We evaluated experimental collection of Pinctada mazatlanica spat on substrates of different textures and colors placed at different depths within settlement tanks. When larvae reached the pediveliger stage (day 25), black-colored spat collectors (“envelope” type) composed of the following materials were offered as settlement substrates: onion bag, mosquito net, fishing net, and 63% shade-cloth. Spat collectors measured 30 × 30 cm and were composed of an outer bag and inner substrate made of the same material. The influence of the color of spat collector material on recruitment was investigated using a second type of spat collector composed of onion bags as the outer bag and inner substrate (“bag” type). Bags were prepared in 3 different outer/inner (O/I) color combinations of green/green, green/black, and red/black (O/I). Both types of collectors were deployed at different depths within settlement tanks. Approximately 2.7% of the initial larval population survived, resulting in 35,583 spat. Of these, 71.3% recruited to bag type collectors, 21.9% to envelope type collectors, and 6.8% to the surfaces of the culture tanks. Spat recruitment was significantly affected by collector material (P < 0.01), with fishing net and shade-cloth yielding highest and lowest density of spat, respectively. Similarly, spat collector color combination significantly influenced spat collection (P < 0.01), with higher recruitment to red and green substrates. For both spat collector types, there was significantly greater (P < 0.01) recruitment of spat to collectors in the middle of the water column (60–90-cm depth). This study showed that both the type and color of material used for spat collectors, as well as depth of deployment, influenced recruitment of P. mazatlanica spat. These results will help fine-tune current hatchery techniques for this species.
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Vol. 24 • No. 1