Sperm features on Atlantic Bluefin tuna (Thunnus thynnus).

In captive Atlantic bluefin tuna, sperm concentration and movement duration values were similar to those reported in wild individuals (Doi et al.,1982). It was observed that spermatozoawere immotile in their seminal fluid but were fully activated with SW but also in non ionic solutions. As in many marine species, the high osmolality of SW relative to that of seminal fluid, constitutes the main triggering signal for flagellar activation (Cosson et al., 2008). Compared to marine fish species studied so far, high sperm concentration, high initial speed and long motility duration of tuna sperm may be a general characteristic of large pelagic fish.