Pressures on the Sanctuary
Numerous human activities, natural events, and processes affect the condition of natural and archaeological resources in marine sanctuaries. This section describes the nature and extent of the most prominent pressures in Cordell Bank sanctuary.
The Cordell Bank area supports an active commercial and recreational fishery (Figure 20). Commercial and recreational fishing combined with habitat destruction, poor recruitment and anomalous oceanographic conditions have contributed to declines of many marine species in central and northern California waters. Several runs of Chinook salmon, Coho salmon, and steelhead (O. mykiss) in central California have been federally listed as endangered and threatened since 1994. The complex life histories of these species, spanning fresh water rivers and ocean environments, subject them to negative impacts from many different sources at all stages of their lives. Many rockfish populations have declined under fishing pressure and years of recruitment failure due to unfavorable oceanographic conditions (Ralston 2003), and several species are currently considered overfished, including cowcod, canary, yelloweye and darkblotched rockfish (S. crameri).
Commercial and recreational fisheries in Cordell Bank sanctuary have generally targeted rockfish, lingcod, flatfish, salmon, Dungeness crab and albacore tuna (Figures 21 and 22). Commercial boats will travel from out of the area to fish for groundfish, salmon and crab. Most of the private boats and charter vessels that fish Cordell Bank sanctuary are from Bodega Bay or San Francisco Bay. Rough ocean conditions often prevent smaller boats from accessing the sanctuary. Gear types used in the sanctuary have included bottom trawl, mid-water trawl, hook and line, gill nets, crab pots and long lines (including troll long line, vertical long line, and fixed gear long line), although not all of these gear types are currently used.
Analysis of temporal patterns of landings indicate that overall landings for Bodega Bay (the closest port for fish caught within Cordell Bank sanctuary) have declined dramatically from 1981 to 2003 (Figure 21). Fisheries that made up the majority of landings in the 1980s (e.g., bottom trawl rockfish and sole, midwater trawl rockfish) have been virtually absent in the Bodega Bay landings data since 2000. Hook and line rockfish, halibut, sablefish, and lingcod made up a small proportion of landings in the late 1980s and 1990s; however, due to a stringent groundfish regulatory environment, landings from these fisheries from Bodega Bay were minimal or non-existent between 2000 and 2003. Landings from trap crab and hook and line salmon appear to be more stable through the years of 1981-2003; however, landings of these species has been low in the last several years due to population declines and restrictions on salmon fishing as well as low catch levels of Dungeness crab.
Fishing activities not only impact target fish populations through direct extraction, but can also influence the sanctuary ecosystem through habitat degradation and bycatch of non-target species. Observations from submersibles have documented the presence of lost fishing gear entangled in rocky areas of the bank (Cordell Bank sanctuary unpubl. data). These bottom-tending gear types can damage sensitive habitats that provide food and shelter for invertebrates and fishes (Barnes and Thomas 2005). In addition, selected open ocean fisheries have significantly reduced some populations of seabirds that are taken as bycatch in these fisheries (Forney et al. 2001). Pinnipeds, cetaceans (Read et al. 2006) and sea turtles (Spotila et al. 2000) are also taken as bycatch and die from entanglement in active and derelict fishing gear.
West Coast groundfish fisheries, and fisheries that may take groundfish incidentally are managed with a variety of closed areas intended to either protect specific overfished groundfish stocks and aid in their recovery (Rockfish Conservation Areas (RCA)) or to protect groundfish habitat (Essential Fish Habitat (EFH) conservation areas). Fishing closures in the vicinity of the Cordell Bank sanctuary include both RCA and EFH conservation areas (Figure 23). Rockfish Conservation Areas are areas where fishing for groundfish is prohibited for 3 different modes of fishing - trawl, non-trawl and recreational. Within the RCAs, certain fishing gears and take of certain species is allowed. Additionally, the RCA boundaries change both within and among seasons. EFH conservation areas are closed to specific types of fishing gear. All EFH conservation area closures were put in place in 2006, while the date in which RCA closures were implemented varied (start date ranged between 2002 to 2005). Specific regulations associated with different gear and seasons as well as updates and archives of past closures can be found here.
