Historical perspective of artisanal encircling gillnet use at the Brazilian coast: Changes in fishing behaviour is mirrored by dwindling stocks

Abstract

Managing coastal resources sometimes requires looking into the past, as this provides a baseline against which present conditions may be gauged. The present study evaluated the circumstances that led Brazilian coastal fishers to modify their use of encircling gillnets. Other stressors (i.e. water pollution and habitat degradation) acted synergistically on the fisheries dynamic between 1950 and 2016. Declining catches of several species were observed through fishers' historical perception and through fisheries landing records. Three notable trends in net handling were associated with distinct historical periods. Specifically, pressures from modern fishery practices and gear (e.g. monofilament nets), the adoption of spiral setting arrangements and the increasing use of trammel nets appear responsible for the decline of many stocks. Mullet, seabass, jack and pilchard stocks decreased over time and were associated the changes witnessed in the encircling net operations. These changes occurred in response to overexploitation of fish stocks, to exploit the dwindling fisheries resources. The study also discusses the reasons leading fishers to accept how encircling gillnets ought to be used, their interpretation of such changes and the implications these changes have for fisheries management.

Fisheries Volume 47 Number 2 February 2022

“…This technology also offers potential for high data gathering performance in remote areas once fi shing can be monitored live, helping managers track the number and type of activities occurring in specifi c areas and thereby understand the ecological effects of fi shing in real time. Combined with limited catch data, a common scenario in developing countries (Reis-Filho 2020 ;Reis-Filho et al 2021 ), UAV survey data can be used to develop nonintrusive stock assessment techniques (Harris et al 2019 ), as well as help to understand the fi shery pressures that impact these stocks (Figure 4 ). These data can be used to establish time-series fi shery databases to estimate stock density, fi shery efforts, and in some cases, sizeclass information by correlating fi shing effort with yields.…”

Perspectives on the Use of Unmanned Aerial Vehicle Systems as Tools for Small‐Scale Fisheries Research and Management

“…The development of more user‐friendly aerial photogrammetry software (e.g., DroneDeploy) with more compatible interfaces has popularized these systems and the application of these devices in environmental studies. Autorecognition software also improves UAV post‐processing efficacy (Seymour et al 2017), with applications for abundance counts of fixed fishing devices (e.g., tidal fish weirs), shellfish gatherers in intertidal landscapes, and estimates of the area swept by surface gill nets and encircling nets (Reis‐Filho 2020). This type of software is also useful for creating image mosaics for fine‐scale analysis, such as estimates of the area exploited by the shellfish gatherers (Table 1; Figure S3) and video recordings of transects.…”

“…This technology also offers potential for high data gathering performance in remote areas once fishing can be monitored live, helping managers track the number and type of activities occurring in specific areas and thereby understand the ecological effects of fishing in real time. Combined with limited catch data, a common scenario in developing countries (Reis‐Filho 2020; Reis‐Filho et al 2021), UAV survey data can be used to develop nonintrusive stock assessment techniques (Harris et al 2019), as well as help to understand the fishery pressures that impact these stocks (Figure 4). These data can be used to establish time–series fishery databases to estimate stock density, fishery efforts, and in some cases, size–class information by correlating fishing effort with yields.…”