碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 94 / The improvement of fishing vessels coupled with advance fishing methods greatly increases the efficiency of offshore fleet to catch fish, however, it leads to over-exploit offshore fishery resources. Recently, there is an increasing consciousness to conserve fishery resources especially the commercially important fishes such as tuna and tuna-like species. In order to meet the international standard of sustainable fishery management we have to understand the current status of our tuna longlining fishery in Taiwan offshore waters. This project is to study multi-species in three fishing ports so as to investigate the general situation of our offshore tuna longlining fishery. Data were based upon selected 42 longliners during March 1998 to October 2003 from NanFanAo, XingKang and DongGang fishing ports. Cluster analysis was first utilized to classify all the fishery species composition in each degree unit into two statistically significant different zones with longitudinal 121°E line as a boundary to separate them as “Eastern zone” and “Western zone”. The main catches in the east zone was dolphin fish and in the west was tunas (yellowfin tuna and bigeye tuna). According to the result of fishing frequency and fishing proportion from cluster analysis, 4 major species, yellowfin tuna, bigeye tuna, dolphin fish and sharks were selected. I then applied general linear model to standardize and used ANOVA to find the effecting factor on each species. For dolphin fish, the catch rate were affected by fishing set time and region in eastern zone. It seemed having regime shift with sharks. As for shark, year became important factor. The main catch in the west zone are yellowfin tuna and bigeye tuna. By using ANOVA, the main factors in tunas were both spatial and regional factors. Lunar phased also have significant effect on bigeye tuna. In addition, I have analyzed satellite data such as pigment concentration and sea surface temperature in relation to catch rate. The east zone, where dolphin fish was high, had high chl-a and sea surface temperature. Shark was, however, in low temperature area. In the west zone, yellowfin tuna preferred sea surface temperature around 23~26°C. Bigeye tuna was found no significant relationship with pigment concentration as well as temperature likely due to their deeper water distribution.
| Identifer | oai:union.ndltd.org:TW/094NTOU5451018 |
| Date | January 2006 |
| Creators | Yi-Hui Cai, 蔡怡卉 |
| Contributors | I-Hsun Ni, Hsueh-Jung Lu, 倪怡訓, 呂學榮 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 100 |
Page generated in 0.014 seconds