Pressures on the Sanctuary
The same coastal waters of Hawai'i that serve as humpback breeding grounds are also subjected to heavy human use by both residents and visitors. Ocean-related industries include recreation, tourism, ocean science and technology, military activities, commercial fishing, existing and proposed alternative energy projects, aquaculture, and seafood marketing. Many tourism activities, the state's primary economic driver, are based around the use of ocean resources; therefore, good water quality and the aesthetic beauty of clean and open coasts are vital to this industry. Ocean transportation is also vital to the state's economy. Approximately 1,200 kilometers (750 miles) of Hawaiian Islands coastline are served by 10 commercial ports and 21 small boat harbors in the main Hawaiian Islands. Hawai'i residents place a high value on everyday access to the ocean, not just for economic livelihoods, but to also maintain a high quality of life.
Despite their economic significance, Hawaiian coastal waters are coming under ever-increasing population pressures that threaten the health of the marine environment (Dollar and Grigg 2004). Ocean-related human uses have the potential to increase pressure on the sanctuary's mission to effectively protect humpback whales and their habitat.
Whale-Vessel Collisions and Entanglement
Entanglement in marine debris and collisions with vessels have been widely identified as the primary human-caused sources of mortality for humpbacks, both in Hawai'i and elsewhere. For example, up to 60 percent of mortalities for humpback whales along the United States' mid-Atlantic and southeastern coasts were determined to have resulted from either gear entanglements or vessel collisions (Wiley et al. 1995). Recent studies suggest that entanglement alone might be responsible for a 3.7 percent annual mortality for humpback whales off the northeastern United States, and North Pacific humpbacks have recently been shown to have entanglement scar rates that are comparable to this population (Robbins et al. 2009). For these reasons, these two activities have been identified as immediate, pressing issues for the sanctuary.
Vessel Traffic
As the population of Hawai'i increases, dependence on ocean transportation is expected to increase. About 80 percent of food and merchandise is imported to Hawai'i, of which 98 percent arrives by ship to commercial harbors around the state (Lee and Olive 1994). Some commercial port facilities would already be at capacity without ongoing adjustments to the shipping lines' operations and efforts to optimize land use by the State of Hawai'i Department of Transportation (DOT) Harbors Division. Such adjustments extend terminal capacities, but ultimately without the expansion of commercial harbors to accommodate the growing demand of imported goods, residents of Hawai'i may experience delays in the delivery of essential commodities, as well as higher shipping costs (HCZMP 2006).
Heavy vessel traffic creates the possibility of collision with humpback whales (Figure 9), and noise from vessels may also affect whales. Discharge of oil, sewage and other non-biodegradable materials from vessels in and outside the sanctuary pose a threat to sanctuary resources. Spills may also result from vessel groundings or sinkings. Herman et al. (2003) assessed the history of whale-vessel encounters and the threat of collision from vessel types including whale watch boats, private vessels and large cargo ships. This study classified the threat and seriousness of ship strikes and concluded that mitigation measures such as visual, radar, sonar and infrared observation, and a reduction of speed in high-density whale areas, could lower the threat level and reduce the probability of a collision.
The operation of commercial and recreational thrill-craft (e.g., water sledding, parasailing vessels and high-speed motorcraft) may also adversely affect humpback whales in Hawaiian waters. Small, fast and highly maneuverable, these craft increase collision risk between whales and vessels. Their small size increases risk of injury to vessel operators and passengers, while their high speed reduces the time for animal and operator to detect and maneuver in order to avoid collision. The state of Hawai'i prohibits parasailing and certain other boating activities in areas off the western and southern shores of Maui during the humpback whale breeding season (Supreme Court of the United States No. 07-1427, 2007). However, thrill-craft continue to operate in other Hawaiian waters where humpback whales are found.
Ocean resource use conflicts are increasing. Resource allocation issues, user conflicts and stress on the marine ecosystem will become more prevalent without proactive management and the setting aside of significant and appropriate areas for conservation and public access (HCZMP 2006).
High-speed vessel operation has been and continues to be an area of interest for sanctuary managers. Historically, ferry systems have operated in Hawaiian waters (Herman et al. 2003). For approximately 10 months between 2008 and 2009, Hawaii Superferry (Figure 10) ran ferry service between O'ahu and Maui with future plans to provide service between O'ahu and Kaua'i and the island of Hawai'i. Hawaii Superferry discontinued service in April 2009. The Hawaii Superferry operation highlighted sanctuary issues regarding new vessel operations and potential impacts on humpback whales as well as issues being faced by the Department of Transportation (DOT) Harbors Division regarding adequate harbor space to accommodate existing and new harbor users. The DOT Harbors Division is currently updating its long-range master plans to address harbor issues. The Hawaiian Islands Humpback Whale National Marine Sanctuary Advisory Council was engaged with Hawaii Superferry prior to and during its brief operation and followed it closely. For example, the council passed a resolution regarding operational concerns and provided comment on the "Draft Statewide Large-Capacity Ferry Environmental Impact Statement," specifically regarding large-capacity ferry operations within the sanctuary.
