The reproductive cycle of Ophichthus rufus (Anguilliformes) in the northwest Mediterranean

The reproductive biology of the Mediterranean snake eel, Ophichthus rufus ( Ophichthidae), was studied on the basis of microscopic and macroscopic anal ysis. Results show that O. rufus is an ovuliparous species with a group syn chronous ovary type. The maturation process of the gonads starts in Decembe r and progress untill August, when ovulation and spawning take place. It is a fractional spawner with buoyant eggs. Potential annual fecundity estimat es ranged from 1426 to 23,605 oocytes. Except for small sizes, a clear pred ominance of females was observed.