The quest to understand and reclaim the lost world of the sawfish through science and conservation
Population Decline
Species Remain
Conservation Status
Imagine a creature from a prehistoric age, a "rhinoceros of the sea," swimming through the shallow, murky waters of a coastal estuary. Its most striking feature is a long, flat snout, edged with teeth like a saw—a weapon, a tool, and a sensory organ all in one.
This is the sawfish, a ray that once thrived in tropical coasts worldwide but is now among the most threatened marine fish families globally, with estimates suggesting only 10 percent of historic populations remain6 .
In the southwestern Atlantic, the memories of sawfish fisheries linger in the stories of fishers and in old landings data, tales of magnificent giants that are now critically endangered.
The erosion of knowledge about these creatures and their historical haunts poses a direct threat to their recovery. Today, scientists are not only relying on these memories but are also employing cutting-edge technology—from environmental DNA (eDNA) to satellite tags—to fill in the blanks, confirm the sawfish's presence in its former range, and guide its path back from the brink5 . This is the story of the quest to understand and reclaim the lost world of the sawfish.
Sawfish are often mistaken for sharks due to their body shape, but they are actually rays. Their gills and mouths are located on the underside of their bodies3 . They belong to a group of cartilaginous fish called elasmobranchs, which includes sharks, skates, and rays3 .
Their most extraordinary feature is their rostrum, or "saw." This elongated snout is lined with sharp, transverse teeth. The rostrum is a multi-purpose tool:
This incredible adaptation, however, is also their greatest vulnerability. The tooth-lined saw is easily entangled in fishing nets, which has been a primary driver of their dramatic decline4 .
Slashing through schools of fish to impale prey
Protection against predators
Detecting electrical fields of buried prey
Easily entangled in fishing gear
Sawfish inhabit shallow coastal waters, estuaries, and river systems in tropical and subtropical regions.
Some species can grow up to 7 meters (23 feet) in length, making them among the largest rays.
Sawfish have existed for over 50 million years, with fossils showing little change from modern species.
In the southwestern Atlantic, as in other parts of the world, sawfish populations have collapsed. The largetooth sawfish, one of the species found in this region, is now listed as Critically Endangered.
The decline can be attributed to two major threats:
Abundant populations in tropical and subtropical coastal waters worldwide.
Commercial fisheries begin targeting sawfish for their meat, fins, and rostra.
Industrial fishing expansion leads to significant population declines.
Many populations reduced to less than 10% of historical numbers.
All species listed as Endangered or Critically Endangered; conservation efforts intensify.
| Fishing Gear Type | Nature of Interaction | Typical Outcome for Sawfish |
|---|---|---|
| Gillnets | Rostrum becomes entangled in mesh | Injury, drowning, or death if not released |
| Shrimp Trawls | Captured while foraging on bottom | Injury or death as bycatch |
| Bottom Longlines | Mouth or body hooked on baited hooks | Injury, often fatal if not released properly |
| Recreational Hook-and-Line | Accidentally hooked by anglers | Potential for safe release if handled correctly |
To recover a species, scientists must first understand it. Research on elusive and endangered sawfish relies on a sophisticated array of tools and methods.
Transmit signals to stationary underwater receivers to monitor long-term movement and habitat use within a specific area2 .
Transmit location data to satellites when at the surface; record depth, temperature to track large-scale migrations2 .
Detects genetic material shed into the water from skin cells or waste to confirm species' presence5 .
Uses DNA sequencing to identify parent-offspring and sibling relationships to estimate population abundance6 .
Uses computer models to correlate sawfish sightings with environmental data to predict potential habitats1 .
Uses underwater cameras with bait to document sawfish presence and behavior in specific locations.
One of the most promising tools for finding sawfish in the vast and murky estuaries they inhabit is the use of environmental DNA (eDNA). A project led by researchers from the Florida Fish and Wildlife Conservation Commission and The University of Southern Mississippi provides a perfect case study of this innovative method in action5 .
The researchers focused on two estuaries in Florida: the Indian River Lagoon on the east coast and Tampa Bay on the west coast. These areas were once part of the sawfish's historical range but are now considered "non-core" areas, making them prime candidates for detecting range expansion5 .
| Estuary | Samples | Positive | Result |
|---|---|---|---|
| Indian River Lagoon | 60 | 5 | Confirmed Presence |
| Tampa Bay | 50 | 0 | No Detection |
The detection in Indian River Lagoon provides evidence that sawfish still occasionally use this historical estuary5 .
The results of this genetic detective work were telling:
The scientific importance of these results is profound. For conservation managers, the detection in the Indian River Lagoon provides a data-driven reason to prioritize that area for further research, such as traditional fishing surveys or tagging efforts. The lack of detection in Tampa Bay is equally valuable, helping to steer limited conservation resources more effectively.
| Estuary | Historical Significance | Number of Water Samples | eDNA Positive Samples | Scientific Implication |
|---|---|---|---|---|
| Indian River Lagoon | Once a thriving nursery5 | 60 | 5 | Confirms occasional presence; prioritizes area for future monitoring. |
| Tampa Bay | Northern limit of core range5 | 50 | 0 | Suggests population is very sparse; guides resource allocation. |
Similar eDNA techniques are now being applied in other critical regions, such as the Amazonian coast of Brazil, which is considered a potential last stronghold for the largetooth sawfish. There, researchers led by Patricia Charvet and Vincente Faria are using eDNA to confirm the species' presence in the sandbanks, mangroves, and murky waters influenced by the Amazon River.
The memories of past sawfish abundance and the new data gathered by scientists are now being translated into concrete conservation actions.
In Brazil, projects are actively working to engage with fishing communities, increase public awareness, and train law enforcement officers to combat the illegal trade in sawfish parts.
Because accidental capture by fishers remains a threat, agencies like NOAA Fisheries have developed and promoted safe handling and release guidelines to increase survival rates3 .
The story of the sawfish is a powerful reminder of humanity's impact on the ocean and its capacity for both loss and recovery.
The "memories" of sawfish fisheries are not just echoes of a vanished past; they are a call to action. By combining traditional knowledge with revolutionary technologies—from genetic sleuthing that finds ghosts in the water to satellite tags that map highways in the sea—we are learning how to listen to that call.
The journey to restore the sawfish is far from over, but it is underway. The same estuaries that once supported vibrant fisheries can become thriving nurseries again. With continued research, dedicated habitat protection, and the help of coastal communities and fishers, the giant with a saw for a face may once again become a common sight in the memories of the next generation.