Further evidence has emerged to support the importance of Marine Protection Areas (MPAs). Recent research provides evidence, for the first time, that larval fish migrate from MPAs and re-seed fish stocks more than 100 miles away.
Marine ecologists from Oregon State University centred their research around the Yellow tang, Zebrasoma flavescens. The species, which is well known to almost every marine aquarium keeper, was chosen as it is not a migratory fish once the larvae have settled onto a reef – living in a range of about half-a-mile in diameter. Thus, if members of the species were to migrate outside of the protection area, it would have to be as larvae, which can drift in ocean currents for up to two months.
Zebrasoma flavescens accounts for 70% by value (80% by number) of all the fish collected for the aquarium trade from the Island of Hawai’i, with only juveniles targeted. This pressure resulted in nine Marine Protection Areas being set up around the Kohala-Kona coast in 1999.
Over the subsequent years it became evident that there was an increase in adult Yellow tangs just outside of the MPAs, demonstrating success. However, there was also an increase in the capture of juvenile Yellow tangs in those areas that weren’t protected, suggesting that the non-protected areas were being seeded by larvae from the MPAs.
To provide evidence to support the findings lead author Mark Christie developed a new approach that employed the Bayesian interpretation of probability, and DNA fingerprinting and sophisticated analysis were able to show that many juvenile fish had travelled up to 114 miles away from their parents, some of which were sampled from protected areas.
"This is similar to the type of forensic technology you might see on television, but more advanced," Christie said. "We're optimistic it will help us learn a great deal more about fish movements, fishery stocks, and the genetic effects of fishing, including work with steelhead, salmon, rockfish and other species here in the Pacific Northwest."
Mark Hixon, a professor of marine biology at OSU says, "We already know that marine reserves will grow larger fish and some of them will leave that specific area, what we call spillover, now we've clearly shown that fish larvae that were spawned inside marine reserves can drift with currents and replenish fished areas long distances away.
"This is a direct observation, not just a model, that successful marine reserves can sustain fisheries beyond their borders," he said. "That's an important result that should help resolve some skepticism about reserves. And the life cycle of our study fish is very similar to many species of marine fish, including rockfishes and other species off Oregon. The results are highly relevant to other regions."
For further information see the paper, available via PLoS ONE: Christie MR, Tissot BN, Albins MA, Beets JP, Jia Y, et al. 2010 Larval Connectivity in an Effective Network of Marine Protected Areas. PLoS ONE 5(12): e15715. doi:10.1371/journal.pone.0015715