SpearMax
07-16-2008, 05:23 AM
I thought these observations about MPAs would interest everyone. This small article comes yesterday in an MPA publication from fish scientist Dr. Ray Hilborn, a very respected individual in the fish science community.
* Cost of MPAs as a fisheries management tool *
Ray Hilborn, a fisheries scientist at the University of Washington (US) who
serves as an advisor to several international fisheries commissions, says
no-take marine reserves are often an inefficient tool for fisheries
management. That is, compared to traditional fisheries management
techniques (e.g., restrictions on gear, fishing times, fish size), reserves
can confer greater costs with fewer benefits (in the form of reduced
catches) depending on a variety of conditions.
Hilborn was asked to compare the costs to industry if traditional management
methods were used in one sample area while no-take reserves were used as a
fishery management tool in another, otherwise-equivalent area. "If there is
well-directed catch regulation in one area and MPAs only in another area,
then one would expect a 'good' outcome in the 'traditional' area, with
stable stock sizes and economic profitability, as found in our better
managed fisheries," says Hilborn. "In contrast, using no-take MPAs only,
you would find sedentary species almost exclusively inside the MPAs and
severely overfished everywhere else. Highly mobile species of significant
economic value would be depleted everywhere." Under this scenario, he
suggests, adjacent ecosystems (as well as fishermen) would bear costs of the
reserve. In reality, notes Hilborn, almost all Western countries combine
MPAs and "traditional" techniques in their fisheries management strategies.
Still, it is possible that long-term benefits to fisheries from a marine
reserve can outweigh the short-term costs. Hilborn, who with Raquel Goņi is
studying the effects of spillover from Spain's Islas Columbretes Marine
Reserve on local lobster catches, confirms this. "It depends primarily on
the fishery management system outside the reserves," he says. "The poorer
the fishery management system, the more likely it is that the fishery will
be better off with the reserves." He also acknowledges that some reserves
are designated primarily to protect biodiversity, and not as a tool to help
manage fisheries and produce higher fish catches. Deciding what is optimal
in terms of costs and benefits therefore depends on your objectives, he
says.
Hilborn has partnered with fisheries scientists Carl Walters and Chris
Costello to produce modeling work for the Marine Life Protection Act (MLPA)
process that is planning a network of marine reserves in the US state of
California. "In our MLPA work, we have found win-win circumstances, where
you get higher catch, catch-per-unit-effort, and abundance [as well as
biodiversity protection]," says Hilborn. "This can occur when you have a
source-sink dynamic in the larval dispersal. In those cases you want to
protect the larval sources, while fishing in the sinks. The question is
whether we know enough about larval dynamics to identify those spots."
* Cost of MPAs as a fisheries management tool *
Ray Hilborn, a fisheries scientist at the University of Washington (US) who
serves as an advisor to several international fisheries commissions, says
no-take marine reserves are often an inefficient tool for fisheries
management. That is, compared to traditional fisheries management
techniques (e.g., restrictions on gear, fishing times, fish size), reserves
can confer greater costs with fewer benefits (in the form of reduced
catches) depending on a variety of conditions.
Hilborn was asked to compare the costs to industry if traditional management
methods were used in one sample area while no-take reserves were used as a
fishery management tool in another, otherwise-equivalent area. "If there is
well-directed catch regulation in one area and MPAs only in another area,
then one would expect a 'good' outcome in the 'traditional' area, with
stable stock sizes and economic profitability, as found in our better
managed fisheries," says Hilborn. "In contrast, using no-take MPAs only,
you would find sedentary species almost exclusively inside the MPAs and
severely overfished everywhere else. Highly mobile species of significant
economic value would be depleted everywhere." Under this scenario, he
suggests, adjacent ecosystems (as well as fishermen) would bear costs of the
reserve. In reality, notes Hilborn, almost all Western countries combine
MPAs and "traditional" techniques in their fisheries management strategies.
Still, it is possible that long-term benefits to fisheries from a marine
reserve can outweigh the short-term costs. Hilborn, who with Raquel Goņi is
studying the effects of spillover from Spain's Islas Columbretes Marine
Reserve on local lobster catches, confirms this. "It depends primarily on
the fishery management system outside the reserves," he says. "The poorer
the fishery management system, the more likely it is that the fishery will
be better off with the reserves." He also acknowledges that some reserves
are designated primarily to protect biodiversity, and not as a tool to help
manage fisheries and produce higher fish catches. Deciding what is optimal
in terms of costs and benefits therefore depends on your objectives, he
says.
Hilborn has partnered with fisheries scientists Carl Walters and Chris
Costello to produce modeling work for the Marine Life Protection Act (MLPA)
process that is planning a network of marine reserves in the US state of
California. "In our MLPA work, we have found win-win circumstances, where
you get higher catch, catch-per-unit-effort, and abundance [as well as
biodiversity protection]," says Hilborn. "This can occur when you have a
source-sink dynamic in the larval dispersal. In those cases you want to
protect the larval sources, while fishing in the sinks. The question is
whether we know enough about larval dynamics to identify those spots."