There continues to be interest in operating high speed vessels in Hawaiian waters. A recent example appears in the Federal Register /Vol. 75, No. 24 / Friday, February 5, 2010 /Notices, where the Department of Defense published a notice of intent entitled, "Preparation of a Programmatic Environmental Impact Statement (PEIS) for the Stationing and Operation of Joint High Speed Vessels (JHSVs)." The notice states, "The Army intends to prepare a PEIS for the proposed stationing and operation of up to 12 JHSVs. The JHSV is a strategic transport vessel that is designed to support the rapid transport of Army Soldiers, other military personnel and equipment in the U.S. and abroad. The PEIS will assess the potential environmental impacts associated with the proposed stationing of JHSVs at the following military port locations: Virginia Tidewater area; San Diego, CA area; Seattle-Tacoma, WA area; Pearl Harbor, HI area; and Guam...". This study will determine appropriate locations to operate high speed vessels and the sanctuary will coordinate with the Department of Defense to minimize impacts to sanctuary resources.
Marine Debris and Fisheries Interactions
Each year, tons of marine debris drift (Figure 11) through waters surrounding the Hawaiian Islands and wash onto their shorelines, posing a threat to humpback whales, Hawaiian monk seals, sea turtles, seabirds and other wildlife through entanglement or ingestion. The debris, including but not limited to ropes, cargo nets and derelict fishing gear, significantly damages seafloor habitat such as coral and algae communities as it washes over the reefs. While some of the marine debris is generated from land-based sources (e.g., storm water runoff, dumps and landfills, streams, sewer overflow, storm drains, and litter), marine-based sources (e.g., trawl nets, gill nets and other lost or discarded fishing gear) can produce substantial amounts of debris that may cause significant damage to the coral reefs of Hawai'i and pose serious threats to marine mammals and other organisms. The impacts of marine debris are particularly apparent because atmospheric and oceanographic forces cause ocean surface currents to converge on Hawai'i, bringing the vast amount of debris floating throughout the North Pacific to the islands (Wilkinson 2004, HCZMP 2006).
Marine mammal entanglement in marine debris is a significant threat to the central North Pacific stock of humpback whales migrating to Hawai'i each winter. Recent analyses of entanglement scarring from the SPLASH project indicate that almost 40 percent of the Hawaiian population have been entangled at least once in their lives (Robbins 2009).
Since 2002, the sanctuary has received more than 144 reports of whales entangled in gear. A total of 83 reports were confirmed as truly involving entangled humpback whales, representing as many as 57 different animals (Lyman 2010). The actual number of entangled whales is likely to be considerably higher, as many go undetected or unreported. Humpback whales in Hawai'i become entangled in fishing gear (both active and derelict) while in their feeding grounds, during migration from higher latitudes of the North Pacific, or locally from fishing gear in Hawaiian waters. Entanglement in active fishing gear, marine debris, and other types of gear (e.g., mooring gear) may result in drowning, starvation, physical trauma, systemic infections, or increased susceptibility to other threats such as ship strikes. Overall, scientists still do not know exactly how many whales die each year from this threat, but studies estimate that entanglement is the most significant cause of human-caused death among all cetaceans (Read et al. 2006), and may be especially true of humpback whales (Robbins et al. 2009, IWC 2010).
Throughout the main Hawaiian Islands and the Northwestern Hawaiian Islands, derelict or "ghost" nets are often found in large conglomerations washed up on shorelines, snagged on reefs, or drifting in offshore waters. Since 1996, NOAA divers have removed over 600 metric tons (660 tons) of nets from the reefs and shorelines of the Northwestern Hawaiian Islands. Since humpbacks are known to use and migrate through the Northwestern Hawaiian Islands, this debris can pose a risk to their health. Much of the debris seen fouling reefs and shorelines in Hawai'i is from fisheries sources elsewhere in the Pacific; the types of gear used in Hawai'i-based fisheries (e.g., longline and pot (trap) gear) are rarely seen (Donohue et al. 2001).
