The aim of this study was to determine the spawning season and length and ages at first maturity lengths of demersal fish species in the central Aegean Sea. Fish samples were collected by bottom trawling in Izmir Bay. Sampling was carried out at monthly intervals over a three-year period. The sample size of 21 species was sufficient to estimate their spawning period and length at first maturity. These species were Arnoglossus laterna, A. thori, Blennius ocellaris, Boops boops, Buglossidium luteum, Cepola macrophthalma, Citharus linguatula, Deltentosteus quadrimaculatus, Dentex macrophthalmus, Diplodus annularis, D. vulgaris, Gobius niger, Lepidotrigla cavillone, Merluccius merluccius, Mullus barbatus barbatus, Pagellus acarne, P. erythrinus, Serranus cabrilla, S. hepatus, Spicara maena and Trisopterus minutus. It was determined that the current prohibited season protects only 47.1% of these during peak spawning periods and that some commercial species' spawning periods are not covered by recent closed seasons. Although it was determined that a total of 13 species were fish targeted by artisanal fisheries, there are only four minimum landing size regulations in place for them. Therefore, for the study area we recommend a new prohibited season for fisheries carrying out bottom trawling as well as minimum landing sizes.