Page 2 - Bearzi_2002

Overvie w sources and fishery-related habitat loss represent
a source of concern in many Mediterranean areas.
Interactions between cetaceans and fisheries While it is known that cetaceans have been
in the Mediterranean Sea are probably as old as facing serious problems owing to fisheries in the
the first human attempts to catch fish with a net. last half-century (Reeves and Leatherwood
Countless reports and artefacts from the former 1994), there is no clear evidence that depredation
Tethys Ocean tell the story of dolphins interact- may have risen in recent times. Therefore, it is
ing with fishermen. The earliest reports describe unclear why the issue appears to be increasingly
idyllic relationships between dolphins and peo- perceived by Mediterranean fishermen to be
ple, but things changed as fisheries developed. causing economic hardship, particularly as far as
As early as in 1587 a Papal Decree was issued small-scale, coastal fisheries are concerned. One
“anathematising the vermin” in response to con- of the reasons may be that small-scale fisheries in
cerns in France about the effect of dolphins on many parts of the Mediterranean have become
fisheries (Smith 1995). Eighteenth century re- economically marginal, whether due to the deple-
ports describe fishermen attempts to keep dol- tion of fish stocks, over-capitalisation, market
phins away from their nets, by means including changes or socio-cultural factors (Reeves et al.
loud noises, dynamite, weapons, modifications of 2001). Therefore, even relatively small losses to
fishing techniques and schedules, and large-mesh dolphin depredation can now have a proportion-
nets surrounding the fishing nets to protect them ally large impact on a fisherman’s livelihood.
from dolphin incursions. The animals were The resulting economic distress may be prompt-
claimed to be “consistently seeking a parasitic ing fishermen to complain about the depredations
life at the poor fishermen’s expenses” and re- by dolphins and to perceive these animals as
quests were repeatedly submitted by fishermen to competitors. Moreover, fishermen have learned
governmental bodies to reduce dolphin numbers of new opportunities to gain compensation and
through culling (Barone 1895, Smith 1995). have therefore become more vocal about the im-
In some Mediterranean areas, direct killings portance of dolphin interactions in recent times
and bounties for dolphins represented the first (Reeves et al. 2001).
human attempts to solve the problem of net dep- Although approaches to marine mammal con-
1
redation , a strategy that was supported by sev- trol such as culling or harassment have become
eral governments for at least one century (Smith illegal in most Mediterranean countries, and are
1995). In the 1950s, retaliation measures were no longer viewed as appropriate by most fishing
still encouraged by State money rewards, result- organisations, direct killings are occasionally en-
ing in hundreds of dolphins being killed annually acted by individual fishermen. Nevertheless,
in the Adriatic Sea (Holcer 1994). many fishermen are becoming aware that blam-
Although bounties are no longer issued, the ing the dolphins for the ongoing changes within
overall impact of world fisheries on cetaceans the ecosystem does not represent sensible behav-
remains extremely high (Reeves et al., In press). iour. If solutions to the problems of cetacean-
Together with deliberate kills, incidental catches fisheries interactions are to be found, these must
of cetaceans in fishing gear also increased with be based on the comprehension of ecosystem dy-
the worldwide development of fisheries. How- namics.
ever, it was only in the last few decades that by-
catch became one of the major threats to the very Impact of cetaceans on fisheries. Interactions
survival of several cetacean populations. In the between cetaceans and coastal fisheries may
Mediterranean, where most data are sparse or dif- negatively affect the fisheries through:
ficult to evaluate, this impact has never been • damage to fishing gear in the form of holes
comprehensively assessed. Nevertheless, unsus- torn in the nets as the dolphins attempt to
tainable bycatch rates have been reported for sev- remove fish, or other forms of gear damage
eral fisheries, and the combined effect of inten- caused by cetaceans;
tional killings, bycatch, reduction of prey re- • reduction in the amount or value of the catch
as the dolphins mutilate or remove caught
fish from nets or longlines;
• reduction in the size or quality of the catch
1 Referring to “predators taking, or attempting to take, prey that are as the dolphins’ presence causes fish to flee
confined in pens or that have been - or are about to be - caught in
fishing gear” (Reeves et al. In press). from the vicinity of the nets;

Cetaceans of the Mediterranean and Black Seas – 9.2