Monterey Bay National Marine Sanctuary

ROCKY SUBTIDAL SYSTEMS   MBNMS Home Introduction Sancutary Program Accomplishments Intertidal Systems Rocky Subtidal Systems Open Ocean & Deep Water Systems The Physical Environment Wetlands and Watersheds Endangered & Threatened Species Marine Mammals Bird Populations Marine Mammals & Bird Surveys Harvested Species Human Interactions Further Reading Credits Research on Rockfishes, Habitats, and the Fishery at Big Creek Ecological Reserve Big Creek Ecological Research Reserve (BCER), an area off the Big Sur coast that officially has been closed to fishing since January 1994, affords a good opportunity to evaluate the contribution that a small marine protected area (MPA) might make to the surrounding environment. The California Sea Grant College System, on behalf of the Department of Fish and Game's (DFG) Marine Ecological Reserves Research Program, currently has funded three studies to evaluate fisheries resources in this area. Two research studies are currently using side scan sonar, bathymetry, and underwater video transect methodologies in and out of BCER to characterize and quantify benthic fish and their habitats. A third study is using social science research methods to examine the relationship between nearby fisheries and the reserve and to evaluate a cooperative data collection system involving local fishers and the reserve manager. During one of these studies, two cruises were conducted by biologists from the DFG's Central California Marine Sport Fish Project aboard the research vessel (R/V) Mako in 1998. Fish populations and seafloor habitats were surveyed using scuba and laser-scaled video. From preliminary analysis, mean fish densities within BCER, to the north, and to the south have remained generally stable from 1996 to 1998. Greater numbers of large sexually mature individuals occurred within BCER than in adjacent areas. A nearshore habitat map of seafloor within BCER (Figure 1) has been completed with cooperation from ABA Consultants. This map was produced from data collected with RoxAnn (an echosounder that indicates substratum roughness and hardness) and a depth sounder on board DFG vessels P/B Bluefin and R/V Melanops. Nine distinct substrate types (and percent coverage) have been identified: sand (23%); rock (20.3%); rock w/turf (20%); gravel (19.6%); rock w/sand (7.1%); biota (5.5%); sediment (4.2%); unknown (1.2%); compacted (<1%). The second study involved the coordinated effort of biologists and geologists from NMFS Pacific Fisheries Environmental Lab, Moss Landing Marine Labs, and DFG. Twenty-eight research dives were made in water depths from 30-270 m inside and outside BCER using the Delta occupied submersible and R/V McGaw. Habitat type and associated fishes were surveyed at about twelve sites in the BCER study area. Several distinct assemblages of fishes have been described in general. Large schools of young-of-the-year (YOY) rockfishes were documented in rock areas of 40-120 m depth; low relief fields of coarse sand and sea pens in about 70 m of water appeared to be a nursery ground for YOY stripetail rockfishes. Adult fishes of small species were associated with sand, fine sediments, and shell-hash substrata of low relief, while large species, especially rockfishes, were closely associated with rock crevices, small caves, and boulders/pinnacles (Figure 2). Bottom types included: rock outcrops primarily in 40-70 m of water; isolated rock pinnacles and single boulders up to 20 m in height and surrounded by sediment; steep rock walls in the head of submarine canyons outside BCER; fields of coarse sand and sea pens; boulder fields; and soft sediment in deep water. With funding from the MBNMS, maps from the deep water study have been developed and eventually will be merged with similar information from the shallow study into one comprehensive map of fishes and habitats of BCER. In a third study, UC Santa Cruz researchers have conducted interviews with local fishers, collected observational and archival data on the relationship between the reserve and nearby fisheries, and begun to analyze fishery-dependent data collected by local fishers in cooperation with the reserve manager (through their "hook-and-line survey"). Preliminary analysis of shore-based observation of fishing activity north and south of the reserve and of Pacific Fisheries Information Network data suggests that fishing activity does not increase with proximity to the reserve, even though such an MPA "edge effect" might be expected. Data collected through interviews and from archival sources are being used to develop explanations for the observed patterns of activity. The hook-and-line survey data - which have been collected since three years prior to the reserve's legal establishment - together with interview data, are being used to evaluate the local fishery, its interaction with the reserve, and the potential value of the cooperative arrangement to resource management. Diver Disturbance in Kelp Forests Recreational SCUBA diving activity has greatly increased in the past twenty years, with the potential for causing disturbance to subtidal reefs. While diver disturbance