## 1 Introduction  
Almost 37% of the global population depends on fish and fish products for their protein intake [1]. Global warming and exponential population growth have largely reduced the food supply from marine environments, and there are concerns about the sustainability of proteins obtained from these marine environments. According to FAO [2], the fishing industry has faced various challenges such as fish stock preservation from overfishing and biodiversity loss and financial sustainability management from profit reduction due to depletion of fish resources. Illegal, unreported, and unregulated (IUU)fishing and overfishing are severe threats to the sustainability of marine ecosystems and fish stock preservation [3; 4; 5]. IUU fishing may cause fishing stock collapse and is not economically viable. Two important IUU fishing types are fishing in areas that have been designated as no-fishing water areas and fishing with unpermitted fishing gears. It is relatively easy for fishery monitoring officers to determine whether a fishing ship is fishing in a no-fishing water area based on its location and speed [6]. In Korea, each fishing ship has its fishing gear license, which is officially registered into the Korean Fishing Ship Register Database [7]. It is illegal for a fishing ship to use some unlicensed fishing gears. Even though a fishery monitoring officer knows the location, speed, and course of a fishing ship in real-time, it is difficult to identify the type of fishing gear being used because fishing ships with a specific type of fishing gear may show many variations in movement trajectories and such identification requires examination of a long trajectory over upwards of 24 h. Hence it is crucial to identify the types of fishing gear used on fishing ships from the available monitoring data for the prevention of IUU fishing. Fishing gear type identification allows to estimate fishing type and fish catch and further helps to detect IUU fishing. Hence such activities are valuable for preserving marine resources and preventing from overfishing. A computerized automatic fishing type identification system with the fishing ship register database can monitor fishing activities in the surveillance regions and detect IUU fishing activities with no risks of collusion between fishers and inspectors [8; 9]. Fishing ships are usually equipped with a VMS (vessel monitoring system)-based communication device, which sends voice and digital messages through a satellite or MF/HF communication channel [10]. As in European countries, Korea has established VHF-DSC and satellite-based VMS system for fishery monitoring in accordance with the FAO guideline for IUU prevention. A VMS device automatically sends status data such as location, speed, and course to fishery monitoring agencies at long intervals such as 1 h or 2 h [11; 12]. There has been some work focused on using VMS data for the identification of fishing activities such as fishing/non-fishing or setting/hauling/others [13; 14; 15; 16; 17; 18]. It is, however, inappropriate to use VMS data for fishing gear type identification because the sparsely available data on ship movement does not provide sufficient information. In accordance with the IMO's (International Maritime Organization) regulations for navigation safety, it is mandatory for fishing ships of minimum length 10 m to be equipped with an AIS (automatic identification system) device which broadcasts messages about location and course at intervals of 2 to 12 s. Most countries including Korea enforce fishing ships to be equipped with AIS devices. Such fine-resolution AIS messages contain information for recovering accurate ship trajectories. Hence AIS data are more advantageous than VMS data for fishing gear-type identification. On the other hand, the movements of fish schools are affected by environmental factors such as water temperature, pH, dissolved oxygen, and food availability (like micro-plankton). Such environmental data are helpful for fishing gear-type identification of fishing ships.