Preprint volume - SIBM

Pre-print Volume –Oral presentations
Topic 4: THE ELASMOBRANCHS
of bottom species in respect to the GRUND one. This means that MEDITS dataset are
not so suitable to describe some aspects of the dynamic population of G. melastomus in
our study area.
Conclusions – If we should observe only GRUND results we would say that G.
melastomus population (both adult and juvenile fraction) of the northern Ligurian Sea
could be undergoing a decline in the last decade. It is important to underline that during
the last years the juvenile component has significantly deceased, specifically on
preferential bathyal grounds. This become even more concerning if we think that
generally in G. melastomus only 25% of the total population is represented by
reproductive adults (Rey et al., 2005). From the maps it is possible to observe that
juveniles never distribute over the line of 500m of depth, while adults are more
concentrated between 500m and 800m of depth. This has been verified both, in the
GRUND and MEDITS campaigns. Moreover the decrease of juveniles is confirmed
also by the increase of the median length of both, males and females and the increase
of the total mean weight. This means that we are fishing bigger animals loosing the
juvenile component and underlines the need to deepen the monitoring of the population
status.
References
BAUM J.K., MYERS R.A., KEHLER D.G., WORM B., HARLEY S.J., DOHERTY P.A. (2003) -
Collapse and conservation of shark populations in the Northwest Atlantic. Science, 299: 289-
392.
CARBONELL A., ALEMANY F., MERELLA P., QUETGLAS A., ROMAN E. (2003) – The bycatch
of sharks in the western Mediterranean (Balearic Islands) trawl fishery. Fish. Res., 61: 7-
18.
ORSI RELINI L., WURTZ M. (1975) – Osservazioni sulla alimentazione di Galeus melastomus
(Chondrichtyes, Scyliorhinidae) dei fondi batiali liguri. Quad. Lab. Tecnol. Pesca, 2 (1): 17-36.
REY J., DE SOLA L., MASSUTI’ E. (2005) – Distribution and biology of the blackmouth catshark
Galeus melastomus in the Alboran Sea (Southwestern Mediterranean). J. Northw. Atl. Fish. Sci.,
35: 215-223.
SERENA F., VACCHI M., RELINI G., MÒ G., COSTANTINI M., NOTARBARTOLO DI SCIARA
G. (2002) – Status of the application of the IPOA-SHARKS to the Mediterranean and proposal
of co-ordinated initiatives aimed at further developments. Biol. Mar. Mediterr, 9 (1): 836-851.
STEVENS J.D., BONFIL R., DULVY N.K., WALKER P.A. (2000) – The effects of fishing on
sharks, rays and chimaeras (chondrichtyans), and the implications for marine ecosystems. ICES
Journal of Marine Science, 57: 476-494.
TURSI A., D’ONGHIA G., MATARRESE A., PISCITELLI G. (1993) - Observations on population
biology of the blackmouth catshark, Galeus melastomus (Chondrichthyes, Scyliorhinidae), in the
Ionian Sea. Cybium, 17: 187-196.
WALKER T.I. (1998) – Can shark resources be harvested sustainable? A question revisited with
review of shark fisheries. Marine and Freshwater Research, 49 (7): 553-572.
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