In the zone: conserving marine life through spatial planning
Marine
Gulf of the Farallones National Marine Sanctuary off the coast of California. Image credit, Jan Roletto.A new planning tool proposed by researchers may help us take the concept of zoning and apply it to resource use in the sea to conserve marine life.
Protected areas come in all shapes and sizes, from fully protected reserves to limited access zones. In the oceans, these areas are, with few exceptions, scattered specs in a largely unregulated sea. The result has been collapse of fisheries and great loss of biodiversity worldwide.
A new emphasis on ecosystem-based management is trying to change this, by using spatial zoning to balance biodiversity conservation with fisheries management and other resource uses. Instead of juggling piecemeal regulations that target one species or industry and often conflict, zoning allows for a holistic management plan for each ecosystem. The hops is that this can more effectively conserve biodiversity while minimizing impacts to fisheries, recreation, and other industries.
To achieve this, scientists need to cost-effectively stitch together multiple types of protected areas to create zones that will meet these complex objectives. The trouble is, most tools for designing reserves can only analyze one kind of reserve at a time. The new planning tool, proposed in the journal, Frontiers in Ecology and Environment, offers a powerful way to design multiple-types of protected areas while minimizing impacts to industry.
How It Works...
“Marxan with Zones” is a planning approach that can simultaneously design different types of protected areas (see separate paper Watts et al., in press for details on the program) while accounting for specific constraints, such as fisheries targets.
The researchers applied this planning tool to data from California’s Marine Life Protection Act Initiative. The authors created five zones, one of which was assigned to each of 3610 planning units along the central California coast: Zone 1 was a fully protected no-take reserve; Zones 2-4 restricted different types of fisheries; and Zone 5 allowed all 8 commercial fisheries. Two scenarios were then run, both minimizing the cost (defined as the sum of the commercial value of fisheries excluded from a particular zone):
- Scenario 1 designed a network of reserves that placed 10% of the distribution of each biodiversity feature in a no-take reserve and an additional 20% of each feature in any of the four protected Zones (1-4).
- Scenario 2 kept the same biodiversity conditions but added an additional constraint: a certain percentage of each fishery’s value had to be maintained.
What they found...
Using Scenario 2, fishing targets of up to 91% (a maximum loss of 9% for each fishery) could be achieved by all fisheries without sacrificing any of the biodiversity outcomes. Not including the fisheries targets (Scenario 1) led to three fisheries having higher losses than the other five (a less equitable result). Both of the scenarios had similar total losses for all commercial fisheries. This total loss was much less than the result from the original Marxan program (which optimized only a single-type of reserve - no-take).
By allowing for constraints to be added, Marxan with Zones provides scientists with the ability to test how specific conditions (such as trade-offs between recreational and commercial fisheries) will affect overall ecological and socioeconomic goals. This flexibility should help conservation planners.
--Reviewed by Marah Hardt
| Source: | Frontiers in Ecology and the Environment |
| Title: | Spatial marine zoning for fisheries and conservation |
| Authors: | a) Carissa Joy Klein, b) Charles Steinback, a) Matthew Watts, b) Astrid Scholz, and a) Hugh Possingham |
|
a) University of Queensland, St. Lucia, Australia |
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