Current conservation status of six freshwater fish species from the Baja California Peninsula, Mexico

The current distribution and conservation status of six native freshwater fishes of the Baja California peninsula (Entosphenus tridentatus, Oncorhynchus mykiss nelsoni, Fundulus lima, Cyprinodon macularius, Gasterosteus aculeatus and Gobiesox juniperoserrai), included in the Norma Oficial Mexicana-059-2010, were assessed on the basis of information generated during the study period of 2000-2014. Except for E. tridentatus in the Santo Domingo river drainage and G. juniperoserrai in the Las Pocitas-San Hilario drainage, most of the species were recorded in the hydrological basins sampled. Oncorhynchus mykiss nelsoni showed a significant population fluctuation in the San Rafael river in relation to the dynamics of the base flow and the forest fire events. Fundulus lima presented the probable extirpation from four drainages (San Javier, Bebelamas, San Luis, and Las Pocitas-San Hilario) that is contrasting with the finding of a new population in the Santa Cruz stream. Cyprinodon macularius in the most important remnant population in Baja California (cerro Prieto geothermal ponds) showed interannual fluctuations related with the level of flooding and availability of marginal habitats. Gasterosteus aculeatus showed a progressive population reduction in the southernmost distributional locality (mouth of El Rosario river), as well as the extirpation in the lower Santo Domingo river basin and its recent presence in the mouth of the Cantamar river. Gobiesox juniperoserrai, known only from the type locality is determined as extirpated.