"These results provide evidence of major changes over the last half century and a window into an earlier, less disturbed fish community…" McClenachan said in the Conservation Biology paper.

McClenachan's studies are part of an emerging field called historical marine ecology, in which scientists study photographs, archives, news accounts and other records to help understand changes in the ocean ecosystem over time and establish baselines for future ecosystem restoration.

McClenachan believes that historical ecology can not only help describe the structure of ecosystems that existed in the recent past, but can be used to establish goals for restoration of large predators, both on land and in the water.