Separation of fish from Nephrops norvegicus into a two-tier cod-end using a selection grid

Graham, Norman; Fryer, R. J.

doi:10.1016/j.fishres.2006.08.011

Cited by 32 publications

(24 citation statements)

References 19 publications

(24 reference statements)

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“…Great efforts have been made to reduce the bycatch in these fisheries, especially of cod, haddock, and whiting. Experiments have been conducted using simple square mesh panels (Krag et al, 2008) as well as more advanced grid systems (Graham and Fryer, 2006;Valentinsson and Ulmestrand, 2008) to utilize spatial and temporal targeting to maximize catches of Nephrops while minimizing the bycatch of whitefish (Bell et al, 2008). Despite promising results, a relatively high bycatch of whitefish remains a problem in many Nephrops fisheries.…”

Section: Species Separationmentioning

confidence: 99%

A study of fish behaviour in the extension of a demersal trawl using a multi-compartment separator frame and SIT camera system

Krag¹,

Madsen²,

Karlsen³

2009

Fisheries Research

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Section: Species Separationmentioning

confidence: 99%

A study of fish behaviour in the extension of a demersal trawl using a multi-compartment separator frame and SIT camera system

Krag¹,

Madsen²,

Karlsen³

2009

Fisheries Research

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“…Fish separation was high but there was a loss of *20% of the legal-sized Nephrops catch. Similarly, Graham and Fryer (2006) trialled a two-tier codend with one grid to separate Nephrops from fish in the lower codend (bar spacing 25 and 30 mm). The level of separation was high for fish over >20 cm and for Nephrops with CL < 50 mm.…”

Section: Separator and Guiding Panelsmentioning

confidence: 99%

Gear technology in Nephrops trawl fisheries

Catchpole

Revill

2007

Rev Fish Biol Fisheries

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Nets with a small mesh size are required to catch Nephrops norvegicus, consequently large quantities of small whitefish are also caught, and much of this bycatch is undersized and is discarded dead. The main bycatch species are whiting (Merlangius merlangus), haddock (Melanogrammus aeglefinus) and cod (Gadus morhua). Here we summarize the known behavioural reactions of these species towards conventional trawls and review the results of using different trawl modifications to increase selectivity of Nephrops trawls. The trawl modifications are categorised as separator grids, separator and guiding panels, square-mesh panels, capture avoidance designs and codend modification. Finally, the extent to which these developments have been legislated for is discussed including the conditions under which new gear regulations have been introduced.Haddock and whiting rise during the trawling process facilitating their separation from Nephrops and escape, however the behaviour of small fish of these species is less consistent. Cod and Nephrops remain on bottom of the trawl, so to separate these species requires some physical filtering process. Overall, there is currently sufficient technical ability to improve selectivity in Nephrops trawls. The design of choice is dependent on the objectives of managers; for reducing discards but retaining marketable fish, square-mesh panels offer the most useful tool; to eliminate all bycatch and create a single-species fishery, grids and traditional Nephrops trawls show most potential. Whatever the objectives of the new measures, it is likely that a short-term economic impact will follow, and some form of incentive may be required to implement effective measures. A voluntary uptake of new measures by industry is preferable, however, to date, restrictions on fishing opportunities have been necessary to introduce innovative gear designs.

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“…For size selection of fish, two methodological approaches are used, one is to insert size selection devices in, or in front of the codend, such as square mesh panels (Armstrong et al, 1998;Briggs and Robertson, 1993) or rigid grids (Fonseca et al, 2005) to allow for escape of juvenile fish, while the other approach is to separate fish from Nephrops to retain the catches in separate codends with different mesh sizes (Graham and Fryer, 2006;Ingólfsson, 2009).…”

Section: Introductionmentioning

confidence: 99%

The effect of forced mesh opening in the upper panel of a Nephrops trawl on size selection of Nephrops, haddock and whiting

Ingólfsson

2011

Fisheries Research

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Separation of fish from Nephrops norvegicus into a two-tier cod-end using a selection grid

Cited by 32 publications

References 19 publications

A study of fish behaviour in the extension of a demersal trawl using a multi-compartment separator frame and SIT camera system

A study of fish behaviour in the extension of a demersal trawl using a multi-compartment separator frame and SIT camera system

Gear technology in Nephrops trawl fisheries

The effect of forced mesh opening in the upper panel of a Nephrops trawl on size selection of Nephrops, haddock and whiting

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