Giant Kelp Reforestation At our Okehampton Bay farm and throughout our leases in the D’Entrecasteaux Channel, Tassal is growing Giant Kelp as part of an Integrated Multi-Tropic Aquaculture (IMTA) program. IMTA utilises by-products, including waste, from one aquaculture species as inputs (fertilizers, food) for another. We are combining fed aquaculture (our salmon) with extractive aquaculture (giant kelp) aiming to create more balanced ecosystems. The growth of the kelp adjacent to our farms is performing above expectations. Now, we are taking hatchery produced kelp seed outside our leases with an initiative, which aims to repopulate Giant Kelp forests at sites where they have disappeared. Tassal’s Eco-Aquaculture Researcher, Dr Craig Sanderson, told Current the Giant Kelp forests on Tasmania’s east coast have progressively disappeared since at least the 1940s, thought to have been due to warmer temperatures and concurrent lower nutrients of the surrounding oceanic waters. This has occurred to such an extent, Tasmanian Giant Kelp communities have been listed by the Federal Government as critically endangered. 30
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“We have so far replanted three species of kelp in the Pirate’s Bay area at Eaglehawk Neck,” he said. “These kelp species include the Giant Kelp: Macrocytis pyrifera, Lessonia corrugata and Ecklonia radiata. These species are all endemic or native to Tasmania.”
“Macrocystis pyrifera (or Giant Kelp) is the largest and fastest growing of the kelps and possibly the fastest of any plant in the world.” “Giant Kelp stands are associated with a higher diversity of marine organisms and form a greater complexity of habitat, which can protect various fish species,” Craig said. “It is also believed to be important to the health of local abalone and lobster populations through providing food, shelter and helping to keep larvae on reefs.” There are upwards of 1000 species of seaweed found in Tasmania’s coastal
waters, approximately one tenth of these are green, a quarter brown and the remainder red. The kelps are brown seaweed and are some of the larger seaweed plants. The local Eaglehawk Dive Centre has been keen to get involved in the project with community support, helping replant Giant Kelp in Pirate’s Bay, in front of the Lufra Hotel and Deep Glen Bay. Mick Baron, co-owner of the dive centre told Current: “Giant Kelp (Macrocystis pyrifera) was everywhere in 1991; there was so much it was a nuisance as it grew around boat ramps, most shallow waters and therefore tended to wrap around propellers. It disappeared from the northernmost dive location for Eaglehawk Neck Dive at Deep Glen Bay around 1997.” Operating in Eaglehawk Neck since 1991, Mick has witnessed the disappearance of the Giant Kelp forests in the area. “The Giant Kelp forest was a major drawcard for any non-Tasmanian diver. It is more than 50% of requests as a dive location as the word spread it was
