Several institutions conduct various research activities on the biology, distribution, and ecology of endangered smalltooth sawfish in the United States. These partners include state and federal governments, universities, nonprofits, museums, and international organizations. The results of these research projects are used to inform management decisions and enhance recovery efforts for this endangered species.
Collecting Sawfish Data
Researchers collect information about sawfish using a variety of methods: (1) sawfish captured during research field surveys for the species, (2) sawfish incidentally caught in federal fisheries, (3) sawfish carcasses, and (4) tissue samples collected from antique sawfish rostra (saws).
Research field surveys for smalltooth sawfish are the most important method for collecting data. A variety of survey methods are used to capture live sawfish for scientific purposes, including longline, rod-and-reel, and gillnets. Once captured, measurements and samples are taken from each sawfish prior to tagging and release. These surveys are instrumental in monitoring trends in the abundance of the population.
Fisheries observers aboard commercial fishing vessels are trained to measure, sample, and tag any sawfish incidentally captured in federally permitted fisheries. These chance opportunities provide valuable insight into the locations where fisheries overlap with sawfish and the condition of sawfish upon release.
Necropsies of sawfish that have died in the wild provide the opportunity to collect data necessary for understanding age, growth, maturity, and reproduction. Carcass recoveries provide valuable opportunities because this data is especially important and can only be collected through dissection, and researchers are currently not comfortable sacrificing any healthy individuals of this critically endangered species.
Sawfish rostra are considered unique “trophies” so many have been retained in both public and private collections and they can provide valuable DNA. To find sawfish rostra researchers scour online databases, ask the public about sawfish rostra they own or have seen, and contact curators at museums, educational centers, aquariums, universities, and other public institutions. (Note: These antique rostra were collected prior to sawfish being listed under the Endangered Species Act in 2003. Now all sawfish species are protected in the United States and the removal or sale of sawfish rostra is illegal.)
Small tissue samples are collected during field capture of live sawfish and from old rostra for genetic and stable isotope studies. Genetics are useful in understanding population structure, diversity within the population, and both the size and health of the current population in comparison to the historical one. Scientists are also using genetics to determine whether there is significant movement and genetic exchange between the U.S. and Bahamas populations of smalltooth sawfish. Stable isotopic analyses are run on tissue samples and compared to a variety of potential prey items in the environment to determine the diet and trophic position of smalltooth sawfish within the food web.
Blood samples are collected from sawfish to investigate reproductive status and stress physiology. Hormones within the blood are used to assess reproductive maturity and timing. Blood samples for stress physiology are being used to assess post-release mortality risk from a variety of fisheries and gears.
Scientists are using state-of-the-art technology to track the movements of smalltooth sawfish. This tracking involves capturing the animals, equipping them with acoustic transmitters, and releasing them. Depending on the objectives of the project, scientists may track them from a boat using hydrophones to determine short-term microhabitat use or set up a network of in-water receivers (acoustic listening stations) to track longer-term broad-scale movements. Acoustic transmitters can be active for up to 10 years.
Larger juvenile and adult sawfish caught during surveys are also often fitted with GPS satellite tags. Because far less is known about these larger animals, researchers hope that satellite tags can reveal important adult habitats, movements, and migrations. Satellite tagging studies to date have shown that larger sawfish spent a large portion of their time in shallow coastal waters with periodic excursions to deeper waters off the shelf edge.
Population Monitoring Through Encounter Reports
If you catch or see a sawfish take a quick photograph of the sawfish, estimate its size, note your location, and please share the details with scientists. The details of your sightings or catches of sawfish help to monitor the population and track the recovery progress. You can share your information by calling 1-844-4-SAWFISH (844-472-9347) or emailing firstname.lastname@example.org.
Did you know scientists can track the movements of endangered smalltooth sawfish for up to 10 years?
For more information about endangered sawfish call 1-844-4SAWFISH, or visit:
Tonya Wiley, President
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