Long Island-Kokomohua

Long Island-Kokomohua Marine Reserve protects roughly 6.19 square kilometres (619 hectares) of clear, sheltered water at the entrance to Queen Charlotte Sound (Tōtaranui) in the Marlborough Sounds, at the top of New Zealand's South Island. ^[1] Established in 1993 as the first marine reserve on the South Island, and managed by the Department of Conservation, it surrounds Long Island and the nearby Kokomohua islands about 35 kilometres by boat from Picton. ^[2] The reserve is fully no-take, meaning all marine life and habitats are legally protected from fishing and collection. Its accessible-yet-undisturbed waters have made it a popular destination for snorkelling, diving and scientific monitoring, and over three decades of protection have allowed rock-lobster and blue cod populations to recover noticeably compared with surrounding fished areas.

The reserve's rocky reefs and kelp beds support abundant marine life, including blue cod, butterfish, blue moki, tarakihi, scarlet wrasse and New Zealand rock lobster (crayfish), which have become notably more abundant and larger within the protected boundary. ^[1] Reef walls host sponges, anemones, nudibranchs and encrusting invertebrates, while paua (abalone) and kina (sea urchin) graze the shallows. The surrounding sounds are frequented by bottlenose and dusky dolphins, New Zealand fur seals, and little blue penguins, and seabirds such as shags, gannets and terns forage over the water. The marine reserve functions as a recovering reference site for the wider Marlborough Sounds ecosystem.

Subtidal habitats are dominated by macroalgae, including bull kelp (Durvillaea) on exposed rock, the large brown kelp Ecklonia radiata forming forests on deeper reefs, and a diverse understory of red and green seaweeds. These algal beds provide food and shelter for juvenile fish and invertebrates. The intertidal zone supports rockweeds, coralline turf and encrusting algae. On the adjacent land of Long Island itself, regenerating coastal forest and scrub of kānuka, mānuka and broadleaf species fringe the shoreline, though the reserve's statutory protection applies to the marine environment below mean high-water mark.

The Marlborough Sounds are a drowned landscape of ria coastline, formed where rising sea levels after the last ice age flooded a series of river valleys carved into ancient greywacke and schist basement rock. ^[1] Long Island and the Kokomohua islets are the partly submerged tops of these ridges, producing the steep underwater rock faces, boulder slopes and sheltered embayments that characterise the reserve. The geology of hard, fractured greywacke creates the complex reef topography that supports rich marine communities, while sheltered inner-sound conditions allow fine sediments to accumulate in deeper basins.

The reserve has a temperate maritime climate moderated by the surrounding sea, with warm, settled summers and mild, wetter winters. Sea temperatures typically range from around 10–12°C in winter to 18–19°C in late summer. The Marlborough Sounds are relatively sheltered, but the outer sounds can experience strong winds funnelled through the channels, and conditions for diving and boating are best in the calmer months from late spring to autumn. Annual rainfall is moderate compared with the wetter west coast, and water clarity is generally good, supporting the reserve's popularity for underwater activities.

The Marlborough Sounds, known to Māori as Tōtaranui, have a long history of occupation and use by iwi including Ngāti Kuia, Rangitāne, Ngāti Apa, Ngāti Toa and Ngāti Koata, who travelled and harvested kaimoana throughout the waterways. The sounds were among the earliest parts of New Zealand encountered by European navigators, with James Cook anchoring at nearby Ship Cove (Meretoto) in Queen Charlotte Sound during his voyages in the 1770s. ^[1] The area's sheltered waters later supported whaling, fishing and farming settlements, and the broader sounds remain culturally and economically important to local communities today.

Long Island-Kokomohua Marine Reserve was formally established in 1993, becoming the first marine reserve on the South Island and part of New Zealand's expanding national network of no-take protected areas. ^[1] It was created to safeguard a representative sample of outer-sound reef habitat and to allow depleted species, particularly blue cod and rock lobster, to recover. The reserve has since served as an important long-term scientific monitoring site, with ongoing surveys documenting the rebound of fish and crayfish abundance inside the boundary relative to surrounding fished waters.

As a marine reserve, the principal attractions lie underwater rather than on marked trails. Visitors come primarily to snorkel and scuba dive among the kelp forests and reef walls, where blue cod, large crayfish and diverse invertebrate life are reliably encountered. ^[1] The sheltered waters are also suited to sea kayaking and boat-based wildlife watching, with opportunities to see dolphins, fur seals and seabirds. Long Island lies within the popular Queen Charlotte Sound, close to the Queen Charlotte Track on the mainland, making the reserve a natural addition to a wider Marlborough Sounds itinerary.

The reserve is accessible only by boat, typically reached by private vessel, water taxi or charter operator departing from Picton, about 35 kilometres away. ^[1] There are no facilities within the reserve itself, and visitors must be self-sufficient. Boundaries are marked to inform boaters, and all fishing and collection of marine life are prohibited. Landing on Long Island is discouraged except in emergencies. Picton, the gateway town and South Island terminus of the Cook Strait ferry, offers full visitor services, dive operators and charter bookings. Calm summer conditions provide the best access for diving, snorkelling and kayaking.

Managed by the Department of Conservation, the reserve is a fully protected no-take zone where fishing, dredging and the removal of any marine life or material are prohibited. Its decades of protection have produced measurable conservation gains, with rock lobster and blue cod populations recovering substantially and demonstrating the value of marine reserves as biodiversity refuges and reference sites. ^[1] Ongoing monitoring tracks ecosystem recovery, and the reserve contributes to wider efforts to protect the ecologically stressed Marlborough Sounds. Public compliance, supported by clear signage and community awareness, is central to sustaining its protected status.