The influence of animal density and water turbulence on growth and survival of cultured spiny lobster ( Jasus edwardsii) larvae

Abstract

The survival and growth of early stage phyllosoma larvae are dependent on establishing suitable larval stocking densities, and controlling the velocity and type of water turbulence within a culture vessel. This study examined the effects of larval density and flow-induced turbulence on growth and survival of Jasus edwardsii phyllosoma in culture. In the first experiment, newly-hatched phyllosoma were stocked at six densities (5–160 larvae l − 1 ) into 1.6 l plastic beakers with water flow introduced at the container floor (0.5 cm above the beaker bottom and parallel to it) facilitating 2.5 exchanges h − 1 and fed 2.5 mm long Artemia supplied at 1.5 ml − 1 . Culture to Stage IV demonstrated that growth and survival were compromised at phyllosoma densities > 40 l − 1 . The second experiment examined the influence of flow-induced turbulence, with a combination of two water exchange rates (2.5 or 5 times h − 1 ), two inlet positions (2 cm above the water surface or 0.5 cm above the beaker bottom and parallel to it), and at two phyllosoma densities (10 and 40 l − 1 ). Larvae were significantly larger at the low density but only at the slower flow rate, while survival was highest at the low density with water introduced 2 cm from the water surface. These conditions allowed larvae to capture sufficient Artemia prey without the stresses associated with uncontrolled swimming. We recommend that larvae be cultured up to Stage IV at densities no higher than 40 l − 1 , under conditions of low turbulence, thus preventing excessive clumping of larvae, while maximising predator–prey ratios.