Search results for "Swimming behaviour"
showing 3 items of 3 documents
Effect of boat noise on the behaviour of bluefin tuna Thunnus thynnus in the Mediterranean Sea
2007
The effect of boat noise on the behaviour of bluefin tuna Thunnus thynnus was investi- gated in the Egadi Islands, Sicily, during spring 2005 using a fixed tuna trap set near shipping routes. Tuna behaviour was observed when exposed to both natural ambient sound and sound generated by hydrofoil passenger ferries, small boats and large car ferries. Acoustical and behavioural analyses were conducted with and without extraneous sound to define a list of behavioural categories. Each vessel produced different engine sounds with regard to their composition and bandwidth, and all were distinctly different from ambient sound levels. In the absence of boat noise, tuna assumed a con- centrated coordi…
Changes in behavioural response of Mediterranean Seabass (Dicenthratus labrax L.) under different feeding distributions
2009
Captive-induced behavioural deviations may involve many aspects of fish behaviour such as swimming activity and enhancement of individual aggressiveness. We studied seabass (Dicentrarchus labrax) behaviour as a function of manual and automatic feeding distribution modes. Under manual mode, the food is distributed over an extended area for a longer period, and its precise location is not always predictable, while with pneumatic automatic feeders, fish receive the same amount of resource, which is concentrated in the same surface area over a shorter period. We compared seabass behaviour under automatic and manual conditions collecting video image recordings before, during, and after feeding d…
Oncomiracidial development, survival and swimming behaviour of the monogenean Sparicotyle chrysophrii (Van Beneden and Hesse, 1863)
2012
Abstract Oncomiracidial development of Sparicotyle chrysophrii , a monogenean parasite of Sparus aurata , was analysed using 450 eggs. Parasite morphological changes in time, data on hatching success, as well as oncomiracidial survival and swimming behaviour were recorded. Eggs were maintained at 20 °C and exposed to LD 12:12. They were observed under the stereomicroscope every 8 h until they hatched. Thereafter, 155 oncomiracidia were isolated in separate wells and observed every 2 h until their death. Most of the hatchings occurred in a short period of time (approximately 24 h). Hatching success was 87% and the hatching period ranged from 5 to 10 days after deposition, with most of the ha…