CETACEAN STRANDINGS ON THE WESTERN TURKISH BLACK SEA COAST BETWEEN SEPTEMBER 2009 - AUGUST 2010
Prepared for the Permanent Secretariat of the Black Sea Commission within the framework of the Project ¨BSC-Cetaceans/2010¨
SEPTEMBER 01, 2009 - NOVEMBER 01, 2010
Coordinator: Arda M. TONAY Ph.D.
Ayhan DEDE Ph.D.
Ayaka Amaha ÖZTŪRK Ph.D.
Bayram ÖZTŪRK Ph.D.
Results of the monthly research/assessment of stranded cetaceans on the Turkish coast of the western Black Sea are presented. This report prepared for the Premanent Secretariat of the Commission on the Protection of the Black Sea includes data of the study between period of September 1st 2009 and will be finished on August 31st 2010.
There are three cetacean species in the Black Sea; Phocoena phocoena (Linnaeus, 1758) (harbour porpoise), Tursiops truncatus (Montagu, 1821) (bottlenose dolphin) and Delphinus delphis (Linnaeus, 1758) (common dolphin). As the top predators of the Black Sea, Cetaceans are faced with several threats such as accidental catch in fishing gear (bycatch), habitat degradation causing the reduction of prey resources, marine pollution and epizootics resulting in Cetacean mass mortality events (Birkun, 2008).
Every year several hunderds of dolphins are drowned in bottom gill nets and stranded ashore. Large numbers of P. phocoena and T. truncatus also die as a result of incidental catch specifically during the turbot fishing season especially between early April and June (Öztürk, 1996). It was estimated that the number of harbour porpoises died in the western Turkish Black Sea during the legal and all (both legal and illegal) turbot fishing period was 361(∓332) and 1829(∓675) (∓SE) in 2007, 608(∓408) and 2249(∓790) (∓SE) in 2008, respectively, The estimated number of bottlenose dolphins died in the same way was 153∓142 (∓SE) in 2007 (Tonay, 2010). Cetacean bycatch has been studied in the Turkish western Black Sea such as: Öztürk et al., 1999; Tonay and Öz, 1999; Tonay and Özt ürk, 2003 and Tonay, 2010. According to these publications, 156 individuals (almost P. phocoena) were reported in 11 years. The CPUE was found to be 0.33 cetacean individuals per kilometer in 2003, 0.19 in both 2007 and 2008. Most of the bycaught harbour porpoises of a total of 19 individuals were observed at the age of 4 (26%) and 5 (21%) (Tonay, 2010).
According to the result of the cetacean stranding surveys; a total of 211 stranded cetaceans were found on the 45 km-long sandy beaches on the Turkish western Black Sea coast during April, May and June in 2003 - 2005 turbot fishery season (Tonay et al., 2008). During the seasonal research between 2007 and 2009, a total of 83 stranded cetaceans were found in the same area. Compared to autumn and winter (28%), more strandings were observed during the late spring and early summer (72%), which covers the illegal turbot fishing season (Tonay et al., 2009 (supported by the BSCPS); Tonay, 2010). The most stranded species in 2003-2005 and 2007-2009 was P. phocoena by 70 percent in a total of 294 individuals. Many individuals were at an advanced stage of decomposition. Some of the stranded cetaceans had their fin parts missing, which is a characteristic mark of bycatch in fishing activity. In the summer of 2009, there was a case of unusual mass stranding, which mostly affected the common dolphins (Tonay et al., 2010).
The full text of the Report (.pdf)