A Comparison of Fishing efficiencies of the Mechanic and Computer Control Panel Squid-Jigging Machines in the Northwest Pacific Ocean

Abstract

To study the functional development of retinal structure in thornfish(Teraponjarbua),histological examinations were carried out to measure the visual acuity.Density and the ellipsoidal heights of cone cells were measured for the estimateof visual acuity.Eye diameters and lens diameters were also measured.The results showed that initial rapid allometric growth of eye diameters andlens diameters accompanying with a sharp decreasing cone density and histologicalvisual acuity are significant during the early stages(larval juvenile stages,standardlength:10.2-30.0 mm).The ellipsoidal heights of single cones did not significantlyincrease when they grew to 74.4 mm.The results obtained in the presentreport concluded that the older thornfish own the smaller visual angle,i.e.thebetter visual acuity.The morphogenetic changes of visual development between the early stagesand the adult stages suggests that thornfish adopt the better visual acuity to adapttheir different habitats during their different growing stages.爲探討花身雞魚(Terapon jarbua)網膜構造改變的功能發育，本報告利用組織學測定其視覺精度之變化、以其眼徑、水晶體直徑、錐細胞高度與密度之變化比較本魚種各階段之視覺解像角度。結果顯示各測定値在發育早期（標準體長10.2-30.0 mm）變化較顯著，但在成長階段具有較小之解像角（即較佳之視覺精度），成長至體長74.4 mm後錐細胞高度則不再顯著改變。因此，發育早期與成長階段間之視覺發育的組織學變化推測本魚種爲適應其早期生活於河口近岸之表層水域具有甚佳之視覺精度，成長後逐漸遷移至離岸較遠且較深之水域，故視覺精度之發育雖趨緩但仍較其仔稚魚具有較佳之視覺精度。