Quantitative Estimation of Zooplankton and Micronekton Biomass Using a High-Frequency Acoustic Method

Abstract

爲了明瞭黑潮在漁場形成過程中所扮演的角色，我們在這個研究中比較了三個與黑潮有關的海洋環境。這三個海洋環境爲：黑潮本區、東海南部及南海北部。黑潮是北太平洋主要的暖流，其表層海水之性質爲貧營養鹽、低浮游動物量；因此，漁業產量也比較低。黑潮的次表層海水則含有相當數量的營養鹽，於是我們預期較高的漁業產量存在於黑潮所引起的局部性湧昇流之中。浮游動物與浮游魚類之線性關聯經常可被證實；在漁業資源的添加過程中，足以引爲粗（初步）產量(apparentproductivity)之預測。雖然比較三個由不同程度的黑潮所影響的區域發現：黑潮中之漁業生產絕對値較低，但在食物鏈之轉換效率上則最高。依資料判斷，約有20種之表層魚，如鬼頭刀、鮪、鰹、旗魚等具有潛能發展爲地方性之漁業。有一些種類的生物學，如成長、成熟較爲人們所知，但進一步評估其資源仍然是迫切地需要加以重視。In this work,three Kuroshio-inundated marine environments around Taiwan,theKuroshio proper,southern East China Sea(SECS)and northern South China Sea(NSCS),were compared to characterize the role played by the Kuroshio in the formation of fishinggrounds.The Kuroshio is a major current in the North Pacific Ocean.Its surface wateris characterized by depleted nutrients and a low density of plankton organisms;hence,fishery production is expected to be minimal.The sub-surface water contains much ofthe nutrients;therefore,greater production of fish is expected in local areas of Kuroshio-triggered upwelling.Zooplankton-ichthyoplankton conversions were adopted to exhibitapparent area productivity.Although fishery production is estimated to be minimal in theKuroshio,maximum conversion of zooplankton to early-staged fish occurs in the Kuroshioarea.Approximately twenty pelagic fish,such as dolphinfish,tuna,mackerel,marlin andshark,were determined to be capable of local fishery development.Some fishery biologicaldata are retrievable for the basis of population investigation.Further stock assessmentis strongly recommended.