Ranching Sustainability under the SA Aquaculture Act

Over 98% of the Australian Southern Bluefin Tuna harvest comes from tuna ranching operations in South Australia. The SBT are captured live in the wild at around 17kg average, and then grown out in the sea off Port Lincoln (see www.pir.sa.gov.au).

As soon as the Southern Bluefin Tuna are transferred from the tow pontoons to ranching pontoons, they pass from Commonwealth to SA Government management under the SA Aquaculture Act. This Act and regulations prescribe sustainability criteria that aquaculture operations must meet.

In the case of SBT:

  1. Ranching is in the special wild tuna Zone. This Zone was declared after a detailed scientific assessment by government scientists, and extensive public consultation.
  2. The ranching is under annual government licences, with strict conditions on stocking rates in the Zone, in each ranching area, and in each ranching pontoon. There are also provisions on any interaction with other species, fallowing, and research.
  3. Each operation has a full environmental assessment annually, with benchmarks measuring any impact on the ocean bottom and water column

(see www.pir.sa.gov.au)

Southern Bluefin Ranching Pontoon

More Facts About Southern Bluefin Tuna Sustainability

FAQs About SBT Sustainability

How are Southern Bluefin Tuna caught?

Southern Bluefin Tuna (SBT) are caught using purse seine in South Australia.

On the east coast of Australia they are caught by pelagic long liners.

In the past SBT were caught using the poling method, but this stopped in the early 1980’s.

Recreational fisherman also catch SBT using rod and reel.

Where are Southern Bluefin Tuna ranched or farmed?

Southern Bluefin Tuna are ranched in the pristine waters of the Lower Spencer Gulf, South Australia.

They are held offshore in pontoons on lease sites, which are between 10km and 40km from Port Lincoln.

Locations of lease sites can be obtained from the Primary Industries and Regions South Australia (PIRSA) public register.

SBT Lease site locations 2013

 

What do Southern Bluefin Tuna eat?

Southern Bluefin Tuna (SBT) eat many different kinds of baitfish.

In the ranched environment, approximately 80% of the diet fed to SBT are locally caught Sardines.

Sardines are sustainably harvested from waters in Spencer Gulf and the Great Australian Bight. They are also a natural food source for tuna in the wild.

Sardinops sagax

Australian Sardine Sardinops sagax

 

Remaining dietary requirements for SBT are met through imported baitfish.

Fish are fed a mixture of frozen and fresh baitfish. Feed may be given to SBT through frozen block feeding, syphoning, bait spinners, shovel or though a shore controlled automated  bait delivery system.