Grenadiers of the World Oceans: Biology, Stock Assessment, and Fisheries

<em>Abstract.</em>—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 <em>Coelorinchus coelorhincus, </em>glasshead grenadier <em>Hymenocephalus italicus, </em>and bluntsnout grenadier <em>Nezumia sclerorhynchus</em>. The studies on the reproduction of grenadiers in the Mediterranean indicate that <em>C. coelorhincus</em>, <em>H. italicus </em>and <em>N. aequalis </em>reproduce asynchronously throughout the year but perhaps more actively in some seasons. Aseasonal continuous spawning can only be assumed for <em>N. sclerorhynchus </em>while <em>Trachyrinchus scabrus </em>seems to be the only studied species with an annual cycle and spawning during winter. Seasonal reproduction during autumn-winter has been suggested for <em>Coelorinchus mediterraneus</em>. Nothing is known for the two lower slope-dwelling Mediterranean macrourids <em>Coryphaenoides guentheri </em>and <em>Coryphaenoides mediterraneus. </em>Immature, maturing, mature and running ripe females of <em>C. coelorhincus, H. italicus </em>and <em>N. sclerorhynchus </em>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 <em>C. coelorhincus</em>, between 275 and 1,806 in <em>H. italicus </em>and between 964 to 3,553 in <em>N. sclerorhynchus. </em>The functional fecundity ranged from 318 to 4,742 in <em>C. coelorhincus, </em>from 84 to 248 in <em>H. italicus </em>and from 258 to 1,057 in <em>N. sclerorhynchus</em>.