Fishing has been a way of life for people in Hawai'i for generations, with fish and shellfish providing the major protein source for the Hawaiian people (Kamakau 1839, Titcomb 1972). However, the coastal fisheries in Hawai'i have undergone significant changes over the past 100 years with respect to target species and gear type (Shomura 1987, Pooley 1993, Friedlander 2004). Entrapment and entanglement in active fishing gear (O'Hara et al. 1986, Wiley et al. 1995) is one of the most frequently identified sources of human-caused injury or mortality to humpback whales (Figure 12). Humpback whales are large enough to sometimes break through netting before becoming entangled, but they occasionally entangle in the lead or anchor ropes, which are more difficult to break. Entangled whales may starve or drown if humans do not intervene to free the whales. The incidence of entanglements could hamper and perhaps prevent population recovery, especially if human efforts to rescue the whales were reduced or if fishing effort increased (Clapham et al. 1999, Robbins et al. 2009).
Noise Pollution
Humpback whales occur adjacent to human population centers and are affected by human activities throughout their range. Their habitat is, therefore, subject to disturbance by human-caused noise (Herman et al. 2003).
According to Herman et al. (2003), the major sources of human-generated sound in Hawaiian waters are local vessel traffic, military underwater communication, and sonar. Noise may affect humpback whales both physiologically and behaviorally. If sounds are loud enough within the hearing range of whales, they may impact the animals' hearing. Physiological impacts may include temporary or permanent hearing threshold shifts, hemorrhaging or other direct physical damage. Changes in the distribution or movements of animals can also be caused by sound (Herman et al. 2003). For example, anthropogenic noise could potentially adversely affect humpback whales by disrupting resting, feeding, courtship, calving, nursing, migration or other activities. Large ships may create disturbing levels of noise for many kilometers around the vessel (Tyack 1989). Herman et al. (2003) reported on noise levels of various types of ships, including cruise ships, merchant ships and whale watching vessels. They concluded that ship traffic and ship noise posed low- to medium-level threats to humpback whales, and both disturbance probability and noise levels are reduced with decreased vessel speed. They recommended studies be conducted to determine areas or routes of travel where reduced vessel speeds may be practical for vessels and beneficial for whales during times when whales are present.
Coastal Pollution
Seven major wastewater treatment plants discharge into the coastal ocean in Hawai'i. All but two of the plants discharge through deepwater outfalls (below 40 meters or 130 feet). Several studies have been undertaken to determine the impact, if any, of the outfalls on the health of aquatic animals and plants. Other discharges permitted through the National Pollutant Discharge Elimination System, such as those from aquaculture facilities, shipyards and power plants, release waste and cooling water through outfalls into estuaries or coastal waters (Friedlander et al. 2005).
Sedimentation runoff is a leading cause of changes to reef community structure in the main Hawaiian Islands (Figure 13). As several coastal areas in the Hawaiian Islands have been reported to have major issues with coastal erosion and sediment transport to adjacent coral reefs in Maunalua Bay on O'ahu (Wolanski et al. 2009) and southern Moloka'i (Field et al. 2008), it is apparent that a land-based management approach is necessary to remediate these water quality issues. However, there is no documented evidence suggesting that sediment runoff significantly impacts humpback whales' use of their breeding habitat. Several major sources of erosion have ceased or are reversing, which will likely lower the potential for negative effects in the future. Examples include the closure of large agricultural plantations, cessation of live-fire training on the island of Kaho'olawe, and culling programs of feral ungulates on the islands of Lana'i and Moloka'i (Friedlander et al. 2005).
In many areas of the Hawaiian Islands, nearshore water chemistry is a mixture of oceanic water and fresh water emanating from both submarine groundwater discharge at or near the shoreline and surface water runoff. Groundwater in Hawai'i typically contains concentrations of dissolved nitrogen and phosphorus two to three orders of magnitude higher than seawater. Thus, groundwater nutrients are an important natural factor of nearshore marine water chemistry. The groundwater nitrogen levels reflect natural background and human-generated sources from wastewater and fertilizers (Friedlander et al. 2005).
Cesspools are a potentially harmful source of untreated wastewater, containing nutrients and pathogens that seep into the ocean along the shoreline. Hawai'i has an estimated 100,000 cesspools, more than any other state in the U.S. (Friedlander et al. 2005).
