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use of the most threatening fishing gear used in bly, the majority of strandings along the Italian
Mediterranean waters, where the fishery has coasts between 1986-90, the cause of which
dramatically impacted several cetacean popula- could be related to fishing gear, were caused by
tions. Multifilament nylon nets for swordfish driftnets (Cagnolaro and Notarbartolo di Sciara
have 36-52 cm mesh and are 2-40 km long, with 1992). Sperm whale and striped dolphin popula-
a typical length of 12-15 km. Similar nets are tions were reportedly the most impacted, but by-
used for albacore, with a mesh size of 16-20 cm catch also involved Cuvier’s beaked whales,
and a total length of 9-15 km (IWC 1994). long-finned pilot whales, Risso’s dolphins, com-
Mediterranean countries with driftnetting mon bottlenose dolphins and short-beaked com-
fleets reportedly included Algeria, Morocco, mon dolphins (IWC 1994). Although fin whales
Spain, France, Italy, Malta, Greece, and Turkey may at times be capable of breaking the nets after
(Di Natale and Notarbartolo di Sciara 1994, Sil- entanglement and find their way out (Di Natale
vani et al. 1999). The number of vessels rapidly 1992), even Mediterranean mysticetes may die in
increased to over 1,000 by 1990 (IWC 1994). pelagic driftnets (Centro Studi Cetacei 1992,
For instance, the Italian driftnet fleet – reported IWC 1994).
as being the largest in the Mediterranean - had When driftnet fisheries reached their peak, a
increased by 57% between 1987-90, totalling 700 total annual bycatch of over 8,000 cetacean
boats carrying nets up to 22.5 km long. After specimens (mostly striped dolphins, but including
management measures taken in 1990, the Italian at least 30 sperm whales) was estimated for the
fleet was reduced to 120 units (Di Natale and No- Italian Seas alone (Di Natale and Notarbartolo di
tarbartolo di Sciara 1994). Based on fishermen Sciara 1994), and perhaps up to 10,000 cetacean
interviews conducted in the southern Tyrrhenian specimens died annually in the whole Mediterra-
Sea, about 90% of the bycatch was composed of nean (IWC 1994). The current annual toll that
“dolphins”, while sperm whales represented the cetaceans have to pay to driftnets fisheries is un-
remaining 10%; up to 15 dolphins were reported known, but remains potentially unsustainable in
to die in fishing gear deployed overnight by a some areas (e.g., in the Tyrrhenian Sea, Mi-
single boat in the area (B. Mussi and A. Mi- ragliuolo et al. 2002). Between 1993-98, it has
ragliuolo, pers. comm.) been reported that 15 of 24 sperm whale strand-
Due to recent regional legislation, the situa- ings in the Balearic Islands where caused by by-
tion is changing in European Union countries, catch in driftnets (Làzaro and Martìn 1999).
where driftnets have been be banned starting
from 1 January 2002; meanwhile, a decommis- Entrapment in bottom gillnets. Bottom gillnets
sioning process of the Italian driftnet fleet is in have been known to cause incidental entrapment
process. However, the unregulated use of pelagic and death of thousands of cetaceans worldwide
driftnets by non EU countries (possibly including (Jefferson et al. 1992, IWC 1994, Read 1996,
both Mediterranean and non-Mediterranean na- Reeves et al., In press). This fishing gear is used
tions) represents a source of concern. Moreover, in coastal waters up to 200 m deep, and usually
illegal driftnetting is still an issue in some EU targets demersal and bentho-pelagic prey.
countries (e.g., in Italy, Miragliuolo et al. 2002). Bycatch in bottom gillnets largely affects
Owing to lack of enforcement measures, in most small coastal cetaceans such as harbour por-
Mediterranean countries cetacean bycatch in poises, bottlenose dolphins (Tursiops sp.), hump-
driftnets and deliberate killing of cetaceans backed dolphins (Sousa sp.), common dolphins
caught alive in these nets occur irrespective of (Delphinus sp.), and virtually all riverine cetace-
national regulations that prohibit the taking of ans (IWC 1994, Reeves and Leatherwood 1994,
marine mammals (Di Natale and Notarbartolo di Read 1996). Mortality in gillnets is considered
Sciara 1994). as the main threat to the survival of the vaquita,
It was estimated that in the ‘90s thousands of Phocoena sinus (Vidal 1995, D’Agrosa et al.
Mediterranean cetaceans have died in pelagic 1995) and the Hector’s dolphin, Cephalorhyn-
driftnets every year, at rates deemed unsustain- chus commersoni (Dawson and Slooten 1993).
able (Di Natale 1990, Notarbartolo di Sciara Conversely, incidental takes of large cetaceans in
1990, Cagnolaro and Notarbartolo di Sciara bottom gillnets are a rare occurrence (Reeves and
1992, Di Natale and Notarbartolo di Sciara 1994, Leatherwood 1994). Factors that may contribute
IWC 1994, UNEP/IUCN 1994, Forcada and to the entrapment of cetaceans in gillnets include
Hammond 1998, Silvani et al. 1999). Remarka- (Jefferson et al. 1992, Lien 1994, Tregenza et al.

Cetaceans of the Mediterranean and Black Seas – 9.5