Population structure and low genetic diversity in the threatened lebranche Mugil liza in the Colombian Caribbean

The lebranche (Mugil liza) is an important commercial fishing species distributed throughout the Colombian Caribbean. However, overfishing and environmental damage are two factors that have significantly contributed to the reduction of its abundance, and there is no knowledge of the number of existing populations to implement the fishery management strategies. Therefore, based on nine microsatellite loci, we evaluated the genetic diversity (Ho and He), the structure (Fis, Fst, AMOVA, DAPC, and Bayesian analysis), and the population connectivity (assignment analysis) of M. liza with samples collected from eight localities distributed along the coastline of the Colombian Caribbean, including four Protected Marine Areas (MPAs). Results indicated low genetic diversity (Ho = 0.351 +/- 0.040) and high inbreeding (Fis = 0.572 +/- 0.041) with all loci evaluated. However, these results contrasted when the loci with the presence of null alleles were excluded (Ho = 0.592 +/- 0.082; Fis = 0.289 +/- 0.069). There is evidence of two populations (population 1: Santuario de Fauna y Flora el Corchal (MPA SFFC) and Via Parque Isla Salamanca (MPA VIPIS); and population 2: the rest of the localities), that did not show a clear relationship with geographic distribution. The role of MPAs and the results of this study in management and conservation plans for M. liza in Colombia are discussed.