Use of otolith microstructure and microchemistry to study life history of the slickhead Alepocephalus bicolor in the northeastern water off Taiwan

• Main Authors: Jyun-Ruei Chen, 陳君睿
• Other Authors: Kwang-Tsao Shao
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/49860758673353239148

碩士 === 國立臺灣海洋大學 === 海洋生物研究所 === 97 === The slickhead Alepocephalus bicolor is the dominant species in deep-sea fish fauna of Taiwan. To understand the unknown life history pattern of the fish, biological measurements as well as otolith structural and microchemistry analyses were conducted on regularly collected samples by the demersal trawl in coastal water of NE Taiwan during 2004 and 2007. Length frequency distributions indicated that the fish inhabited in 400~600 m depth and lengths of the fish, mainly of 160~220 mm, increased with the depth. Males predominated the population and the large-sized individuals skewed toward females. Gonadosomatic indexes indicated that lengths at maturity were 155 mm for male and 200 mm for female with a prolonged spawning season from February to August. Periodically formed growth increments, growth rings, checks of hatching, first feeding and metamorphosis (MC) and a structure of translucent zone (TZ) were discernible in otolith of fish. The growth increments beyond MC did not deposit daily, whereas the growth rings were validated to be annuli that formed every February to March by marginal increment analysis. Back-calculated length and age of the fish when TZ formed were 84 mm and 7.7 yr, which otolith structure might be related to the initial development of gonad and habitat transition of the fish. Longevity of the fish were of 23 yr and the von Bertalanffy growth parameters were 277 mm for L∞ and 0.10 yr-1 for K. Differences of elemental composition in otoliths of the fish among life history stages were discriminated mainly by Sr/Ca and Mg/Ca ratios. Generally, the combined information on reproduction and life history indicated that the slickhead displayed K-select tendencies.