MARINE RESERVES. A BIO-ECONOMIC MODEL WITH ASYMMETRIC DENSITY DEPENDENT
Armstrong, Claire W.
A static bioeconomic model of a marine reserve allowing asymmetric
density dependent migration between the reserve and the fishable area
is introduced. This opens for habitat or ecosystem differences allowing
different fish densities within and outside a reserve, not described
in earlier studies. Four management scenarios are studied; a) maximum
harvest, b) maximum current profit, c) open access and d) maximum sustainable
yield (MSY) in the reserve. These are all analysed within the Induced
Sustainable Yield Function (ISYF), giving the relationship between the
fish abundance inside the reserve and the harvesting taking place outside.
A numerical analysis shows that management focused on ensuring MSY within
the reserve under the assumption of symmetric migration may be negative
from an economic point of view, when the area outside the reserve is
detrimental compared to the reserve. Furthermore, choice of management
option may also have negative consequences for long run resource use
if it is incorrectly assumed that density dependent migration is symmetric.
The analysis also shows that the optimal area to close, either a more
or a less attractive ecosystem for the resource in question, may differ
depending on the management goal.