Shell Growth of the North Pacific Cockle Clinocardium californiense in Hakodate Bay, Hokkaido
1992 Volume 1992 Issue 42 Pages 39-48
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1992 Volume 1992 Issue 42 Pages 39-48
Monthly measurement of growth rings along the shell margin of the North Pacific cockle Clinocardium californiense revealed that a ring is formed annually in September (above one year-old) or in October (0 year-old), when the bottom temperature is high. Age was determined by counting the number of growth rings on the shell. The VON BERTALANFFY growth equation was fitted to the age-shell length relation, and the equation, LT=57.14(1-exp(-0.526(T-0.143))) is obtained, where LT is the shell length (mm) at age T (year). Seasonal growth pattern was estimated by measuring the monthly shell increment from the last growth ring, and the equation obtained is LT=57.35[1-exp(-0.522(T-0.241)+0.085sin(2π(T-0.476)))]. These equations show nearly the same growth rates with those previously reported for cardiid cockles, but are higher than those for other bivalves.
