Cultivo de la ostra del pacífico Magallana Gigas (Thumberg, 1793) a distintas profundidades en Jaramijó, Manabí, Ecuador.

Abstract

The situation observed in Ecuador as a quasi-mono aquaculture producing country requires diversifying the aquaculture and the possibility of cultivating bivalve mollusks, particularly the Pacific oyster Magallana gigas, due to the availability of seeds, rapid growth, the possibility of cultivation with low-scale technology and being naturally fed in the sea, provides advantages for its implementation in the country. The objective of this study was to determine the depth where a better growth of this species can be obtained. The essay was carried out in front of Balsamaragua beach, Jaramijó, Ecuador, 700 m from the coast and at a depth of 9 m between November 9, 2022, and January 25, 2023. Three-level Chinese lanterns were installed in duplicate at 2 m and 5 m from the bottom. In each level, 100 specimens with an average size of 1.5 ± 0.24 dorso-ventral length (DVL) were placed, enclosed in plastic boxes with holes in the walls and covered with 2 mm mesh mosquito netting. The temperature, salinity and seston were measured weekly at the two depths. Salinity and temperature differences were very slight between depths. Specimens grown 5 m from the bottom showed significantly higher growth for two weeks after the start of the trial, reaching an average size of 5.6 ± 2.1 (2.9 - 8.2) cm LDV at the surface lanterns at 79 days and 3.53 ± 1.07 (1.3 – 5.9 cm LDV) at 45 days of culture in the bottom lanterns. Growth rates were 0.52 mm/day at 5 m and 0.44 mm/day at 2 m. Turbidity and mud accumulation in the boxes was higher in the lanterns 2 m from the bottom. The survival rate was higher than 95%. The fowling communities did not affect the oysters kept in the plastic boxes, but they intensely colonized the outside of the boxes. It is recommended to keep cultures of M. gigas at least 5 m from the bottom and to keep oysters in rigid boxes with holes in the walls as a measure to prevent the recruitment of fowling communities when cultured near rocky areas.