Currently, there is limited commercial and recreational fishing for groundfish permitted on Cordell Bank (fishing only allowed for some flatfish, including several species of sole and Pacific sanddab (Citharichthys sordidus) because the bank falls within the Cordell Bank Rockfish Conservation Area established in 2005 by the Pacific Fishery Management Council to protect several species of overfished rockfish (Figure 23). The establishment of Rockfish Conservation Areas has improved the status and recovery of depleted fish stocks, including several rockfish populations. It is unclear when or if these closures will be lifted.
In 2002, sanctuary staff observed fishing gear, primarily long lines, entangled on the bottom, during 18 of 20 dives over rocky habitat on Cordell Bank. Based on these findings, staff worked with their advisory council, NOAA Fisheries and the Pacific Fisheries Management Council to recommend protection for this critical habitat. In 2006, Cordell Bank was identified as a Habitat Area of Particular Concern under NOAA Fisheries Essential Fish Habitat designation and the Cordell Bank (50 fathom isobath) EFH Conservation Area was implemented. Under this designation, the use of bottom contact gear was prohibited in waters shallower than 50 fathoms (90 m) on Cordell Bank. Additionally, the establishment of the Cordell Bank/Biogenic Area EFH Conservation Area and the Seaward of 700 fathom EFH Conservation Area in 2006 prohibited the use of bottom trawls on some of the soft bottom habitat in the sanctuary.
The southeast corner of Cordell Bank National Marine Sanctuary is located approximately five nautical miles (8.9 km) from the terminus of the northern shipping lanes that funnel commercial vessels into and out of San Francisco Bay (Figure 24). This traffic corridor is used by large commercial vessels entering San Francisco Bay from the north or leaving San Francisco Bay and transiting to the north. Because the terminus of the northern lane is adjacent to the sanctuary, all inbound and outbound traffic using the northern lanes passes through the sanctuary on their approach to or departure from San Francisco Bay. In 2004, 2,608 commercial vessels were reported transiting the northbound shipping lanes into and out of the Bay (United States Coast Guard, Automatic Identification System, unpubl. data).
Vessel spills are a major concern when considering potential threats to Cordell Bank's resources. Historically, the total number of oil spills from transiting vessels has been small, but potential impacts could be enormous given the number and volume of vessels and the sensitivity of resources in the area. In addition to oil tankers, large cargo vessels are a concern because in addition to their cargo, they can carry up to one million gallons of bunker fuel, a heavy, viscous fuel similar to crude oil. In late 1984, on-board explosions about eight miles (13 km) seaward of the Golden Gate Bridge disabled the tanker Puerto Rican. The vessel broke apart and discharged refined oil products within the boundary of the Gulf of the Farallones National Marine Sanctuary. Thousands of seabirds were oiled and died. In November 2007, the container ship Cosco Busan collided with the Bay Bridge within San Francisco Bay, spilling 58,000 gallons of bunker fuel that spread throughout the Bay and into coastal waters (Figure 25). Oil from the spill traveled over 25 miles (40 km) and reached beaches adjacent to Monterey Bay and Gulf of the Farallones sanctuary waters. Wildlife impacted from the spill included thousands of seabirds that were oiled and killed (Oiled Wildlife Care Network, unpublished data). There is no evidence to suggest that oil from the Cosco Busan spill reached Cordell Bank sanctuary; therefore, it is not thought that habitats were directly impacted by this spill. NOAA is currently undergoing damage assessment from the spill and it is undetermined if wildlife resources of the sanctuary were impacted. Nevertheless, the impacts of these incidents demonstrate the seriousness of the potential hazards to Cordell Bank sanctuary from vessel spills, including spills from accidents that occur outside the sanctuary boundary.