Stormwater runoff has the potential to be a threat to the marine environment during heavy rains. In 2006, O'ahu endured 42 days of nonstop rain that caused sewers to overflow through manholes and contributed to the break of the beachwalk sewer main in Waikiki. In March 2006, there were as many as 16 sewer overflows happening at the same time. These heavy rains resulted in a 182 million liter (48 million gallon) spill into the Ala Wai Canal. As a result, more than 1,600 temporary beach closures or advisories were issued due to bacteria levels that exceeded federal public health standards. In 2006, beaches in Hawai'i saw 1,073 rain advisories and 32 posted warnings. Total advisory and warning days for events lasting six consecutive weeks or less at beaches in Hawai'i tripled from 2,228 in 2005 to 6,507 in 2006 (Dorfman and Stoner 2007).
The U.S. Geological Survey (USGS) recently completed an assessment of water quality of streams and groundwater on the island of O'ahu from 1999 to 2001.Anthony et al. (2004) found toxic contaminants in streams that drain urban and agricultural land and in groundwater supplies (although few chemicals exceeded the drinking water standards in groundwater). In the urban streams of O'ahu, some of the highest levels of termite-treatment chemicals in the U.S. were reported. The USGS conducted no analyses in the marine environment, where ocean mixing and dilution must be considered. Based on USGS screenings, toxic contaminants in estuaries and coastal waters are easily transported to the ocean with storm flows and may be deposited at stream mouths and on reef flats (Friedlander et al. 2005). Because humpback whales fast while in Hawaiian waters, any exposure to manmade toxins comes from the food they consume in the summer feeding grounds, and their exposure to any contaminants in Hawai'i will be minimal (Elfes et al. 2010).
EMERGING ISSUE: ALTERNATIVE ENERGY PRODUCTION
In 2008, a wind and wave energy project covering up to 725 square kilometers (280 square miles) of open ocean was proposed for construction in the Penguin Bank area of the sanctuary. This particular area is an important habitat for humpback whales during the breeding and calving season. The project proposed the construction of 100 offshore fixed three-leg platforms standing on the seabed that would rise approximately 15 meters (50 feet) above sea level. The design included wave energy converters to be built into each leg of the structure. Wind turbines were also proposed for installation on the platforms. The proposal was later withdrawn in 2009 (Grays Harbor Ocean Energy Company Web site).
In 2009, another alternative energy project was put forward. The proposed project could include a 200-megawatt wind farm on Lāna'i, a 200-megawatt wind farm on Moloka'i and an inter-island undersea cable system connecting the wind farms to O'ahu. As currently proposed, cable routes would be placed on the ocean floor within the sanctuary (Interisland Wind Web site).
EMERGING ISSUE: OPEN OCEAN AQUACULTURE
Open ocean aquaculture (also known as mariculture or cage culture) involves the production of fish in floating pens or submerged cages (Figure 14). A typical system includes a land-based hatchery or other source of juvenile fish coupled with pens or cages placed in the ocean, where the juvenile fish are fed and allowed to "grow out" to a size suitable for harvest, sale and consumption.
Open ocean aquaculture has gained increased popularity in Hawai'i for the production of fish protein. Two open ocean aquaculture facilities are currently in operation in Hawaiian waters, with one located within the sanctuary. Additional projects have been proposed both within and adjacent to sanctuary boundaries. As the open ocean aquaculture industry in Hawai'i continues to grow, the sanctuary, in collaboration with state agencies, continues to closely monitor whether facilities, both existing and proposed, can effectively minimize or, ideally, prevent interactions with humpback whales and maintain existing water quality and habitat conditions. The sanctuary will continue to work with partnering organizations and seek input from community members and industry representatives to minimize any potential for habitat loss for humpback whales in areas where existing or proposed development activities would occupy space in the water column. These include, but are not limited to, submerged and surface fish cages and associated mooring lines that have the potential to obstruct humpback whale preferred migration routes and displace individuals from preferred surface and water column habitat utilized for resting, mating behaviors, calving and nursing.
All proposed open ocean aquaculture projects to date have been proposed in state waters (within five kilometers or three miles off shore) and it is likely that most future projects will also be proposed in state waters, considering the oceanographic characteristics of the Hawaiian archipelago. Hawai'i state law requires project developers to obtain a conservation district use permit and an associated open ocean lease from the Department of Land and Natural Resources. The sanctuary has the responsibility to consult with various state and federal permitting agencies to minimize any potential threats that this growing industry may pose to humpback whales and compatible use activities that are permitted within sanctuary boundaries. Any party that wishes to engage in offshore aquaculture within state marine waters must obtain a series of permits and authorizations from both federal and state agencies, including the U.S. Army Corps of Engineers and the Hawai'i Department of Health and Department of Land and Natural Resources, the sanctuary's state co-management partner.
