RV Corella Fisheries Laboratory cooperated with the Admiralty Research Laboratory to identify fish detected by long-range sonar equipment installed at the Admiralty Experimental Station, Perranporth. The RV "Corella" was directed from the shore to an area some 65 km distant, that was returning a strong and extended echo. The "Corella" was able to correlate this target with shoals detected on a conventional echo sounder, and substantial catches of sprats were taken in the area using a midwater trawl. The RV "Corella" was used throughout the 1970s for pioneering studies on fish migration. Individual plaice ("Pleuronectes platessa") fitted with 300 kHz acoustic transponding
Elassoma evergladei 115 to 500, increasing with the fish's size. The fish has variable color and form. Its body is generally colored brown with darker spots. The fish has several rows of dark red spots on its dorsal and anal fins. "Nonbreeding" fish may have light streaks, mottling, or blotches. Females of the species in general are colored brown on their backs with mottled brown and cream/white coloring underneath, or they may be reddish brown. The females have no markings. "Breeding" males are colored black with iridescent blue spots. Males have black fins with or without brown spots. Male bodies may be