Results 191 to 200 of about 4,677 (222)

Assessing prey fish populations in Lake Michigan: comparison of simultaneous acoustic-midwater trawling with bottom trawling

Fisheries Research, 1997
Abstract The Lake Michigan fish community has been monitored since the 1960s with bottom trawls, and since the late 1980s with acoustics and midwater trawls. These sampling tools are limited to different habitats: bottom trawls sample fish near bottom in areas with smooth substrates, and acoustic methods sample fish throughout the water column above ...
Mary C. Fabrizio, Jean V. Adams, Gary L. Curtis   +2 more
openaire   +1 more source

A new midwater trawl for sampling discrete depth horizons

Journal of the Marine Biological Association of the United Kingdom, 1969
A new midwater trawl based on that designed by Tucker (1951) is described with details of opening and closing equipment, acoustic release gear and depth telemetering pinger. An account is given of the method used in operating the xtrawl from R.R.S. ‘Discovery’.
openaire   +1 more source

Depth control of a midwater trawl gear using fuzzy logic

Fisheries Research, 1995
Abstract This paper describes the model of a simplified trawl system and the design of a control system that uses a fuzzy algorithm in controlling the depth of a midwater trawl net. The practicality of the control system was examined using computer simulation.
openaire   +1 more source

Examining influences of environmental, trawl gear, and fish population factors on midwater trawl performance using acoustic methods

Fisheries Research, 2015
Abstract The performance of midwater trawls used during acoustic surveys for walleye pollock (Gadus chalcogrammus) was estimated using a novel method of combining acoustic and catch information. Direct comparisons of acoustic and catch derived density showed a poor correlation between the two (r2 = 0.07), suggesting this discrepancy might be in part ...
Kresimir Williams, John K. Horne, André E. Punt   +2 more
openaire   +1 more source

Stepped-Oblique Midwater Trawling as an Assessment Technique for Rainbow Smelt

North American Journal of Fisheries Management, 1991
Abstract Discrete-depth midwater trawling for rainbow smelt Osmerus mordax at night in Lake Champlain revealed a delayed vertical migration of smaller fish and size partitioning vertically within the water column. These behavioral observations led to the development and evaluation of a nighttime stepped-oblique midwater trawling technique.
Richard A. Kirn, George W. Labar
openaire   +1 more source

Behaviour of Herring Schools in Response to a Midwater Trawl

Journal of the Fisheries Research Board of Canada, 1968
not available
openaire   +1 more source

Fish behaviour in response to a midwater trawl footrope in temperate reservoirs

Fisheries Research, 2015
Abstract This study addresses fish behaviour at the mouth of a midwater trawl in two temperate reservoirs. Fish distribution and behaviour were monitored using a SIMRAD EK60 (38 kHz) split-beam echosounder with the transducer deployed at the water surface, attached to the surface trawl headrope.
Z. Sajdlová, V. Draštík, T. Jůza, M. Říha, J. Frouzová, M. Čech, M. Vašek, M. Muška, P. Blabolil, M. Tušer, M. Kratochvíl, J. Peterka, T. Mrkvička, H. Balk, J. Kubečka   +14 more
openaire   +1 more source

Characterization of River Herring Bycatch in the Northwest Atlantic Midwater Trawl Fisheries

North American Journal of Fisheries Management, 2014
Abstract In the U.S. northwest Atlantic, the incidental catch of river herring (Alewife Alosa pseudoharengus and Blueback Herring A. aestivalis) by midwater trawl vessels targeting Atlantic Herring Clupea harengus and Atlantic Mackerel Scomber scombrus has become a concern for river herring conservation.
N. David Bethoney, Kevin D. E. Stokesbury, Bradley P. Schondelmeier, William S. Hoffman, Michael P. Armstrong   +4 more
openaire   +1 more source

A Simple Surface-Midwater Trawl

The Progressive Fish-Culturist, 1968
Charles R. Gasaway, Victor W. Lambou
openaire   +1 more source

Trawl impacts on the relative status of biotic communities of seabed sedimentary habitats in 24 regions worldwide

Proceedings of the National Academy of Sciences of the United States of America, 2022
C Roland Pitcher, Jan G Hiddink, Simon Jennings   +2 more
exaly