Italian scientists have documented the first ever occurrence of Zenopsis conchifera in the Mediterranean Sea.
Though common in the eastern central Atlantic, Zenopsis conchifera, commonly referred to as the Silvery John dory, Sailfin dory or Buckler dory, was previously undocumented from the Mediterranean Sea.
The report, published in the last volume of the Journal of Fish Biology of 2007, is based on a single female specimen of Z. conchifera, 64.5 cm in length, caught in July 2006 by a commercial bottom trawler off the northern coast of Tunisia (central Mediterranean).
Alien speciesWith only one documented capture within Mediterranean waters, Z. conchifera has been labeled as an alien species and is not yet considered to be established (which would require three or more records of capture) within the region.
The female specimen of Z. conchifera was caught during a daylight bottom trawl off Capo Farina (northern coast of Tunisia) at a depth between 183-290m. The commercial trawler (an Italian vessel from the southern coast of Sicily) that collected the alien species was targeting Norway lobster and rose spiny lobster at the time of capture.
A member of the family Zeidae, the silvery John dory is widely distributed throughout the Indian Ocean and the eastern and western central Atlantic but has been reported from the north-east Atlantic coasts of Europe since the mid 1960s.
Only one zeid, Zeus faber, commonly referred to as the John dory, is considered native to the Mediterranean Sea. Like other dories, the John dory is a commercially important species and it is widely consumed throughout the coastal Mediterranean region.
Changing faunaOver the last few decades, the fish fauna of the Mediterranean has been increasing at a rate of 1.5 new species per year. The raising number of species is due to the invasion of exotic species, particularly those of Atlantic or Indo-Pacific origin.
An explanation for the increasing number of exotic fish species within the Mediterranean Sea is unclear at present. Increasing seawater temperature throughout the entire Mediterranean basin is considered by some to be one of the most likely reasons for the growing number of exotic species but it is likely that other factors are involved.
The single catch record of the silvery John dory within the Mediterranean Sea to date suggests that this species has only very recently invaded Mediterranean waters.
For more details on the Mediterranean occurrence of Zenopsis conchifera see the paper: Ragonese, S. and G. B. Giusto. (2007). Zenopsis conchifera (Lowe, 1852) (Pisces, Actinopterygii, Zeidae): a new alien fish in the Mediterranean Sea. Journal of Fish Biology, 71: 1853-1857.