Morphometrics, Length-Weight Relationships and Relative Condition Factor Inportunus Sanguinolentus (Herbst, 1783) from Southeastern Arabian Sea

Josileen, Jose and Najmudeen, T M and Retheesh, T and Sunil, K T S and Vijayan, M T (2025) Morphometrics, Length-Weight Relationships and Relative Condition Factor Inportunus Sanguinolentus (Herbst, 1783) from Southeastern Arabian Sea. Crustaceana, 98 (2). pp. 213-229. ISSN 1568-5403

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Abstract

Portunus sanguinolentus is widely distributed all along the Indian coast and the most dominant marine crab landed in the country. In Kerala also, species share is maximum in the marine landings and recorded an average landing of 1200 tonnes during 2007-2018. The bulk of the catch is contributed by trawlers and the species is mainly fished from 20-30 m depth zone. It grows to a maximum size of 20 cm in carapace width (CW) and the estimated life span is approximately three years. Knowledge on the body weight-length/width relationships and relative condition factor in populations is important for estimating the population size of a stock and its exploitation. Hence, the interrelationships between various morphometric characters, viz., Carapace Width (CW) and Length (CL) and Chelar Propodus Length (CPL) and Height (CPH) in males, as well as Carapace Width and length and Abdominal Width (AW) and Length (AL) in females, were estimated using a total of 2476 male and 2965 female crabs. The Carapace Width/Length-Weight relationship was studied in both sexes on a total of 5595 crabs using the allometric growth equation. The allometric relationships between the characters of this set suggest that most relationships are positive and highly significant (P ≤ 0.01). The ‘b’ values for carapace width-weight in males (55-171 mm/CW), females (54-170 mm/CW), and pooled were 2.9657, 2.8028, and 2.8914 respectively. The results show an isometric growth pattern for males and considerable deviation from isometric growth in females and also when all sizes are pooled. An analysis of covariance indicates that there is a significant difference between sexes (P ≤ 0.01) with respect to the carapace width-weight relationship. The condition factor values estimated in males and females (based on CW) were 0.942 ± 0.145 and 1.371 ± 0.255 respectively and the estimated Kn values based on CL were 0.985 ± 0.204 and 1.022 ± 0.233 respectively.

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