Status Estimation of Coconut crab (Birgus latro Linnaeus, 1767) from Andaman and Nicobar Islands, India

The coconut crab ( Birgus latro ) is the largest land-dwelling crustacean in the world, with a unique set of adaptations that allow it to survive in diverse habitats, including forests, beaches, marines, and mangroves. Despite its ecological significance and cultural value as a food source and cultural symbol in many local communities, there is insufficient information available on the current status, distribution, morphometric traits, and management of the coconut crab population in Andaman and Nicobar Islands. To address this gap, the present study is focused on the assessment of population status, distribution, morphometric characteristics, and growth pattern of coconut crab. The intensive surveys on the distribution and density of coconut crab population were made during April 2015 to March 2018 in the Nicobar group of islands (Great Nicobar Island, Little Nicobar group Islands, and Nancowry group of Islands) and Little Andaman Island. Two methods were used in this study: baited stations and transect survey. The baited station method was used to calculate catch per unit effort (CPUE) in the form of crabs per baited station. Transect surveys were used to calculate the number of crabs per unit of area by using Line Intercept Transects. Determination of the sex ratio using χ2 test, size variation, length–weight relationship (LWR) and allometric growth pattern of coconut crabs were carried out for the first time in Andaman and Nicobar Islands. Out of 103 coconut crabs, ( n = 66) are males and ( n = 37) are females. The male-to-female ratio for coconut crab is 1: 0.6 ( n = 103, χ 2 = 8.5, P = 0.004). The thoracic length of the coconut crab population measured varied in size from 13 to 61 mm, weighing between 68 and 779 gm. This study is also evaluated that the growth pattern of both male and female crabs has negative allometric, where the value of allometric constant, b is