INTENSIFICATION OF SCALLOP Nodipecten nodosus FARMING: AN ECONOMIC APPROACH
The farming of scallops Nodipecten nodosus is an emergent industry in Brazil, being performed in Japanese lanterns suspended from long-lines. The lanterns have high cost, so increasing stocking density could improve economic results. Thus, this study aimed to determine the viability of culturing scallops in the growing phase at high densities and assess the economic feasibility of the system intensification by a partial budget analysis (PBA). The experiment was carried out from December 2017 to October 2018 (294 days) at a commercial mollusk farm situated at Cocanha Island, Caraguatatuba, Sao Paulo state, Brazil. Juveniles of N. nodosus (19.2 ± 2.8mm in height), were stocked in lanterns at the density of 1200 m-2 (intermediate phase). After 78 days the lanterns were harvested and the scallops (36.7 mm in height) were re-stocked (growing phase) at three densities: 600, 400 and 200 m-2 (Treatments T600, T400 and T200 respectively). Each 70 days the densities were reduced to half, going to 300, 200 and 100 m-2 and finishing at 150, 100 and 50 m-2. After 216 days, scallops were harvested, counted, weighed and measured in height. Data were compared by ANOVA one-way followed by Tukey test. We observed significant differences among mean heights and number of scallops higher than 65mm, while survivals and total dry mass (24 h at 80oC) did not differ (table below).
For PBA we considered the growing phase of scallop culture starting with 6,000 juveniles and three management systems corresponding to the experimental treatments above. Only revenues and costs directly related to the increase of density were considered. Gross revenues were obtained considering two sales prices: US$ 12.50 and 10.00 for scallops larger and smaller than 65 mm in height respectively. We considered here the costs of the lanterns (US$ 16.00 each) and labor (US$ 3.00 per hour). Estimated labor times were: a) for seeding: 0.2h each lantern; b) for cleaning lanterns: 0.3h each; c) for harvesting: 0.1h each lantern and d) for cleaning scallops: 0.1h each dozen. Although T200 had higher gross revenue, T600 showed greater profit, due mainly to the high cost of lanterns and labor. However, these results should be interpreted with caution, because variations in the cost of lanterns and labor may affect the results.
Research funded by the Sao Paulo State Research Foundation (FAPESP) - Pr. 2016/11122-6
