Giant Kelp Reforestation

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.

“We have so far replanted three speciesof kelp in the Pirate’s Bay area atEaglehawk Neck,” he said.

“These kelp species include the GiantKelp: Macrocytis pyrifera, Lessoniacorrugata and Ecklonia radiata. Thesespecies are all endemic or native toTasmania.”

“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 witha higher diversity of marine organismsand form a greater complexity ofhabitat, which can protect various fishspecies,” Craig said. “It is also believedto be important to the health of localabalone and lobster populationsthrough providing food, shelter andhelping to keep larvae on reefs.”

There are upwards of 1000 species ofseaweed 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 in decline. There are only a few places in the world where this experience is possible,” he said.

“We have also had interest from the community to help replant Giant Kelp in selected areas of the D’Entrecasteaux Channel, which we are looking into,” Craig explained. He said he is proud of the success

Tassal is having with the kelp IMTA program around its leases. “By growing Macrocystis in the vicinity of the cages, this may also encourage the growth of this species on nearby reefs, where it was formerly abundant,” he said. “Macrocystis is one of the fastest growing plants in the world, with recorded growth rates of a massive 50cm a day and can reach 20 to 30 metres in height – in only one growing season! We have seen plants sourced through Tassal and planted in Deep Glen Bay grow from around 20cm tall, to over four metres high in two or three months.”

Photos for this story courtesy of Craig Sanderson and Marine Solutions.

From the laboratory to Tasmania’s oceans - the Giant Kelp reforestation story.

Giant Kelp (Macrocystis pyrifera) for Tassal’s reforestation program begins its life in the laboratory

WE ARE HIRING IN TASMANIA NOW!

We have a wide range of exciting, marine-based job opportunities. Build a career in Tassie with an industry leader. Entry level to experienced vacancies.

Find out more at tassalgroup.com.au/join-our-team