DIVERSITY, MORPHOMETRY, AND POPULATION ABUNDANCE OF SEA URCHIN (Tripneustes gratilla) IN NORTH LOMBOK

Sea urchin Tripneustes gratilla is commonly found in tropical
shallow water-seagrass beds and is consumed for its roe in Southeast
Asia. This study recorded five sea urchin species in the study area:
Tripneustes gratilla, Pseudoboletia maculata, Salmacis bicolor, Salmacis
sphaeroides, and Maretia planulata, with T. gratilla being the most
abundant. The highest absolute abundance of T. gratilla was observed
in August 2023, at 0.30 ind./m2, while from May to July 2024, it
declined to 0.02 ind./m2. The mean diameters of T. gratilla ranged
from 37.59 mm to 44.16 mm between August and October 2023 and
from 17.39 mm to 48.45 mm between May and July 2024, having
wide range of the mean weight. In September 2023, sea urchin with
a test diameter of 35.0 – 39.9 mm were the most frequent to be
found. This study provided baseline data on T. gratilla harvested from
the seagrass habitat by the local community in North Lombok and
highlights the potential for overharvesting in the area