Abundance estimates, morphometric measurements and stable C and N isotope data for larval Spanish Mackerel collected in the northern Gulf of Mexico

These data were included in analyses of larval Spanish Mackerel abundance, condition and trophic dynamics (C and N stable isotopes) in relation to the Deepwater Horizon oil spill (DWHOS). Ichthyoplankton samples were collected monthly (May through August) along a cross-shelf transect off the coast of Alabama (USA) during years prior (2007-2009), during (2010) and after (2011) the DWHOS. Samples were collected during daylight hours using a Bedford Institute of Oceanography Net Sampling System (BIONESS; Open Seas Instrumentation, Inc.). The BIONESS had a 0.25-m2 mouth opening fitted with 333 um or 202 um mesh nets. All Spanish Mackerel larvae used in the morphometric analyses were imaged under a dissecting microscope fitted with a high-resolution digital camera (Canon EOS Rebel T3i). Body dimensions were measured using i-Solution Lite imaging software (IMT i-Solution, Inc.). All stable isotope samples were analyzed using continuous flow stable isotope ratio mass spectrometry (CF-IRMS) with a Costech Elemental Analyzer coupled to a Thermo-Fisher Scientific Delta V Advantage Isotope Ratio Mass Spectrometer at the Gulf Coast Research Laboratory’s stable isotope facility.