Experimental reseeding of juvenile spiny lobsters (Jasus edwardsii): Comparing survival and movement of wild and naive lobsters at multiple sites

Abstract

We used mark-recapture methods to assess the relative survival of naive and wild-caught juvenile lobsters released to coastal reef in southeast Tasmania, Australia. Naive lobsters were captured as pueruli (first benthic post-larval stage) and reared in tanks for 12 to 18 months. Naive and wild-caught lobsters were identified individually by an antennal tag and released by divers at 4 sites. In dive surveys performed over 3 to 5 weeks we resighted similar numbers of wild and naive lobsters at 2 of the sites, but significantly more naive lobsters at the remaining sites. Multistate mark-recapture models detected no difference in apparent survival between treatment groups at 3 of the sites. Lower apparent survival of naive lobsters at the fourth site was attributed to the small size of this reef and the absence of adjacent lobster habitat. Many naive lobsters did not recognise habitat boundaries and moved away from the release reef onto sand. Acoustic tracking revealed that selecting release sites with contiguous reef extending a minimum of 30 m in all directions should negate losses of this kind. At 3 sites apparent survival estimates were low for wild and naive lobsters in the 24 h following release. Apparent survival was much higher when lobsters were released into seafloor cages. Acoustic tracking indicated that low apparent survival of lobsters released outside cages was due largely to emigration from our survey areas rather than losses to predation. By following simple criteria in the selection of release sites it is possible to ensure that survival rates among released naive lobsters are equivalent to those of wild lobsters released in the same manner.