Characteristics of the Trash Fish Generated by Bottom Trawling in Surrounding Waters of Guei-Shan Island, Northeastern Taiwan

Abstract

本研究於2005年3月至2006年2月針對龜山島周邊水域拖網漁業之下雜漁獲進行每月二次之調查採樣研究；結果顯示下雜漁獲可佔本區總漁獲之20-25%左右。硬骨魚類至目前為止共計出現86科215種；而幼稚魚，包括大量商業性魚種之幼魚，如白帶魚，石首魚科魚類，狗母魚及鰻魚等，在下雜漁獲中所佔比例可高達40%以上；而稚魚出現之種類數，物種豐富度及均勻度或歧異度均於春季及秋季較高，夏季及冬季較低。多變量統計分析結果顯示本區幼稚魚主要可以區分為三個群聚，分別是春至夏初，夏末至中秋，及晚秋到隔年早春等三個季節群聚。高種類多樣性的季節與稚魚混獲量高峰期同時出現在春季及秋季的一致性結果，顯示持續大量捕獲這些雜魚，將有害於底棲魚類資源的永續利用，而不應再被忽略；本海域於春、秋季實施相關漁業管理措施，如網目限制等應有考慮的必要，以避免本區魚種的加入量過漁。The trash fish generated by bottom trawling in surrounding waters of Guei-Shan Island, northeastern Taiwan was examined based on bi-weekly samplings from Mar. 2005 to Feb. 2006. The trash fish catch accounted for 20-25% of the total captured biomass in the region. In total, 215 bony fish species from 86 families were recorded. The juvenile fishes including large amount of commercial important species such as: ribbon fish, Scianeidae, lizardfishes and eels etc. accounted for more than 40% (in number) of this catch. The number of species, species richness and diversity for juvenile fishes were higher in the spring and fall, and lower in the summer and winter. Multivariate analyses have identified three juvenile assemblages corresponding to the mid-spring to early-summer, late-summer to mid-fall, and late-fall to early-spring seasons. High species diversity coincided with high biomass and abundance of juvenile fish catch in the spring and fall suggested that continue catch of these ”trash fish” maybe detrimental for sustainable use of demersal fishery resources in the region, and such a situation should not be ignored. The management measures, such as mesh size limitation during the fall and spring may be necessary for the ecosystem to prevent a potential recruitment overfishing of commercial fish stocks in the region.