DURATION OF LARVAL AND SPAWNING PERIODS IN PAGRUS-AURATUS (SPARIDAE) DETERMINED FROM OTOLITH DAILY INCREMENTS

Counts of pre-metamorphic and post-metamorphic daily increments in the sagittae of settled juvenile Pagrus auratus were used to determine du ration of the larval period and to back-calculate spawning dates. The duration of the larval period was 18-32 days, and was longer for snapp er spawned early in the spawning season, when water temperatures were low, than for snapper spawned later in the season when temperatures we re high. Sagitta size at metamorphosis was unrelated to duration of th e larval period or temperature, and mean increment width during the la rval period increased with temperature. These results suggest that met amorphosis is size- rather than age-dependent. Back-calculated spawnin g dates ranged from September to March, and peaked in November-January . Maximum spawning season duration was five months. Spawning onset was earlier when spring water temperature was higher than normal, and fir st spawning occurred at 14.8-15.6-degrees-C over three seasons, indica ting that spawning onset is temperature-dependent.