As any boater who has ever been to the Bahamas with a rod and reel knows, bonefish tend to be happiest in shallow offshore waters, say 30 feet below the surface. But new research shows that, just before spawning, they gather into a spiral that looks like a tornado and includes some 10,000 fish all at once.
Fish ecologist Andy Danylchuk of the University of Massachusetts Amherst and Aaron Adams, director of operations for Bonefish & Tarpon Trust at the Florida Institute of Technology, used tracking tags to study how the bonefish spawn. They had video cameras ready as the fish moved from the shallows to the edge of a reef and a big drop-off, then descended 160 feet and hovered over thousands of feet of open water. The fish stayed there for about an hour before rushing to the surface to release sperm and eggs into the drifting ocean currents. Then they sped back to the shallows.
Check out the video here: http://www.livescience.com/41944-ten-thousand-fish-migrate-to-spawn-video.html
“This new understanding of bonefish movement and spawning aggregations has significant implications for their conservation,” Danylchuk said in a press release.
The findings suggest a need to consider both deep and shallow habitats in conservation plans.