Kate Wing's Blog
MPAs make a difference
February 11, 2008
Posted by Kate Wing in Reviving the World's Oceans
Last Friday, the public got the first look at the results of five years of monitoring at California's Channel Islands and those data are fascinating. Considering the decades-long lifespans of many of our west coast rockfish, it was unclear how much change we might be able to observe in only five years. Turns out, what mom always told you about that scab is true: if you stop picking at it, it'll heal. Here are some of the most interesting tidbits, linked to PDFs of the summaries. You'll find all the presentations here.
- Lobsters seemed to benefit the most from reserves, with substantially more lobsters inside reserves than outside. Matt Kay gave a great presentation on these results, which result from an impressive partnership between scientists and local lobster fishermen called CaLobster. Matt's summary isn't up yet but should be later today.
- Species diversity is greater inside the reserves, with an average of one more species inside than out. ROV surveys, which reached areas inaccessible to divers, found a greater abundance of many fishes like California sheephead, lingcod, copper and gopher rockfish. Differences were greatest for species that are fished.
- The annual number of trips by sportfishing party boats -- aka CPFVs or "six-packs" -- to the northern Channel Islands decreased between 1998 and 2003, prior to the creation of the Channel Islands MPAs. Since 2003, the annual number of trips has increased slightly in both the Channel Islands and southern California
- For California sheephead and kelp bass, abundance is higher towards the center of reserves and declines towards the boundaries. This pattern could result from fishing at the edges of reserves or variations in habitat. It could also be due to the territorial nature of the fish, where a fish whose home turf is completely within the reserve boundary is never exposed to fishing, while a fish whose range is bisected by the boundary can be hauled in during part of its daily routine.
- Even highly mobile fish gained some benefit from the reserves. Giant seabass tagged in the islands spent about 25% of their time inside one reserve or another.
There were also a number of studies where the results were unclear, since the 12 Channel Islands reserves were just one of the many changes in Southern California over the last five years. From the fallout of the groundfish disaster to El Nino conditions, there were larger changes afoot that swamped our power to detect what changes are attributable solely to the new MPAs. Still, the take home message seems to be that our investment is paying off, including our investment in monitoring.
The Channel Islands MPAs galvanized funders, fishermen, and scientists to focus their energies on the region. I'd say that in another five years, we'll understand more about the complexities of these nearshore ecosystems than we've learned from decades of traditional, single species stock assessments. We're getting another step closer to managing fish and fishermen as they really are in the sea, not just as mathematical abstractions.
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