高解析度之臺灣沿岸魩仔漁獲及混獲組成以及其歸因之時空及環境因子

High resolution larval fish compositions of catch and by-catch species in coastal waters of Taiwan, ascribable to spatiotemporal and environmental factors

蔡旻祐(Min-Yu Tsai)

指導教授 ： 柯佳吟

國立臺灣大學/生命科學院/漁業科學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201903163

摘要

魩仔漁業係臺灣以鯷科(Engraulidae)和鲱科(Clupeidae)仔稚魚為目標漁獲物種的沿岸漁業之一，其中日本鯷(Engraulis japonicus)、異葉公鯷(Encrasicholina heteroloba)及刺公鯷(Encrasicholina punctifer)三鯷科物種是魩仔漁業主要之組成組成。過去研究發現，部分海域鯷科仔稚魚會隨著環境改變漁況，且漁獲組成隨時空變化有明顯不同。然而，過去對於魩仔研究主要以月別採樣，對於更細時間尺度下此漁業漁獲之不同海域漁獲組成、混獲歧異度變動與其驅動因子瞭解仍然有限。因此，本研究透過2018年全台6個地點(屏東、高雄、台中、新北、宜蘭、花蓮)以週別高頻度的魩仔樣本採集，與相關生物及環境因子收集，探討目標漁獲與混獲組成時空變化及混獲率(Bycatch rate)和混獲歧異度(Bycatch diversity)分別受生物和環境因子影響情形。研究結果發現，全年各地魩仔漁獲物種組成可分成五群，其中四群與三種鯷科主要漁獲物種有關，第五群則以黃帶圓腹鯡(Dussumieria elopsoides)為主要漁獲組成；多數海域混獲率與混獲歧異度不相關；而廣義加性模型(Generalized additive model)中則可發現，全年各地混獲率主要可由海表溫度、地點與三鯷科物種之標準體長三個因子解釋，混獲歧異度主要可由地點與三鯷科物種之準體長兩個因子解釋，且兩者中地點均有最高的解釋力。本研究結果說明漁獲樣本頻度會影響魩仔漁業資源評估，如黃帶圓腹鯡過去可能被低估；且地點或地點因子代表之綜合因素解釋該漁業混獲問題之程度會比環境因子高，而主要漁獲魚種體長較長時因有較強游泳能力會形成群聚(Schooling)，可能使空間中物種組成單純化，進而降低混獲情形。綜合而言，高頻度及長時間採收可以更全面了解此漁業資源利用之情形。

關鍵字

混獲率 ； 混獲歧異度 ； 魩仔漁業 ； 黃帶圓腹鯡 ； 仔稚魚

並列摘要

“Bua fisheries” is the larvae fisheries targeted at Engraulidae (Anchovies) and Clupeidae (Herrings). It is commonly practiced in the coasts of Japan, Taiwan and mainland China, and the catches were mainly composed of Engraulis japonicas, Encrasicholina heteroloba, and Encrasicholina punctifer. The catch composition of Bua fisheries showed significant seasonal and geographical shifts in parts of waters around Taiwan based on previous studies with monthly samplings. To explore the catch composition variance in a shorter time period, we collected and analyzed weekly Bua catch in Taiwan waters from Ilan, Hualien, Pingtung, Kaohsiung, Taichung and New Taipei City in 2018, and the satellite environmental data at these locations. Generalized additive model investigated the relationships of environmental and biotic factors between bycatch rate and bycatch diversity. In this study, samples were clustered into five groups, including four groups related to anchovies and a group was composed of round herring (Dussumieria elopsoides), which was seldom discussed in the past. Models showed the sea surface temperature, location and length of anchovies significantly affected the bycatch rate. Likewise, location and length of anchovies significantly affected the bycatch diversity. Results from this study indicated high frequency sampling may provide more information about the Bua fisheries, and the resource of round herring might be underestimated in previous studies. Location or the mixed factor that location represented might affect the bycatch rate and diversity more than the environmental data we used in the study. We speculated larger anchovies have enhanced-movement behavior to form small pelagic fish schooling, and which might simplified the composition in unit space and decrease the bycatch rate. We suggest long-term and high frequency samplings should be considered to assess fisheries resource comprehensively.

並列關鍵字

Bycatch rate ； Bycatch diversity ； Bua fishery ； Dussumieria elopsoides ； Larval fish

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