Number Dynamics of Mass Ichthyoplankton Species in the Waters of Morocco

Abstract

Data on the number dynamics of the mass fish species at early developmental stages in the northern and southern regions of Morocco during 2003–2016 have been analyzed. The values of number index and absolute number of eggs and larvae of the mass fish species have been calculated. As a rule, the values of absolute number of ichthyoplankton are 1.3–2.9 times higher than of the number index values. In general, the trends of interannual fluctuations of these values are similar. The study revealed that the patterns of fluctuations of the subtropical fish species at early developmental stages (European pilchard Sardina pilchardus, Atlantic horse mackerel Trachurus trachurus, and mackerel Scomber japonicus colias) are similar over the whole study area within the Morocco economic zone (32°–21° N). The fluctuations in the number of the tropical fish eggs and larvae (round sardinella Sardinella aurita and Cunene horse mackerel T. trecae) are not identical in the northern and southern parts of Morocco. No clear correlation between these fluctuations in the bordering regions is revealed.