It is early summer on California’s Central Coast, and Pigeon Guillemots are rushing back and forth between their breeding crevices along the rocky shore and the kelp beds nearby. With chicks to feed, the birds are actively foraging on juvenile fishes concentrated just offshore.
|A popular landing spot for guillemots, with their catch. Photo by Ron LeValley.|
Hoards of small rockfish, having drifted at sea as planktonic larvae over the past winter, arrived on springtime currents in the nearshore habitats where they will grow to adult size. This process revitalizes California’s nearshore fish populations and provides an important food resource for coastally breeding seabirds raising their rapidly growing young.
PRBO is investigating the relationship between the seabirds and their prey to help understand the health of fish populations-and to support new efforts in California to conserve vital nearshore ecosystems.
Through the Marine Life Protection Act (MLPA), California is establishing a network of marine protected areas (MPAs). The goal is to sustain nearshore resources for the continued benefit of wildlife and humans over time. The state will need to determine whether or not the MPAs are serving their purpose. PRBO’s science can assist in this.
The management approach mandated by the MLPA is “ecosystem-based” and considers all major components, from plankton and small invertebrates to top predators including seabirds. It recognizes that the recovery of fish populations will depend not only upon changes in human behavior but also on natural processes. One such natural event is the arrival each spring of swarms of juvenile fish nearshore. Without this, even an area closed to fishing will not see the adult population grow.
|Sites where PRBO monitors coastally breeding seabirds offer a vantage onto the nearshore marine ecosystem. PRBO photo.|
PRBO has two powerful ways of helping California achieve ecosystem-based management of MPAs. In ocean-going research (ACCESS, explained below) we study plankton abundance at sea. At coastal seabird colonies we measure foraging rates and breeding success. Thus we can understand patterns of fish abundance as larval plankton and as juveniles joining adult populations-both important to population recovery.
The MLPA also calls for “adaptive management” or periodic evaluation of MPAs and, if they fall short of their goals, adjusting strategies. But not all sections of coastal California respond equally to protection. Areas where lower concentrations of larval fish occur will likely not respond as quickly to protected status.
As scientific partners helping evaluate MPAs, PRBO has emphasized the need to ask scientific questions in order for adaptive management to succeed. What changes are expected as a result of establishing a Marine Protected Area, and roughly how quickly should these changes take place? If realistic expectations are not established up front, managers may falsely assume that a given MPA is not working.
The vital indicators that PRBO studies-from plankton to great whales surveyed at sea, and seabirds that we monitor in coastal colonies-will help us address these focal questions.
We have partnered with the Gulf of the Farallones and Cordell Bank National Marine Sanctuaries to create ACCESS-Applied California Current Ecosystem Studies
(Observer 163, Winter 2011). This ocean-going reseach enables us to gain knowledge at varying scales, compare protected areas with sites outside them, and support California’s monitoring effort for MPAs.
Along the coast, as we gather data on guillemots, cormorants, and other breeding seabirds, we gain understanding of when and where juvenile fishes are delivered into their nearshore adult habitat.
Importantly, we are gaining insight into mechanisms that will govern change within California’s new MPAs. We hope this will help establish realistic expectations for the responsible management of our marine ecosystem.