Article Title

Ecological and Distributional Status of the Continental Fishes of Northwestern Baja California, Mexico





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The ecological and distributional status of the continental fishes of northwestern Baja California, Mexico, was seasonally monitored between Feb- ruary 1996 and March 1997. A review of records in literature and of specimens collected between 1983 and 1995 in the study area, provide the data upon which this report is based. A total of 23 species (19 native and 4 exotic) belonging to 22 genera and 15 families was registered. This fish fauna is ecologically composed of species of marine derivation (78.9% sporadic and 21.1% diadromous) and by 8 permanent species (34.8%), 9 tidal visitors (39.1%) and 6 occasional visitors (26.1%). From the ichthyogeographical point of view, most of the species are of Calif omian affinity (68.4%) and the remaining related to northeastern Pacific (15.7%), Holarctic (5.3%) and circumtropical (5.3%) regions. Only one taxon {Oncorhynchus mykiss nelsoni) is endemic (5.3%) to the study region. Ten species are new continental records for Baja California [Norte], and seven taxa reach their southernmost continental ranges in northwestern Baja California. The conserva- tion status of Gasterosteus aculeatus microcephalus is considered as threatened. The main problem that affects the ecosystemic integrity of the streams of this region is the progressive alteration of the aquatic and riparian habitats caused by anthropogenic impact.