Optimizing Harvest Time Through Absolute and Relative Growth of the Black Clam, Chionista fluctifraga, Cultivated in the Intertidal Along the Southeastern Coast of the Gulf of California

The shell height-body weight relationship of the black clam Chionista fluctifraga cultivated in the intertidal of the southeastern Gulf of California, was evaluated for the first time, to improve the knowledge in determining its harvesting time. Clam seeds (n=900,000; 6.1±1.9 mm) were produced in the laboratory. The culture was divided into pre-fattening in racks on the bottom (2 months) and fattening directly in the bottom (16 months) from May 2018 to October 2019. Each month, 60 (n=1080) clams were randomly selected to stablish the morphometric relationship between shell height (SH) and body weight (BW). The growth rate (mm/d and g/d) was recorded. The SH-BW Interaction in both cultivation phases showed positive allometry. SH in prefattening and fattening registered a growth rate of 0.072 and 0.058 mm/d, respectively. In fattening, the interaction BW-SH displayed a high coefficient of determination (R2=0.99). A final survival rate of 90% was obtained. The results yielded the equations that describe the relative growth of C. fluctifraga for the fattening stage. A harvesting time after 10 months of fattening in the intertidal zone is stablished to reach the commercial size (35 mm, SH).