室內孵化之黑殼沼蝦Macrobrachium Asperulum(Von Montans,1868)之幼苗變態研究

Morphological Observation on the Development of Larval Macrobrachium Asperulum(Von Martens,1868)(Crustacea,Decapoda,Palaemonidae)Reared in the Laboratory

林水治(Shui-Chih Lin) ； 施志昀(Jhy-Yun Shy) ； 游祥平(Hsiang-Ping Yu)

《臺灣水產學會刊》 15卷2期 (1988/12) Pp. 8-20

https://doi.org/10.29822/JFST.198812.0002

摘要

爲了嘗試能否直接從魚探記錄辨識皮刀魚及究明其標的物反射强度以做爲定量參數。本研究選取尾叉長3.9至22.4公分之皮刀魚，在音響水槽實驗室內，用懸垂法懸掛測試魚體，並以側傾、俯仰、横搖等三平面旋轉之，模擬200 KHz之超音脈波入射魚體不同方位時之反射特性。其結果如次：(1)超音脈波入射皮刀魚體兩側扁部位時，其反射强度較背腹部或頭尾部高20 dB以上，在Rollplane下，經測定其反射强度之頻度分布呈Rayleigh分布，此一高度方向性之特性，加上其側扁體形易受海潮流影響之結果，使其在魚探記錄紙上呈現濃淡相間之羣聚型縱型記錄跡。(2)超音脈波入射在任一同方位之大小不同皮刀魚時，其反射强度與皮刀魚之尾叉長及體重等成正比關係，故200 KHz之超音脈波探測皮刀魚時並無共振現象，用超音波定量計測是可行的。唯皮刀魚之體形側扁，成羣之方向性不明，故羣體之定量反射特性有待進一步之究明。

關鍵字

蝦 ； 黑殼沼蝦 ； 幼苗變態 ； 后期幼蟲

並列摘要

For the purposes of identification and abundance estimation,the acoustic scatteringproperties of 3.9-cm to 22.4-cm moonfish sampled in the coastal waters of WesternTaiwan were measured.Target specimens were suspended and rotated to accept theultrasonic pulses with frequency of 200 KHz from various aspect angles,and thebackscattering strengths from each aspect angle were measured and analyzed.Theresults are summarized as following:1)Polar plots show that the moonfish was omnidirectional in its sound scatteringcharacteristics.The echo level of the dorsal-ventral side(or head-tail aspect)was atleast 20 dB below the lateral-flat side aspect echo level.When the target was rotatedwith roll plane,the distribution of the target strength followed the Rayleighdistribution.This acoustic property of a moonfish patch is characterized by analternating heavy and light echogram.2)The target strength at any aspect angles was dependent on fork length andbody weight of moonfish.Hence the mechanical resonances of the moonfish could benegligible.It is possible to estimate the abundance by acoustic methods.

並列關鍵字

Prawn ； Macrobrachium Asperulum ； Larva Development ； Postlarva