A Review on the Reproduction of Grenadiers in the Mediterranean with New Data on the Gonad Maturity and Fecundity
Gianfranco D’Onghia, Porzia Maiorano, and Letizia Sion
Abstract.—This paper reviews the literature on the reproduction of grenadiers in the Mediterranean Sea providing the first data on fecundity and oocyte dynamics for saddled grenadier Coelorinchus coelorhincus, glasshead grenadier Hymenocephalus italicus, and bluntsnout grenadier Nezumia sclerorhynchus. The studies on the reproduction of grenadiers in the Mediterranean indicate that C. coelorhincus, H. italicus and N. aequalis reproduce asynchronously throughout the year but perhaps more actively in some seasons. Aseasonal continuous spawning can only be assumed for N. sclerorhynchus while Trachyrinchus scabrus seems to be the only studied species with an annual cycle and spawning during winter. Seasonal reproduction during autumn-winter has been suggested for Coelorinchus mediterraneus. Nothing is known for the two lower slope-dwelling Mediterranean macrourids Coryphaenoides guentheri and Coryphaenoides mediterraneus. Immature, maturing, mature and running ripe females of C. coelorhincus, H. italicus and N. sclerorhynchus were collected during June and October 2005 in the northwestern Ionian Sea (eastern-central Mediterranean). From running ripe ovaries, the absolute (total number of eggs > 0.1 mm) and functional fecundity (hydrated oocytes) were estimated. The oocyte diameter distributions showed a multimodal trend in all three species in both seasons, confirming that these grenadiers reproduce serially as multiple batch spawners. The absolute fecundity was between 1,320 and 8,897 in C. coelorhincus, between 275 and 1,806 in H. italicus and between 964 to 3,553 in N. sclerorhynchus. The functional fecundity ranged from 318 to 4,742 in C. coelorhincus, from 84 to 248 in H. italicus and from 258 to 1,057 in N. sclerorhynchus.