California ports handled an estimated 650 cruise ship port calls in 2004. In 2003, the cruise industry predicted a 25 percent increase in the number of vessels operating in the waters of California over the next 10 years (California Environmental Protection Agency 2003). Cruise ships make port calls to at least six locations in California, including San Francisco and Monterey Bays. Many of these ships have over 3,000 people on board and have the potential to severely impact water quality in localized areas if they are not responsibly operated. Cruise ships are capable of generating massive volumes of waste. The main pollutants generated by a cruise ship are: sewage (also referred to as black water), gray water, oily bilge water, hazardous wastes, and solid wastes. Cruise ships are the equivalent of small cities with respect to waste production, and though these vessels generally incinerate the majority of waste produced, they are not subject to the strict environmental regulations and monitoring requirements imposed on land based facilities, such as obtaining discharge permits, meeting numerous permit conditions, and monitoring discharges.
Within sanctuary waters, disposal of bilge water with any concentration of oil, and disposal or discharge of any harmful substance is prohibited. However, discharge of water and other biodegradable effluents incidental to vessel use, including treated effluent from a Type 1 or Type 2 marine sanitation devices, deck wash down, and engine exhaust, is currently allowed.
Sunken vessels residing on the seafloor have the potential to leak oil or other contaminants into the sanctuary. To date, there are no documented findings of any shipwrecks on the seafloor of the Cordell Bank sanctuary. However, the Farallon Islands and the mainland coast north of San Francisco have historically provided hazardous navigational obstacles to shipping. Many known shipwrecks litter the seafloor of the nearby Gulf of the Farallones National Marine Sanctuary; therefore it is possible that shipwrecks exist within the boundaries of the Cordell Bank sanctuary and will eventually be identified. It is uncertain if sunken vessels are currently decreasing the water quality within Cordell Bank sanctuary.
In addition to the threat of materials being deposited from vessels into the sanctuary, vessels themselves could directly affect various sanctuary resources. Vessels can potentially alter the behavior of marine mammals and seabirds, changing the distribution of the animals or the amount of time that they spend feeding and/or resting. Vessels can also injure or kill marine mammals through collisions; although no marine mammal injuries or mortalities due to vessel strikes have been directly observed within Cordell Bank sanctuary (Figure 26). In the Eastern North Pacific, the average number of humpback whale and blue whale deaths due to ship strikes was at least 0.2 per year from 1999-2003 and 1998-2002, for humpback and blue whales, respectively (Carretta et al. 2007). In the fall of 2007, there were at leastthree blue whales deaths off the coast of southern California that were attributed to ship strikes. This number of deaths so close together is considered a highly unusual event, and scientists are investigating potential contributing factors to these deaths.
The level of noise pollution in the oceans has increased dramatically during the last 50 years, with much of this due to commercial shipping (National Research Council 2003). As ships get bigger and noisier, this could become a larger issue within sanctuaries. Another source of noise pollution that has the potential to impact sanctuary resources is exploration for oil and gas. Although oil exploration/production is currently prohibited within the Cordell Bank sanctuary, activity adjacent to the sanctuary would have the potential to affect the integrity of its resources. An additional source of noise pollution is from sonar activities, including human-generated mid-frequency sonar from military vessels.
The effects of noise on marine mammals, seabirds, fishes, and turtles are not entirely known, though some mass strandings of cetaceans have been spatially and temporally coincident with the deployment of military sonar (Rommel et al. 2006). Many marine mammals respond to noise by altering their breathing rates, increasing or reducing their time underwater, changing the depths or speeds of their dives, shielding their young, changing their song durations, and swimming away from the affected area. Extreme noise pollution may cause temporary or permanent hearing loss in marine mammals and other organisms. Disorientation and hearing loss may account, in part, for cases in which ships collide with marine mammals that are apparently unaware of the approaching vessel (NRC 2005). Oil exploration-related seismic surveys may cause fish to disperse from the acoustic pulse with possible disruption to their feeding patterns. Available data on fish indicates potential effects on sensitive egg and larval stages within a few meters of the sound source (Lagardere 1982). These surveys may also disrupt prey location and communication among marine mammals and in severe cases cause internal injuries.
