Age-growth and reproduction of Taiwan shoveljaw carp (Onychostoma barbatulum) in Yu-Fong Stream of Shihmen Reservoir watershed

• Main Authors: Yun-Yu Hsieh, 謝昀諭
• Other Authors: Ying-Chou Lee
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/88046690410905877474

碩士 === 國立臺灣大學 === 漁業科學研究所 === 102 === Taiwan shoveljaw carp (Onychostoma barbatulum) is one of the most distributed primary division freshwater fish in Taiwan. It is also the dominant species in upstream of Shihmen Reservoir watershed. However there is no complete are-growth research in the past. So this research investigated the age-growth of O. barbatulum to add its basic biological information and wish it can assist future conservation and management decisions. The present research collected O. barbatulum in Yu-Fong Stream of Shihmen Reservoir watershed from February 2012 to April 2014. All fishes measured the fork length (FL), total length (TL) and body weight (W) onsite and took some fishes randomly immersed with 10% formalin solution back to the lab(n = 220). The present research investigated the age and growth of O. barbatulum based on scales. We also dissected fishes and took out gonads to analysis the sex and gonadosomatic index (GSI) to estimate its breeding season. The results showed that, the fork length ranged from 3.2-22.4cm (n = 703), and focus on 6-10cm. The rings of scales formed annually. The von Bertalanffy growth curves computed by observed length at- age data and was expressed as l_t=30.17(1-e^(-0.22(t+1.19) )). The age composition of O. barbatulum in Yu-Fong Stream were 0 year old fish 10.5%, 1 year old fish 41.8%, 2 years old fish 24.1%, 3 years old fish 21.8% and 4 years old fish 1.8% respectively. The sex ratio was 1:1 of total sample fishes but not followed of over 3 years old fishes (most were female). We estimated the breeding season of O. barbatulum in Yu-Fong Stream was March to May. Scale is an ideal age character for age determination for O. barbatulum, and maybe we can use another age characters such as otolith or spine compared with scale to enhance the accuracy of age determination in the future.