Distribution, Biology, and Population Dynamics of Aristaeomorpha Foliacea (Risso, 1827) (Decapoda, Natantia, Aristeidae) in the North-Western Ionian Sea (Mediterranean Sea)

Abstract

The distribution, biology, and population dynamics of Aristaeomorpha foliacea (Risso, 1827) have been investigated in the north-western Ionian Sea (middle-eastern Mediterranean). A total of 9,637 specimens, 5,570 females and 4,067 males, was collected during twelve trawl surveys carried out between 350 and 750 m of depth. Aristaeomorpha foliacea is found on muddy bottoms with the highest densities generally in the upper 600 m and in a zone where canyons cross the bottoms. A spatio-temporal distribution correlated to bio-ecological aspects was shown in the population. An increase in males on the fishing bottoms was shown during winter when maturity of this sex begins and shortly after mating occurs in the population. During the winter-spring season the whole population migrates to the upper slope. After the mating peak, in summer, when spawning is at its maximum, the population is again displaced to the deeper grounds. The ovary maturation period is between May and September and the largest specimens are the first to mate and reach sexual maturity. The size of maximum reproductive potential is 37.11 mm carapace length. Recruitment occurs in spring and the stock is mostly represented by young individuals. Both female and male growth rates fit a Von Bertalanffy function. Both female and male stocks appear to be mortality-dominated (Z/k > 1). Estimates of the exploitation ratio (E = F/Z) are between 0.43 and 0.62 in females and between 0.46 and 0.65 in males.