3 research outputs found
AKUSTİK YAKLAŞIMLAR İLE GÜNEY KARADENİZ SETASE DAĞILIMININ BELİRLENMESİ
No full textLarge numbers of small cetaceans (common dolphin, harbor porpoises and bottlenose
dolphins) were hunted in the Black Sea until the hunting of cetaceans was banned in
Turkey in 1983. Even though the practice of hunting cetaceans has ceased by Turkish
fleets, ongoing threats such as viral infections, overfishing, by-catch, habitat loss,
seismic surveys and the pressure of fishermen continue to persist. One of the most
overwhelming reasons as to why overcoming these threats proves so difficult, is the
insufficient data available for these populations.
This thesis study aims to evaluate the distribution and abundance of the Black Sea
cetaceans for the future conservation of these species. To fulfill this role, i) hydroacoustics,
ii) passive acoustics and iii) visual observation methods were performed
over transects during two one month cruises held in July and October 2014, covering
up to 120 miles off the Black Sea coast of Turkey (approximately 150 000 km2). For
the fisheries hydro- acoustics, three scientific echo sounders (38 kHz, 120 kHz and 200 kHz, SIMRAD EK60) were operated continuously over the cruise transects. For
the passive acoustics, C-POD (Chelonia Ltd., Cetacean Monitoring Systems) was
deployed at up to the 93 stations. In addition, a new methodology for cetacean detection
was developed. During the development of the new methodology, dolphin presence
in fisheries hydro-acoustic data, i.e. the “noise”, was processed into the “data”
by validation with cetacean observation data. C-POD data was used both for confirmation
of cetacean species and characterization of cetacean vocalizations. Finally, the
abundance of cetacean species in the Exclusive Economic Zone of Turkey were examined
using the data generated by the three respective methodologies.
With the combination of these methods, the distribution of especially one vulnerable
(IUCN) Black Sea cetacean, the short-beaked common dolphin (Delphinus delphis
ssp. ponticus, Barabash-Nikiforov, 1935) was assessed. Results suggest that cetaceans,
especially common dolphins, are concentrated mainly in the Eastern region of
the Black Sea and harbor porpoises are distributed coastally in lesser numbers. Furthermore,
bottlenose dolphins were scarcely observed in the study area. As a result of
abundance estimations it was found that, common dolphins display the largest population
size, followed by harbor porpoises and bottlenose dolphins, respectively. Additionally,
comparisons with 11 years of past visual observation data demonstrated an
overall decrease in Black Sea cetacean populations. Lastly, the methodology developed
proved that the hydro-acoustical data collected for fisheries purposes can also be
used in cetacean research.Avcılığı en son Türkiye’de 1983 yılında yasaklanmadan önce, Karadeniz’de bulunan
küçük setaseler (tırtak, mutur ve afalina) yüksek miktarlarda avlanmışlardır. Avın,
Türk filoları durdurulmasından sonra bile bu popülasyonlar, viral enfeksiyonlar, aşırı
balık avcılığı, habitat kaybı, sismik araştırmalar ve balıkçı baskısı gibi hala süregelen
tehditler sebebiyle düzelememişlerdir. Bu popülasyonlarla ile ilgili veri eksikliği bu
tehditlerin aşılamamasının en büyük nedenidir.
Bu tez çalışması, setaselerin gelecekte korunabilmesi için gereken yayılım ve bolluk
verisini sağlaması amaçlamaktadır. Bu amacı sağlamak için, i) hidro-akustik, ii) pasif
akustik ve iii) gözlem yöntemleri’nin kullanıldığı, Temmuz ve Ekim 2014’de Karadeniz’in
120 mil açıklarına ulaşan aylık seferler düzenlenmiştir. Hidro-akustik örneklemesi
için, seyir hatlarında üç tip eko-sounder kullanılmıştır (38 kHz, 120 kHz ve
200 kHz, SIMRAD EK60). Pasif akustik kapsamında sayısı 93’e varan istasyonlarda
C-POD (Chelonia Ltd., Cetacean Monitoring Systems) atılmıştır. Ardından, setase
tespiti için yeni bir metod geliştirilmiştir. Bu metotta, hidro-akustikle alınan yunus gözlem
metodu olarak kullanılabileceğini kanıtlamıştırM.S. - Master of Scienc
