Deep-sea Mediterranean biology:: the case of Aristaeomorpha foliacea (Risso, 1827) (Crustacea: Decapoda: Aristeidae)

Data on the distribution, abundance and biological parameters of the giant red shrimp Aristaeomorpha foliacea were collected during a research survey in deep waters (600-4000 m) of the Mediterranean Sea at three locations: the Balearic Sea, the western Ionian and the eastern Ionian in early summer 2001. The shrimp was mainly found in the shallower zone (< 1000 m) of the eastern Ionian Sea. Few specimens were caught in the deeper waters of this region, with 1100 m being the lower limit of its distribution. This is the maximum depth reported for the species in the Mediterranean. At the other two locations, the species was scarcely caught and only in the shallowest zone (< 1000 m). In the area and depth zone of high abundance, 5 modal groups for females and 3 for males were distinguished using the Bhattacharya method. The recruitment seems to take place at the shallowest stations (600 m). More than 50% of adult females were in advanced maturity stages. The striking abundance differences of the species between the western and eastern locations may be explained by the different exploitation level of the deep waters (almost null in the eastern Ionian Sea and extensive more westwards). However, the distribution and biological characteristics of A. foliacea indicate a higher vulnerability to over-fishing comparing to the other commercial co-occurring deep-water shrimp Aristeus ontennatus.