In 12th January, 2017, Prof. Izumi Kinoshita from Kochi University, Japan has brought a variety of contents to Vietnamese ichthyologists, lecturers and students from Faculty of Biology, HNUE. His speech was about an endemic giant perch fish to Japan, Lates japonicus, which is the biggest in Japanese fresh- and brackish water fishes, attaining to over 1 m in body length.
First, he told about the meaning of the name, akame, which has red eyes in Japanese and its distribution raning from southern Kyushu to central Honshu. However, the distribution areas are limited to south-eastern Kyushu and southern Shikoku.
Second, the nursery ground of akame was delivered to the audiences, with a note of the estuarine environment, where akame larvae and juveniles use eelgrass beds as their nursery. He found that akame offspring had a static, and kept a head-down position parallel to a leaf of eelgrass, called “Camouflaging with eelgrass leaf”. One of important contents in this part was about development of akame, which was divided into pelagic and immigrated stages. It is stated that the recruitment in eelgrass beds occurs around 5 mm, which is quite metamorphosing period, i.e. much critical period.
Third, based on otolith daily ring data, the spawning season of akame was also indicated. Modes of distributions of hatching dates quite accord with full and new moons from June to August, thus this fish reproduces synchronously with spring tides. In addition, changes of food habits with growth showed that main food for akame ranging 2 to 20 mm were shrimps.
To summarize his lecture, he told about the life history of akame, with an interesting data on annual year between male and female. Spawning ground or spawning migration of akame needs to examine further and present in another visit.
Besides the mentioned lecture, Prof. Kinoshita and his students took a survey in the Tien Yen estuary to discover the spawning ground of Japanese sea bass (Lateolabrax sp.) and visited some historic sites in Hanoi as well as supported the fish larval identification for the students from the HNUE.
Here are some photos from the visit:
