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Smalltooth Sawfish and Climate Change: Impacts of Habitat Loss on Range and Distribution

July 18, 2023

Unpredictable weather patterns, warming ocean temperatures, and rising sea levels caused by climate change reduce available habitat for the endangered smalltooth sawfish.

smalltooth sawfish swimming under the water
Smalltooth sawfish get their name from their distinct rostrum—a long, flat snout edged with teeth—which they use to slash through schools of fish, swinging it from side to side to impale and stun prey. Their rostra also contain electro-sensitive organs, which help sawfish identify when prey is nearby. Credit: NOAA Fisheries

Smalltooth sawfish are an endangered species found in the Southeastern United States, primarily in the Florida Everglades. Like sharks and rays, their skeletons are made of flexible tissue called cartilage instead of bone. Smalltooth sawfish are anadromous, meaning they spend portions of their lives in both freshwater and saltwater habitats. 

The main threats to smalltooth sawfish include habitat loss due to coastal development and death due to direct and accidental capture in fisheries. In response to these threats, this species was listed under the Endangered Species Act in 2003. Climate-related impacts such as warming ocean temperatures, rising sea levels, unpredictable storms, and more severe flood and drought cycles pose significant threats to the smalltooth sawfish (especially juveniles) because of their effects on preferred sawfish habitat.

In 2023, NOAA Fisheries celebrates the 50th anniversary of the Endangered Species Act. Since it was enacted, no listed marine or anadromous species have gone extinct. However, as climate change intensifies, the recovery of endangered species, like the smalltooth sawfish, may become

more challenging. Through climate-focused research and management, NOAA Fisheries aims to mitigate the potential impacts of climate change on endangered species to foster their continued recovery.

Climate-Related Impacts

The greatest potential for climate-related impacts to sawfish lies in changes to their habitat. Sawfish rely on coastal nursery habitats where the salinity varies, such as red mangrove shorelines and shallow flats. Early juvenile sawfish remain inshore for their first 2 years, maturing in shallow rivers, bays, and lagoons. Once they reach roughly 7 feet in length, the juveniles move out of shallow estuaries into other coastal habitats. Sawfish give birth to relatively few young, reach maturity late, and exhibit moderate rates of population growth. All of these traits may make it difficult for sawfish to adapt to rapidly shifting habitat conditions. 

 

Red mangroves with prop roots.
Red mangroves with prop roots. Credit: NOAA Fisheries

Salinity 

Smalltooth sawfish require specific salinities (i.e., concentrations of salt dissolved in seawater) to maintain proper fluid levels in their bodies. Climate change-related weather shifts in the southeastern United States, like extreme storm events, flooding, and drought, can lead to variable inputs of freshwater into their coastal habitats. These events can alter saline concentrations in those areas. As a result, juvenile sawfish may have to travel farther up or down rivers to meet their salinity requirements. This shift could put younger sawfish, which tend to remain in shallow protected waters, at greater risk for predation as they leave safe nursery areas in search of suitable conditions. Alternatively, young sawfish may choose to stay in preferred nursery sites and cope with the modified salinity, which could affect an individual's health.

Sea Level Rise

Red mangrove shorelines and shallow brackish waters are essential nursery areas for smalltooth sawfish. As sea levels rise, shallow water habitats disappear, particularly in areas where coastal development and armored shorelines prevent inland migration. Established mangrove forests may also struggle to adapt to water levels that are rising faster than they can repopulate on higher ground, particularly in developed areas. Larger, more imminent threats include increasingly frequent, intense storms that uproot or damage plants, and deforestation for development or aquaculture purposes. Loss of safe shallow water and mangrove habitats could make sawfish populations more vulnerable to predators and decrease the availability of prey that also rely on mangrove habitats. 

Increasing Water Temperatures

Sawfish require specific water temperatures. Increasing ocean temperatures could result in northward range expansion for smalltooth sawfish as they seek more suitable waters. Reports and detections of juvenile sawfish in areas north of the species’ core range, such as Tampa Bay, Florida, have increased recently. Ongoing monitoring of sawfish distribution is crucial to determine whether this northward movement will continue. 

a combined photo of sawfish and fishing vessel
Despite ESA protection, smalltooth sawfish are often captured as bycatch in nets and lines from commercial fisheries, especially shrimp trawl fisheries. NOAA Fisheries has presented safe handling and release procedures to mitigate the threat of bycatch incidents. Credit: NOAA Fisheries

Recovery Efforts

Since NOAA Fisheries designated the smalltooth sawfish as an endangered species in 2003, its population decline has slowed, and researchers are beginning to see positive signs in the population. The recovery effort continues to progress as research reveals more information about this species’ needs and responses to climate change. With our partners, we have taken a series of steps to advance climate-focused science and management.

Critical Habitat

We have designated more than 3,000 square kilometers of critical habitat for juvenile smalltooth sawfish in two broad areas in southwest Florida. In 2009, NOAA Fisheries identified nursery habitats essential to the conservation of smalltooth sawfish. These habitats included areas adjacent to red mangroves and shallow brackish habitats with water depths of less than about 3 feet. 

Education and Outreach Efforts

Our education and outreach efforts have included:

  • Participating in International Sawfish Day to celebrate this species and share conservation messages
  • Hosting an annual gathering of sawfish experts to assess new data, and, in 2023, releasing a documentary about regional sawfish research
  • Evaluating the success of ongoing conservation efforts
  • Conducting field work to further understand climate-related distribution shifts  

Online resources and reporting hotlines are available with further information about sawfish and their recovery. 

New Technology Program

We launched the Advanced Sampling and Technology for Extinction Risk Reduction and Recovery (ASTER3) program. It was established to prevent extinction and promote recovery of protected species through transformational technological advances including satellite tagging, artificial intelligence, statistical models, and biomolecular sampling.

Climate, Ecosystem, and Fisheries Initiative

NOAA’s Climate, Ecosystem, and Fisheries Initiative builds ocean models and provides climate-relevant information that supports decision makers, including those who manage protected species and habitats, as they prepare for and respond to changing conditions.

These activities improve our understanding of climate change impacts on smalltooth sawfish and their habitats. We use this world-class science and data in our climate-informed actions to enhance species’ adaptations and resilience to changing conditions in the next 50-plus years under the Endangered Species Act.

You Can Save Sawfish

You can help save endangered sawfish. Protecting and recovering sawfish populations in the southeastern United States is a team effort. Do your part by minimizing bycatch and protecting their important habitats. 

  • If a sawfish is caught or becomes entangled in your fishing gear, use safe handling and release guidelines to safely release incidentally captured sawfish or other protected species 
  • Protect coral reefs, seagrass beds, and mangrove forests by fishing smart in these essential fish habitats. These ecosystems are extremely valuable to fish and our coastlines, and you can help keep them safe by using safe fishing practices. 
  • Report sawfish sightings to (844) 4SAWFISH or sawfish@MyFWC.com, including the date and time of the encounter, the location, the estimated length of each sawfish, the water depth, and any other relevant details

 

Last updated by Office of Protected Resources on July 19, 2023