| dc.description.abstract | This study focused on the management of the red sea urchin Loxechinus albus fishery in
Chile. The main objective was to design, consuct, implement and assess a computerbased
simulation model to analyse the biological effects, socio-economic consequences
and spatial dynamics resulting from coastal management plans applied to this resource
under the system of AMEBR. This was accomplished by using systems dynamics (SD) and
geographical information systems (GIS) modellmg, in a process of model development,
run, optimisation, sensitivity analysis and risk management, and a series of fleid-based
activities carried out at the cove of Quintay.
The GIS model developed for allocating sea urchins restocking sites offered a flexible,
cost-effective, user-friendly and descriptive technique for support decision-making on
management of this species and other benthic resources. Final site selection for restocking
was based on the identification, quantification and selection of higher
suitabilityavailability combinations (site categories). This map showed 16 different
suitabilityavailability combinations or site categories, ranging from 4:100 to 8:100
(suitability pointsavailability %). These had an average of 6.446937 (covering an area of
82.5 Ha overali equivalent to 81.21% of the study area. This site classification
demonsfrated high heterogeneity between options, and revealed the fuli variety of
altematives for decision-making. More iinportantly, the generaily high suitability indexes
as well as available area emphasised the prospects for restocking sea urchins in this study
area.
Over and aboye of the quantitative outcomes obtained from running the GISRM (suitable
and available restocking sites) and the BSESM (alternative strategic management plans),
the case study-based analysis made it possible to disc lose the wider issues related to the red
sea urchin coastal management.
These results demonstrated the biological inefficiency of traclitional size/seasonal
restriction-based approach (macro-scenario 1) for sustainable management of the target
species. More importantly, final outcomes strongly suggested that a combination of
adaptive restocking-based enhancement activities and flexible exploitation constituted a
highly attractive approach (macro-scenario 3) for stock management of this fishery in
terms of harvestable stock and related incomes. However from the economie analysis, stocking was also found to be economically
unfeasible, bemg a rather cost intensive exercise negatively affected by high natural
mortality rates. A single-variable optimisation analysis demonstrated that a higher survival
rate is needed to generate sufficient profits to cover major restocking costs and a positive
payment, or a cost reduction is essential to make up for the loss.
On top to these practical constraints, based on the distinctive modest economic situation
prevailing for most Chilean co yes and hence their limited capacity to pay for stocking
material, unless adequate and constant funding is available to support artisanal
associations, they are vety unlikely to develop mass release programrnes.
Given the economic (i.e.: high operatmg costs) and technical (i.e: low survival rates)
limitations conditioning stocking-based management cost-effectiveness and applicability,
wide imp lementation of mass releases as a major approach for management of the red sea
urchin fishery is very unlikely to take place in Chile.
This study presents a methodology and offers a tool to design, evaluate and optimise
coastal management plans for the red sea urchin in a dynamic, interactive, systematic,
integrated and flexible way. The optional strategic management plans proposed on this
study may not be applied equally to any AMEBR, as they are the outputs arising from a
single cove-specific analysis. Still, the complete methodological framework and analysis
procedures developed may be applied to run the BSESM and optimise management of a
red sea urchin fishery at any other AMEBR case of study. | |
