Sascha M. M. Fässler
Wageningen University and Research Centre
Target strengthEcho soundingFisheryPelagic zoneBiology
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Publications 37
#1Martin J. Baptist (WUR: Wageningen University and Research Centre)H-Index: 12
#2Rob van Bemmelen (WUR: Wageningen University and Research Centre)H-Index: 3
Last. S.C.V. Geelhoed (WUR: Wageningen University and Research Centre)H-Index: 3
view all 8 authors...
The Lesser Black-backed Gull, Larus fuscus Linnaeus, 1758, is a surface feeder with a broad prey spectrum that forages in the North Sea on subsurface pelagic fishes and crabs swimming within 0.6 m of the sea surface. In July 2006 and in July/August 2009, we surveyed the Frisian Front area in the southern North Sea (53.4°N–54.3°N, 4.0°E–5.5°E) to determine the prey base for Lesser Black-backed Gulls. In July/August 2009, we conducted bird counts in an integrated ecosystem survey by simultaneously...
#1Gavin J. MacaulayH-Index: 13
#2Ben Scoulding (CSIRO: Commonwealth Scientific and Industrial Research Organisation)H-Index: 4
Last. Sascha M. M. FässlerH-Index: 8
view all 4 authors...
A time-series of acoustically derived aquatic biomass estimates relies on the acoustic equipment maintaining the same performance throughout the time-series. This is normally achieved through a regular calibration process. When the acoustic equipment changes it is necessary to verify that the new equipment produces a similar result to the old equipment, otherwise an unknown bias can be introduced into the time-series. The commonly used Simrad EK60 echosounder has been superseded by the Simrad EK...
2 CitationsSource
#1Mark R. Payne (DTU: Technical University of Denmark)H-Index: 21
#2Alistair J. Hobday (Hobart Corporation)H-Index: 52
Last. Ernesto VillarinoH-Index: 6
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Recent years have seen a rapid expansion in the ability of earth system models to describe and predict the physical state of the ocean. Skilful forecasts ranging from seasonal (3 months) to decadal (5-10 years) time scales are now a reality. With the advance of these forecasts of ocean physics, the first generation of marine ecological forecasts has started to emerge. Such forecasts are potentially of great value in the management of living marine resources and for all of those who are dependent...
22 CitationsSource
The landing obligation for pelagic fisheries was introduced in January 2015 by the European Commission and will gradually be extended to all fisheries in 2019. This regulation follows the trend for sustainable fisheries in Europe and states that all catches must be landed and counted against the quotas. Pre-catch acoustic fish classification can remotely provide information about fish school composition in terms of species and size distribution. This technique has been tested using three commerc...
#1Ben Scoulding (Hobart Corporation)H-Index: 4
#2Sven Gastauer (Curtin University)H-Index: 4
Last. Paul G. Fernandes (Aberd.: University of Aberdeen)H-Index: 23
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Atlantic mackerel Scomber scombrus is a small pelagic, migratory fish which supports commercial fisheries. These fish school and are detectable using echosounders, yet fishery-independent estimates of their abundance in the North East Atlantic do not consider acoustic data. Accurate estimates of mean target strength (TS) are presently limiting echo-integration surveys from providing useful estimates of Atlantic mackerel abundance and distribution. This study provides TS estimates for in situ mac...
4 CitationsSource
#1Sven Gastauer (Curtin University)H-Index: 4
Last. Ben ScouldingH-Index: 4
view all 13 authors...
Abstract Northern blue whiting is a small abundant pelagic gadoid that is widely distributed in the northeast Atlantic and one of the most commercially valuable species west of the British Isles and Ireland. Over the last two decades the northeast Atlantic stock has undergone dramatic changes in abundance. The stock size decreased dramatically from 2007 to 2011, but has since shown signs of recovery. Changes in recruitment levels have occurred almost simultaneously with unusual changes in the no...
6 CitationsSource
Atlantic mackerel is a small pelagic, migratory fish which supports valuable commercial fisheries. Despite the fact that these fish school in massive numbers, and are readily detected using echosounders, fishery-independent estimates of the abundance of mackerel in the Northeast Atlantic do not yet consider acoustic data. Echo-integration surveys could provide annual estimates of abundance, with additional scope for studying mackerel distributions throughout the year. However, as in all acoustic...
2 CitationsSource
Fish target strength is primarily dependent on the physical dimensions of the fish, the acoustic frequency, and the orientation of the fish. In traditional vertically observing echosounder surveys, fish are insonified in the dorsal aspect with fairly limited tilt angle variation. In oblique-angled sonar surveys, however, fish may be insonified at other aspects. For herring, target strength is also depth dependent as they cannot refill the swimbladder at depth. Understanding the depth dependent t...
#1Sven Gastauer (Curtin University)H-Index: 4
#2Ben ScouldingH-Index: 4
Last. Miles Parsons (Curtin University)H-Index: 8
view all 5 authors...
Red emperor (Lutjanus sebae) is a long-lived tropical demersal snapper which is widely distributed in the Western Pacific and Indian Ocean. Despite the commercial and recreational importance of the species for the Northern Demersal Scalefish Fishery off the Northwest coast of Western Australia, we still lack a thorough understanding of its distribution and abundance in the area. To better understand the acoustic scattering properties of red emperor its acoustic backscattering characteristics wer...
2 CitationsSource