Download
1 / 22
220 likes | 228 Vues
ATHENS EFIMAS MEETING. A comparison between capacity reduction and temporary withdrawal in the Ligurian Sea Hake fishery. Institute for Economic Research in Fishery and Aquaculture (IREPA). Athens, 19th-20th October 2006. Model structure.
E N D
ATHENS EFIMAS MEETING A comparison between capacity reduction and temporary withdrawal in the Ligurian Sea Hake fishery Institute for Economic Research in Fishery and Aquaculture (IREPA) Athens, 19th-20th October 2006
Model structure The proposed tool is a bio-economic simulation model. The objective is to evaluate the effects of the management measures Economic box Catch Profit Tax Subsidies Management Activity Capacity Selectivity Biological box State Variation Activity Capacity Activity Capacity t = t+1
Age-structured model for the target species: european hake A modified Schaefer model for the group “other species” Biological box
Economic box • Prices by species and fleet segment: • Constant • Landings function by flexibility coefficients • Differentiated by length classes • Costs by fleet segment: • Variable costs in function of days at sea • Fixed costs in function of GRT
Step: monthly Fishing gears: Trawl Gillnet 1 Gillnet 2 Step: yearly Fleet segments: Bottom trawl Small scale Polyvalent Biological box vs. Economic box Biological box Economic box
Fleet segments → Fishing gears For each target species and month, landings and days at sea by fleet segments are transformed in landings and days at sea by fishing gear. Cs is the vector of the monthly landings by fleet segment. Ds,a is the distribution matrix of landings by fleet segments to the fishing gears. Ca is the vector of monthly landings by fishing gear.
State variation This box considers the endogenous variables in the model subjected to be modified by the natural dynamic of the fishery sector: • Average days at sea by fleet segment; • GRT by fleet segment; • Fishing mortality by new investments in technology. • Prices by species and fleet segment.
Management measures • Technical measures: gear-species selectivity variation; • Temporary withdrawal; • Capacity reduction plans; • Fishing gear suspension; • Variations in tax rates and subsidies; • Mixed measures based on the above variable.
Output data • Biological variables (by fishing gear-species) • Economic variables (by fleet segment-species) • Technical variables (by fleet segment) • Biological indicators (by fishing gear-species) • Economic indicators (by fleet segment-species)
Simulation: management measures • Capacity reduction: a 20% reduction in term of GRT for the vessels practising trawl fishery. The management measure is implemented in the year 2008. • Temporary withdrawal: a stop of 45 days for the bottom trawlers, from 1st August to 15th September for each simulation year by starting in 2008.
Basic assumptions • Prices by species and fleet segment: constant; • Average days at sea by fleet segment: constant; • GRT by fleet segment: constant; • No effect on the fishing mortality by investments in technology. The technology is considered constant along the whole simulation period.
