Effects of tag-related injuries and timing of tagging on growth of rock lobster, Jasus lalandii

The effects of capture, tagging and release on the growth of male Cape rock lobster Jasus lalandii collected at Olifantsbos (historically a slow-growth site) and Knol (fast-growth site) were studied under controlled conditions in aquaria, cages at sea, and in situ. Growth increments achieved after the first captive moult were related to year and area of capture, moult-condition (pre- or intermoult) at tagging with T-bar anchor tags, and treatment of lobsters (tagged, injured or starved, the latter a proxy for displacement from suitable habitats). Captive lobsters moulted between August and October, as in wild populations, and lobsters collected from Knol grew more than those from Olifantsbos. Premoult lobsters tagged during 2002 grew an average of 62% (Knol) and 67% (Olifantsbos) less than untagged control animals, and 24 and 32% less in 2003. Lobsters treated during intermoult generally grew significantly more than those treated during premoult. Loss of appendages and restricted feeding also reduced growth, although the extent varied between years and treatments. The most important result emanating from this study is that tagging during premoult negatively impacts on growth of J. lalandii, but this effect is absent when lobsters are tagged during intermoult.