Abstract
Monitoring the use of anchored fish aggregating devices (AFADs) is essential for effective fisheries management. However, detecting the use of these devices is a significant challenge for fisheries management in Indonesia. These devices are continually deployed at large scales, due to large numbers of users and high failure rates, increasing the difficulty of monitoring AFADs. To address this challenge, tracking devices were attached to 34 handline fishing vessels in Indonesia over a month period each. Given there are an estimated 10,000–50,000 unlicensed AFADs in operation, Indonesian fishing grounds provided an ideal case study location to evaluate whether we could apply spatial modeling approaches to detect AFAD usage and fish catch success. We performed a spatial cluster analysis on tracking data to identify fishing grounds and determine whether AFADs were in use. Interviews with fishers were undertaken to validate these findings. We detected 139 possible AFADs, of which 72 were positively classified as AFADs. Our approach enabled us to estimate AFAD use and sharing by vessels, predict catches, and infer AFAD lifetimes. Key implications from our study include the potential to estimate AFAD densities and deployment rates, and thus compliance with Indonesia regulations, based on vessel tracking data.
Highlights
Since their widespread introduction in the early 1980s, artisanal fisheries have relied on Anchored Fish Aggregative Devices (AFADs) as a fishing aid to increase catch rates[1,2]
We explore the use of inexpensive tracking devices to answer three key questions about anchored fish aggregating devices (AFADs) use by hand line small-scale vessels: (1) can we use tracking data on small-scale vessels to estimate AFAD locations and use patterns; (2) can this information be used to predict the relationship between the number of vessels and the number of AFADs, given complexities such as AFAD sharing; and (3) is it possible to infer catches of vessels based on their use of AFADs and other characteristics of their trips?
Under collaboration with a non-governmental organization (NGO) Masyarakat Dan Perikanan Indonesia (MDPI), SPOT Trace devices were voluntarily attached to 34 different hand line fishing vessels in three different provinces in Indonesia: West Nusa Tenggara (N. 15), East Nusa Tenggara (N. 11) and South of Celebes (N. 8)
Summary
Since their widespread introduction in the early 1980s, artisanal fisheries have relied on Anchored Fish Aggregative Devices (AFADs) as a fishing aid to increase catch rates[1,2]. In most countries and regional fisheries management organisations (RFMOs), the management of AFADs to date has focused on preventive actions such as temporal closures, regulations of gear types, and licence regimes[11,12] These actions rely heavily on the compliance of fishers and do not address illegal d eployments[13,14]. Identifying lower-cost solutions to monitor AFAD use is of relevance, in small-scale fisheries Vessel tracking technologies, such as vessel monitoring system (VMS) transponders, are commonly used to monitor fishing activity and compliance around the world[19,20] and have been suggested as an approach to infer FAD use[21]. VMS is currently utilised solely on larger vessels (e.g. > 30 gross tonnes in Indonesia) and such mandatory systems have generally not been required on small fishing vessels to date
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