The main objective of this study is to provide,for the first time,fisheries-dependent,spatially explicit information on the activity for the black scabbard fish(Aphanopus carbo)longline fleet operating off the Portugu...The main objective of this study is to provide,for the first time,fisheries-dependent,spatially explicit information on the activity for the black scabbard fish(Aphanopus carbo)longline fleet operating off the Portuguese coast.Fisheries monitoring data were analysed,covering the period 2014–2016,aiming at identifying deep-sea fishing grounds,gaining a better understanding of the fleet spatial dynamics,quantifying fishing effort and providing information on the species distribution and abundance.E-logbooks were used to define general patterns of fishing activity,while the combined analysis of Vessel Monitoring System(VMS)and Automatic Identification System(AIS)data allowed to spatially identify fishing trips and define haul-back trajectories corresponding to fishing events.A total of 19 vessels were found to be involved in this fishery,mainly operating at depths from 1000 to 1500 m,landing the black scabbard fish in two main ports located in the centre and three secondary ports in the northern region.Fishing effort and catch per unit of effort(CPUE)were estimated and mapped for the period in study and the geographic extension of the fishery in the Portuguese continental slope was highlighted.Vessels keep their activity spatially restricted,in a clear strategy to avoid competition;their areas of activity are contiguous and generally related to the closest port.Some recommendations are drawn in support of a continuous monitoring programme for this fishery.展开更多
Underwater imaging is being used increasingly by marine biologists as a means to assess the abundance of marine resources and their biodiversity. Previously, we developed the first automatic approach for estimating th...Underwater imaging is being used increasingly by marine biologists as a means to assess the abundance of marine resources and their biodiversity. Previously, we developed the first automatic approach for estimating the abundance of Norway lobsters and counting their burrows in video sequences captured using a monochrome camera mounted on trawling gear. In this paper, an alternative framework is proposed and tested using deep-water video sequences acquired via a remotely operated vehicle. The proposed framework consists of four modules:(1) preprocessing,(2) object detection and classification,(3) object-tracking, and(4) quantification. Encouraging results were obtained from available test videos for the automatic video-based abundance estimation in comparison with manual counts by human experts(ground truth). For the available test set, the proposed system achieved 100%precision and recall for lobster counting, and around 83% precision and recall for burrow detection.展开更多
文摘The main objective of this study is to provide,for the first time,fisheries-dependent,spatially explicit information on the activity for the black scabbard fish(Aphanopus carbo)longline fleet operating off the Portuguese coast.Fisheries monitoring data were analysed,covering the period 2014–2016,aiming at identifying deep-sea fishing grounds,gaining a better understanding of the fleet spatial dynamics,quantifying fishing effort and providing information on the species distribution and abundance.E-logbooks were used to define general patterns of fishing activity,while the combined analysis of Vessel Monitoring System(VMS)and Automatic Identification System(AIS)data allowed to spatially identify fishing trips and define haul-back trajectories corresponding to fishing events.A total of 19 vessels were found to be involved in this fishery,mainly operating at depths from 1000 to 1500 m,landing the black scabbard fish in two main ports located in the centre and three secondary ports in the northern region.Fishing effort and catch per unit of effort(CPUE)were estimated and mapped for the period in study and the geographic extension of the fishery in the Portuguese continental slope was highlighted.Vessels keep their activity spatially restricted,in a clear strategy to avoid competition;their areas of activity are contiguous and generally related to the closest port.Some recommendations are drawn in support of a continuous monitoring programme for this fishery.
基金Project supported by the UTAR Research Fund from the Universiti Tunku Abdul Rahman,Malaysia(No.IPSR/RMC/UTARRF/2013-C2/L03)
文摘Underwater imaging is being used increasingly by marine biologists as a means to assess the abundance of marine resources and their biodiversity. Previously, we developed the first automatic approach for estimating the abundance of Norway lobsters and counting their burrows in video sequences captured using a monochrome camera mounted on trawling gear. In this paper, an alternative framework is proposed and tested using deep-water video sequences acquired via a remotely operated vehicle. The proposed framework consists of four modules:(1) preprocessing,(2) object detection and classification,(3) object-tracking, and(4) quantification. Encouraging results were obtained from available test videos for the automatic video-based abundance estimation in comparison with manual counts by human experts(ground truth). For the available test set, the proposed system achieved 100%precision and recall for lobster counting, and around 83% precision and recall for burrow detection.
