Diapositiva 1

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Ex. Report ALB SCI-017
North and South Atlantic albacore (Thunnus
alalunga) stocks assessment ICCAT WG ALB, 26
Sept., 2007
Multifan Inputs for ALB Assessment, March 2007
SCI-030 /2007
Detail Albacore stock assessment, July 2007-
SCI-036 /2007
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ALB- Atlantic Biology

• Stock structure for assessment North and South
  stocks in the Atlantic ocean separated at 5º and
  Mediterranean stock. Intermingling of Indian and
  Atlantic oceans needs research.
• Present knowledge on habitat distribuition by
  size, spawning areas, maturity based on limited
  studies mostly from past years.
• Revised vB growth equation was estimated for
  South Atlantic stock based on aging dorsal fin
  ray section
• Vertical distribution immature at sub-surface
  above thermocline in summer. Adult distribution
  at wider range from surface to 300m depth.

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ALB - Spatial distribution based on average catch
2000 - 2005 period
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Catch trend Northern stock ALB 1930-2005 years
1975 VPA
LL
TROL
BB
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Fisheries indicators in North Atlantic
Overall description

• Targeting immature and sub-adults (50- 90 cm FL)
  by surface fisheries in the North Eastern
  Atlantic from Azores Is. to northern lalitude (SW
  Ireland) and Bay of Biscay areas, during spring,
  summer and autumn.
• Targeting immature and adult albacore (60-130 cm
  FL) by longline fisheries in Central and Western
  Atlantic waters all year round.
• Catch was extended back to 1930 after revision
  for stock assessment.
• Trend declining began in 1986 due to reduction
  of traditional surface fleets (Troll and
  Baitboat) and longline fleets. Stabilization
  observed in the 90s due to incorporation of new
  fleets (drifnets mid-water pair pelagic trawl).
  Maximun catch of 38,063 t registered in 1993.
  Followed by the lowest on record of 22,685 t in
  2002. Since then and steady increase until
  reaching a peak of 36,077 t in 2006.

LL
TROL
BB
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Surface Fisheries

• Gears troll, baitboat, mid-water pair pelagic
  trawl (MWPT).
• Main fleets involved EC (Spain, France Portugal
  and Ireland)
• In 2006 the surface fishery represented the 86
  of total catch in North stock
• EC-France MWPT reported the highest catch of
  recent years in 2005, but decreased the 30 in
  2006.
• EC-Ireland MWPT catch has decreased since 2002.
• EC-Spain increased the baitboat catch by 49
  respecting 2005 catch and the troll catch in 2006
  was similar to 2005 level.

LL
Longline Fisheries
BB

• Longline catches decreased in 2006, due to a
  decrease of landings by
  Chinese-Taipei fleet of 60 compared to 2005
  caused by decline in fishing effort.

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Catch trend Southern stock ALB 1956-2005 years
LL
LL
BB
LL
BB
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Fisheries indicators in South Atlantic
Overall description

• Targeting immature and sub-adults (70- 90 cm FL)
  by surface fisheries in the South Eastern
  Atlantic in coastal waters of Namibia and South
  Africa from October to May.
• Targeting adult albacore (gt 90 cm FL) by
  longline fisheries in Northeast coast off Brazil
  (5ºS-20º S) and over the South Atlantic area by
  longline fleet from Chinese-Taipei Central all
  year round.
• Trend total reported catch in 2006 was 24,375 t
  , an increase of about 5,000 t respect 2005. The
  Chinese Taipei catch increased in 2006 to 12,293
  t. As for Brazilian catches, the Chinese Taipei
  vessels (incluidng Belize and St. Vincent flagged
  boats ) stopped fishing for Brazil in 2003, then
  albacore was only caugth as by-catch in the SWO
  and Trop target longline fisheries, reaching 267
  t.
• The decreased of albacore in 2006 in inshore
  waters of South Africa and unfavorable foreign
  currency has caused a reduction in number of
  active baitboat vessels.

LL
TROL
BB
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Catch trend Mediterranean stock ALB 1964 -2005
years
Main Fleets
Longline
Other Surf
LL
LL
BB
LL
BB

• Reported catches in 2006 were 5,874 t, an
  increased with respect to 2005.

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Assessing the State of Atlantic stocks
Background

• Thorough revision of North and South Atlantic
  stock data Task I and Task II, was done and more
  robust method was implemented to analyse
  Catch-at-Size (CAS) information.
• Historical Catch for North Atlantic stock was
  recovered and incorporate to the analyses up to
  1930.
• Catch rates analyses were reviwed and new model
  applied for some longline fleets resulting in
  better fit to data.
• Substantial work was undertaken to implement new
  methods which do not assume that CAA is known
  whitout error, to assess the albacore stocks.
• This new implemented method provided the
  opportunity to evaluate a range of hypothesis
• - how the fisheries operated over time
  and their impact in the population ?

