Histological study on nutritional status of larval Japanese anchovy (engraulis japonica T. & S.)

• Main Authors: Hong, Shang Ren, 洪尚仁
• Other Authors: Qiu, Tai Sheng
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/20394554937106029708

碩士 === 國立臺灣大學 === 漁業科學研究所 === 83 === In this study the assessment of the early reduction of the Japanese anchovy (Engraulis japnoica) in I-Lan Bay was based on the nutritional status of the newly hatched larvae. The Japanese anchovy immigrate to I-Lan Bay to lay eggs in the spawning season. During the spawning season of 1994, from February to April, I took fortnight plankton samples, six times in total. Anchovy larvae were sorted from the samples and their nutritional status was evaluated based on the histological condition of the midgut cells. I defined the nutritional status of anchovy larvae by the histological condition of the midgut cells and applied this method to study the Japanese anchovy larvae collected from a transect crossing Kuroshio, upwelling zone, and continental shelf of the East China Sea in the North Pacific off northeastern Taiwan. My results showed that among the anchovy larvae sampled from the I-Lan Bay, 54% were classified starved. Anchovy larvae caught in the mid spawning season (March 14, starved rate 36%) seemed to have better nutritional status than those caught at the beginning of the season (February 23, starved rate 52%). I found that the nutritional status of anchovy larvae was correlated with the zooplankton biomass in the same sample (rs = -0.94 P=0.004),but not with the zooplankton biomass of the environment in general. When these methods were applied to the Japanese anchovy larvae from the different water mass in the North Pacific northeast off Taiwan, I found that the larvae from the upwelling zone had good nutritional status and low starved rate (19%). Their resistence to hunger was stronger than that of the larvae from the I-Lan Bay