Morphometric Evaluation of Three Indigenous Freshwater Mussel Species in Assam, India, to Assess Anatomical Suitability for Pearl Production
Rohit Kumar Singh, Akalesh Kumar Verma, Namram Sushindrajit Singh, Saddam Hussain, Manashpratim Talukdar, Tabu Kaishyap Borthakur, Abhinandan Choudhury, Dibyajyoti DekaIntroduction/Objective:
Morphometric data on indigenous freshwater mussels from northeastern India are limited. This study compared 38 shell parameters and pearl production outcomes across Lamellidens marginalis (Asian pearl mussel), Lamellidens corrianus (Freshwater Pond mussel) and Parreysia corrugata (Pearly mussel) from Assam, India, to identify the species best suited for pearl farming.
Methods:
A total of 120 mussels (40 per species) from five districts were measured for shell dimensions, curvature, thickness, dentition and internal features. Interspecific differences were tested by one-way ANOVA with Tukey HSD, Welch's ANOVA with Games-Howell, and Kruskal-Wallis with Dunn's tests. A further 300 mussels (100 per species) received nucleus implants (two per mussel) and were cultured for 15 months. Post-grafting mortality was compared using Chi-square tests with Bonferroni correction; pearl quality was scored on a three-point scale.
Results:
Lamellidens corrianus showed the highest average body weight (90.9 ± 5.9 g) as well as the largest shell length (94.3 ± 3.2 mm). Most parameters differed significantly among species (p < 0.05) but not among districts. Post-grafting mortality was 35% (L. marginalis), 50% (L. corrianus), and 80% (P. corrugata) (χ2 = 42.42, p < 0.0001). Only L. marginalis produced high-quality pearls.
Discussion:
L. marginalis combined adequate body size for 8-12 mm nuclei, the highest proportion of high-iridescence nacre (44%), near-absent umbo erosion, and the lowest mortality, explaining its superior pearl output. P. corrugata was limited to small nuclei (5-8 mm) and suffered mortality well above acceptable thresholds.
Conclusion:
Size is relevant because the larger the mussel, the easier the implant or grafting operations to produce pearls. L. marginalis is the most practical pearl culture host in Assam. L. corrianus is a usable alternative; P. corrugata is unsuitable.