The calendar year at the Cordell Bank sanctuary is comprised of three distinct oceanographic periods. These periods, described as upwelling, wind relaxation (oceanic), and winter storm (Davidson Current) seasons are associated with distinct oceanographic conditions. The amount of production in surface waters and the extent to which organisms disperse is directly affected by these different conditions. In response to oceanographic drivers (as well as seasonal migration patterns), the abundance and diversity of organisms present in a given region change dramatically throughout the year and from one year to the next.
In addition to seasonal and annual climatic variations that influence productivity of the sanctuary, longer-term climatic phenomena influencing the region include the El Niño-Southern Oscillation, the Pacific Decadal Oscillation, global climate change, and other processes that operate on varying spatial and temporal scales. Off the coast of California, El Niño events are characterized by increases in ocean temperature and sea level, enhanced onshore and northward flow, and reduced productivity. During this period, survivorship and reproductive success of some seabirds and fishes decreases with reduced plankton abundance. The disruption of the food web also impacts higher level predators like marine mammals that depend on krill and fish for food, leading to widespread starvation and decreased reproductive success. In addition, changes in current patterns and increased water temperature affect immigration of warm-water species and emigration of cold-water species.
Pacific Decadal Oscillations are periods of sustained climate conditions associated with shifts in ecosystem production regimes in cycles of about 50 years duration. Associated with these cycles, the surface waters of the central and northern Pacific Ocean shift several degrees from the mean temperature. Such shifts in mean surface water temperature have been detected five times during the past century, with the most recent shift in 1998. Biological patterns are related to these climate ‘regime shifts’. The Pacific Decadal Oscillation affects production in the eastern Pacific Ocean and, consequently, affects organism abundance and distribution throughout the food web. For example, the alternating 20 to 30 year cool and warm periods in the Pacific cause the abundances of anchovies (cool periods) and sardines (warm periods) to alternate (Chavez et al. 2003).
As evidence has mounted in recent decades for accelerated warming of the world’s oceans (Levitus et al. 2000), increased attention has been focused on the potential impacts of this change on marine organisms. Researchers predict that a gradual increase in ocean water temperature will cause a northward shift in the ranges of at least some species. It is also possible that some organisms will move to deeper, cooler water. Of course, not all species will shift their ranges in response. If their rate of northward migration is too slow to keep pace with the changes, they will adapt, live under suboptimal conditions, or vanish locally. Regardless, the composition of local species assemblages is expected to change.
An increase in the amount of CO2 in the atmosphere has lead not only to increased temperatures on Earth, but also to higher levels of dissolved CO2 in the world’s oceans (Feely et al. 2004). Since CO2 reacts with seawater to form carbonic acid, the addition of increased amounts of CO2 has lowered the pH of the oceans (a condition termed ocean acidification) and has reduced the amount of freely available carbonate ions. These conditions could be detrimental to many marine organisms, including mollusks, corals, and certain shell-producing plankton which rely on carbonate from seawater to build their shells and other hard parts. Recent work demonstrates that large sections of the continental shelf of western North America are affected by ocean acidification, as seasonal upwelling brings corrosive deep water (enriched in CO2 and undersaturated with respect to aragonite) closer to the surface and near the coast (Feely et al. 2008).
Levels of debris in both the ocean and at the land-sea interface are of growing concern. Marine debris poses a growing threat to marine life and biological diversity. Various types of debris are known to have adverse effects on marine species. Ingestion and entanglement are two of the largest problems associated with marine debris, which may cause injury and death to selected marine wildlife, including some endangered and protected species found in the Cordell Bank sanctuary. Marine debris originates from both land and ocean-based sources, although the majority of marine debris (approximately 80%) appears to come from land-based sources (U.S. Dept. of Commerce and U.S. Navy 1999). Land-based sources include: littering, storm water runoff, coastal municipal landfills, loss during garbage transport, open trash collection containers, industrial facilities, and beach-goers. Ocean-based sources include: commercial and recreational fishing, overboard disposal of passenger and commercial shipboard waste, and cargo containers falling off ships in high seas. The potential impact of floating marine debris on living resources in Cordell Bank sanctuary was highlighted by high rainfall in 2006, which flooded inland areas in the San Francisco Bay watershed and resulted in large amounts of debris washing 50 miles (80 km) to the northwest to Cordell Bank (Cordell Bank sanctuary, unpubl. data).
