Harmangers Maskin and Marin AB

Stocka, Sweden

Harmangers Maskin and Marin AB

Stocka, Sweden
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Lundin M.,Harmangers Maskin and Marin AB | Ovegard M.,Swedish University of Agricultural Sciences | Calamnius L.,Harmangers Maskin and Marin AB | Hillstrom L.,University of Gävle | Lunneryd S.-G.,Swedish University of Agricultural Sciences
Fisheries Research | Year: 2011

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.


Lundin M.,Swedish University of Agricultural Sciences | Lundin M.,University of Gävle | Lundin M.,Harmangers Maskin and Marin AB | Calamnius L.,University of Gävle | And 3 more authors.
Fisheries Research | Year: 2015

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. © 2014 Elsevier B.V.


Lundin M.,Swedish University of Agricultural Sciences | Lundin M.,University of Gävle | Lundin M.,Harmangers Maskin and Marin AB | Calamnius L.,University of Gävle | And 2 more authors.
Fisheries Research | Year: 2015

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. © 2014 Elsevier B.V.


Lundin M.,Swedish University of Agricultural Sciences | Calamnius L.,Harmangers Maskin and Marin AB | Lunneryd S.-G.,Swedish University of Agricultural Sciences
Fisheries Research | Year: 2012

A common problem in the Baltic Sea and Gulf of Bothnian herring trap fishery is the bycatch of undersized Baltic herring (Clupea harengus membras). By equipping a pontoon trap with a rigid grid with vertical bars, a substantial proportion of the undersized herring can escape from the gear by swimming through the grid. However, it has not been clear whether or not the young fish are injured by their passage through a grid and what their fate is. The purpose of this study was to investigate the short term mortality of herring after passage through a grid. To capture young herring, a selection grid was mounted at the entrance to the fish chamber of a pontoon trap, so that only young herring (approximately 12-18. cm in length) could swim in. The trap was then closed and the herring were confined in the fish chamber for seven days before assessing survival rates. The same procedure was performed with control herring which were trapped without passing through any grid. The whole trial was repeated three times. On average about 7% of the young herring selected through a sorting grid died during the experiment. The results demonstrated that passing through a rigid grid did not affect the short term mortality of young herring during the seven days in captivity. The highest mortality (45%) was in fact observed in one of the control groups presumably in connection with extreme temperature fluctuations. © 2012 Elsevier B.V.

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