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In press) Following strict regulations to reduce  kills every year unsustainable numbers of endan-
               bycatch, dolphin mortality in Pacific tuna nets  gered baiji (Perrin et al. 1989).
               has substantially decreased in recent years. How-  Longlines are commonly used in the Mediter-
               ever, the past and present impact may be signifi-  ranean for catching tuna, albacore, swordfish and
               cantly underestimated because of unobserved  a number of other fish (Di Natale  1990).  Al-
               deaths of nursing calves due to separation from  though a few cases of incidental catches of ceta-
               their mothers during fishing (Archer et al. 2001).   ceans have been reported, clear evidence is often
                  Fishing with purse seines aimed at tuna ap-  missing because cetaceans can be released alive
               pears to be scarcely practiced in the Mediterra-  at sea by fishermen.  Reports of cetaceans caught
               nean, where purse seining appears to be mostly  by longlines include a few striped dolphins,
               targeted to small epipelagic schooling fish.  In the  common bottlenose dolphins, Risso's dolphins,
               Italian seas, Di Natale and Notarbartolo di Sciara  false killer whales and sperm whales taken in It-
               (1994) reported only ten tuna nets being used, for  aly and Spain (Di Natale and Mangano  1983, Di
               a total of 1,000 fishermen involved and a fishing  Natale  1990, Mussi et al.  1998).  In all these
               period of 60 days per year. Bycatch in purse   cases, the gear was a surface drifting longline for
               seines would mainly affect small odontocetes  swordfish.
               such as striped dolphins, bottlenose dolphins and   In the Italian seas, most reports of entangle-
               common dolphins (Di Natale     1983a,  1983b,  ment in longlines have involved small Odonto-
               1990, UNEP/IUCN 1994).   Rare reports exist of  cetes, particularly striped dolphins, but docu-
               cetaceans bycaught in tuna purse-seine in the  mented cases exist for Risso’s dolphins (Catald-
               Mediterranean (e.g., Magnaghi and Podestà  ini and Bello     1987), common bottlenose dol-
               1987).  Overall, the impact of these nets on Medi-  phins, long-finned pilot whales, sperm whales,
               terranean cetaceans is commonly considered to  and a young fin whale (Di Natale       1990,
               be negligible (Di Natale and Notarbartolo di Sci-  UNEP/IUCN  1994,  Centro  Studi   Cetacei
               ara  1994).  However, reliable information is  1987÷1998, Mussi et al.  1998).  Some individu-
               completely lacking, and thus an accurate assess-  als (striped dolphins, Risso’s dolphins and com-
               ment of the impact of tuna purse seine fishing on  mon bottlenose dolphins), have been found
               cetaceans in the Mediterranean is presently im-  stranded with hooks in their mouths, or with fish-
               possible.                                      ing lines in their larynx, suggesting that in some
                                                              cases these animals may try to feed on bait or
               Entrapment in longlines.  Longlines consist of a  hooked fish. Mussi et al. (1998) reported interac-
               series of baited hooks attached to a long, horizon-  tions with fisheries using illuminated handlines
               tal line by short connecting lines. This type of  for squids. These involved small groups of
               fishing gear can be configured to take a wide va-  striped dolphins, Risso's dolphins, and long-
               riety of fish, from small, bottom-dwelling species  finned pilot whales waiting near the fishing boats
               to large pelagic species such as swordfish, tuna  until the light had attracted a great number of
               and sharks. The use of different hook sizes and  squids.  Cetaceans would then take profit of the
               fishing depths allows fishermen considerable  higher prey density and forage near the fishing
               flexibility in their choice of target species. In  boats. However, no cetacean bycatch was re-
               many areas longlines are important components  ported during these interactions.
               of coastal and pelagic fisheries (Read 1996).     Comprehensive studies on the potential im-
                  Cetaceans may get entangled in the line fila-  pact of longlines on cetaceans in the Mediterra-
               ments or in other parts of the gear, or get hooked  nean have never been conducted.  However, this
               (Green  et al.  1991, Read  1996).  In some areas  seems likely to represent a minor threat in the ba-
               around the world, mortality related to longline  sin.
               fisheries may be significant (Crespo  et al.  1997,
               Reeves  et al., in prep.).  For instance, in the  Entrapment in discarded or abandoned nets.
               southern U.S., short-finned pilot whales can get  Nets that remain entangled on the sea floor, or
               entangled in longline fisheries for swordfish and  that are damaged or worn out, may be discarded
               tuna; most entangled animals are released alive,  or abandoned by fishermen at sea.  Gillnets,
               but it is not known what effects the hooks and/or  driftnets or other fishing gear may also be broken
               entanglement may have on their survival after re-  or dispersed by storms.  These nets can then con-
               lease (Read  1996).  In the Yangtze River, China,  tinue to catch and kill cetaceans and other marine
               a bottom longline fishery called 'rolling hooks'  animals for decades, until the net filaments com-

                                    Cetaceans of the Mediterranean and Black Seas   –   9.8
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