In the beginning of October, 2015, live juvenile lobsters (Panulirus gracilis) were purchased from a local fisherman at 10.3 g average weight and stocked into a zero water exchange system. Over the course of the next 7 months lobsters were fed various prepared and raw feeds and average weights and feed conversion ratios (FCR) were calculated monthly with widely varying results of 2 to 43. Although mostly proteins are widely consumed in the wild, there were vast differnces in FCRs, meaning that these lobsters can digest and assimilate marine proteins differenty. Lobsters weighed only 27 g at the end of four months with regular mortality of 3-6% per month. Runts were typically culled out by cohorts, as the sizes of lobsters became more uniform.

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From 20-May-16 to 8-Sept-16, survivals were 100% and water quality in the closed system was near perfect. Growth, FCRs and % increase in biomass varied from month to month as different combinations of feeds were offered (see table below). As of 10-Sept-16 biomass was up to 4.3 kg/m3, with lobsters reaching 137 g on average (picture right).

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The diet for lobsters during 8-Sept to 10-Oct was radically changed which produced 1/2 of the growth of the previous month. Some wasted feed was found during sampling and NO2 in the system had increased from 0.5 to 2.5 during the week before sampling. A single lobster was found that was gray in color and had a bacterial disease which was apparent on the tail as an open sore (photo right). Survivals were still 100%. Nitrite in the system was quickly reduced in 24hrs wtih a contingency treatment used previously in other systems.

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Picture at lower right shows sexual dimorphism for this species in pleopod shape.

 

Please Note:

This is not only the first time this lobster species has been grown in an aquaculture system but the first time in a zero water exchange system as well.

 

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Update 10.Jan.17

Growth for the previous month was 6.1 g/wk which is 2x of the average of the previous 3 months. Mortalities increased due to bacterial infection which was evident from sampling as so a new protocol will be used. Lobsters reached 1/2 lb as of this sampling date (pic right) with biomass > 5 kg/m3.

 

 

 

 

 

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