Authors

Cesaria R. Jimenez

Author

Henry E. Dejarme

Co-author

Jaime U. Jimenez

Co-author

Ruth D. Gaid

Co-author

Mindanao State University at Naawan, 9023 Naawan, Misamis Oriental, Philippines

*Corresponding author: [email protected]

ABSTRACT

Lutraria sp., locally known as lapis, is an edible bivalve collected in Taguines Lagoon, Benoni, Camiguin much sought after by local resort visitors for the squid-like flavor and high nutritive value of its meat. Indiscriminate harvesting of this clam through the years had resulted in observable, though undocumented, reduction in its abundance and catch rates. Despite this, no investigations have been made about its habitat, life history, and aquaculture potential. This report presents the findings on the habitat characterization, spawning, fecundity, and larval development of Lutraria sp in Taguines Lagoon conducted in 2007. The substratum of the lagoon consisted predominantly of fine sand with coarse and very fine sand occurring in smaller proportions. Sediment pH was within a narrow range of 8.0-8.5, the organic matter content was low (0.742 - 1.490%), salinity was at 33 ppt and water temperature ranged from 28-300C. The diatoms Chaetoceros sp., Thalassiosira sp. and Coscinodiscus sp. dominated the phytoplankton; Calanus sp., Oithona sp. and Acrocalanus sp. were the dominant zooplankton; and nematodes, foraminiferans and bivalves dominated the meiofauna. Adult clams were commonly collected buried 30cm in the substrate although one juvenile was found buried at 12cm deep. Natural spawning under laboratory conditions was attained two months after broodstock conditioning and occurred either on the first quarter, full moon or last quarter phase of the moon. Only two female clams (SL=78.8mm and 89.7mm) survived under laboratory conditions, which released from 250,000 to 9 million eggs upon spawning. The fertilized eggs had a mean diameter of 56μ. Two-cell stage was reached 25 minutes after fertilization and trochophore stage was reached after 6 hours which hatched into D-larvae (SL=90μ) 18 hours later. Four-day old veligers (SL =120μ) became globular as the hinge line began rounding off and reached late umbo stage (SL=160μ) on Day 7. Pediveliger stage (SL= 201.38μ) was attained on Day 8 and began to settle as spats (SL=266.67μ) on Day 10. Research findings are useful in developing a sound and realistic strategy for management of this species, especially in its culture and large-scale seed production to replenish natural stocks and for future commercial utilization.