Pressures on the Sanctuary
The number of people living near the coastal zone and using its resources has significantly increased (U.S. Census Bureau 2000 Web site). This urbanization has increased human demands on the ocean, including commercial and recreational fishing, tourism, and other activities. A burgeoning coastal population has greatly increased the use of coastal waters as receiving areas for human, industrial, and agricultural wastes. In addition, new technologies for fishing have placed pressure on fish populations and are partly responsible for declining stocks (Jackson et al. 2001). Concurrently, there have been fluctuations in weather and climate, including phenomena such as El Niño weather patterns and oceanographic regime shifts (McGowan et al. 1998, Mantua and Hare 2002).
The proximity of the Channel Islands to the mainland coast makes them accessible from Santa Barbara, Ventura, Port Hueneme, and Channel Islands Harbors, as well as from ports in Los Angeles County. Also, human use of the sanctuary is not limited to regional residents; almost 20 percent of those who use California’s coastal areas for recreation are interstate or international visitors (Resources Agency of California 1997). In addition, population growth in Southern California has risen sharply over the last 20 years. The two counties adjacent to the sanctuary, Santa Barbara and Ventura, have a combined population of over 1.1 million and more than 20 million people live in the greater Southern California Bight region (U.S. Census Bureau 2000 Web site). As the number of people increases, the number of potential sanctuary users who may engage in a wide variety of activities, also increases.
Commercial and Recreational Fishing
The combination of direct take, bycatch, indirect effects, and habitat damage and destruction has adversely affected the marine environment around the Channel Islands. In the Channel Islands area, commercial and recreational fisheries target more than 100 fish species and more than 20 invertebrate species (Figure 14). Targeted species have exhibited high variability in landings from year to year and several species have seen extensive declines in catch (Dugan and Davis 1993, Love et al. 1998, Rogers-Bennet et al. 2004). Bycatch, defined here as unintentional take of non-target species, may be significant for some fisheries (Harrington et al. 2005). Fishing can alter ecosystem structure by removing species that play key ecological roles (Dayton et al. 1995, Tegner and Dayton 2000). Some types of fishing gear can cause temporary or permanent damage to marine habitats. The abrasive contact of mobile fishing gear with the seafloor, particularly trawling and dredging gear, can damage or destroy benthic habitats and fauna (Jones 1992, Watling and Norse 1998).
Commercial Fishing
Many targeted species have seen historic declines in catch at the Channel Islands. For example, abalone populations were severely depleted resulting in closure of the fishery in 1997. All species of abalone are now uncommon in the sanctuary (except red abalone at San Miguel Island) as a result of disease and overfishing. Both white and black abalone are on the federal endangered species list (Hobday et al. 2001, Rogers-Bennet et al. 2004, http://swr.nmfs.noaa.gov). A number of rockfish species have also seen dramatic declines (Love et al. 1998) that have resulted in bottom fishing closures in large areas of the sanctuary. Of the sanctuary’s commercially caught species, market squid, sea urchin, spiny lobster, and halibut are some of the most economically valuable. Commercial fishing gear used in the sanctuary includes nets, traps, lines, and dive equipment. Most recent data (from 2001) shows that approximately 450 commercial vessels fish in the sanctuary (Leeworthy and Wiley 2003) with most of the vessels concentrating close to the islands (Senyk et al. 2008).
Recreational Fishing
Recreational fisheries have seen declines in catch of rockfish and other species, partly as a result of overfishing (Love et al. 1998). Recreational fisheries in the sanctuary access both nearshore and offshore areas, using hook-and-line and spearguns to target bottom and mid-water fish species. Invertebrates are harvested with traps, hand-capture, and nets – these activities may be conducted from shore or vessels, or by freediving or using scuba equipment. Recreational fishing is primarily in the eastern half of the sanctuary that lies within easy boating distance to the mainland (Senyk et al. 2008) indicating that these areas may receive heavier recreational fishing pressure.
Shipping and Boating
Heavy vessel traffic creates the possibility of collision with large marine mammals, and noise from vessels may affect marine animals. Illegal discharge of oil, sewage, and other non-biodegradable materials from vessels in the sanctuary pose a threat to sanctuary resources, as well as air and water polluting activities that occur beyond the boundaries of the sanctuary. Spills may result from vessel groundings, sinkings, and plane crashes. Ballast water of cargo ships may transport non-indigenous species that, if released, could be damaging to sanctuary ecosystems.