lastics in the marine environment never fully degrade and recent studies show plastic is consumed by organisms at all levels of the marine food web. Given the quantities of plastic debris floating in the ocean, the potential for ingestion is enormous. For example, survival of endangered sea turtles is threatened by ingestion of plastic; studies have found that as many as 75% of sampled loggerhead sea turtles (Caretta caretta) had plastic debris in their digestive tracks (Tomas et al. 2002). Plastic marine debris also impacts many seabird species. Surface feeding seabirds, including albatrosses, shearwaters, fulmars, and storm-petrels, are most susceptible to plastic ingestion, with frequency of individuals with plastic in the stomach ranging from 50 to 80% (Nevins et al. 2005). For example, adult Black-footed Albatross often mistake floating plastic debris as food and ingest huge quantities of plastic bottle caps, plastic fragments, discarded cigarette lighters, and plastic toys (Figure 27). When these adults return to their nests on the Northwestern Hawaiian Islands to feed their chicks, a high percentage of the meal is composed of plastic. Tagging studies have documented Black-footed Albatross crossing the eastern Pacific to feed in and around Cordell Bank sanctuary (Hyrenbach et al. 2006); it is unknown what proportion of plastic these birds ingest comes from within sanctuary waters.
Entanglement in marine debris is another serious problem, and it has been linked to measurable population declines for a variety of marine mammals. Scientists have estimated that thousands of marine mammals are killed by entanglement in debris each year in the North Pacific (Wallace 1985). Recent stock assessments indicate that annual mortality and injury due to entanglement is 1.2 individuals per year in the eastern north Pacific stocks of humpback whales (data from 1999-2003: Carretta et al. 2007).
Significant amounts of derelict fishing gear have been documented in Cordell Bank National Marine Sanctuary (Cordell Bank sanctuary, unpubl. data) (Figure 28). This includes long lines, gill nets, and crab gear entangled on and around the bank. One concern is that the abandoned fishing gear on Cordell Bank may be harming sanctuary resources, creating artificial habitat for marine life, and potentially impacting the physical structure of the bank. Derelict gear also poses a danger to personnel and equipment involved in sanctuary research and monitoring activities.
Non-indigenous species can alter species composition, threaten the abundance and diversity of native species, and interfere with healthy ecosystem function. Once established, non-indigenous species can be extremely difficult to remove, especially in deep water habitats like Cordell Bank.
A number of non-native species are present in the marine environment near the Cordell Bank sanctuary, but none are known to currently exist in the sanctuary. Non-native species are still considered to be a potentially major threat to living resources and habitats in the sanctuary. Numerous non-indigenous species have been found in the adjacent Gulf of the Farallones National Marine Sanctuary (deRivera et al. 2005, Byrnes et al. 2007), and a list of non-native species that have a high probability of being found in the Cordell Bank sanctuary has been compiled (J. Byrnes, unpubl. data). The list was obtained by comparing lists of species within and around sanctuary waters to lists of known invaders within California, Bodega Harbor, Tomales Bay, and Elkhorn Slough. The list should therefore be regarded as conservative, including some species that may not yet be within sanctuary waters, but given their geographic proximity, have a high probability of invading in the near future. For example, there is concern regarding an invasive tunicate Didemnum sp. that has been observed in nearby coastal areas (Tomales Bay and Bodega Bay, CA) and has the potential to cause great ecological and economic damage (Bullard et al. 2007). This invasive species is known to spread rapidly, alter benthic habitats, and overgrow sessile organisms such as sponges, anemones, bryozoans, hydroids, macroalgae and tunicates (Bullard et al. 2007) (Figure 29).