on coral reefs has been assessed in a number of studies, effects on kelp forests have not been previously examined. Researchers from Moss Landing Marine Laboratories estimated diver disturbance in southern Monterey Bay giant kelp forests by following forty-two divers in summer 1997 and recording disturbances they caused. During a one-half hour dive, the average diver contacted the bottom forty-three times, touched four animals, and detached two algal blades. It is estimated that over 60,000 divers use these kelp forests every year. The study's initial results, released in early 1998, suggest that the concentration of large numbers of divers in local, usually wave-protected kelp forests could lead to alterations in community structure. Such effects might be mitigated through more environmentally aware diving promotion, better training, and designation of ecologically resilient shore entry and exit points and underwater training areas. Of these recommendations, the Sanctuary is pursuing, with local and national dive organizations, the development of educational programs and products to ensure that diver effects within kelp forests are reasonably minimized. Tim M. Schaeffer and Michael S. Foster Moss Landing Marine Laboratories Results of these studies are important in the resource assessment and management of BCER, and will contribute to our understanding of the role that habitats within an MPA play in maintaining populations of marine fishes that are being harvested in unprotected areas. From a social scientific perspective, monitoring the fisheries adjacent to BCER will help us understand the dynamic relationship between MPAs and local fisheries. In particular, assessing the spatial and temporal patterns of both the fishes and fisheries associated with MPAs will contribute to effective design, management, and evaluation of MPAs. The results of all three studies will be especially valuable to the long-term characterization and monitoring of the natural and human resources of the Sanctuary. Mary Yoklavich NMFS Pacific Fisheries Environmental Laboratory David VenTresca California Department of Fish and Game Caroline Pomeroy University of California Santa Cruz Kelp Habitat The rocky nearshore environment of the Monterey Bay National Marine Sanctuary is characterized by forests of giant kelp (Macrocystis pyrifera) and bull kelp (Nereocystis leutkeana) that occur on rocky substrates at depths of two to over thirty meters. These forests are host to a rich mosaic of benthic algae and provide habitat for numerous fish and invertebrate species. Although giant kelp is perennial, in Central California its populations exhibit seasonal patterns of abundance, attaining maximum surface canopies in summer and minimum canopies in winter. Increased water motion from winter storms, coupled with entanglement with drifting plants, appears to be the primary source of annual giant kelp mortality along much of its distribution. During 1997 and 1998, several local research programs examined the effects of both natural and anthropogenic disturbances on Central California's kelp forest communities. The 1997-98 El Niño event, one of the most severe in recent history, resulted in abnormally warm water and strong swell activity along much of California's coast. Whereas the majority (up to 100 percent in many areas) of the adult giant kelp occurring south of Point Conception was removed during this period, populations along Central California (including the Sanctuary) were relatively unaffected. The most dramatic reductions in kelp density in this region were observed along the Big Sur coast, where populations are less protected from the large ocean swells. In this region, although giant kelp densities remained fairly high, there appeared to be a shift in relative species abundance after the storms; giant kelp tended to decrease in abundance while bull kelp increased. A similar shift was observed after the 1982-1983 El Niño. The large disparity observed between southern and Central California was most likely due to large-scale oceanographic differences between the two regions. In southern California, unusually warm ocean temperatures and associated low nutrients probably resulted in the giant kelp being in generally poor condition when the large swells arrived, leading to extremely high kelp mortality. In contrast, the cooler ocean temperatures and higher nutrients along Central California may have allowed the kelp to remain in comparatively better condition when the swells arrived, resulting in much higher survival. Other research programs around the Sanctuary have examined additional factors that may potentially impact its kelp forest communities. For example, Moss Landing Marine Laboratories researchers are examining the effects of commercial kelp harvesting on the giant kelp surface canopy along the Monterey Peninsula. Their study should elucidate the comparative effects of kelp removal by anthropogenic and natural processes. Matthew S. Edwards University of California Santa Cruz (Note: kelp as a harvested resource is discussed on page 22.)

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Last modified on: June 1, 1999