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Size selective capture of Atlantic cod (Gadus morhua) in floating pots

Ovegard, M; Konigson, S.; Persson, Anders LU and Lunneryd, S. G. (2011) In Fisheries Research 107(1-3). p.239-244
Abstract
Little is known about the size selectivity of cod in static fishing gears such as pots and traps. In this field study, floating fishing pots were equipped with 40, 45 and 50 mm square mesh escape windows in order to estimate the size selectivity of cod at different mesh sizes. Relationships between selectivity parameters and mesh size, as well as an optimal mesh size for the escape window with respect to current minimum landing size of cod in the Baltic Sea were sought. The results show that the floating pot is not only species selective when used in the Baltic Sea cod fishery, the implementation of an escape window reduced the proportion of undersized bycatch in the pots by more than 90%. The estimated length at 50% retention was found to... (More)
Little is known about the size selectivity of cod in static fishing gears such as pots and traps. In this field study, floating fishing pots were equipped with 40, 45 and 50 mm square mesh escape windows in order to estimate the size selectivity of cod at different mesh sizes. Relationships between selectivity parameters and mesh size, as well as an optimal mesh size for the escape window with respect to current minimum landing size of cod in the Baltic Sea were sought. The results show that the floating pot is not only species selective when used in the Baltic Sea cod fishery, the implementation of an escape window reduced the proportion of undersized bycatch in the pots by more than 90%. The estimated length at 50% retention was found to be a direct function of fish body length (girth) and mesh size of the escape window, while the estimated selection range remained unchanged regardless of mesh size. Optimal mesh size, with respect to the length at 50% retention and current minimal landing size of 38 cm in the Baltic, was determined to be 45 mm. Strong indications (significant on the 0.01 probability level in the case of 50 and 40 mm escape windows) suggested that the relative fishing power of the pots increased with the implementation of an escape window. This result could be explained as a "saturation effect", i.e. the probability of cod entering the pot is likely to be negatively dependent on cod density in the pot. The high species selectivity and the low catch rate of undersized fish have consolidated the floating pots position as a highly benign fishing method and the foremost alternative gear for the future coastal cod fishery in the Baltic Sea. (C) 2010 Elsevier B.V. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Escape window, Size selection, Select model, Gadus morhua, Floating pots
in
Fisheries Research
volume
107
issue
1-3
pages
239 - 244
publisher
Elsevier
external identifiers
  • wos:000287113600026
  • scopus:78650311109
ISSN
0165-7836
DOI
10.1016/j.fishres.2010.10.023
language
English
LU publication?
yes
id
d4427658-9f41-43a9-a23a-30ceb70941ed (old id 1872949)
date added to LUP
2011-04-18 11:04:28
date last changed
2017-10-08 03:10:43
@article{d4427658-9f41-43a9-a23a-30ceb70941ed,
  abstract     = {Little is known about the size selectivity of cod in static fishing gears such as pots and traps. In this field study, floating fishing pots were equipped with 40, 45 and 50 mm square mesh escape windows in order to estimate the size selectivity of cod at different mesh sizes. Relationships between selectivity parameters and mesh size, as well as an optimal mesh size for the escape window with respect to current minimum landing size of cod in the Baltic Sea were sought. The results show that the floating pot is not only species selective when used in the Baltic Sea cod fishery, the implementation of an escape window reduced the proportion of undersized bycatch in the pots by more than 90%. The estimated length at 50% retention was found to be a direct function of fish body length (girth) and mesh size of the escape window, while the estimated selection range remained unchanged regardless of mesh size. Optimal mesh size, with respect to the length at 50% retention and current minimal landing size of 38 cm in the Baltic, was determined to be 45 mm. Strong indications (significant on the 0.01 probability level in the case of 50 and 40 mm escape windows) suggested that the relative fishing power of the pots increased with the implementation of an escape window. This result could be explained as a "saturation effect", i.e. the probability of cod entering the pot is likely to be negatively dependent on cod density in the pot. The high species selectivity and the low catch rate of undersized fish have consolidated the floating pots position as a highly benign fishing method and the foremost alternative gear for the future coastal cod fishery in the Baltic Sea. (C) 2010 Elsevier B.V. All rights reserved.},
  author       = {Ovegard, M and Konigson, S. and Persson, Anders and Lunneryd, S. G.},
  issn         = {0165-7836},
  keyword      = {Escape window,Size selection,Select model,Gadus morhua,Floating pots},
  language     = {eng},
  number       = {1-3},
  pages        = {239--244},
  publisher    = {Elsevier},
  series       = {Fisheries Research},
  title        = {Size selective capture of Atlantic cod (Gadus morhua) in floating pots},
  url          = {http://dx.doi.org/10.1016/j.fishres.2010.10.023},
  volume       = {107},
  year         = {2011},
}