MERC M2 radar in action, tracking multiple vessels crossing into and out of the Miloliʻi CBSFA.
The Village of Miloliʻi, located in the District of South Kona on Hawaiʻi Island, is home to a native Hawaiian community dating back many centuries. Miloliʻi Village also sits at the epicenter of one of the most biologically rich coral reef and coastal ocean ecosystems remaining in the Hawaiian Archipelago. The area harbors more than 100 species of reef fish, 35 coral species, and thousands of marine invertebrate species. The Miloliʻi area represents a last stronghold for Indigenous people and biodiversity.
Hawaiian cultural practices involving nearshore resources evolved over centuries prior to western contact. However, for more than 200 years since contact, the region has undergone many phases of exploitation, land speculation, and resource extraction. On the South Kona reef near Miloliʻi, periods of commercial activity, including aquarium fish collection for mainland sales, took a negative toll on the ecosystem. For this reason, Hawaiian community leaders long voiced the need for marine protections and management.
Following years of community and government dialogue, Miloliʻi Village succeeded in August 2022 by getting their desired regulatory rules approved for implementation as the Miloliʻi Community-based Subsistence Fishing Area (CBSFA). The Miloliʻi CBSFA stretches 18.6 miles along the coast, generating one of the largest managed reefs in the State of Hawaiʻi. The CBSFA is co-administered by a local non-profit called Kalanihale and the State of Hawaiʻi Division of Aquatic Resources (DAR). Their combined management efforts are supported by other organizations including Ocean Janitors for reef debris removal and the Hawaiʻi Marine Education and Research Center (MERC) for scientific and law enforcement support.
Miloliʻi Village community members, Hawaiʻi Department of Land and Natural Resources, and supporting NGOs join Governor David Ige in celebrating the establishment of the Miloliʻi CBSFA in August 2022.
One can describe a CBSFA as a type of culturally-based marine managed area, where the reef ecosystem is preserved and sustained for long-term subsistence and cultural practices. Commercial use of the reef is regulated, and fishing and gathering rules are disseminated to educate visitors and residents of the island. When needed, a group of volunteers from Miloliʻi, accompanied and supported by the neighboring community, all trained by State and Federal environmental law enforcement, proactively share information, educate, and report infractions to the DLNR Division of Conservation and Resource Enforcement (DOCARE). This group is known as the Miloliʻi Makai Watch.
Prior to the signing of the Miloliʻi CBSFA by former Governor David Ige in August 2022, the regional reef ecosystem had been frequented by land and sea for its iconic fish such as parrotfish, tangs, and butterflyfish. Additionally, the region had long been a hotbed for collectors of more than 20 reef fish species bound for U.S. mainland aquarium shops. Extensive collection of shoreline and reef invertebrates, plus illegal poaching of large numbers of reef fish, was once rampant. Between 2008 and 2018 alone, our scientists documented a 67% decrease in adult reef fish targeted for human consumption.
Hawaiʻi MERC and the M2 radar is located at the north end of the Miloliʻi Community-based Subsistence Fishing Area (CBSFA), providing a digital checkpoint for all vessels entering or exiting the marine managed area from harbors to the north.
While Miloliʻi Village worked to establish CBSFA rules in collaboration with the State government, Hawaiʻi MERC increased its effort to monitor regional activity and assist law enforcement. The MERC’s law enforcement sponsor – Global Conservation – contacted ProtectedSeas and subsequently facilitated installation of the MERC Marine Monitor (M2) radar. The M2 radar is strategically situated 65 feet above sea level at the far north end of the CBSFA. Since 100% of vessel traffic entering the CBSFA from outside of Miloliʻi Village comes from the north, the M2 radar is well positioned to monitor CBSFA use emanating from all external harbors. Serving as a digital checkpoint for vessels entering or exiting the CBSFA, the M2 radar provides 24-hour monitoring to a maximum distance of 8 nautical miles (nm) from shore.
In the year prior to the establishment of the Miloliʻi CBSFA, Hawaiʻi MERC began operating the M2 radar with support from ProtectedSeas to monitor vessel traffic into and out of the area. In parallel, through the work of Kalanihale and its network of collaborating organizations, the story of the CBSFA, including its history, impetus, and rules, was shared with audiences at the community, regional, and State levels. During this pre-CSBFA period in 2022, MERC recorded nearly 12,000 vessel crossings within the 0-8 nm zone using the M2 radar. Zooming in, the radar flagged that nearly 10,000 of these vessels were crossing within 3 nm of shore, demarcating State jurisdictional waters.
Vessel crossings into and out of the Miloliʻi CBSFA region at 3 nm and 8 nm distance from shore.
In 2023, as the Miloliʻi Makai Watch, Kalanihale, and Hawaiʻi MERC became increasingly active alongside State Division of Conservation and Resource Enforcement (DOCARE) officers and NOAA Office of Law Enforcement (OLE) personnel, a precipitous decline in vessel traffic became apparent by the summer season (July-August), a two-month period normally associated with the highest intensity use of the Miloliʻi reef. In 2023, vessel crossings into and out of the area declined by 24% to 8700 out to 8 nm, and by 20% to 7400 between 0-3 nm, from shore. In 2024, vessel crossings further declined by 37% and 48% out to 8 nm and 3 nm from shore, respectively. For 2025, vessel entries and exits to the CBSFA declined yet another 12% and 23% for these two distances from shore, respectively.
Overall, from 2022 to 2025, vessel crossings near the CBSFA declined by 58% from 0-8 nm and 68% from 0-3 nm. While a portion of this decline is attributed to a post-COVID recession from elevated resource use in the pandemic, improved M2 radar calibration, and weather conditions, the overall trend in vessel traffic is attributed to the socialization, monitoring, and enforcement of the Miloliʻi CBSFA. These declines indicate a voluntary regional reduction of fishing pressure on the reef ecosystem, which has been corroborated by regular field observations made by MERC personnel and collaborators at sea.
As the Miloliʻi CBSFA continues into the future, Hawaiʻi MERC, working alongside Kalanihale and Miloliʻi Village, remains committed to supporting its iconic people and rich coastal and coral reef biodiversity.
by Greg Asner, Kaʻimi Kaupiko, Tahaʻa Kahele, and Robin Martin