英文摘要 |
The major fishing methods for catching small shark species in Changhua and Yunlin and Penghu areas were bottom trawl, shrimp beam trawl and drift gill net which were known from the results of pervious studies. The major fishing ground was between 119°5’E-120°25’E in longitude and 23.5°N-23.05°N in latitude. And the operation depth for catching these sharks was about from 10 m to 100m. Recently, the main elasmobranch which caught in these areas were skate and rays while some small shark species have been captured occasionally.
Galeus sauteri, a bottom-dwelling shark, is the most abundance species of catshark in Taiwan inshore waters. It is a by-catch species of trawl fisheries. A total of 1,806 specimens were collected on basis twice a month from August 2007 to July 2008 at fish market. A Likelihood ratio test indicated that there is a significant difference on the weight (WT) and total length (TL) relationship between sexes. Thus, the TW-TL relationships were expressed as TW=0.00204TL3.1112,(n=872); TW=0.00337TL2.9513,(n=695) for female and male, respectively. The sex-combined von Bertalanffy equation by using the MULTIFAN for G. sauteri was Lt=55.3(1-e-0.145t). There were 11 age classes of the sample and dominant by the first, second, third, eighth and ninth age classes. |