Commercial shipping is prevalent in the sanctuary. Over 7,000 vessels transited the Santa Barbara Channel in 2005 (Santa Barbara County Air Pollution Control District 2006). The container trade at the Port of Long Beach has grown 150 percent since 1990 and is expected to continue to increase over the long term. However, the industry tends to track the economic climate and as such experienced an approximate 10% decline in 2008 (D. McKenna, 2008, Marine Exchange of Southern California, pers. comm.) The Santa Barbara Channel is a main thoroughfare, with the shipping lanes passing through a portion of the sanctuary. However, large cargo ships (greater than 300 gross registered tons) are prohibited by sanctuary regulation from entering waters within one nautical mile of the islands.
Smaller vessels are also prevalent in the sanctuary. Nearby harbors contain over 5,000 slips used by smaller recreational, commercial, and research vessels. Wildlife viewing, sailing, diving, and fishing trips take place year round, but whale watching is especially popular in the winter and spring during gray whale migratory season. Sanctuary visits by private boaters are expected to increase as the coastal population grows.
A higher volume of shipping traffic and larger commercial ships have caused anthropogenic noise in the ocean to increase over the past few decades (Andrew et al. 2002). In Southern California in particular, ocean noise has increased significantly since the 1960s (McDonald et al. 2006). Although large commercial ships account for most of this increase, other sources of noise are military activities, construction, oil and gas production, and smaller boats. Effects from high decibel noise, especially at close range, can cause acute physiological effects in living marine resources, such as tissue damage in lungs and ears and ruptured or hemorrhaged body parts (
Evans and England 2001, reviewed in Polefka 2004). Other effects include masking of important signals (such as those used for echolocation, intra-species communication, and predator-prey cues) (Southall 2005), behavioral alterations (such as changes in migration patterns or abandonment of important habitats), and adverse effects to animal energy and physiology (Richardson and Wursig 1997, Ketten 1998). Fish and invertebrates may experience damage to eggs, reduced reproduction rates, and physiological or morphological damage (Myrberg 1990, Hastings 1991).
Offshore Oil and Gas Industry
Spills from oil platforms operating close to sanctuary boundaries and effects of oil production on water quality are of concern. Since the sanctuary was designated, all new oil and gas exploration, development, and protection activities are prohibited within sanctuary boundaries. However, there are 39 developed or active leases in the Channel Islands region. Two of these lease tracts that pre-date sanctuary designation slightly overlap the sanctuary at its eastern boundary; the rest are outside of the sanctuary (Figure 15).
Before sanctuary designation, an oil platform spill in 1969 released 200,000 gallons of oil into the Santa Barbara Channel. Although spill response contingency plans and improved platform technologies and practices are now in place, such spills remain a threat to the sanctuary. Oil and chemical spills in the sanctuary region can result from accidents associated with oil production and could range from small, localized spills to large events that span hundreds of kilometers of coastline. A large spill could have a major impact on foraging birds, marine mammals, fishes, and kelp, as well as wetlands and rocky shores, and on tourism and the coastal economy.
The region is also known for natural hydrocarbon seeps. Natural oil seeps at Coal Oil Point in the Santa Barbara Channel are estimated to discharge approximately 150-170 barrels (6,300-7,140 gallons) of oil per day (Hornafius et al. 1999). Some of this hydrocarbon discharge enters the sanctuary and affects water quality.
Climate Change
Climate change is projected to profoundly affect coastal and marine ecosystems on a global scale, and the Channel Islands sanctuary is expected to manifest the consequences as well. The Channel Islands are at a transition zone between cold northern currents and warm southern currents (Figure 16). Geographic position and variability in the transition zone are important drivers of community structure. Changes in that boundary driven by large-scale climate alteration can be expected to have correlated large scale changes in the marine community. These community changes may occur as a result of habitat changes and shifts in species ranges; the Channel Islands are a northern or southern range limit for many species. In addition, many local species have multiple, different habitat requirements within their life-histories making access to the diversity of conditions seen in the sanctuary a critical component of ecosystem health. Furthermore, climate change could affect species through changes in phenology and disease ecology. For example, reproductive performance of Cassin’s Auklets may be affected by oceanographic conditions and prey availability during breeding seasons (Adams et al. 2004) and alterations due to climate change may exacerbate these conditions. In addition, although the red abalone population at San Miguel Island does not exhibit symptoms of withering syndrome, at least half of the population harbors the infectious bacterium responsible for the disease (CDFG 2007). It appears that the symptoms are more prevalent in populations located in warmer water; therefore, increases in seawater temperature may lead to outbreaks of the disease.
