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Site Characterization

A Site Characterization Study was conducted in 1994 with the purpose of gathering the recent and substantive information available concerning existing resources in the designated area. The objective of the Site Characterization Study was to identify existing physical and ecological resources within the congressionally designated sanctuary boundaries as well as historical and cultural resources associated with the use of the marine environment.

Information on physical parameters such as the geology, oceanography, and water chemisny of the area, and current uses was collected. Management issues dealing with the protection and utilization of existing resources were also examined. Special attention was given to humpback whales and their habitat although other marine resources were examined as well.

The following text is an excerpt of the March 1994 Site Characterization Study which was prepared for NOAA by the Univeristy of Hawaii Sea Grant College Program, School of Ocean and Earth Science and Technology.

The full Site Characterization Study is available in pdf format.

Physical Oceanographic Conditions
Nearshore Marine Communities
Cetaceans in Hawaiian Waters
Other Threatened and Endangered Species
Traditional Uses
Current and Potential Uses
Management Issues

Physical Oceanographic Conditions

The Hawaiian Islands were formed during the last few million years by the gradual accretion of basaltic lava flows and ejecta. Their geologic features have been formed by successive periods of volcanic activity interspersed with submergence, weathering, and eustatic changes in sea level. Abundant rainfall and persistent northeasterly trade winds contribute to the steady weathering of the islands. Sandy beaches are found along the shorelines of all the islands but are best developed on Kauai, the oldest of the main islands, and least developed on Hawaii, where mountain building is still occurring.

Although the Hawaiian Islands are at the northern edge of the tropics, they have a subtropical climate due to the cool ocean currents and persistent northeasterly trade winds that occur ahout 80% of the time. The average wind velocity is between 10 and 20 kt, but velocities over 20 kt for over a The Hawaiian Islands were formed during the last few million years by the gradual accretion of basaltic lava
flows and ejecta. Their geologic features have been formed by successive periods of volcanic activity
interspersed with submergence, weathering, and eustatic changes in sea level. Abundant rainfall and persistent
north&sterly trade winds contribute to the steady weathering of the islands. Sandy beaches are found along
the shorelines of all the islands but are best developed on Kauai, the oldest of the main islands, and least
developed on Hawaii, where mountain building is still occurring.
Although the Hawaiian Islands are at the northern edge of the tropics, they have a subtropical climate due to
the cool ocean currents and persistent northeasterly trade winds that occur ahout 80% of the time. The average
week are not uncommon. Ocean temperatures are less than that of other areas at the same latitude and range from 21 degrees C to 29 degrees C (70 degrees F to 85 degrees F).

Coastal current measurements off the Hawaiian Islands suggest a mean velocity at less than 20 cm/sec in most cases, although, extreme variability is the rule, not the exception. Water circulation around the islands is driven by a combination of forces including tides, the West Wind Drift, circulation of the Eastern Pacific Gyre, and local wind and eddy systems.

There may be many unique or unusual features found within the proposed sanctuary boundaries, however, those pertinent to the physical oceanography seem to focus on two very distinctive characteristics: bathymetry and eddy circulation. The bathymetry of the area, bound by Maui, Molokai, Lanai, and Kahoolawe, along with the extension of the shallow Penguin Bank southwest of Molokai, represents a unique, semi-enclosed shallow protected sea in the midst of an expansive ocean. There is almost no information in the published literature as to the specific characteristics of this interisland area.

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Nearshore Marine Communities

The Hawaiian Islands are among the most isolated in the world. This isolation has played a major role in the development of the archipelago's shallow marine communities. The origin of most Hawaiian inshore marine species is from the Indo-West Pacific Faunal Region, the center of which is in the region of the Malaysian Peninsula and the Philippine Islands. Because of the isolation and northerly geographic setting (resulting in relatively low water temperatures), the shallow Hawaiian marine fauna is considered to be depauperate. There
are about 450 species of inshore fishes and 40 species of corals in Hawaiian waters. Many of the shallow water invertebrates have a greater diversity of species; the Mollusca are represented by about 1,000 species, the Polychaeta by about 243 species and the Bryozoa by about 200 species.

More than half of the shoreline of the older islands of the chain (i.e., Kauai, Oahu, Molokai, Lanai, and Maui) is fringed by coral reef. In general, Hawaiian reefs are not as well developed or diverse as reefs of other Pacific islands, again due to the relative isolation of the archipelago and its geographic position at the northern extreme of coral reef development. The reefs are wide, shallow platforms extending as much as 300 m seaward from the shore. The reef flats are predominately sand, coral rubble, and coralline algae. Crustose coralline algae are the dominant reef builders on Hawaiian reefs with coelenterate corals being relatively unimportant in the overall fringing reef habitat.

