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Calamnius, L., Lundin, M., Fjälling, A. & Königson, S. (2018). Pontoon trap for salmon and trout equipped with a seal exclusion device catches larger salmons. PLoS ONE, 13(7), Article ID e0201164.
Open this publication in new window or tab >>Pontoon trap for salmon and trout equipped with a seal exclusion device catches larger salmons
2018 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 7, article id e0201164Article in journal (Refereed) Published
Abstract [en]

The growing seal populations of the Baltic have led to more frequent interactions with coastal fisheries. The motivation for seals to interact with fishing gear is high. It provides high densities of fish. A successful means of mitigating the conflict is the pontoon trap. Seal visits here have been frequent. Seals have access to most parts of the trap system including the middle chamber, which is an overhead environment. Concerns have been raised about seals possible entanglement in this specific part of the trap. As a means of keeping seals from entering the middle chamber, two different Seal Exclusion Devices (SEDs) were tested. A diamond mesh SED and a square mesh SED, which was rotated 45. The aim was to compare the functionality of the different SEDs with respect to seal deterrent abilities and catch composition. The hypothesis tested were (i) that seals would not be able to enter the middle chamber, (ii) that the catch would increase and (iii) that the SED would deter larger fish from swimming into the middle chamber. Catch data and underwater film were collected. Larger salmons were caught in traps equipped with SEDs. The SEDs did not affect the number of caught fish or the total catch per soak day. © 2018 Calamnius et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Place, publisher, year, edition, pages
PLoS, 2018
Keywords
animal experiment, animal trapping, Article, Baltic Sea, controlled study, fishery, fishing, intermethod comparison, nonhuman, organismal interaction, Pinnipedia, pontoon trap, Salmo trutta, salmonine, seal exclusion device, swimming
National Category
Fish and Aquacultural Science
Identifiers
urn:nbn:se:hig:diva-27634 (URN)10.1371/journal.pone.0201164 (DOI)000439952400056 ()30048493 (PubMedID)2-s2.0-85050665604 (Scopus ID)
Funder
Swedish Board of Agriculture
Note

Operational Program for Fisheries in Sweden 2007 - 2013 (Swedish Board of Agriculture)

European Union, European Fisheries Fund Investing in sustainable fisheries Grant no 18-7965/11

Harmangers Machine and Marine  

The Wildlife Damage Centre, through the Swedish Agency for Marine and Water Management  

County Administrative Board of Gavleborg  Grant no 2342-15 

University of Gävle  

Sven-Gunnar Lunneryd of Program Seals Fisheries 

Available from: 2018-08-14 Created: 2018-08-14 Last updated: 2018-09-05Bibliographically approved
Lundin, M., Calamnius, L. & Fjälling, A. (2015). Size selection of whitefish (Coregonus maraena) in a pontoon trap equipped with an encircling square mesh selection panel. Fisheries Research, 161, 330-335
Open this publication in new window or tab >>Size selection of whitefish (Coregonus maraena) in a pontoon trap equipped with an encircling square mesh selection panel
2015 (English)In: Fisheries Research, ISSN 0165-7836, E-ISSN 1872-6763, Vol. 161, p. 330-335Article in journal (Refereed) Published
Abstract [en]

Many fishing methods result in significant catches of non-target species or individuals that are too small to be retained for economic values or within quota regulations. In the Baltic Sea trap fishery, the major problem is the bycatch of juvenile and non-marketable whitefish (Coregonus maraena) which constitutes a threat to the sustainability of the fishery and a time-consuming problem for the fishers. This study evaluates the effectiveness of a modified fish trap in reducing such bycatch. An encircling selection panel consisting of 50 × 50 mm square mesh netting was installed in a pontoon fish chamber of a salmon/whitefish trap. Comparative fishing was conducted against a control trap without selection panel in the inshore waters of the Bothnian Sea. Comparisons of catch compositions between the traps showed that there was a 72% reduction in juvenile whitefish catch in the experimental trap. The length at 50% retention (30.1 cm) corresponded well to the minimum market size (>30 cm) of whitefish that are desired for the local market. Fishers are advised to use a netting panel of 50 × 50 mm square mesh for their traps to reduce undersized whitefish. The results are important for the sustainability of whitefish stocks in the Baltic Sea.

