Effects of nearness to reef and exposure to sea-swell on estimates of relative abundance of Jasus verreauxi (H. Milne Edwards, 1851) recruits on collectors.

The hypothesis tested was that catches of J. verreauxi recruits (numbers of pueruli to early juveniles) on sea-weed-type collectors were affected by the nearness of the collectors to vegetated reef and relative exposure of the collectors to sea-swell. Numbers of recruits on collectors set far from reef were greater than on collectors near reef. Collectors far from reef may be the first, preferred type of habitat encountered by recruits as they move across the Continental Shelf. Alternatively, fewer recruits may inhabit collectors set near reef because of the nearness of natural, vegetated reef. A cost-benefit analysis determined that the optimal sampling strategy for surveys of the abundance of recruits at one location and time, would be three replicate collectors at each of three sites. Sampling once with this strategy at one location would give a standard error of around 20% of the mean. This information was used in developing a uniform and optimal methodology for full surveys to monitor the relative abundance of J. verreauxi recruits along the coast of New South Wales.