Early choice of European
spiny lobsters for control of maturation
Aquaflow Technical Leaflet 2002-50
European Network for the Dissemination of Aquaculture
RTD Information (Q5CA-2000-30105) and previously FAIR-3837, URL: http://www.aquaflow.org/
Studies are currently being undertaken at Guia Marine
Laboratory on the feasibility of the control of maturation in two eastern
Atlantic spiny lobster species held in captivity and the future culture of
their larval stages (phyllosomas). Two species of Palinurid spiny lobsters
commonly available in European coastal waters, Palinurus elephas (common spiny lobster) and Panulirus regius (royal spiny lobster) were selected in the first
instance to evaluate species adaptation to long term captivity and the
compliance of control of maturation through successful spermatophore
transfer and egg spawning.
Species are being reared in community white fibre
glass tanks of 4 m3 (2.2 m diameter; 3.8 m2 area of
base) with recirculated seawater. Each tank was initially stoked with 10
animals (7♀:3♂) measuring an average of 70 mm carapace length
and 400 g of weight. No shelters were provided, but green plastic mesh
covered the whole lateral surface of tanks (7.6 m2). Illumination
was provided by fluorescent tubes (total of 80 w) with photoperiods
simulating early summer conditions of temperate northern hemisphere.
According to their latitudinal distribution in Europe, the common spiny
lobster was subjected to 18 and 23°C and the royal spiny lobster to 23 and
25°C. Feed consisted of frozen items like mussel, squid and dogfish flesh.
After a one-year period of assays no control of
maturation was yet achieved for both species. Nevertheless some facts
regarding species adaptation to long-term captivity are now apparent.
Mortality rate for both species in community husbandry was too high,
although by different reasons. Half of the population of the royal spiny
lobster was lost to cannibalism after carapace moulting and half of the
common spiny lobsters was also lost but through parasitic infections. That
seems to suggest that Palinurus
elephas is much less prone to cannibalism than Panulirus
regius even taking into account that the former moulted twice and the
later three times. If temperature, especially above 20°C, is taken into
consideration, than mortality for the common spiny lobster rises further due
to facilitated parasite (fungus) attack noticeable through black branchial
necrosis. Higher temperatures (25°C) did not look to adversely affect the
survival of the royal spiny lobster.
Efforts will be from now on focused on overcoming the
cannibalism of the royal spiny lobsters by testing the use of specific
shelters. Infection in the common spiny lobster will be prevented by better
management of water quality as well as the effect of shelter. This species
has already been the subject of study in Japan, where control of maturation
and spawnings were reported to be achieved although the rearing of larval
stages showed to be a more difficult task. New approaches for culturing
phyllosomas are being devised and tested, namely the production of
alternative sources of live zooplankton other than the common brine shrimp Artemia sp.
For more information :
Dr.
Orlando Luis
Departamento Zoologia, Universidade de Lisboa
Laboratório Marítimo da Guia
Estrada do Guincho, 2750-642 Cascais, Portugal
Phone:+351 214869211
Fax: +351 214869720
E-mail: ojluis@fc.ul.pt