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Exploring the depths of a trawl-banned Gulf

Monday, 1 December, 2014

 The oceanographic vessel Astrea leaves the continental harbor of Castellammare di Stabia (Naples, Campania) on the 4th of October 2014, to reach the Gulf of Patti, the second study area in Italy situated in the northern coast of Sicily. On board the crew members and the ECOSAFIMED scientific staff composed by: Marzia Bo, from the University of Genova; Jordi Grynyo, from the Superior Council of the Scientific Investigation of Barcelona; Simonepietro Canese, from ISPRA. After one transfer day, the vessel reached the harbor of Milazzo (Messina, Sicily), where the last member of the scientific staff, Adriana Profeta, from the University of Genova, was embarked.

The oceanographic activities started on October 7th. Our mission was to complete an oceanographic survey, comprehensive of both high resolution topographic mapping and ROV investigations, of the Gulf of Patti study area. Based on previous investigations with local fishermen, six different fishing grounds in the Gulf of Patti and one additional extra site (Brolo) exploited by the artisanal fishing fleet, were identified. The Gulf of Patti is a trawl-banned area, so the area outside the Gulf was selected in a trawled zone in order to use it as a comparison area for impacted soft bottom communities. Our goal was to map the areas and find evidences of benthic communities composed of structuring species, such as corals, sponges and bryozoans, that are the most sensitive to the impact of demersal fishing gears such as trammel and gillnets used by local fishery targeting common pandora, European hake and mullet. Various ROV dives were planned between 50 and 200 m depth in order to characterize the benthic communities and put in evidence potential impacts of both different gears in areas subjected to different fishing effort. A total of 10 MultiBeam maps were made and 15 dives were carried out in the study area between the 7th and the 11th of October. 15 ROV transects (corresponding to over 12000 m of linear ground explored) were carried out for a total of over 17 hours of video footage and about 1420 high resolution photographs. Some very interesting coral communities were reported in this survey, among all rich forests of Spinimuricea klavareni and Lytocarpia myriophyllum. It is noteworthy that 10 colonies of S. klavareni were collected and kept alive in the aquarium of the vessel and were successively transported to the Institute of Marine Sciences of Barcellona for specific analyses related to trophy and reproduction of this poorly known Mediterranean species. Among the most dominant species reported in the area, there are soft bottom gorgonians and sea pens, hydroids, black corals and the scleractinian Dendrophyllia ramea. Important traces of fishing impact, attributable not only to professional gears but also to recreational ones were detected especially on the hardgrounds found along the two capes of the Gulf.

Numerous fishermen (and other members of the community) were hosted on board at the end of the working days in the harbor and a selected choice of videos and photographs were showed and discussed. A major work of data analysis to be carried out in the near future will help us to delineate a general picture on the distribution of the benthic communities in Patti and on the major sources of impact in order to define the most suitable conservation strategy for the area.

Marzia Bo and Adriana Profeta
Dipartimento di Scienze della Terra, dell'Ambiente e della Vita - Università degli Studi di Genova