Effect of food strategy and stocking density on larval performance of captively reared Mytilus galloprovincialis

¹ Research team of Agriculture and Aquaculture Engineering G2A, Polydisciplinary Faculty of Larache FPL, Abdelmalek Essaadi University, Tétouan, Morocco
² Amsa Shellfish Station, National Institute of Fisheries Research (INRH), Amsa, Tétouan, 93022, Morocco

^* Corresponding author: hafsa.janah@etu.uae.ac.ma

Abstract

Food availability is a crucial factor influencing the behavioral responses, development and physiology of bivalve’s larvae. In this study, we investigated the effects of two feeding strategies (F_v: number of microalgae cells per volume and F_b: number of microalgae cells per biomass) on Mytilus galloprovincialis larvae reared at three different stocking densities (D₅: 5 larvae/ml, D₁₅: 15 larvae/ml and D₃₀: 30 larvae/ml). The results showed that larvae fed per volume (F_v) exhibited the highest survival rates across all tested densities (59%, 53% and 39% for D₅, D₁₅and D₃₀ respectively), compared to larvae fed per biomass (F_b) (40%, 39% and 32% for, D₁₅, D₃₀ and D₅ respectively). Conversely, feeding per biomass led to a significant increase in cumulative shell length gain (D₅: 211.4 µm; D₁₅: 214.99 µm and D₃₀: 208.11µm) compared to feeding per volume (D₅: 201.12 µm; D₁₅: 166.23 µm and D₃₀:130.09 µm). Statistical analysis revealed that food availability significantly influenced survival only at low larvae density (D₅: F=20.13; P<0.01). However, it significantly affected cumulative gain only at high stocking densities D₁₅ (F=148.96; P<0.001) and D₃₀ (F=318.74; P<0.001). These findings emphasize the importance of feeding strategy and stocking density as crucial factors in regulating larval performance during captivity rearing.