MEDITERRANEAN SWORDFISH
Post on 30-Jan-2016
48 Views
Preview:
DESCRIPTION
Transcript
MEDITERRANEAN SWORDFISH
SCI-020
Background
Unique genetic stock Some mixing with the N. Atlantic one Different biological characteristics than the Atlantic stocks Last assessment few weeks ago.
Fishery Catches around 12000-16000 t in the last decade. 14000 t in 2005. Incomplete information for 2006. Gears: Longlines & Gillnets
Catch composition Large catches of juveniles (50-70%)
SWO Figure 4 Proportion of catch numbers at age by year.
Stock assessment Two assessment types
Production modelling (long data series)
Age based VPAs (short data series) }Stock decline
State of the stocks
Production modeling
Current stock level about 13% lower than optimum
Current F about 25% higher than optimum
VPA40% reduction in spawning stock level but modest changes in the last decade
Stable recruitment over the past 20 years.
Current spawning stock level half than optimum
Current F double than optimumY/R
Current (2005) stock status
Prod. Mod. medianVPA median
Time trends
Production modelingVPA
Projections
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2000 2005 2010 2015
Year
B/B
MS
Y
10,000 t
12,000 t
14,300 t
16,000 t
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2000 2005 2010 2015Year
B/B
MS
Y
10,000 t12,000 t14,300 t16,000 t
VPA Production modeling
Assessment conclusions
The stock is below the level which can support MSY
Current fishing mortality exceeds FMSY.
The degree to which biomass is below BMSY and F is above FMSY
differs between assessment models.
Fishing pressure needs to be reduced to move the stock towards to
biomass levels which could support MSY and away from levels
which could result in non-negligible risks of rapid stock decline;
although such worrying signals have not been seen so far in the
fisheries.
Maximum Sustainable Yield 14,250-15,500 1
Current (2005) Yield2 14,600 t
Current (2007) Replacement Yield ~12,000-14,000 t1
Relative Biomass (B2005/BMSY) 0.26-0.87 1
Relative Fishing Mortality F2005/FMSY
F2005/FMAX
F2005/F0.1
F2005/F20%SPR
F2005/F30%SPR
1.3 (0.6-2.5) 3
2.9 (2.4->5) 4
4.6 (3.7->5)4
3.0 (2.6->5)4
4.2 (3.6->5) 4
Management measures in effect No ICCAT regulations; national closed areas, minimum size and effort controls.
Mediterranean Swordfish Summary
Exploitation scenarios
Fishery closures during recruitment
Management recommendations
Adoption of a management plan with the goal of rebuilding the stock to levels that are consistent with the ICCAT Convention objective.
Technical measures, such as fishery closures and gear modifications, as well as capacity reductions should be considered in the frames of a management plan
top related