750 t and a median of 26,000 t (Figure 6). Averaging all scenarios, projections at a level consistent with the 2016 TAC (24,000 t) showed that probabilities of being in the green area of the Kobe plot would be higher than 60% in 2020 (Figure 7a and b).

Projections at FMSY, without considering implementation errors, suggested that the probability of the stock to be in the green quadrant of the Kobe plot would not consistently increase over time, while it would when projected at 0.95*FMSY or any lower fishing mortality rate.


Figure 6 South Atlantic Albacore. Maximum catch which enables the stock to be in the Kobe green zone in 2020 with a probability higher than 60%, for each ASPIC and BSP run. Average and median across runs is also provided.



(a) Probability F<Fmsy

(b) Probability B>BMSY

(c) Probability of green status (B>BMSY and F<FMSY).
Figure 7 South Atlantic albacore estimated probabilities (in %) that the South Atlantic albacore stock fishing mortality is below FMSY (a), biomass is above BMSY (b) and both (c). Projections for constant F and constant catch levels are shown, combining all base case scenarios.
Management
Management unit: Yes


Effects of current regulations

In 2013 the Commission established a new TAC of 24,000 t for 2014-2016 [Rec. 13-06]. The Committee noted that, since 2004, reported catches remained below 24,000 t, except in 2006, 2011 and 2012, where reported catches were slightly above this value (Table 1). As in the case of the North Atlantic, the Committee did not test the effect of perfect implementation of the TAC.
Management Advice

Results indicate that, most probably, the South Atlantic albacore stock is not overfished and that overfishing is not occurring. However, there is considerable uncertainty about the current stock status, and the effect of alternative catch limits on the rebuilding probabilities of the southern stock. The different model scenarios considered in the south Atlantic albacore stock assessment provide different views on the future effects of alternative management actions. Projections at a level consistent with the 2016 TAC (24,000 t) showed that probabilities of being in the green quadrant of the Kobe plot across all scenarios would increase to 63% by 2020. Further reductions in TAC would increase the probability of being in the green zone in those timeframes. On the other hand, catches above 26,000 t will not permit maintaining the stock in the green area with at least 60% probability by 2020.

SOUTH ATLANTIC ALBACORE SUMMARY
Maximum Sustainable Yield 25,901 t (15,270-31,768)1
Current (2016) TAC 24,000 t
Current (2015) Yield 15,144 t
Yield in last year of assessment (2014) 13,677 t
BMSY 120,465 t (71,312-208,438) 1
FMSY 0.202 (0.119-0.373) 1
B2015/BMSY1 1.10 (0.51-1.80)1
F2014/FMSY1 0.54 (0.31-0.87) 1
Stock Status Overfished: NO
Overfishing: NO
Management measures in effect:

[Rec. 13-06]: TAC of

24,000 t for 2014-2016


1 Median range and 80% CI calculated for the whole range of the 8 base cases.
Source of information
 
Standing Committee on Research and Statistics (SCRS) . “Albacore, 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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