Sex and Length as Predictors of Vertical Movements in Smalltooh Sawfish(Pristis pectinata)

Smalltooth sawfish (Pristis pectinata) are listed as ‘critically endangered’ species by the IUCN and listed as Endangered under the U.S. Endangered Species Act (ESA). Smalltooth sawfish are extremely vulnerable to being caught as bycatch due to their long, toothed rostrum that can easily become entangled in fishing nets, especially in shrimp trawling fisheries. Several studies have been conducted on smalltooth sawfish since being listed under the ESA in 2003, but their vertical movements and use of depth have still not been thoroughly studied. Until recently sawfish were thought to stay at a depth of 10 m or less, but studies have now shown that they occupy much deeper. Due to this, data on their depth use is limited and is the reason why depth was chosen to be the focus of this study. The purpose of this study was to assess whether sex or length has an influence over the percentage of time a sawfish spends at a particular depth. Satellite telemetry was used to track the movements of the tagged sawfish. The data collected from the pop-off satellite tags showed smalltooth sawfish spend most of their time in shallow water, but do frequently occupy deeper depths. Sex was found to be a significant factor, while length was not. Females were found to spend more time at deeper depths than males. Females frequently occurred at deeper depths while males mostly remained in shallow waters. Understanding how sawfish use depth is important in order to predict population processes and dynamics. Knowing the factors that affect a sawfish’s depth use would be beneficial to efforts to manage and conserve this species. With the decline of smalltooth sawfish and being vulnerable to population loss, more research needs to be conducted in order to create more effective management and recovery plans.