Waikato District Council is cleaning up near Lake Hakanoa today after hundreds of dead fish were found in a drying drain.
The dead fish, mostly rudd, are in a drain which normally flows out of Lake Hakanoa and Environment Waikato staff were out at the weekend investigating the cause of the deaths. Ready Response officer Rob Dragten said it was likely that dry, warm weather had depleted the oxygen in the drain and water had dried up below the lake level.
Rudd were sensitive to oxygen depletion, and other fish, such as goldfish, were seen gulping at the surface where they could extract oxygen from the air.
The dead fish were creating an odour nuisance, and Waikato District Council staff worked this morning to clean up the dead fish with nets and bury them at a landfill.
Mr Dragten said the deaths were caused by a natural process, and more fish may die before rain re-filled the drain. Environment Waikato had also taken samples of algae to rule out any toxic algal bloom as the cause of the deaths. Results will not be known until next week.
Lake Hakanoa already has a health warning as a result of an algal bloom, making it unsafe for people to swim or use the water for contact recreation.