Critical habitats for smalltooth sawfish
The barriers to the successful recovery of smalltooth sawfish are formidable, and some say it would take a century. But Ashley is hopeful that more can be done to ensure that we hasten these Critically Endangered rays towards recovery. Using the information from over 500 acoustic receivers and more than 50 adult and large juvenile smalltooth sawfish tagged by the Grubbs Lab since 2016, Ashley will look out for mating areas for this species in the USA. Identifying critical-use areas forms a key part of the recovery plan that can set sawfish populations on a positive trajectory.
Ashley Mackenzie Dawdy
In 2005, the Georgia Aquarium opened in downtown Atlanta near where I was growing up and I convinced my parents to get us an annual pass. I soon became enamoured of this underwater world I had never seen before, including the diverse array of behaviours of the animals I could now observe. Before starting my undergraduate course, I volunteered at the aquarium at every opportunity. I would spend hours talking to guests about what was happening in the tanks or what these species’ lives are like in the wild, which gradually turns into what we can do as...
Social movement behavior of the critically endangered smalltooth sawfish (Pristis pectinata) in Florida, USA
The primary objective of this project is to define critical habitat, including potential mating areas, for large juvenile and adult smalltooth sawfish in the USA. This is intended to have immediate use in species conservation action and decisions.
A crucial part of species conservation involves defining critical habitat, or important areas for various life stages. Critical habitat has been defined for juvenile smalltooth sawfish, but has yet to be determined for larger juveniles and adults, partly because the movement data for adults are more limited.
A limited geographical range, a conservative life history, a small active population size, heavy fishing pressure and the loss of critical habitat all contribute to the serious risk that the Critically Endangered smalltooth sawfish Pristis pectinata faces in its path to recovery, which is already slated to take a century. This sawfish became the first marine fish to be listed as Endangered under the United States Environmental Species Act in 2003, the result of a drastic population decline and subsequent range contraction. The species has since been listed as Critically Endangered by the IUCN. The decline in the smalltooth sawfish population was attributed primarily to bycatch in commercial fisheries, particularly in shrimp trawls. Other causes for decline include poaching to obtain rostra for shark fin soup or to be sold as curios, entanglement in marine pollution and loss of coastal mangrove habitats due to the urbanisation of coastlines.
Critical habitat has been defined for juvenile sawfish but not for large juveniles and adults. Driven by conservation needs, the primary goal of this project is to identify potential mating areas for adult smalltooth sawfish in the USA, as an urgent goal laid out in the species recovery plan is to define critical habitat for large sawfish. This will be accomplished firstly by assessing the social behaviour of tagged large sawfish, including which geographical locations and habitat types are most likely to yield interactions between mature males and females; and secondly by combining movement data and genetic data to determine years in which tracked females were reproductively active. This project will have immediate implications for conservation and management. The Grubbs lab and colleagues have internally tagged more than 80 large juveniles and adults since 2016 that have since been detected on over 500 acoustic receivers.
- To identify shifts in space and habitat use of smalltooth sawfish as individuals reach sexual maturity, in order to inform species management for targeted age or size classes.
- To provide insight into critical habitat designations for smalltooth sawfish by identifying potential mating areas, as well as areas with increased likelihood of social interactions between adult males and females or repeated use by sexually mature individuals during the mating season.
- To increase the sample size of an under-represented size class by targeting and acoustically tagging additional adult female smalltooth sawfish near Cape Canaveral, Florida.