Preprint volume - SIBM
Preprint volume - SIBM Preprint volume - SIBM
Pre-print Volume –Invited presentations Topic 4: THE ELASMOBRANCHS Le reti da posta sono una vasta categoria di attrezzi che catturano circa il 25.5% dei Condritti, pari a circa 350 t. I palangari nel loro complesso mostrano sbarchi equivalenti a circa l’11,8% del totale dei condritti, pari a circa 162 t, con prevalenza della verdesca (Prionace glauca), con oltre 153 t. Viene documentato, sulla base dei dati FAO, il crollo delle catture in Italia degli squaliformi dopo il 1995 da 10.000 t a meno di 1.000 t nel 1998, e dei raiformi dalle 5.000 t del 1998 a qualche centinaio di t nel 2000. Per quanto riguarda il punto 5 è stata fornita una revisione critica dei piani di azione della FAO IPOA-sharks, dell’UNEP-MAP RAC/SPA di quello preparato alcuni anni fa dall’ICRAM (ora ISPRA), nonché delle raccomandazioni dell’UE. È stata anche fatta una panoramica sugli strumenti normativi riguardanti la tutela delle specie di Elasmobranchi nei paesi del Mediterraneo e le valutazioni dell’IUCN. Per quanto riguarda il punto 6 sono state elaborate le linee guida essenziali per un Piano d’Azione Nazionale per la Conservazione e Gestione dei pesci Cartilaginei. Questo documento, oltre a radicarsi nel quadro della Convenzione di Barcellona e nel Contesto più ampio della Convenzione UNCLOS e del suo Accordo per le Specie Transzonali e Altamente Migratorie delle Nazioni Unite (vedi Accordo Straddling Stock, Appendice A), trova inoltre ragion d’essere nel contesto internazionale promosso dalla FAO e dalla U.E. Questo documento si compone di tre Parti e otto Temi per un totale di 21 Azioni. Per ciascuna di queste Azioni è indicato il grado di priorità (A, B e C) in funzione dell’urgenza richiesta e del tempo di realizzazione. Per quanto riguarda le attività di campo riportiamo solo alcuni dei dati più salienti per lo strascico, i palangari pelagici e per le osservazioni fatte a bordo di natanti con palamiti di superficie e ferrettara. Nello sbarcato dello strascico sono state rilevate 17 specie. La maggior ricchezza specifica risulta in Sardegna, dove le razze raggiungono il 43-45% dei selaci. Incredibilmente basso è il numero di specie a Lampedusa ed a Gallipoli. Nello sbarcato dei palamiti pelagici le specie sono ridotte a 6 e la percentuale dei selaci nel pescato sbarcato oscilla da 2 a 23%. Il numero di specie si riduce a 4 (5 se si tiene conto della ferrettara) nelle catture osservate a bordo dei natanti che usano il palamito di superficie. La specie maggiormente catturata è P. violacea, che fa alzare di molto la percentuale dei selaci rispetto al pescato totale. In conclusione il progetto ELASMOIT ha contribuito a migliorare le conoscenze sui condroitti presenti nei mari italiani, con particolare riguardo agli squali pelagici. Nel confronto preliminare tra i dati storici e quelli ottenuti dalle attività di campo emergono alcune criticità che confermano l’attuale stato di depauperamento di questa importante frazione del popolamento ittico dei nostri mari, sia in termini di numero di specie, sia di abbondanza. Nei casi in cui è possibile valutare la struttura della popolazione, di solito si registrano preoccupanti diminuzioni della taglia media. Nel 2009 l’UE ha approvato le linee guida del Piano d’Azione Europeo per la tutela e gestione dei pesci cartilaginei, primo passo verso una specifica Direttiva in materia. In questo contesto l’Italia, con i risultati del progetto ELASMOIT, benché preliminari, risponde prontamente all’orientamento dell’UE, dimostrando sensibilità e concretezza. In tal senso l’Italia si è dotata di specifiche linee guida che mostrano le matrici più sensibili, le quali dovranno essere approfondite al fine di consentire la formulazione di un reale Piano Nazionale di Azione. 41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010 197
Pre-print Volume –Oral presentations Topic 4: THE ELASMOBRANCHS Y. ARTIOLI, E. VISENTIN 1 , A. BARAUSSE 2 , C. MAZZOLDI 1 Plymouth Marine Laboratory, Prospect Place, Western Hoe, PL1 3DH, Plymouth, UK. 1 Dept of Biology, University of Padova, Italy. carlotta.mazzoldi@unipd.it 2 Environmental Systems Analysis Lab, University of Padova, Italy. WHAT HISTORICAL DATA AND PREDICTIVE MODELS CAN TELL US ABOUT ELASMOBRANCH FUTURE IN THE NORTHERN ADRIATIC SEA CONSIDERAZIONI SUL FUTURO DEGLI ELASMOBRANCHI NEL NORD ADRIATICO INTEGRANDO DATI DI PESCATO E MODELLI PREDITTIVI Abstract – With the aim to assess elasmobranch fishery status and predict future trends with different management scenarios, in this study long term landing data (1945-2008) of Chioggia, the major fishing fleet of the Northern Adriatic Sea, were analysed; surveys at the fish market were performed to assess elasmobranch catch composition; an individual based model was developed for two species, Mustelus mustelus and Scyliorhinus canicula. Landing data highlighted a dramatic decline in elasmobranch landing, particularly for skates and Scyliorhinus spp. Landings presented periodic fluctuations, correlated in skates with climate indices (NAO and WeMO). At present, elasmobranch composition of landing includes 13 species, with M. mustelus representing more than 60% of the total. A high proportion of landed males were sexually immature. Model results predicted that, without management, in the next 50 years M. mustelus population would decrease of 80%, and S. canicula of more than 90%. A management approach aimed to protect juveniles performed far better than the fishing effort reduction. The results of this study highlight the urgency to develop management actions for elasmobranch conservation and suggest a feasible and promising management approach. Key-words: shark fisheries, conservation, models. Introduction - Elasmobranchs are exploited worldwide, and their fishery is increasing as response to the growing demand and the accessibility of new areas to fishing boats. Elasmobranchs are recognized to be highly vulnerable, due to their life history characteristics (Bonfil, 1994). And indeed, even if data on elasmobranch landing and stock status are often poor (Bonfil, 1994), several elasmobranch populations, in particular those of large predatory species, show dramatic decline or collapse in different areas (Dulvy et al., 2008; Ferretti et al., 2008). Moreover, elasmobranchs often constitute bycatch of fisheries targeting other more abundant or valuable resources (Bonfil, 1994) and, consequently they are not subject to economic extinction prior to get close to local extinction. The decline of several elasmobranch stocks, their high vulnerability to fishery, and the lack of data for several species and areas, call for the improvement of international actions for the management of sharks and their relatives. This study aims to forecast elasmobranch fishery in the Northern Adriatic Sea (NA) analyzing and integrating: time series of landing statistics (1945-2008) from the fish market of Chioggia; data of the present (2006-2007) elasmobranch landing composition; results of a demographic model to predict population trends under different management scenario based on data collected for Mustelus mustelus and Scyliorhinus canicula. Materials and methods – Fishing fleet consisted in 2007 of ca. 389 boats, using different fishing gears. Official annual elasmobranch landings for the capture fisheries of Chioggia from 1945 to 2008 were obtained from the Chioggia fish market (in 41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010 198
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Pre-print Volume –Oral presentations<br />
Topic 4: THE ELASMOBRANCHS<br />
Y. ARTIOLI, E. VISENTIN 1 , A. BARAUSSE 2 , C. MAZZOLDI 1<br />
Plymouth Marine Laboratory, Prospect Place, Western Hoe, PL1 3DH, Plymouth, UK.<br />
1 Dept of Biology, University of Padova, Italy.<br />
carlotta.mazzoldi@unipd.it<br />
2 Environmental Systems Analysis Lab, University of Padova, Italy.<br />
WHAT HISTORICAL DATA AND PREDICTIVE MODELS CAN TELL US<br />
ABOUT ELASMOBRANCH FUTURE IN THE NORTHERN ADRIATIC<br />
SEA<br />
CONSIDERAZIONI SUL FUTURO DEGLI ELASMOBRANCHI NEL NORD<br />
ADRIATICO INTEGRANDO DATI DI PESCATO E MODELLI PREDITTIVI<br />
Abstract – With the aim to assess elasmobranch fishery status and predict future trends with different<br />
management scenarios, in this study long term landing data (1945-2008) of Chioggia, the major fishing<br />
fleet of the Northern Adriatic Sea, were analysed; surveys at the fish market were performed to assess<br />
elasmobranch catch composition; an individual based model was developed for two species, Mustelus<br />
mustelus and Scyliorhinus canicula. Landing data highlighted a dramatic decline in elasmobranch landing,<br />
particularly for skates and Scyliorhinus spp. Landings presented periodic fluctuations, correlated in skates<br />
with climate indices (NAO and WeMO). At present, elasmobranch composition of landing includes 13<br />
species, with M. mustelus representing more than 60% of the total. A high proportion of landed males were<br />
sexually immature. Model results predicted that, without management, in the next 50 years M. mustelus<br />
population would decrease of 80%, and S. canicula of more than 90%. A management approach aimed to<br />
protect juveniles performed far better than the fishing effort reduction. The results of this study highlight<br />
the urgency to develop management actions for elasmobranch conservation and suggest a feasible and<br />
promising management approach.<br />
Key-words: shark fisheries, conservation, models.<br />
Introduction - Elasmobranchs are exploited worldwide, and their fishery is increasing<br />
as response to the growing demand and the accessibility of new areas to fishing boats.<br />
Elasmobranchs are recognized to be highly vulnerable, due to their life history<br />
characteristics (Bonfil, 1994). And indeed, even if data on elasmobranch landing and<br />
stock status are often poor (Bonfil, 1994), several elasmobranch populations, in<br />
particular those of large predatory species, show dramatic decline or collapse in<br />
different areas (Dulvy et al., 2008; Ferretti et al., 2008). Moreover, elasmobranchs<br />
often constitute bycatch of fisheries targeting other more abundant or valuable<br />
resources (Bonfil, 1994) and, consequently they are not subject to economic extinction<br />
prior to get close to local extinction. The decline of several elasmobranch stocks, their<br />
high vulnerability to fishery, and the lack of data for several species and areas, call for<br />
the improvement of international actions for the management of sharks and their<br />
relatives. This study aims to forecast elasmobranch fishery in the Northern Adriatic Sea<br />
(NA) analyzing and integrating: time series of landing statistics (1945-2008) from the<br />
fish market of Chioggia; data of the present (2006-2007) elasmobranch landing<br />
composition; results of a demographic model to predict population trends under<br />
different management scenario based on data collected for Mustelus mustelus and<br />
Scyliorhinus canicula.<br />
Materials and methods – Fishing fleet consisted in 2007 of ca. 389 boats, using<br />
different fishing gears. Official annual elasmobranch landings for the capture fisheries<br />
of Chioggia from 1945 to 2008 were obtained from the Chioggia fish market (in<br />
41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010<br />
198