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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Study of the acoustic characters of eleven soniferous fish in the western coastal waters of Taiwan

Tsai, Kai-en 28 August 2009 (has links)
Six sciaenid species including Johnius tingi, Johnius sina, Pennahia argentata, Pennahia pawak, Chrysochir aureus and Otolithes rubber from the western coast of Taiwan were studied. Pennahia argentata¡¦s disturbance sound was most distinct in which the pulse period is almost 2~3 times larger than that the other five sciaenid species. The dominant frequencies of C. aureus and O. rubber¡¦s disturbance calls were low (i.e. usually below 500 Hz). In the six sciaenids there was significant difference in the pulse repetition rate, which may be a useful parameter for recognition of sciaenid species. Among the other fishes surveyed in this study, the inter-pulse interval of pearlperch¡¦s (Glaucosoma buergeri) disturbance call is very short or nearly zero. The pulse is composed a low frequency and a high frequency parts, and the frequency range is wide. Most energy was concentrated in the 2nd and 3rd pulses of the Priacanthus macracanthus¡¦s disturbance soundand its pulse period is not stable. The special acoustic character of Pelates quadrilineatus¡¦s disturbance sound is the extremely short inter-pulse interval (< 1ms).The seacatfish Arius maculates¡¦s disturbance sound can be sorted into three types. Type¢¹is a low frequency sound and usually under 1000Hz; it is very similar to sciaenids¡¦ calls with stable pulse period and dominant frequency. Compared to Type¢¹, Type¢º and Type¢» were high-frequency sounds (i.e. usually up to 8kHz) and their pulse periods are less stable. Pomadasys kaakan¡¦s disturbance sound is emitted by stridulating of its pharyngeal teeth and these sounds were high frequency (i.e. usually higher than 10 kHz). Both Johnius tingi females and males possess extrinsic sonic muscles. The dominant frequency of the males¡¦ disturbance call is significant higher than that of females¡¦ and the length of males¡¦ sonic muscles are also significantly longer than that of females¡¦. It is hypothesized that a longer sonic muscle can generate higher tension leading to a higher frequency sound. Comparing my data to the eleven sound types collected from the western coast by other workers in which the sound producers are still unknown, Type A, Type F, and Type G are more similar to that of the disturbance sound of J. sina¡BP. pawak and J. belengerii, respectively.

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