LL
LL
BB
LL
BB
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ALB- North stock. Total Catch-At-Age (CAA)
1 to 8 age group
Bubble size proportional to number of fish
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ALB- North stock. Catch-At-Age (CAA) by Fishery
1 to 8 age group
LONGLINE FLEETS
By-catch USA
Target Ch-TAI
By-catch
By-catch JPN
SURFACE FLEETS
Target BB ESP
Target TR ESP
Target OTHER
Bubble size proportional to number of fish on
each fleet
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ALB- North CPUE time series
Surface TR fleet
Longline Taiwan LL target
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ALB-N- Recruitment and Spawning stock
Age 1- recruit MFCL model 2005 high but uncertain
1930- 2005 MFCL model SSB ¼ Max in 40s
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ALB- N- Relative F, SSB and status stock
relative to MSY
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ALB- North State of stock

• SSB has decreased to one fourth of the SSB in the
  highest level in the 40s
• Recruit decreased from the 60s until 2004. In
  2005 the estimated recruitment is high 60s,
  but magnitude is uncertain.
• The stock rebuild to levels near BMSY (SSB
  20 below MSY) vs 2000 assessment when SSB 50
  below MSY
• Current F is 50 above F msy
• Estimates of MSY varied over time as a
  combination of surface and longline fisheries
  with changing selectivity pattern over time
  period.
• MSY for 3 recent years 32.000 t , but over time
  ranged from 26.000 t to 34.00 t.

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ALB- North Atlantic Fishing
trajectory and 2005 status
status in 2005
1930-2005 evolution of relative biomass and
fishing mortality estimated trajectory relative
to MSY
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ALB- North Atlantic Uncertainty of 2005 status
determination
2005 status F/Fmsy 1.5 B/Bmsy 0.81
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ALB- N- Projections
2006 CATCH of 36.000 t
32.000 t
TAC of 34.500 t
VPA
relative SSB (SSB/SSBMSY) for scenarios of cte
catch 2008 -2020
Projected Current catch for 2006 2007
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ALB- N- VPA Projections scenarios assuming strong
year class
32.000 t TAC
34.500 t TAC
relative SSB (SSB/SSBMSY) for scenarios of cte
catch 2008 -2020
Projected Current catch for 2006 2007
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ALB- South stock. Total Catch-At-Age (CAA)
1 to 8 age group
Bubble size proportional to number of fish
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ALB- South stock. Catch-At-Age (CAA) by Fishery
1 to 8 age group
LONGLINE FLEETS
Target and By-catch BRA
Target Ch-TAI
By-catch JPN
SURFACE FLEETS
Target BB SA
Target BB NAM
Target OTHER
Bubble size proportional to number of fish on
each fleet
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ALB South CPUE time series
Longline Taiwan Target
Surface Baitboat
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ALB- South Atlantic Fishing
trajectory and 2005 status
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ALB- South Atlantic Uncertainty of 2005 status
determination
2005 status F/Fmsy 0.63 B/Bmsy 0.9
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ALB- South State of stock

• Last assesmment was done in 2003
• Longline CPUE show a declining trend at the
  begining of time series, less marked in the
  recent period. Thos indices traget adult
  albacore.
• Surface CPUEs (Baitboat) target mostly immature
  albacore and no trend is seen.
• Current SSB has declined 25 from unfished SSB.
• Accordingly it is likely that in 2005 SSB is
  about 90 of Bmsy and F is 40 below F msy
• Estimates of current MSY is around 33.300 t and
  Replacement yield is around 29.000 t, current
  catch 24.460 t is below.

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ALB- S- Projections
10 years projections
BMSY
SSB over time trend and 80 confidence bounds
Projected cte catch 25.000 t
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ALB- N MANAGEMENT Rec.

• Current TAC is 34.500 t
• 2005 and 2006 catches have been above
• Projections indicate that stock will not recover
  from overfished state if catch level remain gt
  30.000 t
• If strong year class enters the fishery the
  stock would recovered faster

ALB- S MANAGEMENT Rec.

• Current TAC is 29.900 t
• 2Recent catches have been below
• Projections indicate that catches at 2006 level
  will recover the stock from overfished state
• Current management scheme is sufficient for
  recovery of South stock

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THANKS