The region is affected locally by climatic short-time scale events such as El Niño-related sea surface temperature anomaly and upwelling variability (McGowan et al. 1998), and decadal-scale variability such as the Pacific Decadal Oscillation (Mantua and Hare 2002). Upwelling variability, driven by variability in the path of the atmospheric jet stream, combined with local El Niño anomalies (Bane et al. 2007), is an important driver of zooplankton productivity and food web integrity on the scale of the California Current (Barth et al. 2007). Changes in upwelling driven by climatic alteration, such as changes in jet stream intensity and trajectory (Archer and Caldiera 2008), can therefore be expected to have a direct impact on ecosystem health in the Channel Islands sanctuary. Other possible threats from climate change include changes in ocean chemistry and sea level rise.
Large scale changes in ocean chemistry, and acidification specifically, are increasingly recognized as threats. The impacts are expected to be intense and widespread – particularly at the bottom of the food web where trophic processes are so tightly coupled to environmental chemistry (Hays et al. 2005, Fabry et al. 2008). The impacts of climate can be expected to be profoundly transformative and widespread across all components of the ecosystem. However, specific, reliable forecasts are still not possible. An important contributor to forecast uncertainty is that the important drivers for climate alteration, greenhouse gas emissions, have exceeded even the most extreme predictions of the last 10 years (Raupach et al. 2007). Without reliable forecasts of the ecosystem drivers, confident predictions of ecosystem changes will be impossible.
Pollutants and Marine Debris
Poor water quality can cause illness or disease, impair condition and reproductive capacity, and decrease productivity in marine organisms. It can also endanger human users of the sanctuary. Sources of water quality impairment in the sanctuary are land-based discharges from the mainland and the islands (for example, runoff can include sediment, bacteria, and agricultural-based chemicals such as pesticides and herbicides), vessel discharges from recreational, commercial, and industrial vessels (sewage, bacteria, and marine debris), and discharges associated with oil production (Engle 2006). Nonpoint source pollution from the mainland may reach the eastern portion of the sanctuary (Anacapa and Santa Cruz Islands) during major runoff events via plumes from the Ventura and Santa Clara Rivers (Engle 2006) (Figure 17). Agricultural and urban runoff, as well as effluent from municipal wastewater treatment plants, may be some of the sources of pollution from the mainland that reach the sanctuary. Because pollutants can be carried to the sanctuary by ocean currents, or transported through the food chain, the spatial extent of water quality threats is much larger than the sanctuary itself. For example, the pesticide DDT was manufactured in Los Angeles until the early 1970s and discharged into the ocean off the Palos Verdes peninsula. The chemical-contaminated fish within those waters were in turn eaten by seabirds and marine mammals. This affected foraging communities throughout Southern California, including the Channel Islands, long after the chemical production stopped. Levels of DDT and a derivative DDE are still measurable in sediments. Some wildlife species such as bald eagles are only now beginning to recover.
Marine debris threatens sanctuary resources. Marine animals are harmed by ingestion of or entanglement in marine debris (reviewed in Derraik 2002). Debris can also endanger divers and boaters. Typical debris includes lost fishing gear, household and industrial plastics, and styrofoam. These forms of debris can originate from land, offshore vessels, or may be transported from distant sources in currents. Marine debris is a worldwide problem due to the many potential sources of debris, longevity of debris (especially plastics) in the marine environment, and continuing impacts caused by debris even as they degrade to smaller particles.
Visitor Use
Visitors can affect sanctuary resources through activities such as harvesting, polluting, littering, disturbing wildlife, anchoring in sensitive habitats, and trampling. The sanctuary is located close to the heavily populated area of Southern California where population growth has risen sharply over the last 20 years. As the population increases, so does the potential number of sanctuary users who may engage in a variety of activities such as fishing, marine wildlife viewing, boating, snorkeling, diving, and kayaking (Figures 18,19).
