Fish populations have shown signs of rebounding in state marine protected areas off California's Central Coast, but more time is needed for them to flourish, according to a recent study conducted by Cal Poly and the California Sea Grant.
The study examined the first seven years of monitoring of fish within four marine protected areas (MPAs) between San Francisco and Morro Bay.
Fishing within MPAs is generally prohibited or severely limited to allow refuges for fish species that are harvested commercially.
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MPAs make up about 18 percent of the state water territory.
“These marine reserves are going to work, but they’re not a short-term solution for commercial fisheries,” said the study’s lead author, Rick Starr, director of the California Sea Grant’s Extension Program.
Starr said that fish populations go up and down based on environmental conditions, and they’ve not detected much difference in populations inside and outside the protected areas.
“In the seven years of data examined, we didn’t see much change that could be attributed to the MPA status,” Starr said.
That could be partly due to reduced fishing pressure through regulations in non-protected areas, the scientists said.
However, Starr believes more time is needed to assess the newer MPAs.
In comparison, the much older Point Lobos State Marine Reserve, protected since 1973, is thriving with an abundance of fish.
Cal Poly biological resources researcher Dean Wendt, a co-author of the study, said about 20 fish per hour can be caught recreationally in Point Lobos near Monterey — compared to about seven fish per hour in the MPAs Año Nuevo (north of Santa Cruz), Piedras Blancas (between Morro Bay and Monterey) and Point Buchon (near Morro Bay). That’s an indicator that the Point Lobos zone is far more populated.
A director with theMorro Bay Commercial Fishermen’s Organization
, Jeremiah O’Brien, said that he has appreciated the collaboration between fishermen and scientists in the research.
But O’Brien said he’s skeptical about the type of ocean management that blocks off large areas off the coast from fishing.
“These MPAs were mandated by many who know nothing about fishing and less about ocean issues,” O’Brien said. “There are many management tools available, and this is a poor choice. Seven years and there is no difference — one would think that there would be some noticeable change no matter how small.”
O’Brien, however, added that “we have a lot of respect for Dean Wendt, and he always tries to include commercial fisherman in his work.”
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Starr and Wendt, who is dean of research in Cal Poly’sbiological sciences department
, coordinated with a team of marine researchers and more than 700 volunteer fishermen to sample fish within and outside of the protected areas.
The scientists attribute the study results to several factors, including the longer life and reproductive cycles of cold-water California fish, including some that live to be more than 50 years old and can take several years to reproduce.
However, lingcod, which take 3 to 5 years to mature, have seen increases in population within the MPAs, Wendt said.
Fish recruitment — meaning how well local juvenile fish are surviving — is another factor.
In some years, conditions can be right for juvenile fish to significantly add to the population, while in other years ocean currents channel them farther out to sea, where they die. In El Niño years, juvenile fish don’t have enough to eat.
Rockfish recruitment is particularly sporadic, meaning it can be more difficult to gauge how well the MPAs are working.
The idea behind the MPAs is that eventually the protected zones will contribute to a “spillover” effect in which species move from the protected areas to surrounding ocean vicinities to help grow populations.