Salmon farming methods and operations
How will global warming affect our salmon farming industry?
- Salmon farming requires water temperatures of 8 – 14 degrees Celsius. Recently water temperatures in Hobart ranged from 11 to 15 degrees, and there have been large fish losses during heat spikes, most recently in the Tamar River. Global warming means that our ocean temperatures are rising quite rapidly, and will continue to rise, which will make current salmon farming marginal at best within a few years.
- Worldwide, the salmon industry is exploring moving to colder deep ocean areas. But there is a much greater effort towards raising salmon ashore, in Reticulated Aquaculture Systems (RAS). The fish are raised in huge tanks, using water that is filtered and recycled, with fish waste removed and used for agricultural fertiliser. Tasmania is falling rapidly behind.
How does industrial open-pen salmon farming work?
- Salmon production takes about 3 years. Hatching occurs in controlled freshwater environments, usually on land, and when the salmon are about a year old, they are transported to seawater pens. They reach a harvestable size after 12-18 months, then they are killed and prepared for sale.
What do they feed the salmon?
- Farmed Atlantic salmon are fed pellets of fish feed. The Food and Agriculture Organisation states that typical fish feed contains:
- Protein supplements such as high-quality fishmeal, plant protein products (soybean meal, corn gluten meal, canola meal, pea meal), animal by-product meal (poultry by-product meal, meat meal, blood meal, hydrolyzed feather meal) and crustacean meal (krill, shrimp, crab).
- Feed additives to enhance growth, flesh pigmentation, physical properties, digestibility, osmoregulation, palatability and preservation of the feed.
- Carotenoids, including synthetic astaxanthin and canthaxanthin, and certain natural supplements such as yeast (e.g. Phaffia rhodozyma), algae (e.g. Hematococcus pluvialis) and crustacean products (e.g. krill and shrimp), used to impart an attractive pink-red colour to the salmon flesh.
- Antioxidants such as ethoxyquin, added to fishmeal and fish oil to increase their stability.
(FAO Aquaculture Feed and Fertilizer Resources Information System. Downloaded 15 May 2023)
This introduces several problems:
- Poultry by-product meal is the ground up waste from intensive farming, including beaks and feathers, and may contain residual medications such as antibiotics used to manage sickness and promote growth in hens. This is a possibility even if there are no antibiotics added during the salmon farming itself. For more information on antibiotics, see our Food Quality page.
- Ethoxyquin is banned as a food additive in Europe. For more information on this, see our Food Quality page.
Most importantly, krill are an absolutely vital part of the food chain in Antarctica, and are being ruthlessly exploited by commercial fishing operations, including those that service the industrial salmon farming industry. This threatens the very existence of all animal life higher up the food chain, from small fish, and penguins, through to whales. (see "We thought we'd saved the whales. Were we wrong?" Amanda Hooton, Sydney Morning Herald Good Weekend, 13 May 2023)
Surely fish farming on land would be too expensive, just as contaminating, or just too impractical?
- Any potential contamination from closed-loop fish farming (RAS) can be strictly controlled and monitored. The main effluent from a fish farm is faeces – and that's a good agricultural fertiliser which is easily marketed.
- The set-up costs of closed-loop fish farming ashore are considerable. However, the long term costs of running the installations have to be balanced against the cost of maintaining fish pens that require towing, cleaning, repairing and protecting from weather.
- Land based operations are intrinsically safer for staff, and cause less stress and harm to salmon stock.
Is salmon farming on land viable?
- The Tasmanian industry says no, but does not provide any evidence for their exaggerated cost and energy claims. They claim to have RAS systems, but this applies only to about half of their hatcheries, and all their salmon are matured in open pen setups at sea.
- The past decade has seen huge investment overseas in developing RAS systems (self-contained land-based fish farming) – even in Dubai, hardly the coldest place in the World.
- Here is a report of the development of a $750 m RAS facility in Saudi Arabia -the Saudi kingdom plans to produce 600,000 tons a year by 2030. And at Grimsby in the UK. And in Germany. And in the USA, where one of many RAS facilities uses its waste as fertiliser for its associated farm producing more than two million kilograms of salad greens a year.
- And? (spoiler alert - more and more and more).
Surely fish farming out at sea would be too expensive, and incredibly difficult and dangerous?
- Scandinavian and Chinese producers have developed ways of farming fish in deep, stormy ocean waters: look at China's newest deep-sea pen with capacity for 200,000 fish, or their giant aquaculture ship.
- There is no shortage of genuinely innovative industry leaders for Tasmanian fish farmers to follow, yet they persist with basically the same technology they began with 30 years ago.
- NOFF is neutral on the economics of such methods when it comes to the smaller Tasmanian enterprises, but we suspect that moving onshore would be more economically viable.