Tasmania salmon farms report devastating loss of 4 million fish in 2025 as ocean temperatures rise

A staggering 4 million salmon died prematurely at fish farms across Tasmania in 2025, according to new data from the state’s Environmental Protection Authority (EPA), highlighting the growing impact of rising ocean temperatures on aquaculture operations. The massive die-off has prompted animal welfare advocates to call for companies to face fines under existing legislation.

The death toll reached particularly alarming levels during the warmer months, with approximately 500,000 fish perishing in November and December alone as ocean temperatures climbed. This timing coincides with Tasmania’s summer season, when warming waters create increasingly hostile conditions for Atlantic salmon farming operations along the island’s coastline.

Scientific research shows that Atlantic salmon begin experiencing serious health impacts when ocean temperatures approach 18°C (64°F). As waters warm beyond this threshold, the fish face a cascade of life-threatening conditions: reduced oxygen levels in the water make breathing difficult, while the stress triggers severe liver and kidney damage. The elevated temperatures also suppress their appetite and weaken their immune systems, leaving the salmon vulnerable to diseases that would normally be manageable.

This environmental crisis underscores the mounting challenges facing Tasmania’s aquaculture industry as climate change drives ocean temperatures higher. The massive fish deaths not only represent significant economic losses but also raise serious questions about the sustainability and animal welfare practices of intensive salmon farming operations in warming seas.