In addition to coral communities associated with fringing reefs, corals extend subtidally to depths of at least 50 m in Hawaiian waters, although the greatest development of these reefs is at depths from a few meters down to about 30 m. Prime examples of coral community development may be seen on submarine surfaces of recent lava flows off the coast of Maui and in the waters between Maui and Molokai. Coral communities are well developed around the islet of Molokini where commercial dive tours have capitalized on this. Coral communities are better developed where they are protected from high wave activity; thus, the leeward (western) coasts often have well-developed examples. Hawaiian coral communities show a zonation that is related primarily to wave exposure and indirectly to depth.

Disturbance on coral reefs comes from many sources including those that are natural (such as storm waves or storm water runoff) to those caused by human activities. Impacts from natural sources may include intense storm events, volcanic eruptions, large-scale El-Nino events, episodes of massive sedimentation, and population explosions of the coral-feeding crown-of-thorns starfish, all of which may cause large-scale mortality in coral communities.

There are numerous human-induced disturbances that occur on coral reefs. Some of these anthropogenic stresses are more wide-spread than are others. Important forms of human disturbance include (1) sedimentation, (2) pollution, (3) the discharge of heated effluents, (4) over-fishing, and (5) the introduction of exotic fishes.

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Cetaceans in Hawaiian Waters

A total of 24 cetacean species (five Mysticetes; 19 Odontocetes) have been observed in Hawaiian waters, though only 15 with any regularity. Of the Mysticetes, humpback whales are the only species with more than incidental occurrence. Since humpback whales presumably do not feed while in Hawaii, the primary forces affecting their behavior and distribution while wintering in Hawaiian waters are those associated with reproductive success.

Based on the 1993 aerial survey results, four Odontocete species were identified as occurring in shallow coastal waters along the major Hawaiian Islands, thus potentially falling under the jurisdiction of the sanctuary. These species include bottlenosed dolphins (Tursiop gilli) false killer whales (Pseudorca crassidens), spinner dolphins (Stenella longirostis), and spotted dolphins (Stenella attenuata). The 1993
survey results indicated Odontocete species to be particularly abundant in the waters surrounding Kauai and Niihau. They were less abundant in the four-island region (Maui, Kahoolawe, Lanai, Molokai) and Penguin Bank regions where humpback whale densities are greatest.

Comparison of results from earlier aerial surveys (1977-80) with recent surveys using identical methods (1990) suggest that the number of humpback whales wintering in Hawaiian waters may be increasing. Additionally, abundance estimates from surveys performed between 1977-93 have shown a consistent pattern of increase.

Humpback whales generally prefer shallow waters. Of the 403 groups of humpback whales sighted in 1993, 73% were in waters less than 100 fathoms.

The combined aerial survey results show clear preferences of humpback whales for different island regions. Ranked in decreasing order of sighting rate (pods/hr of survey), the regions are as follows: Penguin Bank, four-islands regions (Maui, Lanai, Molokai, and Kahoolawe), Kauai and Niihau, Hawaii, and Oahu. This preference has been stable for 15 years of surveys.

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Other Threatened and Endangered Species

Five species of marine turtles are known to inhabit Hawaiian waters: green sea turtle (Chelonia mydas),hawksbill sea turtle (Eretmochelys imbricata), leatherback (Dermochelys coriacea), loggerhead (Caretta
caretta), and the olive ridley (Lepidochelys olivacea). Only the endangered hawksbill turtle and the threatened green sea turtle are commonly found in Hawaiian waters. Hawksbills nest on the main Hawaiian islands primarily on several sand beaches on the island of Hawaii and on the east end of Molokai. More than 90% of the breeding and nesting of green turtles occurs at French Frigate Shoals in the Northwestern Hawaiian Islands (NWHI), although a substantial population resides and returns to the waters within Maui and Kauai Counties.

Of the 30 species of native Hawaiian birds listed as endangered or threatened by the U.S. Fish and Wildlife Service, only one is commonly found in the vicinity of the designated sanctuary, the Hawaiian dark-rumped petrel (Pterodroma phaeopygia sandwichensis).

