Size Structure and Gonad Characterization of Gari elongata (Lamarck 1818) from the Coastal Areas of Hinatuan, Surigao Del Sur, Philippines

Abstract

Size-structure analyses and gonad characteristics of the elongate sunset clam Gari elongata from the coastal waters of Hinatuan, Surigao del Sur, Philippines, was determined in this study. An opportunistic sampling approach was applied during the collection of G. elongata from the coastal waters of Brgy. Loyola and Brgy. Aquino. A total of 1437 G. elongata individuals were subjected to length-weight measurements, and gonads from five (5) individuals per sex among size classes were processed for histological characterization. The maximum total length of G. elongata recorded is 5.42 cm, way smaller than its congeners elsewhere, which is at 7.0-9.2 cm. The size-structure analysis shows that G. elongata from Brgy. Loyola exhibited negative allometric growth while those gleaned from Brgy. Aquino exhibited positive allometry indicating variation in growth dynamics. Known as a gleaning source, Barangay Loyola is abundant in G. elongata, but individuals are much smaller compared to those gathered from Barangay Aquino. A ratio of 1:1 for male and female classification was observed, as seen from gonad histological analyses. Ovaries were found in the spawning capable state with gonads in ripe (30%), spent (25%), early development (25%), and partially spawning (20%) stages. Testes were found to be in the ripe (40%), early developing (10%), spent (10%), and partially spawning (40%) stages. Gari elongata exhibits spawning capable gonads at 2.85 cm and 2.95 cm for males and females, respectively, which suggests that the shellfish has adapted early to reproduction to maintain its population in the coastal waters of Hinatuan. The small body lengths of individuals with mature gonads indicate that G. elongata may have been exposed to some stress in their natural environment. Regulated management of G. elongata to avoid over-harvesting and assessment of water and sediment quality of their natural habitat is highly recommended