Results 161 to 170 of about 2,878 (177)

Avoidance and escape behaviour by herring encountering midwater trawls

Fisheries Research, 1997
The main objective of this study was to assess how and to what extent Baltic herring avoid and escape midwater trawls under commercial fishing conditions. Information was obtained by acoustic, visual and direct sampling techniques. The majority of herring schools in the path of an approaching trawl were observed to enter the trawl.
Suuronen, Petri, Lehtonen, Esa, Wallace, John   +2 more
openaire   +1 more source

A new electronic system for the rectangular midwater trawl (RMT)

Marine Biology, 1990
This paper describes a modified modern version of the original rectangular midwater trawl (RMT) manufactured by the Institute of Oceanographic Sciences (IOS). The shipboard acoustic transducer and the underwater RMT-monitor were replaced by an electronic interface box was while the data transfer, realized by a single-conductor cable.
W. Dimmler, H. Klindt
openaire   +1 more source

Quantification of water flow and net drag in midwater trawls

Fisheries Research, 1993
Abstract The flow velocity and hydrodynamic drag of 18 quarter-scale midwater box trawl nets were quantified in a circulating water channel using electromagnetic current meters and strain gauges, with the mouth of each net attached to a rigid pipe frame to maintain geometric similarity.
Buxton, N. G., DeAlteris, J. T.
openaire   +2 more sources

Development of a low-energy midwater trawl with different combinations of trawl nets and trawl doors through model experiments

Fisheries Science, 2018
Greenhouse gas (GHG) emissions from fisheries are of primary concern because of their effects on the environment. GHG emissions from fisheries are mainly related to their fuel consumption. Furthermore, the fuel consumption of fisheries also influences their economics. Therefore, many studies have been conducted to find ways of reducing fuel consumption
Jihoon Lee, Chun-Woo Lee, Songho Park, Jieun Kim, Subong Park, Taeho Kim   +5 more
openaire   +1 more source

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