Breeding populations of the endangered Hawaiian monk seal, (Monachus schauinslandi) occur almost exclusively in the NWHI. The population is estimated to be approximately 1,200 individuals. Monk seals are rarely seen in the main Hawaiian Islands although, seal births were observed on Kauai in 1988 and on Oahu in 1991.

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Traditional Uses of the Marine Environment

The Hawaiian Islands were most probably settled by Polynesian voyagers sailing from the Marquesas Islands. A second group of Polynesian settlers arrived later from Tahiti. Hawaiians used the ocean for fishing, aquaculture, trade, transportation, and communication. In addition, the marine waters figured predominantly in religious practices including the worship of personal deities.

Hawaiians evolved a different set of "use rights" than the Western practices of open access to marine resources. The vestiges of these use rights carry over today and may have a bearing on the management of the proposed sanctuary. Based on customary land and nearshore reef tenure there exist "konohiki fisheries" in which access to fish is controlled by the adjacent land owner. About 41 konohiki fisheries are in existence today. Additional rights in deeper water fisheries known as "koa huna" fisheries may also exist.

Aquaculture was another important historical use of the marine environment. Fishponds were introduced on Oahu prior to the thirteenth century by settlers from the Society Islands. Estimates vary from 360 to 488 on the number of fishponds that were built in the Hawaiian Islands. Only the remains of 157 fishponds can be found today. Of the 157, fewer that 57 could be considered in restorable condition.

Control of Hawaii's channel waterways was an important part of Hawaiian society. This importance is reflected today in modem Hawaii's claim to state ownership of interisland waters.

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Current and Potential Uses

Current and potential uses of the waters of the designated Hawaiian Islands Humpback Whale NationalMarine Sanctuary include commercial fishing, beach-going, boating, boardsailing, yachting, kayaking, tour boating, snorkeling, whale watching, jet skiing, parasailing, canoeing, charter boat fishing, shipping, research, waste disposal, ocean thermal energy conversion activities, high voltage seabed mining, and the installation of an underwater cable.

The commercial fishing catch from Maui represents nearly 3% of the state total. Molokai and Lanai each contribute 0.25% and O.11%, respectively. Penguin Bank, located west of Molokai and within the sanctuary's boundary is noted for its productivity.

The shoreline of Maui is heavily used for recreation while Molokai and Lanai are less intensely used because of a smaller population and fewer visitors to those islands. Recreational boating is an important activity in Maui and Kauai Counties.

The tour boat business includes activities such as snorkel cruises. scuba diving, raft rides. day trips to Lanai, whale-watching, and excursions on submarines and semi-submersibles. Of the 30 companies active in the Maui County tour boat industry in 1990, snorkeling cruises on sail and motor boats provided about 79% of the revenue. Whale watching provided the next highest amount of income of 8% and the remaining revenue was produced by activities such as ferry transportation to Molokai and Lanai, sail charters, glass bottom boat trips: sunset and dinner cluises, inflatable raft riding, and submarine tours.

The charter boat fishing industry in Maui has been active and thriving for many years. The Maui-based charter boat fishing fleet is divided between Lahaina, Maalaea Harbor and Mala Wharf, with the majority of vessels based at Lahaina.

Recreational fishing is a significant, yet unquantified fishery in sanctuary waters. Recreational fishers outnumber commercial fishers 50 to 1, and nearly 75% of small boat owners engage in fishing as their primary activity.

The two major harbors in the designated sanctuary are Kahului on Maui and Nawiliwili on Kauai. The shipping routes for the harbors on Maui and Molokai transit the sanctuary waters through the interisland
channels of the Maui County islands.

There is one National Pollution Discharge Elimination System (NPDES) permit for direct point-source discharge of wastes into the waters of the sanctuary and this is for the Lahaina Sewage Treatment Plant. Of greater concern than direct discharges of waste into the sanctuary waters, is nonpoint source pollution. Hawaii State Department of Health reports that the most critical marine water quality problem facing the state is sedimentation, a type of nonpoint source pollution.

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Management Issues Related to Activities and Uses in Sanctuary Waters

The primary management issues facing the national marine sanctuary are (1) reducing the density of ocean activities in the humpback whale habitat to prevent detrimental interference with the whales, (2) working with the existing program to control nonpoint source pollution affecting the quality of the coastal waters of thesanctuary in which the humpback whales live, and (3) addressing the concern of the effectiveness and fairness of the distance regulations in dealing with intentional interference of vessels with humpback whales. If the scope of the sanctuary expands to include other marine resources, then management issues related to coral reef conservation will need to be addressed.


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