[MARMAM] Overfishing and the disappearance of short-beaked common dolphins from western Greece

Giovanni Bearzi giovanni.bearzi at gmail.com
Sat Jul 5 22:48:16 PDT 2008

The following article has just been published on Endangered Species

Bearzi G., Agazzi S., Gonzalvo J., Costa M., Bonizzoni S., Politi E.,
Piroddi C., Reeves R.R.  2008.
Overfishing and the disappearance of short-beaked common dolphins from
western Greece. 
Endangered Species Research 5:1-12.

ABSTRACT: Once one of the most common cetaceans in the Mediterranean Sea,
the short-beaked common dolphin has declined throughout the region since the
1960s and in 2003 this population was classified as Endangered in the
International Union for Conservation of Nature (IUCN) Red List. Here, we
document the species' precipitous decline in eastern Ionian Sea coastal
waters across 13 yr. While 150 animals were present in the study area (1050
km2) in 1996, only 15 were observed in 2007. A 12 mo assessment of fishing
effort and catch, together with circumstantial evidence, suggests that the
decline was caused largely by prey depletion resulting from overfishing. We
analyzed the impacts of various fishing gear and estimated the degree of
resource overlap between common dolphins and local fisheries. The total
biomass removed annually by 308 fishing boats in the study area averaged
3571 t, while that consumed by common dolphins was 17 t. Resource overlap
between common dolphins and fisheries‹expressed as an average Pianka index
of 0.5‹differed according to fishing gear, being higher for purse seiners
(0.7) and beach seiners (0.4) and lower for bottom trawlers (0.1), trammel
boats (0.2) and longliners (0.0). Only about 10 active purse seiners (4% of
the total active fishing fleet) were responsible for 33% of the biomass
removal, and likely had the greatest impact on prey of common dolphins. This
study indicates a high risk of local disappearance of common dolphins in the
very near future, unless fishery management measures are implemented
immediately. Purse seining should be the main management target.

The pdf version of this article can be downloaded from the link below:

Additional articles on Mediterranean common dolphins can be downloaded from:

Giovanni Bearzi, Ph.D.

President, Tethys Research Institute
Viale G.B Gadio 2, 20121 Milano, Italy


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