On a crisp morning in early April, conservation officers waded through cracked mud and shallow pools at Pukepuke Lagoon, scooping up nearly 3,000 stranded shortfin eels in a desperate bid to save them from suffocation. The sight was both heartening and haunting—a community rallying around a species that has slipped silently toward oblivion for decades. But beneath the surface of this rescue operation lies a deeper, more troubling story: the slow-motion collapse of a coastal wetland system that once teemed with life, now unraveling under the combined pressures of climate shifts, land-use changes, and decades of fragmented management.
This isn’t just about eels. It’s about the quiet unraveling of an ecosystem that has sustained Māori communities for generations, filtered runoff from intensifying dairy farms, and buffered the Horowhenua coast against storm surges. As the Department of Conservation (DOC) and Horizon Regional Council launch a joint investigation into the lagoon’s rapid drying, experts warn that Pukepuke may be a canary in the coal mine for dozens of similar coastal lakes dotting New Zealand’s western flank—each facing an uncertain future as rainfall patterns shift and groundwater demands intensify.
The immediate trigger for the eel stranding appears to be a combination of below-average autumn rainfall and reduced inflows from the Manawatū River catchment. Data from NIWA’s climate monitoring network shows that the Manawatū-Whanganui region received just 65% of its long-term average rainfall between February and April 2026, marking the driest start to autumn in over 40 years. At the same time, consents for groundwater extraction in the lagoon’s recharge zone have risen steadily over the past decade, with Horizon Regional Council records showing a 22% increase in approved takes since 2018, primarily for agricultural irrigation.
“We’re seeing a perfect storm of reduced surface flow and increased subsurface demand,” says Dr. Mereana Pohatu, a freshwater ecologist at Massey University who has studied Pukepuke for over 15 years. “The lagoon isn’t just losing water—it’s losing its resilience. When the system gets this stressed, even compact climate variations can push it past a tipping point.”
“Pukepuke Lagoon is a shallow, intermittently closed coastal lake—exactly the kind of system most vulnerable to climate-driven hydrological shifts. What we’re observing isn’t an anomaly; it’s an acceleration of a trend we’ve been tracking since the early 2000s.”
— Dr. Mereana Pohatu, Freshwater Ecologist, Massey University
Historically, Pukepuke Lagoon has acted as a critical nursery for juvenile shortfin eels (Anguilla australis), which migrate from the ocean to freshwater systems to grow before returning to spawn in the Pacific. The lagoon’s brackish margins and dense raupō beds provided ideal foraging grounds, allowing eels to accumulate the fat reserves needed for their epic 3,000-kilometer journey to breeding grounds near Tonga. But as water levels drop and salinity fluctuates unpredictably, these vital habitats are shrinking—or disappearing entirely.
Local iwi, particularly Rangitāne o Manawatū, have long viewed Pukepuke as a taonga (treasure), not only for its ecological value but for its cultural significance in traditional eel harvesting practices known as tuna fishing. “When the lagoon suffers, we suffer,” says Hemi Te Kanawa, a Rangitāne elder and kaitiaki (guardian) of the Manawatū waterways. “The eels aren’t just a resource—they’re kin. Their decline mirrors our own disconnection from the land and water that shaped us.”
“We’ve seen generations of knowledge about reading the lagoon’s moods—where the water pools, where the eels hide, when to fish—fade as the lagoon becomes unpredictable. Restoring Pukepuke isn’t just ecology; it’s cultural reclamation.”
— Hemi Te Kanawa, Rangitāne o Manawatū Elder and Kaitiaki
The joint DOC-Horizon investigation, launched mid-April, is examining not only climatic factors but also land drainage practices in the surrounding catchment. Historical aerial imagery from LINZ reveals that over 40% of the lagoon’s historical wetland margin has been converted to pasture since the 1970s, with tile drainage systems now commonplace on adjacent farms. These alterations accelerate runoff during storms but reduce slow-release groundwater flow during dry periods—exacerbating the lagoon’s vulnerability to drought.
Horizon Regional Council’s 2023 State of the Environment report noted declining water quality in Pukepuke, citing elevated nitrogen levels from agricultural runoff and persistent turbidity from livestock access to margins. Whereas recent fencing initiatives have excluded stock from 60% of the lagoon’s perimeter, experts argue that broader catchment-scale interventions are needed—including wetland restoration, riparian planting, and a reevaluation of groundwater allocation limits.
“We can’t maintain treating symptoms,” says Lisa Thompson, Horizon’s Team Leader for Freshwater Management. “Pukepuke needs a whole-catchment approach. That means working with farmers to restore marginal lands, upgrading drainage design to mimic natural hydrology, and ensuring environmental flows are protected—not just in the lagoon, but in the streams that feed it.”
The eel rescue, while successful in the short term, has sparked renewed calls for a long-term management plan for Pukepuke—one that integrates mātauranga Māori with scientific monitoring and adaptive governance. Similar efforts at Lake Horowhenua and Lake Wairarapa have shown promise, combining community-led riparian planting with real-time water level sensors and adjustable weir systems to maintain minimum viable habitats during dry spells.
As climate projections indicate increased frequency of seasonal droughts in the lower North Island, the fate of Pukepuke Lagoon may hinge on whether regional authorities can move beyond crisis response to proactive, landscape-scale restoration. For now, the 3,000 eels returned to deeper waters carry more than just survival—they carry a warning. And perhaps, a chance.
What does it indicate to save a lagoon when the waters that sustain it are slipping away—not in a single storm, but in a thousand small cuts? The answer may lie not in engineering fixes alone, but in rekindling the old understanding that land, water, and people are not separate entities, but threads in the same woven mat.