Research and monitoring related to humpback whale impacts resulting from aquaculture activities are minimal, due to this form of ocean use being relatively new. Therefore, the extent to which open ocean aquaculture adversely impacts humpback whales in Hawai'i is not known. Currently, due to the relatively low number of existing aquaculture facilities, this activity does not appear to pose a major threat to humpback whales in Hawai'i. However, concerns over possible increases in aquaculture activities in the future have been raised. Experiences elsewhere and the physical removal of habitat occupied by these projects have led to concerns regarding potential unwanted impacts. The sanctuary will continue to closely monitor and be actively involved in this emerging issue and associated concerns that include:
- Displacement from habitat and/or habitat loss
- Entanglement (Australia 2005)
- Attraction of predators (Kemper and Gibbs 2001)
- Increased disturbance from vessels
Coastal Development
Coastlines of Hawai'i continue to be developed for a variety of land uses (Figure 15). Agricultural land on each island, primarily used for sugarcane and pineapple, is transitioning to residential and resort uses. Coastal development can bring a suite of social and environmental consequences, including conflicts over shoreline access and view planes, requirements for floodwater storage and protection, infrastructure demands, and degradation of coastal waters from cumulative increases in runoff and groundwater contamination. Human impacts to adjacent watersheds, including creation of impervious substrates such as pavement, channelization of streams, construction of sea walls and destruction of coastal wetlands all contribute to sediment transport to coral reefs in Hawai'i (Wolanksi et al. 2009). However, changes in land use from large-scale agriculture, which periodically exposes land to erosion, may result in an overall decrease in sediment delivery to the ocean (Friedlander et al. 2005).
Harbor facilities on all the main Hawaiian Islands are being modified or have been modified to accommodate new large cruise ships, large container ships and the Hawaii Superferry (an inter-island car/cargo ferry no longer in operation). Harbor improvements involve dredging to deepen and widen entrance channels and turning basins, as well as construction of new piers, waterfront work areas, jetties and breakwalls. The harbor improvements have the potential to impact coral reefs and areas used for recreation such as surfing and canoeing. Proposed expansions can affect longshore transport of sand and sediment and water quality, as well (Friedlander et al. 2005).
It is uncertain whether nearby intensive human activities have inhibited occupation by or repopulation of humpback whales in their habitats. However, this may have occurred on O'ahu. Herman (1979) summarized evidence from newspaper reports and other sources to suggest that humpbacks occurred along the coast of O'ahu from the 1930s to 1950s, but less so after the later 1960s, until recent increases in overall population. Although the apparent disappearance could be related to increased commercial hunting in the North Pacific during the early 1960s, Herman (1979) speculated that accelerated coastal development of O'ahu may have displaced the whales, citing potential disturbance by pile drivers and other construction noises, increased runoff, and increases in boat and air traffic. This interpretation is complicated by the lack of documentation on the existence of humpback whales around the Hawaiian Islands prior to about 1850 (Herman 1979).
Climate Change
Most of the world's scientists agree that global warming caused by human activity is occurring. The exact implications of these changes are unknown, but it is predicted that there will be reduced productivity of Southern Ocean ecosystems and unpredictable weather events caused by increasing ocean water temperatures, changing ocean currents, rising sea levels and reductions in sea ice (IPCC 2007a, IPCC 2007b).
The potential impacts of climate and oceanographic change on humpback whales are twofold:
- Habitat availability: Humpback whale migration, feeding, resting, and calving site selection may be influenced by factors such as ocean currents and water temperature. Any changes in these factors could affect humpback whale population recovery by rendering currently used habitat areas unsuitable or undesirable.
- Food availability: Changes to climate and oceanographic processes may also lead to decreased productivity and different patterns of prey distribution and availability. Such changes would certainly affect the feeding grounds of dependent predators such as humpback whales. While humpback whales do not feed in Hawaiian waters, preliminary evidence suggests that some baleen whales may migrate further poleward in order to find the food resources they require. This could result in either longer migrations, with subsequent energetic and timing consequences, or a shift in breeding grounds to shorten the transit (Simmonds 2009).
- Increasing diseases: Changes in climate could potentially expose humpback whales to new or resurging diseases, although these would be most likely to manifest in the feeding grounds. Currently, most of the concern about emerging or resurging cetacean diseases associated with climate change has focused on their feeding grounds, as some scientists around the world have indeed noticed increases in diseases in those habitats that may be associated with climate change (IWC 2007). While humpback whales fast during their season in Hawaiian waters, as a breeding ground, this is where any increase in sexually transmitted diseases could manifest themselves.