Population structure, age and growth of macrourid fish from the upper slope of the Eastern‐Central Mediterranean

Abstract

Hymenocephalus italicus, Nezumia sclerorhynchus and Coelorhynchus coelorhynchus were found in 80, 75 and 69% of trawl hauls carried out between 250 and 750 m on the upper slope of the Ionian Sea. The abundance of H. italicus and N. sclerorhynchus increased with depth while in C. coelorhynchus the highest densities were observed in the uppermost 500 m. In all three grenadiers the average size increased with depth. The populations had a multimodal sizefrequency distribution. In H. italicus adults were generally more represented in the population and the abundance of juveniles varied with seasons. In N. sclerorhynchus and mostly in C. coelorhynchus the bulk of the population was generally made up of small individuals the year round. In N. sclerorhynchus a seasonal pattern was shown in the depth distribution of juveniles. The sex ratio was in favour of females in larger specimens and in each bathymetric stratum. Seasonal growth was detected in the otoliths of the three species. Maximum ages were around 9 years in H. italicus and N. sclerorhynchus; 8 years in C. coelorhynchus. Although some differences have been detected in the population ecology of the three species, they are characterized by a prolonged recruitment during the year, slow growth, longevity and delayed maturity. 2000 The Fisheries Society of the British Isles

Population structure and reproductive patterns of the NW Mediterranean deep-sea macrourid Trachyrincus scabrus (Rafinesque, 1810)

“…Although these authors did not find spawning females, their data on the reproductive period of T. scabrus in the western Mediterranean are in agreement with our data. In contrast, a study conducted in the central Mediterranean Sea found spawning females in August and January(D'Onghia et al 2000), which suggests that the breeding season differs depending on the region. This implies that environmental conditions could play an important role in determining the reproductive processes of this deep-sea species.…”

Reproductive biology of three gadiform fish species through the Mediterranean deep-sea range (147-1850 m)

“…In the Mediterranean, other gadifirm species living in the upper-middle slope can present a continuous reproductive pattern as in Nezumia sclerorhynchus (D'Onghia et al, 1996(D'Onghia et al, , 1999(D'Onghia et al, , 2000, N. aequalis (Massutí et al, 1995) and Hymenocephalus italicus (Massutí et al, 1995;D'Onghia et al, 1996), a quasi-continuous strategy with a reproductive peak as in Coelorhynchus coelorhynchus (Massutí et al, 1995;D'Onghia et al, 1996D'Onghia et al, , 1999, or a seasonal pattern as in Trachyrhynchus trachyrhynchus (D'Onghia, 1996). The lower slope macrourid studied, Coelorhynchus labiatus, has an autumn-winter spawning (Massutí et al, 1995).…”

Biological patterns and ecological indicators for Mediterranean fish and crustaceans below 1,000 m: a review

“…Species of the family Macruridae like Hymenocephalus italicus, Nezumia sclerorhynchus, and Coelorhynchus coelorhynchus (D'Onghia et al 2000) and the family Alepocephalidae like A. rostratus (Morales-Nin et al 1996b) spawn quasi-continuously. In all these species the sex ratio is significantly skewed towards females, which tend to have higher proportions of ripe individuals towards the lower boundaries of their depth ranges.…”