Preprint volume - SIBM

Pre-print Volume –Oral presentations
Topic 4: THE ELASMOBRANCHS
main time periods, in order to facilitate the estimation of eventual changes over time:
from 1940’s to 1960’s, from 1960’s to 1980’s and from 1980’s to present.
As concerns elasmobranchs, specific questions were made to ask for trends over time,
as well as on catches, economic importance and eventual disappearance or rarefaction
of species. The collected information was entered in a standardised data base: data
were analysed to obtain quantitative or semi-quantitative results.
Results - Thirty five interviews were realized in these ports of GSA 9: Viareggio and
Livorno (Ligurian Sea), Castiglione della Pescaia, Porto Santo Stefano and Porto
Ercole (northern Tyrrhenian Sea), Civitavecchia and Fiumicino (central Tyrrhenian
Sea).
According to what reported by the fishermen, the importance of elasmobranchs, both in
terms of abundance and commercial value, was higher in the past that at present. The
main species caught in the past were rays (Raja spp.), small spotted catshark
(Scyliorhinus canicula), smoot hound (Mustelus spp.) and spiked dogfish (Squalus
spp.). Sixty four percent of the interviewed fishermen reported that Elasmobranch
catches in the earlier period (from 1940’s to 1960’s) were more abundant (at least two
times) than those of the present (Fig. 1). This percentage decreases in the comparison
with the second period (51%) and it is very low for the most recent one (6%). Many
fishermen declared that from the 1980’s the catches of elasmobranchs were more or
less the same than those of the present and 14-30% of fishermen was not able to
evaluate the temporal trend of abundances. The percentage contribution of
elasmobranchs to the total catch showed a decrease over time as well (Tab. 1).
100%
75%
50%
25%
0%
1940-1959 vs
present
1960-1979 vs
present
1980-2008 vs
present
Less abundant
The same
More abundant (two times)
Much more abundant (more than three times)
Not able to evaluate
Fig. 1 – GSA 9, fishermen interviews. Comparisons of the elasmobranch catches of different time
periods with those of the present.
GSA 9, interviste ai pescatori. Comparazione delle catture di elasmobranchi di diversi
periodi con quelle attuali.
41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010
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