西北太平洋長鰭鮪流刺網之網目選擇性

Mesh Selectivity of Gill Nets for Albacore,Thunnus Alalunga,in the Northwest Pacific Ocean

郭慶老(Chin-Lau Kuo) ； 黃士宗(Shih-Tsung Hwang)

《臺灣水產學會刊》 19卷1期 (1992/03) Pp. 13-23

https://doi.org/10.29822/JFST.199203.0002

摘要

理論上，魚類對一特定頻率之聲探系統的標物强度與以公分為單位之體長的平方值成正比；因此，如果能測取同一魚種在自然游泳狀態下之現場標物强度，則有可能推測該魚種在自然水域之體長組成及分布。本實驗以雙波束計測法測取在臺灣東北部鹽寮灣水域集魚作業中之扒網漁船所趨集魚種之單體現場標物值，趨集魚種之漁獲實驗顯示鎖管及鰺科佔99.5%，比較其標物强度分布與漁獲體長分布，結果發現無鰾之鎖管的標物强度較鰺科魚種小，用雙波束法不獨可區分該二混合魚種，而且其現場標物强度之頻度分布與漁獲體長之頻度分布極為吻合；因此，以雙波束法現場計測反射强度不但可做為現存量評估時之校準因子(scaling factor)，而且可推測實驗海域該魚種在各水層之體長分布情形。

關鍵字

流刺網 ； 長鰭鮪 ； 網目選擇性

並列摘要

The in situ target strength is an important parameter,not only for obtainingthe scaling factor of echo integrator but also for estimating the fishlength that is related to target strength.Dual-beam acoustic surveys toestimate the size distribution of squid(Loligo edulis)were conducted in theYen-Liao Bay during September 2 and 6,1989.Many individual targets wereobtained by dual-beam method.The net samplings indicated that 99.5% of thecatches were squids and carangids.Results of the analysis indicate that boththe in situ target strength and size distribution estimated by dual-beam methodmatch well to the catch data obtained from net sampling.Therefore,thedual-beam technique is potentially appliable to the acoustic estimation of thesize of squid in the northeastern waters of Taiwan.

並列關鍵字

Gill Net ； Albacore ； Mesh Selectivity