To find a missing fish, you have to go back through time.

Scientists from Stanford have recreated history in the Mediterranean to find ways to restore the region’s populations of sawfish, a globally endangered shark-like ray characterized by a long, toothed snout. Their study is published in the journal Fish and Fisheries.

“The loss of marine species, even charismatic ones such as sawfish, can go unnoticed,” said study co-author Fiorenza Micheli, the David and Lucile Packard Professor of Marine Science and a senior fellow at the Stanford Woods Institute. “This observation suggests that many more marine populations may have disappeared without us noticing and doing something about it.”

For decades, scientists had assumed the Mediterranean Sea was too cold for sawfish and that any catches were only migrating through. But by using statistics, historical documents, images and even museum specimens, scientists were able to fill in the blanks and find evidence of sawfish living in the Mediterranean.

This finding opens the possibility for sawfish restoration in new areas, well outside the places where sawfish were thought to occur. It also shows that historical records might improve our understanding of the pre-exploitation baselines of other species. This could inform conservation by, for example, suggesting appropriate restoration targets for large marine predators.

“There is a huge amount of ecological information waiting to be extracted and interpreted from other kinds of historical records,” said lead author Francesco Ferretti, a postdoctoral scholar in biology at Stanford University’s Hopkins Marine Station. “Equipped with computer science and statistical tools, expertise in history, forensic tools and lots of ecological questions we are now at the gate of the next frontier of marine biology and ecology: traveling back in time to understand the true ecology of marine ecosystems.”

The research, which also involved scientists from Spain, France and Croatia, was supported by the Lenfest Ocean Program.

Backgroud on Sawfish
Sawfish are the largest of the rays, reaching over seven meters in length. Once found in the coastal waters and rivers of more than 90 tropical and subtropical countries, all five species are today classified as Endangered or Critically Endangered on the IUCN Red List TM. Mortality from targeted and incidental fishing is the main threat to sawfish. Their rostra – which they use to detect and wound prey are easily entangled in many types of fishing gear, particularly trawls and gillnets. The destruction of key habitats, such as mangroves, also poses a threat to sawfish survival.