Biological knowledge of jack mackerel is not extensive,and as yet no information on maturity or growth ratehas been documented. Analysis of fish caught in theSouthern California Bight indicates a spawning seasonfrom March through October. By the end of their firstyear, most females (70%) are capable of spawning, andthe percentage increases with age.Weight-length curves were calculated for a 2 monthperiod (July and August), and for the entire year. Avon Bertalanffy growth curve was determined fromJuly-August data to represent size of each age groupnear the designated August 1 birthdate. (328pp.)