There was a recent question on the CTURTLE listerserv about recording movements of offshore fishers during bycatch studies. I have previously used the GR-312 USB GPS Receiver and Data Logger Dongle with the BB-100 Battery Bank from NaviSys at https://www.navisys.com.tw (Figure 1). Weighing <50g, the dongle and battery bank are not waterproof but can be protected within a capped PVC tube or other plastic sealed container and attached to the deck of fishing vessels. Provided they are in direct line of sight to the sky, the system will receive and log GPS signals at pre-programmed time intervals. Vessel speeds can be determined by the distance travelled between intervals’ signals and used to determine fishing activity levels. The NaviSys GR-312 (with BB-100 as standard) costs ~US$30, operates within normal temperatures experienced on a fishing vessel, and provides up to 24 hours of continuous working time to record latitude, longitude, velocity, date, and time. Longer recoding times can be achieved with an external battery pack like those used to recharge mobile phones and other electronic devices. Data upload can be wired (USB) or wireless (Bluetooth).

Two free PC/Windows management tools are provided: NaviLogManager allows the user to set a unique logging ID, logging interval, download data, and clear the memory, while NaviFilter retrieves data and generates reports for the preferred trip interval. Data can be integrated with Google Earth to generate tracking images.

Figure 1. GR-312 GPS Tracker (left) and BB-100 Battery Bank (right) from NaviSys