Póster.-- IX International Symposium on Marine Sciences, celebrado en Valencia del 10 al 12 de julio de 2024., This study provided fundamental information on the reproduction of western Mediterranean populations of Callinectes sapidus. Results show that ovigerous female appearance is similar to those found in eastern Mediterranean, but lower of this in the Atlantic. The breeding season shows a peak of reproduction in September, sames as in other Mediterranean localities. The inverse relationship between IGS and HSI suggests the use of part of the energy stored in the liver (glucogen) for the synthesis of gonadal tissue. On the other hand, Salinity and temperature could be used as predictors of maturity development status as has been found in others studies (Mente, 2008)., The study framework is the project: I+D+i ECESIS (PID2020 118476RR-C21) and PID2020-118476RR-C22, funded by MCIN/AEI/10.13039/501100011033/., Peer reviewed