Early growth of green abalone in hatchery and field

Abstract

The green abalone, Haliotis fulgens, native to shallow marine waters of southern California and northern Mexico, has been heavily fished by sport and commercial divers. Natural stocks have declined with exploitation throughout its range. This species has proved amenable to artificial propagation, however. Its tolerance to relatively high water temperatures (to 31.50C = 88.70F) with a growth optimum for juveniles at 24-26C prompted interest in the green abalone for culture in thermal effluent, inland seawater systems, and tropical mariculture. Progeny from hatchery production have shown promise as subjects for field release in fishery enhancement and ocean-based mariculture. This presentation discusses recent developments in the culture of the green abalone and reports observations on growth both in the hatchery and in the field. Growth rates of hatchery-reared young released in San Diego waters have matched closely those of natural recruits (average monthly shell growth for juveniles 3-8 cm at marking was 3.5 cm). Growth varied by season as well as by size class. Young green abalone at Bird Rock, La Jolla, reach six inches (15.2 cm) in about four years. A reusable plastic "temporary shelter" is described which facilitates planting and minimizes initial losses due to handling and predation. Several recent "abalone plants" using the shelters have been carried out off Point Lama and La Jolla by members of the San Diego Council of Divers. An account of some aspects of these projects is given in the concurrent poster session.