Murray River lampreys vanish as massive algal bloom sweeps South Australia

For the past decade, SARDI has used fishway traps to track the migration of the ancient, eel-like Murray River lamprey each winter. Senior researcher Chris Bice says the usual haul of 20-100 individuals vanished during the last two monitoring periods, with no specimens captured despite concerted effort. He attributes the loss primarily to the harmful algal bloom that spread over 20,000 km² starting in March 2025 and has already caused roughly one million animal deaths among 600 species, according to the Australian Marine Conservation Society.

Estuarine ecologist Faith Coleman notes that shifting climate patterns and the lamprey’s tendency to sink when dead may further obscure detection. While the fish pose no threat to humans once in freshwater, their absence raises concerns about ecosystem health. Bice remains optimistic that the species will reappear in future surveys as the bloom recedes.