Les pêcheurs professionnels français de Manche veulent étudier l’impact des filets calés sur les populations de mammifères marins. Cette action vise à améliorer le dispositif prévu par le règlement (CE) n° 812/2004 ou y trouver des alternatives. Des observaterus à la mer on tété deployés durant deux années aux deux extrémités de la Manche pour avoir une information sur les taux de captures. Trois marsouins, un globicéphale et un phoque ont été capturés lors des 610 jours de mer avec observateurs. L’un des marsouins a été capturé dans un filet à sole en zone IVc, et deux autres en Manche-ouest, dans la partie la plus occidentale. Cet effort global du projet correspond à près de 1700 levées de filets répartis pour moitié dans le Nord-Pas de Calais et pour moitié en Bretagne nord. Le taux de capture dans les filets à sole du Nord-Pas de Calais est de l’ordre de 1 marsouin pour 1400 km de filets mais ces résultats ne reposent que sur une seule capture. Une globalisation de Pingiroise et de Filmancet permet d’avoir une couverture géographique plus étendue sur les zones côtières VIIe de la Bretagne pour les années 2009-2010. Les trois marsouins capturés dans les filets à baudroie induisent un taux de l’ordre de 1 marsouin pour 700 km de filets à baudroie en VIIe. Il convient aussi de signaler qu’aucune capture de marsouin n’a été dans la partie orientale de la zone VIIe (c'est-à-dire entre Paimpol et Saint–Malo) malgré l’observation d’un bon nombre de marées dont certaines ciblent l’araignée. Une synthèse sur toutes les données disponibles en zone VII et issues d'observateurs à bord des navires opérant au filet a été réalisée. Les données disponibles couvrent la période 2007-2010 et incluent les observations Filmancet. Une extrapolation a été tentée aux flottes. Les résultats montrent une grande différence dans les taux de captures de marsouin selon les divisions Ciem VIIe et VIId figurant parmi les zones à plus faible taux de captures. En manche ouest, il y aurait plus de captures de phoques que de marsouins, ce qui n'est pas sans soulever des questions autour de la répulsion acoustique des marsouins telle qu'exigée par le règlement européen 812/2004.

Up to now there has been no strong investigation on by-catch of marine mammals in the French set net fisheries of the English Channel (ICES areas VIIe,d & IVc) as the EC 812/2004 Regulation does not oblige the state members to put observers on board of vessels in the ICES area VII. A study named FilManCet has been started end 2008-beginning 2009 to focus on the by-catch occurring on the set net vessels (whatever the hull length is) issued from Boulogne and Dunkerque ports (fisheries in VIId&IVc) and also from several ports of North of Brittany. In this study which is conducted by the Fishing Industry, the data are made available to the scientists of Ifremer who has prepared also the sampling scheme for observation at sea. Two observers are employed full time in the North of France coasts by the regional committee for marine fisheries (CRPMEM) and four observers are employed by the company SINAY. The observation program is carried on for 2 two years. A total of 610 fishing days were observed (172 fishing days in areas VIId&IVc and 438 fishing days in area VIIe). Even if the coverage is not as high as planned, the observations in the North of Brittany (VIIe) are regular, covering all the months in the two years from Morlaix to Saint-Malo. The bycatch in VIIe was 2 porpoises, 1 pilot whale and 1 grey seal. No porpoise bycatch was observed between Paimpol and Saint-Malo. The Filmancet data were pooled with Pingiroise data (commercial nets from ports of Le Conquet and Audierne observed during one year), the total amount of bycatch was then 3 porpoises, 1 pilot whale and 1 grey seal for 610 days at sea with 550 trips with 936 hauls during the two years of observation. In these coastal areas the vessels are mainly less than 12 meters long and the observed nets were 3000 km of non pingered nets. The bycatch rate for porpoises was one animal for 700 km of monkfish nets (167200 km*h), one grey seal was observed in 540 km of spider crab nets (160000 km*h) in VIIe. In the area VIId-IVc where 840 hauls are recorded, one porpoise was observed in the 1400 km of sole nets and the bycatch was located in the area IVc. By taking into account the average duration of the nets (24h), the rate is 1 porpoise for 33840 km*h in the observed areas of VIId &IVc. However these results are obtained from only one bycatch. In a second step, the Filmancet data were pooled with the data from all the other programs of area VII & IV managed since 2007. This gives an amount of around 1000 days at sea which represents a global coverage equal to 3 % of the fishing effort. The estimate of annual bycatch is around 400 porpoises for all these prospected areas including the estimate of 230 animals for the area VII. The bycatch rate for porpoises were found higher in VIIf,g,h and IVc than in VIIe,d. In VIId, no porpoise was recorded in 196 days at sea. The bycatch rates of porpoises and seals in area VIIf,g were found much higher than in the French coastal areas of VIIe during two consecutive summers in 2007 and 2008. The days at sea with observers are in great number in VIIe (600 days). The global bycatch rate of porpoises for VIIe was 1 animal for 120-150 days at sea or 1 animal for 700 km of monkfish nets. No bycatch of porpoise was observed in the eastern part of VIIe with 373 trips between Paimpol and Saint-Malo with 670 hauls representing 2200 km of nets. Eight grey seals were caught in area VII (6 in VIIe and 2 in VIIf). Seals are usually attracted by the nets with fish. The presence of seals in the fishing grounds of VIIe,f raises the question of using pingers as told by the UE Regulation n° 812/2004 as some acoustic equipments may increase the depredation and the bycatch of seals in set nets through a « dinner-bell effect ». All these information indicate that by-catch rates are very variable between areas inside ICES area VII. The by-catch rate in the south of area VIIe is very low compared to other areas as VIIf,g. Such an information can help to improve the UE 812/2004 Regulation.