Feeding biology and artificial diet development for the culture of Jasus edwardsii and Jasus verreauxi spiny lobster Phyllosomas

Abstract

Spiny lobsters (Decapoda: Palinuridae) are large, abundant, arthropods and one of the world's most valuable seafoods. Concern for the sustainability of spiny lobster fisheries has created significant interest in their aquaculture. A complex larval life history about which little is known has proven to be a major obstacle to both collection of wild phyllosoma for study and also to laboratory culture. The primary limitation on culture is the provision of an adequate diet during the long phyllosomal larval phase. Development of a suitable diet is only possible by thorough examination of the underlying feeding biology. However, obtaining this information is near impossible without a reliable source of phyllosomas at each developmental instar. This research has focused on the systematic analysis of feeding biology and the development of an artificial diet for Jasus edwardsii and Jasus verreauxi phyllosomas. Results presented here have provided a breakthrough for phyllosoma research, now making possible further investigations into the feasibility of large-scale commercial culture and a reliable source of pueruli. The research identified four key areas central to the understanding of phyllosoma biology and initiation of the development of larval diets; feeding behaviour and sensory structures; mouthpart morphology and function; foregut structure and function; and interactions of wild phyllosomas with potential prey. Results obtained from this work were then used to formulate and test a diet for early instar phyllosomas. The research has done much to overcome the obstacles to experimental culture and study of the phyllosoma larvae and their development. Phyllosomas are able to capture and manipulate large prey items using their sharp dactyls on the endopod of the pereiopod and triserrate setae to adhere to prey. Phyllosomas are able to detect live and inert prey items using chemosensory setae and hydrodynamic flow detectors. Mouthparts increase in size, robustness and complexity with larval development and mastication improves with age. Early instar phyllosomas have simple anterior and posterior foregut structures, reduced setation and filter smaller volumes whereas later instars have improved filtration and internal mastication, increased setation and can filter larger volumes. In the wild, mid and late instar phyllosomas are likely to prey on gelatinous zooplankton, as well as some small crustacean prey, such as krill. Based on the above work, an artificial diet was developed and tested on instar 1 and 2 J. edwardsii phyllosomas. Morphological and behavioural evidence presented in this thesis and examination of associations between wild phyllosomas and likely prey, give confidence that the artificial diet I have developed has significant potential for application in rock lobster phyllosoma aquaculture, here in New Zealand and overseas. I suggest diets comprising softer prey items with a uniform matrix, such as microencapsulated pellets or pastes are most suitable for early instar phyllosomas. Later instar phyllosomas are more suited to larger, fleshier prey items with particulate, non-uniform matrices. It is essential that the feeding biology of spiny lobster phyllosomas is much better understood before a suitable artificial diet can be developed. To achieve this, a reliable source of phyllosomas at each developmental instar must be available. A lack of knowledge of larval biology in a species with such importance in the subtidal community presents a series of obstacles. These problems prevent successful aquaculture of the species and restocking of already depleted wild populations. The new advances in phyllosoma biology presented in this thesis are expected to contribute significantly to successful experimental culture of phyllosomas for larval life history studies and for laboratory-scale production of pueruli.