Effect of farming method, explant size and environment on the success of bath sponge aquaculture in Torres Strait (CRC-TS Project: Task Number T1.6a)

Brief description

Sponges were experimentally farmed at three sites in the Yorke Islands: Kodall Island North, Masig Island East and Masig Island North. Sites were located on the leeward side of the islands. At each site, Coscinoderma matthewsi explants were farmed at a depth of 12 m, using riser lines, approximately 3 m apart. For each farming experiment, 10-50 sponges were partially harvested, whereby one third of each sponge was left behind to regrow. The collected sponge tissue was cut into explants, each with at least one side still covered in pinacoderm. At no time were sponges or explants exposed to air. For each experiment, 15-20 explants were measured at the start of the experiment to determine initial explant size and all surviving explants were measured at the end of each experiment. The length, width and height of each explant were measured with a ruler to the nearest centimeter and the volume calculated. Because of slight differences in initial size between some explants, percent growth was calculated.Explants of Coscinoderma matthewsi were experimentally farmed for nine months using three methods, threaded line, mesh and mesh-line, with each method testing two material types. Coscinoderma matthewsi was experimentally farmed at Kodall North and Masig North, with three riser lines per treatment at each site. Each riser line had 6 explants, thus 36 explants were cultured per treatment. In total, 216 explants were experimentally farmed with a mean initial size of 113 ± 9 cm³.Coscinoderma matthewsi was experimentally farmed at Kodall North, Masig East and Masig North, with explants transplanted at the end of summer (March 2005) and at the end of winter (September 2005). Explants would therefore experience either falling or rising water temperatures, respectively, for the first 6 months of culture. Two riser lines were deployed per farming site/seasonal transplant, with one mesh panel holding 6 explants attached to each riser line at 6 and 12 m. Due to inadequate flotation, the riser lines were not vertical in the water column through out the entire tidal cycle, and thus we could not accurately determine the effect of depth. Twenty-four explants were farmed per site/seasonal transplant, with 144 explants experimentally farmed in total. The mean initial size of explants between sites/seasons ranged from 166 ± 15 to 255 ± 18 cm³. This experiment ran from March 2005 to September 2006.A temperature recorder (HOBO® Water Temp Pro), deployed at 12 m at the Masig North site, recorded water temperature during the length of the project. A water flow meter (General Oceanics INC) was also deployed for 24 hr periods for three times at each site.At Kodall North, explants of three initial sizes were experimentally farmed: small, 39 ± 5 cm³; medium, 104 ± 8 cm³; and large, 313 ± 27 cm³. Explants were farmed inside mesh panels, attached to riser lines. Three riser lines were used, each holding 5 explants of each size treatment. In total, 45 explants were cultured. This experiment started in June 2005 and ran for 6 months.A temperature recorder (HOBO® Water Temp Pro), deployed at 12 m at the Masig North site, recorded water temperature during the length of the project. A water flow meter (General Oceanics INC) was also deployed for 24 hr periods for three times at each site. This research was undertaken to develop aquaculture methods for optimal and environmentally sustainable commercial production of bath sponges in at least one location selected for the project. Another aim of this project was to promote the transfer of skills and technology from this project directly into the local community, by involving York Islanders in diving and monitoring the farming experiments.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: Statement: Sites were established on the leeward side of the islands, which are largely protected from the south-easterly trade winds, and thus easily and safely accessible using small community boats.The riser lines used for farming consisted of a vertical rope held upright using subsurface floats and anchored using one 20 l drum filled with concrete. Farming methods:For the threaded line method, explants were threaded onto 4 mm nylon or polypropylene line for the duration of the experiment. In the mesh method, explants were farmed for nine months in either ¿spider¿ (Australian Netmakers) or monofilament mesh panels, with the former consisting of more rigid and thicker plastic mesh. For the mesh-line method, explants were placed in mesh panels for 3 months (nursery period) allowing sufficient time to fully heal, and were then threaded onto nylon or polypropylene line.

Notes

Credit
Duckworth, Alan R, Dr (Principal Investigator)