Interannual variations of environmental factors and the effects on larval fish habitats in the Upper Gulf of California during early summer

To define the larval fish habitat distributions in the Upper Gulf of California and their response to interannual environmental variability, satellite and hydrographic data and zooplankton samples, from three cruises made in early summer (June 2008, June 2010, and June 2013) were analyzed. Monthly averages of SST satellite data from June 2002 to June 2017 indicated negative anomalies during June 2008 and 2010. In spite of this, a recurrent larval fish habitat was defined in the shallowest (<39 m) and saltiest (>36.5 g kg⁻¹) part of the northern UGC. The indicator species of this habitat were the demersal fishes Gobulus crescentalis and Cynoscion othonopterus. A second habitat associated with an oxygenated stratification front (>4.8 μmol kg⁻¹) located in the middle of the UGC, was defined during Junes with SST negative anomalies (2008 and 2010); with Opisthonema spp. being the indicator species. In the southern part of the UGC, sampling station groups were defined with different indicator species. This could be related to the variability of the adjacent circulation of the Northern Gulf of California, and the influence of remote ocean conditions that could be impacting the pelagic ecosystem.