Molecular Biological Analysis of Ichthyoplankton Collected from Ulleung and Dokdo Islands

Abstract

The ichthyoplankton survey was conducted in the waters around Ulleung and Dokdo Islands in the months of March, May, August and November, 2016. Eleven stations were established along the area and samples were collected using a bongo net with 550µm mesh size that was double obliquely towed from surface to 100m. Fish larvae and eggs samples were sorted and counted using stereomicroscope and molecular approach was used for identification. Species name was assigned in samples with sequence identity of more than 98%. A total of 14 species were identified for fish eggs and among them, Cololabis saira (Pacific saury) and Seriola quinqueradiata (yellow tail) were commercially important species in Korea. Deep sea egg species including Coelorinchus sp. (grenadiers or rattails) and Trachipterus trachypterus (ribbonfish) were identified for the first time in this study and further studies are needed to verify their existence in the survey area. For fish larvae results, a total of 28 species were identified and Scomber japonicus (chub mackerel), Scomber australasicus (spotted mackerel), Cololabis saira (Pacific saury) and Auxis rochei (bullet tuna) were commercially important species. The occurrence of ichthyoplankton species during different months of survey suggests spawning period. However, further studies are still needed to verify and confirm this result.