Catadromous species. When sexual maturity is reached they leave the river. Spawning migrations occur mainly during the second half of the year but have been observed year-round, usually commencing during dark nights (Ref. 172). Maturity is obtained during the spawning migration (Ref. 88171). Actual spawning has never been observed but is believed to occur solely in the Sargasso Sea between March and June (Ref. 89144). After spawning (at 600 m depth) adults die. Sigmund Freud described the testicles of eel (Ref. 72449).