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action is urgently needed to prevent their extirpa- ahead, but cetacean deaths in various fishing gear
tion in this region (Reeves et al., In press) . Relic occur virtually everywhere, and are often among
common dolphin sub-populations are still report- the main causes of human-related mortality for a
edly involved in fishery depredations in coastal number of cetacean species. Incidental captures
portions of the Mediterranean, including Tunisia in fishing gear – the impact of which is often un-
and Cyprus (UNEP 1998b, Reeves et al. 2001). derestimated - certainly represent a serious threat
The striped dolphin - by far the most abundant to the survival of many cetacean populations
cetacean in the Mediterranean - has a pelagic dis- around the world, and in some areas have brought
tribution and largely feeds on non-commercial cetacean species or populations close to extinc-
prey species (Notarbartolo di Sciara and Demma tion (IWC 1994, Reeves and Leatherwood 1994,
1994). Therefore, it rarely represents a problem Read 1996).
to coastal fisheries, apart from gear damage or In the Mediterranean, the problem of inciden-
time loss for fishermen when the animals get en- tal mortality in fishing gear has caught the atten-
trapped in fishing gear. tion of both scientists and the general public due
to high-seas driftnet fishing by vessels flying Ital-
Impact of fisheries on cetaceans. Fisheries can ian and other flags. A recent European Union
affect cetaceans both directly and indirectly. Ef- ban of driftnetting may result in decreased by-
fects on the animals may include: catch rates in portions of the basin, however the
problems remains in unregulated waters and in
1. bycatch in fishing gear; areas where illegal use of driftnets is an issue.
2. injury or mortality from retaliatory measures In the Italian seas alone, where an effective
taken by fishermen who may perceive the cetacean stranding network exists, it has been
animals as competitors, or blame them for calculated that 83% of the stranding events oc-
gear damage or catch reduction; curred between 1986-90, for which the cause of
3. unintentional disturbance by fishery-related death could be established, resulted from bycatch
operations; in driftnets (Cagnolaro and Notarbartolo di Sciara
4. reduction of food prey availability or changes 1992). Although bycatch has been reported for
in food prey composition/distribution caused most Mediterranean species, incidental captures
by overfishing; in fishing gear have mostly affected sperm
5. habitat loss and/or degradation (e.g., from whales, common dolphins, bottlenose dolphins,
bottom trawling); and striped dolphins (Perrin 1988, Di Natale and
6. short- to long-term modifications in cetacean Notarbartolo di Sciara 1994, Northridge and
behaviour leading to emigration, dispersion Hofman 1999).
or reduced reproductive rates as a conse-
quence of direct or indirect interactions with Entrapment in pelagic driftnets. Pelagic drift-
fisheries. nets are long, non-selective nets with strong,
loose nylon mesh that can virtually entrap all
The part that follows specifically focuses on kinds of large marine animals. Worldwide, these
the potential or known impact on Mediterranean nets have been depleting a number of cetacean
cetaceans of the threats listed above, with the ex- populations, including species of all sizes (Read
ception of item listed as n. 2 (“injury or mortality 1996). Driftnet fisheries around the world that
from retaliatory measures …”), which was dealt have shown to be highly detrimental to cetacean
with elsewhere in this Report (Notarbartolo di populations include the Japanese North Pacific
Sciara and Bearzi 2002). driftnet fishery for salmon (Ohsumi 1975), the
Taiwanese driftnet fishery for shark, tuna, and
mackerel off northern Australia (Harwood and
Fishery interactions involving unintentional Hembree 1987), the French tuna driftnet fishery
takes (bycatch) in the north-eastern Atlantic (Goujon et al. 1993),
and several others (Northridge and Hofman
Before the mid to late 1960s, there was no 1999).
place in the world where the magnitude of by- In the Mediterranean, pelagic driftnets are
catch was considered great enough to threaten a used by the drift gillnet fishery for small pelagic
population of cetaceans (Reeves and Leather- fish, and by the drift gillnet fishery for swordfish
wood 1994). We are now only a few decades and albacore (IWC 1994). The latter involves the

Cetaceans of the Mediterranean and Black Seas – 9.4