Investigation and Economic Performance of Acoustic Detterent Devices Used in Bottom Gillnets (Pingers) for Bottlenose Dolphin (Tursiops truncatus)

The study was performed in Sinop between September 2015-January 2017 to investigate whether it is a profitable application to attach pinger devices to bottom-gillnets used in coastal fisheries. Gear specifications of both fishermen group were same as follows; mesh size: 34 mm, length: app. 1,1km. The frequency range of the pinger device is 1–500 kHz and effective up to 200m. The most important distinctive feature of those devices is having a built-in rechargeable 1,6 Ah NiMH battery pack but limited up to 2-2,5 months (1000-1500h) total lifetime. In experimental group; average fish catch in the first periods (September-December 2015) was 15,34±1,22 kg and it decreased by 56% to 6,83±0,31 kg between January 2016–2017. According to results obtained from both control and experimental group, Catch Per Unit Effort (CPUE) was calculated as 0,63±0,02 kgkms-1 and 0,67±0,02 kgkms-1, respectively. Total incomes from the sale of fish were 20880,90 TL and 22259,65 TL for control and experimental groups. The fishermen in control group spent 4000 TL to repair nets damaged due to dolphin presence while other fishermen spent 3400 TL to repair nets. Considering the device expenses for the experimental group (2x1500 TL), total cost was calculated as 6400 TL for experimental group and 4000 TL for control group. Therefore, net income was calculated as 16879,90 TL in control group while it decreased to 15859,65 TL in experimental group, representing 6% decline