THE GROWTH AND SIZE DISTRIBUTION OF CURRENT YEAR CLASS LOLIGO PEALEI

¹ Systematics-Ecology Program, Marine Biological Laboratory, Woods Hole, Massachusetts 02543

1. This paper reports estimates of the growth rate and size distribution of current year class L. pealei based upon the population statistics of daytime, otter trawl collections in Menemsha Bight during the second half of 1967.

2. The selectivity of a #35 otter trawl with a 1.25-inch mesh (3.2-cm.) stretched measure cod end liner was estimated by a 50% retention of L. pealei with a dorsal mantle length of approximately 3.7 cm.

3. The current year class, summed older year classes and individual older year classes of L. pealei were found to have lognormal size-frequency distributions.

4. The current year class could readily be separated from the older year classes by the use of Cassie's method on lognormal probability paper.

5. The growth rate of a median individual in the current year class of 1967 was found to be 1.8 cm. dorsal mantle length per month for the first four months past hatching.

6. Approximately one-half of the one-year-old L. pealei did not mature sexually before the second fall migration. None of the current year class L. pealei matured before the first fall migration.

7. The results indicate that L. pealei egg deposition is isolated in time and location, and repeated throughout the Vineyard Sound area from at least June through September.