SCUBA diving for coral reef fish investigation in Cat Ba Islands

 In July 2014, we implemented a field survey trip with the thirty SCUBA diving sections of biodiversity investigation in Cat Ba Island. Then, the survey trips of coral reef monitoring were continuously implemented from 2016, 2017 and 2018 at 08 locations in Cat Ba Islands, including: Cat Dua, Tung Gau, Ba Trai Dao, Gio Cung, Van Ta, Van Ha, Van Boi and Dong Dau Be. The 169 species of coral reef fishes were identified under 113 genera, 58 families, 14 orders, 02 classes. Among them, the ray-finned fishes (class Actinopterygii) had the highest number of species (165), then chondrichthian fishes (class Chondrichthyes) with 4 species under subclass Elasmobranchii (shark, rays). The average density of coral reef fishes was from 135.38 individual/500m² (2014) to 535.25 individual/500m² (2018).

A increasing tendency of the individual number and fish size in Cat Ba Islands

All three size groups (<5 cm, 5-10cm and ≥ 10cm) were recorded to increase over the study period, among them the size of group less than 5cm increases the most. In the three investigated fish groups (Serranidae, Chaetodontidae, Pomacentridae), the Chaetodontidae have been showing a increasing tendency of the individual number and fish size. This tendency indicates that the coral reef ecosystem may be gradually being restored in Cat Ba Islands. At present, RIMF is cooperating with Cat Ba National Park to keep going the biodiversity investigation and monitoring of coral reef ecosystem in Cat Ba Islands.

Tran Van Huong

Email: huongsbn@gmail.com