Populations may be deceiving. When the great Atlantic East Coast deep-sea fishery from George's Bank to the Grand Banks and Labrador Strait was going down from over-fishing, fish stocks, particularly cod, were concentrated in unprecedented numbers---hundreds of thousands of tons---in places they had never been seen before. Displacement was never explained fully although temperatures were believed part of it. Habitat shrinkage could be part of doodle numbers. If it is, a cautionary note: Those last great fish stocks were fished to near-extinction. We've been waiting for nearly 40 years for them to come back.