We studied the hydrography and nutrients concentration to the East of Margarita Island (Venezuela) every
15 days for 10 years (January 2003 to December 2012), in an area that had national importance for the sardine Sardinella
aurita fishery until 2005, when the sardine crisis begins and still continues (2013). We collected 852 water samples (at 1 and
20 m depth) to determine the temperature, salinity, dissolved oxygen and nutrients (nitrite, nitrate, ammonium and
phosphate). Average values were calculated for total and seasonal periods: upwelling (January-May) and relaxation (June-
December). Differences were found in the hydrography and nutrient concentration during the study years, and in some
variables between periods, and depth. In the first years of the study (2003 and 2004) the hydrography was similar and the
mean temperature was <24°C during the upwelling period (minimal value 21.6°C) with annual values of 24.5 and 25.0°C.
Between the years 2005 to 2012, the average values during upwelling varied between 24.8 and 25.69°C and the annual ones
between 25.75 and 27.03 °C. In the period 2005-2012 a notable increase of temperature and of dissolved oxygen appears,
also the salinity showed an increase. During these years the upwelling was weak and slightly perceptible in the study area.
During the years 2005-2012 the range of annual averages of nutrients were lower than those reported previously in nearby
areas, confirming that during this period aquatic fertility declined which affected the abundance of fishery resources. In
addition, the increase of water temperature did not favor shoals of sardine to come near shore at the east coast of Margarita
Island.