Fish larvae distribution in the western Arabian Gulf: Spatiotemporal patterns in relation to water column characteristics

Larval fish studies are essential to fisheries science since they provide crucial information on spawning periodicity, breeding season, breeding grounds, and the annual recruitment pattern of fish in a particular area. However, there is a knowledge gap in the basic information on larval fish populations and their environmental preferences from many parts of the Arabian Gulf. This study describes the spatiotemporal fluctuations in the abundance, composition, diversity, and distribution of planktonic fish larvae and eggs in the Saudi Arabian waters of the Gulf between November 2002 and August 2003. Fish larvae belonging to 62 families, of which 47 identified down to genera and 11 down to species levels, were recorded. The mean relative abundance (in percentage) of larval fish belonging to 22 families of commercial importance revealed the predominance of Gobiidae, Engraulidae, and Clupeidae in Saudi Arabian waters. Both fish eggs and fish larvae had their highest abundance in southern waters during late fall and spring, respectively. The highest number (49) of families were recorded in spring and the lowest (25) in summer. This study showed significant seasonal heterogeneity in the larval fish distribution in the coastal and southern waters, while the distribution was homogenous in all other areas. The average species richness index (Margalef, d) ranged from 3.3 (nearshore) to 7.6 (southern) on a spatial scale and from 4.06 (summer) to 7.55 (spring) seasonally; species diversity (Shannon Wiener, H’) from 1.0 (nearshore) to 1.9 (offshore) spatially, and from 1.3 (summer) to 1.98 (spring) seasonally, and evenness index (Pielou’s, J’) from 0.78 (nearshore) to 0.85 (central) spatially and from 0.74 (late fall) to 0.89 (winter) seasonally. Water temperature, salinity, dissolved oxygen, and Chl a were the most crucial background variables explaining the abundance and spatiotemporal distribution patterns of fish larvae in Saudi Arabian territorial waters. Notwithstanding the archival nature of the data, in the absence of adequate information on the fish eggs and larvae, this study provides reliable baseline information on which subsequent changes in the fish larval community of the northwestern Gulf could be investigated.