The Extinction Diet: Tasmanian Atlantic Salmon versus the Maureen Skate

• Main Author: John Paull
• Format: Conference Object
• Language: unknown
• Published: 2023
• Subjects: Extinction; Tasmania; environmental management; Atlantic salmon
• Online Access: https://zenodo.org/record/8373569; https://doi.org/10.5281/zenodo.8373569

If the price of Tasmanian Atlantic Salmon is extinction for the Maugean Skate, is the price too high? Fish farming of Atlantic Salmon in Macquarie Harbour expanded rapidly in 2016'. This coincided with the rapid decline in the the Maugean Skate population, from c.3,200 individuals in 2016 to a 47% decline by 2021. The present population may be down to 1,000 individuals. For the Tasmanian ecosystem, Atlantic salmon is an alien invasive species. The fact of this invasive species being crammed into sea-cages for fast fattening makes them no less invasive. Tonnes of fish-feed pellets are tossed into Macquarie Harbour on a daily basis (>10,000 tonnes pa). Blanketing the harbour floor under the cages is fish-food waste (pellets not consumed as they sink), along with tonnes of fish faeces. This putrid blanket of muck sucks oxygen from the water and creates dead zones. The Australian Government has identified: “The primary threat to the Maugean skate is habitat degradation resulting from sustained reduction of dissolved oxygen … the most important anthropogenic contributor to the oxygen debt in Macquarie Harbour is ongoing salmonid aquaculture”.The proverbial ‘canary in the coal mine’ is not primarily about the canary, it is about the healthy state (or not) of the mine. The Maugean Skate is the ‘canary’ for Macquarie Harbour, a sentinel species. The Skate being in jeopardy for its continued existence reveals that the broader ecosystem of Macquarie Harbour is in existential jeopardy. What is bad for the Maugean Skate is bad for the natural ecosystem of the Harbour, and what is bad for Macquarie Harbour is industrial scale aquaculture. Invasive and non-native species are known to cause economic loss, ecosystem degradation, and drive extinctions. The time has come to shut down the industrial fish farms of Macquarie Harbour, for the survival of the Maugean Skate and for the health of the ecosystem of the Harbour.