Fisheries and Resources Monitoring System

EspañolFrançais
Albacore - Northern Pacific
Marine Resource  Fact Sheet
Stock status report 2020
Albacore - Northern Pacific
Fact Sheet Citation  
Owned byInter-American Tropical Tuna Commission (IATTC) – More
Related observationsLocate in inventorydisplay tree map
 
Species:
FAO Names: en - Albacore, fr - Germon, es - Atún blanco, ru - Тунец длинноперый
Geographic extent of Albacore - Northern Pacific
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Regional
Management unit: Yes        Reference year: 2019
 
 
Biological State and Trend
State & Trend Descriptors
PartnerFIRMS
Exploitation rateModerate fishing mortalityModerate fishing mortalityGreen
Abundance levelIntermediate abundanceIntermediate abundance
FAO Categories
Exploitation stateModerately exploited
Habitat and Biology
Bottom type: Unspecified.   Depth zone: Abyssal ( >1000m).   Horizontal distribution: Oceanic.   Vertical distribution: Pelagic.  

Geographical Distribution
Jurisdictional distribution: Highly migratory

Water Area Overview
Spatial Scale: Regional

Geo References
Resource Structure
Considered a single stock: Yes
Exploitation
 

Data provided by the relevant Members on catches of albacore, by gear and area (north and south of the equator), are shown in (Table A-6). Albacore catches for the entire EPO are shown in (Table A-2a). A portion of the albacore catch is taken by troll vessels, included under “Other gears” (OTR) in Table A-2a.

There are two stocks of albacore in the Pacific Ocean, one in the northern hemisphere and the other in the southern hemisphere. Albacore are caught by longline gear in most of the North and South Pacific, but not often between about 10°N and 5°S, by trolling gear in the eastern and central North and South Pacific, and by pole-and-line gear in the western North Pacific. In the North Pacific, about 40% of the catch is taken by pole-and-line and troll fisheries that catch smaller, younger albacore, and about 50% was taken by longline. In the South Pacific, almost all the albacore was taken by longline. The total annual catches of South Pacific albacore ranged from about 25,000 to 50,000 t during the 1980s and 1990s but increased after that and are currently at the highest levels. During 2016-2018, the albacore catches in the south Pacific averaged about 81,000 t of which about 30% was taken in the eastern Pacific Ocean (EPO) (Figure F-1a)
Figure F-1a: Retained catches of South Pacific albacore, by region. EPO catches broken down by gear: LL: longline; LTL: troll; OTR: other.

The total annual catches of North Pacific albacore peaked in 1976 at about 125,000 t, declined to about 38,000 t in 1991, and then increased to about 122,000 t in 1999 (Figure F-1b).




Figure F-1b: Retained catches of North Pacific albacore, by region. EPO catches broken down by gear: LL: longline; LTL: troll; OTR: other.

They declined again in the early 2000s, then recovered, but since 2012 they have declined from about 92,000 to about 57,000 t in 2018, averaging about 58,000 t in 2016-2018, of which 23% was taken in the EPO. Those declines in catches coincide with decline in effort in the north EPO.

Juvenile and adult albacore are caught mostly in the Kuroshio Current, the North Pacific Transition Zone, and the California Current in the North Pacific and in the Subtropical Convergence Zone in the South Pacific, but spawning occurs in tropical and subtropical waters, centering around 20ºN and 20ºS latitudes. North Pacific albacore are believed to spawn between March and July in the western and central Pacific.

The movements of North Pacific albacore are strongly influenced by oceanic conditions, and migrating albacore tend to concentrate along oceanic fronts in the North Pacific Transition Zone. Most of the catches are made in water temperatures between about 15º and 19.5ºC. Details of the migration remain unclear, but juvenile fish (2- to 5-year-olds) are believed to move into the eastern Pacific Ocean (EPO) in the spring and early summer, and return to the western and central Pacific, perhaps annually, in the late fall and winter, where they tend to remain as they mature. This pattern may be complicated by sex-related movements of large adult fish (fork length >125 cm), which are predominately male, to areas south of 20°N. The significance of such movements for the demographic dynamics of this stock are uncertain at present.

Less is known about the movements of albacore in the South Pacific Ocean. The juveniles move southward from the tropics when they are about 35 cm long, and then eastward along the Subtropical Convergence Zone to about 130°W. When the fish approach maturity they return to tropical waters, where they spawn. Recoveries of tagged fish released in areas east of 155°W were usually made at locations to the east and north of the release site, whereas those of fish released west of 155°W were usually made at locations to the west and north of the release site.

The most recent published stock assessments for the South and North Pacific stocks of albacore are from 2018 and 2020, respectively. The assessments indicate that it is not likely that either stock is overfished or that overfishing is taking place.

