New Zealand Journal of Marine and Freshwater Research abstracts

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Short communication

Combining passive integrated transponder tags with conventional T-bar tags to improve tag reporting rates in a rock lobster trap fishery

Stewart D. Frusher¹

David Hall²

Paul Burch^1,3,4*

Caleb Gardner¹

1Marine Research Laboratories

Tasmanian Aquaculture and Fisheries Institute

University of Tasmania

Private Bag 49, Hobart

TAS 7001, Australia

email: stewart.frusher@utas.edu.au

2Hallprint Pty Ltd

15 Crozier Rd, Victor Harbor,

SA 5211, Australia

3School of Mathematics and Physics and

 Tasmanian Aquaculture and Fisheries Institute

University of Tasmania

Private Bag 49, Hobart

TAS 7001, Australia

4Also at CSIRO Marine and Atmospheric

Research, Hobart, Tasmania, Australia.

*Present address: SARDI Aquatic Sciences, 2 Hamra Ave, West Beach, South Australia 5024. email: Burch.Paul@saugov.sa.gov.au

Abstract Tag reporting rate is an important parameter required for estimating fishing and natural mortality in fished populations. It is an extremely difficult parameter to estimate and can vary both during the fishing season and between fishing years. Improving tag reporting rates has been identified as a cost-effective way of improving precision in fishing and natural mortality estimates derived from tagging data. In this study we evaluated the use of passive integrated transponder (PIT) tags to improve tag reporting rates in a lobster (Jasus edwardsii) trap fishery. To minimise the risk of PIT tag ingestion by consumers, we tested insertion of the PIT tag into the base of the antennae, the base of the walking leg, and the base of the telson. The base of the antennae proved to be the best option for lobster health although impacts were observed at all tag insertion sites. We further developed and tested a hybrid tag that combined a conventional external T-bar tag with a PIT tag embedded within the shaft. PIT tag scanners were positioned in bottlenecks in the capture process so that all lobsters retained on board the vessel were passed through a scanner. Thus, the tag reporting rate was expected to be 100% for the subsample of the fleet fitted with scanners when scanners were operational. Scanner malfunction was a major issue and further engineering solutions are required to ensure that scanners are reliable when working in harsh marine conditions such as on-board fishing vessels. Advantages of the hybrid tag are: the ability to be detected by both automatic detectors and fishers; known tag-induced mortality and tag loss rates from previous research; and PIT tagging without risk of human ingestion.

Keywords lobsters; mortality rates; Jasus edwardsii; hybrid tag; tag location

 

New Zealand Journal of Marine and Freshwater Research, 2009, Vol. 43: 347–353

0028–8330/09/4301–0347 © The Royal Society of New Zealand 2009

M07082; Online publication date 24 February 2009

Received 30 November 2007; accepted 25 June 2008

PDF file of entire paper: Print-quality (325K) | screen-quality (211K)

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