STUDIES ON SOUTHERN AUSTRALIAN ABALONE (GENUS HALIOTIS) .16. RECRUITMENT, HABITAT AND STOCK RELATIONS

The dynamics of a population of the greenlip abalone, Haliotis laeviga ta, was studied from 1978 to 1990 in Waterloo Bay, South Australia. Du ring this period the fishery was closed from 1982 to 1986 and the size limit was increased in 1986. The spatial distribution of recruitment (measured as the abundance of the 2+ age class) was correlated during every year of study with a complex gradient comprising water movement, habitat complexity and predator density, and for six years of the stu dy with depth. Recruitment in the six years from the closure was 2.7 t imes higher than that in the preceding seven years. The intensity of a ggregation of the adult (greater than or equal to 4 years) fraction of the population varied with density and habitat complexity. Under inte nse fishing, aggregations were fewer and smaller. This paper weights s tock abundance according to a model relating intensity of aggregation with fertilization success and presents a stock-recruitment relation f or the Waterloo Bay population. The curve is a classical Ricker type s howing compensation at high stock sizes. This curve indicates that bel ow adult densities of about 0.15 to 0.2 m(-2) the population is increa singly vulnerable to recruitment failure and ultimately to collapse.