See also fishery fact sheet:EPO Tunas and billfishes fishery
Figure F-1a: Retained catches of South Pacific albacore, by region. EPO catches broken down by gear: LL: longline; LTL: troll; OTR: other.
Assessment
 
Overall Assessment Results

A new stock assessment was completed in 2020 by the Albacore Working Group (ALBWG) of the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean (ISC) (ISC/20/Annex/12, SAC-11-INF-I). The north Pacific albacore tuna stock has been exploited for a long time, the catches were the highest in 1976 (about 127,000 t) and the lowest in 1991 (about 37,000 t). During the assessment period (1994-2018), the highest catches were in 1999 (about 119,000 t) and the lowest in 2018 (about 52,000 t). About 2/3 of the catches come from surface fisheries (troll and pole-and-line) that harvest mainly juveniles, and the rest from longline fisheries. On average, about 20% of the catches are taken within the area of application of the Antigua Convention.

The assessment was done using the “best model” approach. The working group concluded that the stock was not experiencing overfishing and was probably not overfished as shown in (Figure F-2)


Figure F-2 Effort in vessel-days and number of vessels for the North Pacific albacore tuna in the eastern Pacific Ocean.

And also in (Table F-1).

The current depletion is 0.46 ((SSB(2018))/SSB_d , where SSB_d is the dynamic spawning stock biomass without fishing for 2018)). The ratio of ((SSB(2018))/(S(MSY)) = 3.01)). The relative current fishing mortality is (F(2015-2017))/(F(50%))= 1 , (F(2015-2017))/(F(20%)) =0.62, (F(2015-2017))/(F(MSY)) =0.60. The current depletion is 0.46 ((SSB(2018))/SSB_d , where SSB_d is the dynamic spawning stock biomass without fishing for 2018)). The ratio of ((SSB(2018))/(S(MSY)) = 3.01)). The relative current fishing mortality is (F(2015-2017))/(F(50%))= 1 , (F(2015-2017))/(F(20%)) =0.62, (F(2015-2017))/(F(MSY)) =0.60

The current IATTC conservation and management measures for north Pacific albacore (Resolutions C-05-02, C-13-03 and C-18-03) are based on maintaining the fishing effort below the 2002-2004 levels. The effort levels in eastern Pacific Ocean for 2017-2019 are 72% and 69% of those in 2002-2004, for vessel-days and number of vessels respectively (Figure F-2).
Figure F-2 Effort in vessel-days and number of vessels for the North Pacific albacore tuna in the eastern Pacific Ocean.

The Working Group is currently undertaking a Management Strategy Evaluation (MSE) for the North Pa-cific albacore stock. The first round of the MSE was concluded and reported during the 4th ISC ALB MSE workshop in March 2019 (ISC/19/ANNEX/06).

Several operating models were developed, and equal weights was assumed for all alternative operating models when evaluating the HCRs. The results indicated that total allowed effort (TAE) control rules performed better than total allowed catch (TAC). In TAE control, catches adjusted quickly, without management interventions, in response to changes in biomass between assessment periods. Across target reference points (TRPs), there was no single best-performing HCR for all performance metrics (PMs).

Trade-offs were evident between relative catch and relative biomass, catch stability, and odds of no fishery closure. HCRs with the lowest fishing intensity TRP (F50), maintained the population at a higher level than those with the highest fishing intensity TRP (F30), requiring less management intervention and resulting in lower catch variability between years but had the lowest catches.

However, rules with an intermediate TRP of F40 had comparable or higher relative catch than F30 rules despite lower fishing intensity because of fewer closures and higher catch stability. The results of the first round were deemed useful to understand the tradeoffs and potential performance of candidate reference points and harvest control rules by the participants. Additional work was deemed necessary to test all proposed HCR, and to include new operating models. There is a plan to continue into a second round of the MSE. The workshop participants developed a focused list of candidate reference points and harvest control rules to be examined during the 2nd round of MSE, planned to be completed still in 2020. A 5th ISC ALB MSE Workshop is planned for the end 2020, when the results of the 2nd round of the MSE should be presented (ISC/20/PLENARY/02).

The following management objectives for the North Pacific albacore tuna were developed in the context of the MSE process:

Overarching objective: maintain the viability and sustainability of the current NPALB stock and fisheries

1.Maintain spawning biomass above the limit reference point

2.Maintain total biomass, with reasonable variability, around the historical average depletion of total biomass

3.Maintain harvest ratios by fishery (fraction of fishing impact with respect to SSB) at historical average

4.Maintain catches by fishery above average historical catch

5.If a change in total allowable effort and/or total allowable catch occurs, the rate of change should be relatively gradual

6.Maintain F at the target value with reasonable variability

Given the relative stability in the biomass and fishing mortality in recent years, and in view of the 2nd round of MSE, the staff considers that the current resolutions should be continued and that the recommendations from the 4th ISC ALB MSE workshop be adopted. The staff recommends that the management objectives for the North Pacific albacore tuna developed in the context of the MSE process be adopted, then prioritized, ranked, or weighted, to advice the ongoing North Pacific albacore MSE process.
Management
Management unit: Yes
Source of information
 
Inter-American Tropical Tuna Commission (IATTC). “"Report on tuna fishery, stocks, and ecosystem in the Eastern Pacific Ocean in 2019. Inter-American Tropical Tuna Commission." Fishery Status Report. IATTC 2020.” Click to openIATTC-95-05_The fishery and status of the stocks 2019
powered by FIGIS  © FAO, 2021
Powered by FIGIS
crawl