Microgeographic differences in growth, mortality, and biochemical composition of cultured Pacific oysters (Crassostrea gigas) from San Quintin Bay, Mexico
Z. Garcia-esquivel et al., Microgeographic differences in growth, mortality, and biochemical composition of cultured Pacific oysters (Crassostrea gigas) from San Quintin Bay, Mexico, J SHELLFISH, 19(2), 2000, pp. 789-797
Changes in shell height, tissue dry weight (TDW), mortality, and biochemica
l composition of Crassostrea gigas were evaluated at two commercial sites i
n San Quentin Bay (SQB), Mexico, during the first 9 mo post-settlement. She
ll growth rates were 1.5x higher at the mouth (0.36 mm d(-)1) than the head
of SQB (0.23 mm d(-1)). Tissue dry weight was also 7- to 8-fold]higher in
oysters From the mouth (2.1-2.16 g TDW oyster(-1)) than the head of SQB (0.
23-0.33 g TDW oyster(-1)) at the end of the 9-mo experiment. Market size (9
cm) was reached after 9 mo at the mouth and at an estimated age of 13 mo a
t the head of the bay. Highest mortality occurred within the first month po
st-settlement (50%-60%) and reached approximately 63% to 87% throughout the
whole study period. Proteins (48%-64%) and lipids (2%-9%) were the most ab
undant biochemical components during early spat development. When oysters r
eached a size between 48 and 55 mm (shell height) in the fall, glycogen (1%
-22% replaced lipids as the main energy depot. The changeover occurred earl
ier in oysters at the mouth than in oysters from the head of the bay. it is
suggested that between-site differences in growth and biochemical composit
ion in oysters are the result of longer immersion/feeding period experience
d by oysters at the mouth of SQB.