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Assessing Marine Protected Areas

Seabird Insights

Dan Robinette


Santa Cruz Island, off southern California, is now a site of PRBO coastal seabird monitoring. Biologist Abigail Cannon scans for seabirds foraging near their colony. Photo by Cassie Bednar / PRBO.
Building on expertise assessing the health of ocean life, PRBO is contributing to an ambitious effort to sustain vulnerable wildlife and fisheries throughout California’s nearshore ocean waters. With passage of the Marine Life Protection Act (MLPA) in 1999, the state set out to establish the first true network of marine protected areas (MPAs) in the U.S.—a great challenge but crucial, as stresses on marine life mount.

PRBO provides insight into the marine ecosystem through studies of breeding seabird populations. This long-term work began on the Farallon Islands in 1968 and, in 1999, expanded to the coast of Vandenberg Air Force Base (near Santa Barbara); it now includes other coastal sites in central and southern California. Our science contributed to the process of designating the new MPAs, which soon will encompass critical zones in coastal waters from the Oregon border to the Mexican border.
Double-crested (left) and Brandt’s Cormorant in breeding plumage. Photo by Tom Grey.

Now begins the work of assessing whether the new MPAs are effective—no small task. PRBO is partnering with a new California agency, the Monitoring Enterprise, whose overarching goal is to take the pulse of the MPAs as they mature. By documenting changes that occur, the Monitoring Enterprise can evaluate how well MPAs meet their stated goals, leading to policy adjustments if needed. This approach is called adaptive management.

By taking an ecosystem perspective—encompassing entire marine communities, not just single species, and preserving natural processes—the new protected areas can act as a buffer to larger-scale threats due to climate change. PRBO is now applying and expanding our studies of coastally breeding seabirds to help understand community-level changes within the MPA network.

Seabird populations can register benefits from the establishment of marine protected areas: direct benefits include reduced interaction with humans, especially fisheries “bycatch” and disturbance to breeding and roosting sites; indirect benefits include reduced competition for prey resources.

Our work for the Monitoring Enterprise will likely embrace the entire MPA network. We began studying how seabirds use MPAs at Vandenberg Air Force Base in 2000 and have since begun monitoring sites from Bodega Head in central California to La Jolla in southern California, including Santa Cruz Island in the Channel Island chain. While we aim to monitor changes in breeding population size, reproductive performance, foraging rates, and rates of human-caused disturbance inside and outside of MPAs, we are also able to probe some oceanographic mechanisms that lead to community change within nearshore ecosystems.
On the cliffs of Santa Cruz Island, cormorants and other seabirds breed. At right, PRBO biologist Cassie Bednar works on the western edge of the island, in chilly springtime weather. Photos by Julie Howar / PRBO.

In studies at Vandenberg, we have found that seabird diet and foraging distribution are linked to variability in the arrival (or “recruitment”) of juvenile fish to nearshore habitat. This factor can be difficult to measure, but juvenile fish recruitment is a key factor in the changing populations of adult fishes. Our goal through this ongoing work is to better understand the ocean processes involved in young fishes’ arrival in nearshore habitats. This will help the Monitoring Enterprise and other ocean stewards explain the changes occurring within the maturing network of MPAs—and allow for adaptive management to improve the performance of the network as a whole.

California’s rich coastal waters provide many ecosystem services, from the seafood we eat to recreational and education opportunities to the potential for helpful scientific discovery. Informed management of nearshore ecosystems is vital to ensuring the availability of these services to future generations. Through our work with the Monitoring Enterprise and its many partner organizations, PRBO will develop indicators to help take the pulse of coastal ecosystems over time, providing ocean stewards with information needed to confront the large-scale changes on the horizon.