| Summary: | 碩士 === 國立高雄海洋科技大學 === 漁業生產與管理研究所 === 95 === To establish the relationship of in situ target strength (TS) and length (L), and standing crop of Taiwan mauxia shrimp (Acetes intermedius), 5 fishery-acoustic cruises were carried out in waters off Tungkang, Taiwan from Oct. 8th to 30th and Nov. 5th to 6th, 2006. Except for collecting the fishery-acoustic data, a paired trawl was operated simultaneously to identify the target and sample the length strata each cruise. Depth of trawl net was adjusted by judging from the echo trace on the echo sounder. It was assumed that the distribution of A. intermedius was homogeneous and no significant difference in waters during the period of study. The linear relationship of in situ TS and L was established by substituting length strata of A. intermedius sampled from the paired trawl to estimate theoretical TS and to compute its slope a and intercept b.
Results indicated of this study that: 1. the component of trawl fishing was mainly consisted of A. intermedius up to 99.98%; 2. 5 relationships of in situ TS and L established from 5 cruises were certified without any difference one another; 3. a compound relationship was found to be as TSall = 28.2 log L–117 (L:16~35mm, n=111,480, r=0.917). Data collected from 241 effective elementary sampling distance units (ESDUs) was used to compute standing crop of A. intermedius in this study after establish the relationships of in situ TS and L.
Spatial-temporal length distribution of A. intermedius was divided into two groups: one of large-sized shrimp distributed from Kaopeng Gulch to north part of small-Ryukyu Island and the other of smaller shrimp scattered closely to estuary of Linbian River. Density and total standing crop of A. intermedius were estimated to be 77.77 g/m2 and 34,144 tons, respectively. Results show that the utilization of this species was 7% by comparing catch of mid-water trawl and scoop net with the estimated standing crop in this study.
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