A small fishery developed in Tasmania for southern calamary in the early 1980's, with annual landings of around 10-30 tonnes up until 1997/98. Catches have risen pretty quickly over the last few years, recently fluctuating around the 80-100 tonne mark and prompting several research projects into the biology of southern calamary. The Recreational Fishery Trust, DPIWE, Tasmanian Industry Fishing Council, individual commercial fishers, and the Australian Research Council, are all supporting an exciting new calamary tagging and hi-tech tracking project, based at the Tasmanian Aquaculture & Fisheries Institute. The project began in May this year and will run until April 2006, with most of the fieldwork conducted over the next two spring/summer spawning seasons.
Southern calamary (Sepioteuthis australis), is one of the most common cephalopods in the coastal waters of southern Australia, and is an important component of the coastal ecosystem as a primary consumer of crustaceans and fishes, and a significant food source for marine mammals, sharks and larger fish. These large inshore squid have fast growth rates, and a lifespan of less than one year. This makes them quite a productive species, but also makes their populations subject to major and rapid fluctuations in abundance - making them vulnerable to over fishing and the assessment of resource status very difficult. The tagging and tracking project has the broad aim of trying to determine movement and migration patterns in calamary, in order to understand how populations along the east coast of Tasmania may be linked. Calamary hatch as very competent miniature adults (competent enough to cannibalise each other straight after emerging from the egg!), and migrations in the order of a few hundred km's are well within the physiological potential for southern calamary.
The new project is using a combination of three different methods to look at calamary movements: high-tech acoustic tracking technology, traditional t-bar filament tags, and chemical signatures left in each squids ear bone that may reveal clues about where they came from. The University of Tasmania is one of the first marine institutes world wide to use the new state of the art "VR2 acoustic receiver system" to track marine animals. Dr's George Jackson and Jayson Semmens were awarded grants to buy the cutting-edge equipment worth over $300,000. Just recently a successful trial, involving many researchers and lots of different projects, was completed in southeast Tasmania to monitor the movements of a range of species including; arrow squid, draughtboard shark, rock lobster and octopus.
The VR2 tracking systemThe VR2 acoustic receiver system involves using miniature uniquely identifiable sonic tags (VR2 tags) placed inside each animal to be tracked, in association with many VR2 receivers stations that are placed on the ocean floor. The VR2 receivers are sited on the sea floor using a simple mooring system and when a VR2 tagged animal swims within a 500m radius of a VR2 receiver, the date, time, and tag ID are recorded. By aligning these receivers in lines across bays, "acoustic listening curtains" are created and all tagged animals swimming past are detected. Unlike traditional tags, the VR2 system allows for many readings from a single animal without the stress of multiple recaptures. The end result is a level of detail on individual animal movements over small and large scales previously unheard of.
In July 2003, a total of 81 VR2 receivers were deployed at a range of strategic locations within Great Oyster Bay and Mercury Passage (see Figure). When any of the 50 acoustic tagged calamary passes within 500 meters of a receiver, the date and tag number will be recorded. When the receiver system is retrieved in mid-January, the data can be downloaded from each receiver, and it is hoped that researchers at TAFI will have a comprehensive data set showing the movement of these individuals, in particular evidence of the degree of mixing between and within these areas. Up to 2000 calamary will also be tagged using traditional T-bar tags to give a broader overview of the movement of the species. The unique advantage of using a combination of tagging techniques is that the VR2 stations will record fishery independent data on the movement of individuals, while the traditional tagging method will provide a larger volume of "bigger picture" data. Using both tagging techniques, the movement to spawning or feeding grounds, and residence times of calamary in fishing or protected regions will be determined - all critical factors related to policy development for ecosystem and fishery management. Both long and short-term movements of squid will be tracked to indicate patterns of habitat usage over days, seasons and throughout the life cycle.-
A tag lottery will be running, with lots of great prizes donated from Spot-on Fishing Tackle and a range of businesses. Any acoustic tagged squid that are returned to TAFI earn extra entries in the lottery - acoustic tags are black plastic, about the size and shape of a pen lid and will be placed just inside the mantle near the funnel. All acoustic tagged squid will also have t-bar tags in them. So if you catch a t-bar tagged squid, please keep it intact, look for an acoustic tag, and remove the acoustic tag before freezing the squid. Record the tag number, date, and location of capture and contact TAFI on (03) 6227 7277 as soon as possible and we will arrange to collect the squid from you, and enter you in the lottery
Please take care when fishing and navigating near the receiver curtains. They have been designed and deployed in a way that should minimize interactions with boats and fishing gear. However, there is still the potential that damage could be caused to fishing gear (especially nets) and the receivers. Flyers will be posted at popular launch ramps and fishing locations to remind fishers to be aware of the receivers. The best course of action would be to avoid deploying nets near receiver locations, when ever possible.
Tracking squid with trace elements from ear bonesThis study will also assess the use of trace element "fingerprints" in the ear bones of squid, as possible natural "tags" to determine an individuals spawning ground of origin. Recent studies suggest that the elemental composition of fish ear bones can provide a powerful approach to determining the movements of marine fish including the discrimination of nursery habitats. In the southeast region of Tasmania, the flow of major currents (East Australian Current and the Zeehan current) and position of anthropological influences (eg: zinc works at mouth of the Derwent Estuary) provide a reasonable expectation of differences in water chemistry between the locations. This should result in squid producing a unique elemental fingerprint within their ear bone corresponding to the region they were hatched in. This section of the study, together with the t-bar and acoustic tagging, allows for movement and migration throughout the entire life cycle to be examined - this would be a world first for any cephalopod species.
How can recreational fishers help the project?? Promote awareness of the tagging program among recreational fishers - we need those tags back and we're sure you'd think the tag lottery prizes were just Spot-on!!? Become involved in the tagging - we'll be tagging from August to December, from Bicheno to Bruny Island.? Let us know when you see squid eggs, or large numbers of adult or juvenile squid - many eyes on the water saves us searching time so we can tag more squid. ? Help us to inform fishers to avoid netting in areas close to the VR2 receivers - we don't want your nets damaged, and damaged receivers means no squid tracking data!
For more information contact:
Please make sure you observe bag limits when catching calamary - there is a daily bag limit of 20 calamary per person, with a possession limit of 30. There may also please short-term closures on the east coast at different times of the year - please check by phoning if unsure.