Sampling and analytical procedures:
Egg samples were collected from 20 August, 2020 through 8 March, 2022 from the research pier at the University of Texas Marine Science Institute (UTMSI), located in the Aransas Pass inlet by deploying a 500-micron mesh plankton net. Egg samples were also collected by deploying a plankton net from a small boat from a location outside the extent of the Red drum egg boon in the Aransas Bay (Mud Island) from 20 August, 2020- December 2021. Egg samples were collected bi-weekly during the Red Drum spawning season (August – December) and monthly outside the Red drum spawning season from both locations. Eggs were sorted by morphology to isolate sciaenid eggs and molecular PCR techniques were applied to subsamples of eggs to confirm the species identification.

DNA was extracted from a single egg using a commercial kit (Thermo scientific Gene JET genomic DNA purification kit K0721). The following cycle conditions were used to run PCRs: an initial denaturing step of 94°C for 2 minutes followed by 30 cycles of 30 seconds at 94°C; 30 s at 60°C and 1 minute at 72°C, with a final extension of 5 min at 72°C. A species-specific primer set (NADH dehydrogenase 4 mtDNA gene) was used to identify wild caught sciaenid eggs (Carreon-Martinez et al., 2010). A set of universal primers (18S ribosomal RNA gene) was used as a positive control for the DNA extraction and PCR reaction. PCR products were size separated by gel electrophoresis (1.5% agarose) and visualized by 1% ethidium bromide solution (Fisher-Scientific). The species-specific primers identified southern king fish (550 bp), gulf kingfish(400 bp), black drum (350 bp), red drum (651 bp), Atlantic croaker (850 bp), and spotted seatrout (1201 bp) using DNA ladder.

** Note: Eggs were not tested for black drum if egg collection date was outside the spawning season of black drum and egg size was smaller than 1.00 millimeters

FAML: pier at in Corpus Christi Channel, Port Aransas, TX, United States, Fisheries and Mariculture Laboratory of the University of Texas Marine Science Institute (lat. 27.8396111, lon. -97.0727222); 

MI: Mud Island in Aransas Bay, TX, United States (lat. 27.9362222, lon. -97.0217777)).