Keywords
Baltic Sea, Pontoon trap, Bycatch, Coregonus maraena, Size selection, Square mesh panel
National Category
Other Biological Topics
Identifiers
urn:nbn:se:hig:diva-17704 (URN)10.1016/j.fishres.2014.08.020 (DOI)000345478600037 ()2-s2.0-84908377303 (Scopus ID)
Available from: 2014-10-22 Created: 2014-10-20 Last updated: 2018-03-13Bibliographically approved
Lundin, M., Calamnius, L., Lunneryd, S.-G. & Magnhagen, C. (2015). The efficiency of selection grids in perch pontoon traps. Fisheries Research, 162, 58-63
Open this publication in new window or tab >>The efficiency of selection grids in perch pontoon traps
2015 (English)In: Fisheries Research, ISSN 0165-7836, E-ISSN 1872-6763, Vol. 162, p. 58-63Article in journal (Refereed) Published
Abstract [en]

In commercial fishing, minimizing the bycatch of undersized fish or non-target species is highly beneficial, to avoid unnecessary fish mortality and to save time for the fishers. Two pontoon traps developed for perch fishing were equipped with size selection grids, and the efficiency with which under-sized fish could escape was tested. Average size of perch, roach, and whitefish was larger in traps with selection grids compared to in control traps without grids. Selection efficiencies using these comparisons were 82–86% for perch, 33% for whitefish and 100% for roach. The selection grids were filmed with an underwater video camera over the daily cycle, to estimate timing, and total number of exits from the traps. Selection efficiencies, calculated by extrapolating number of escapes observed to the total time of trap submergence, were 94–100% for perch and 100% for roach. The discrepancy in the selection efficiency estimates for perch probably depends on an uncertainty in the extrapolation, because of the variation in escape rate across time periods. Perch and roach differed in time of day for escapes. For perch most escapees was seen in the evening, and for roach most fish escaped at night, probably reflecting the general activity cycles of the two species. Over a fishing season, several thousands of fish would be able to escape from each trap, and an increase in the use of size selection grids could potentially be an efficient tool for fish population management.

Keywords
bycatch, perch, pontoon trap, selection grid, selection efficiency
National Category
Other Biological Topics
Identifiers
urn:nbn:se:hig:diva-17705 (URN)10.1016/j.fishres.2014.09.017 (DOI)000347761700010 ()2-s2.0-84910026330 (Scopus ID)
Available from: 2014-11-10 Created: 2014-10-20 Last updated: 2018-03-13Bibliographically approved
Lundin, M., Ovegård, M., Calamnius, L., Hillström, L. & Lunneryd, S.-G. (2011). Selection efficiency of encircling grids in a herring pontoon trap. Fisheries Research, 111(1-2), 127-130
Open this publication in new window or tab >>Selection efficiency of encircling grids in a herring pontoon trap
Show others...
2011 (English)In: Fisheries Research, ISSN 0165-7836, E-ISSN 1872-6763, Vol. 111, no 1-2, p. 127-130Article in journal (Refereed) Published
Abstract [en]

High bycatches of undersized herring constitute a major problem in the Baltic Sea herring trap fishery. In an attempt to reduce these bycatches, this field study evaluates the efficiency of rigid selection grids encircling a herring pontoon trap. The results show that 54-72% of the undersized herring were removed from the catch. The introduction of such grids would therefore represent a significant step towards a more efficient and sustainable herring fishery in the Baltic Sea. © 2011 Elsevier B.V.

Keywords
Baltic sea, Bycatch, Efficiency, Grid, Herring, Pontoon trap, Selection, Clupeidae
Identifiers
urn:nbn:se:hig:diva-10402 (URN)10.1016/j.fishres.2011.06.015 (DOI)000295350700014 ()2-s2.0-80051669497 (Scopus ID)
Available from: 2011-09-25 Created: 2011-09-25 Last updated: 2018-03-13Bibliographically approved
Lundin, M., Calamnius, L., Hillstrom, L. & Lunneryd, S.-G. (2011). Size selection of herring (Clupea harengus membras) in a pontoon trap equipped with a rigid grid. Fisheries Research, 108(1), 81-87
Open this publication in new window or tab >>Size selection of herring (Clupea harengus membras) in a pontoon trap equipped with a rigid grid
2011 (English)In: Fisheries Research, ISSN 0165-7836, E-ISSN 1872-6763, Vol. 108, no 1, p. 81-87Article in journal (Refereed) Published
Abstract [en]

A sustainable fishery in the Baltic and Bothnian Seas requires the development and introduction of fishing gear which fishes selectively and at the same time excludes raiding seals. The purpose of this study was twofold: firstly to test and evaluate rigid grids as a method for retaining only larger herring in a pontoon trap, and secondly to analyze which factors were influencing the selection process. The results demonstrate that it is indeed possible to sort herring by size in a pontoon fish chamber. The efficiency of excluding undersized herring was at best 27%, using a selection grid covering just over 0.1% of the fish chamber wall. The factors which have most effect on the selection were the quantity of fish in the trap, the season of the year, the time of day and the presence of seals. (C) 2010 Elsevier B.V. All rights reserved.

Keywords
Grey seal, Bothnian Sea, Herring, Pontoon trap, Selection, Baltic, Grid, Sorting
Identifiers
urn:nbn:se:hig:diva-10258 (URN)10.1016/j.fishres.2010.12.001 (DOI)000287428500011 ()2-s2.0-79251599704 (Scopus ID)
Available from: 2011-09-22 Created: 2011-09-21 Last updated: 2018-03-13Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-3073-0496

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