Seal exclusion devices in cod pots prevent seal bycatch and affect their catchability of cod

Königson, Sara; Lövgren, Johan; Hjelm, Joakim; Ovegård, Mikael; Ljunghager, Fredrik; Lunneryd, Sven-Gunnar

doi:10.1016/j.fishres.2015.01.013

Cited by 20 publications

(19 citation statements)

References 32 publications

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“…In the first experiment we tested two models of pot: Newfoundland-style pots (hereafter NL), and Norwegian-style pots (hereafter NOR). We selected these pot types for comparison because both are currently in use in fisheries targeting cod; the former, by a small group of fishers on Fogo Island NL [ 26 ], and the latter by fishers in Norway and Sweden [ 27 – 30 ]. In our second experiment, we assessed five pot types: NL, NOR, modified NL (NL-mod), modified NOR (NOR-mod), and a four-entrance pot of our design (4-ent).…”

Section: Methodsmentioning

confidence: 99%

Comparing catch efficiency of five models of pot for use in a Newfoundland and Labrador cod fishery

2018

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Sustainability of commercial fisheries is best achieved when fishing gears are selective and have low impacts on bottom habitat. Pots (baited traps) are a fishing technology that typically has lower impacts than many other industrial gears. In this study we compared the efficiency of five models of pots (baited traps) designed to catch Atlantic cod (Gadus morhua) for use in Newfoundland and Labrador (NL)’s expanding cod fishery. We compared catch per unit effort (CPUE) and total lengths of cod across each pot type, as well as bycatch rates of each model. All pot types were successful at catching cod, but two models (the modified Newfoundland pot, and a four-entrance pot of our design) had highest CPUE. Specifically, we found that modifying Newfoundland pots increased their CPUE by 145% without a corresponding increase in bycatch. None of the pot types produced substantial amounts of bycatch. This study demonstrated that potting gear is an effective way to catch cod in NL, and that there is flexibility in which pot fishers can use, depending on the layout of their fishing vessel.

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Section: Methodsmentioning

confidence: 99%

Comparing catch efficiency of five models of pot for use in a Newfoundland and Labrador cod fishery

2018

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“…in Tasmania [ 10 ], Chile [ 11 ], the North American East and West coast [ 9 , 12 ], Scotland [ 13 ] and in the Baltic Sea [ 14 ]. They cause damage to gear and catch, generate less evident catch losses [ 15 ] and occasionally become entangled in the gear, succumbing to accidental death [ 16 – 18 ]. As a means to minimize bycatch (non-target species caught in fishing gear) and to mitigate the interactions between pinnipeds and fisheries or fish farms, a variety of mitigation means have been tried and implemented with varying degrees of success.…”

Section: Introductionmentioning

confidence: 99%

“…fish farms [ 30 ]. SEDs are installed in existing fishing gear and functions as both an escape means to reduce bycatch in trawls [ 17 , 18 , 31 , 32 ] or to exclude seals from the catch in cod pots, while concurrently reducing bycatch [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…Designing a SED is a compromise between not having any adverse effect on the catch, while simultaneously preventing seals from entering [ 16 , 34 , 35 ]. The size and shape of the openings in the SED are critical.…”

Section: Introductionmentioning

confidence: 99%

“…The size and shape of the openings in the SED are critical. Smaller openings may lead to a better retention of fish [ 16 ]. If the openings are too small, or the wires or twine in the entrance too conspicuous, the fish might turn and swim out.…”

Section: Introductionmentioning

confidence: 99%

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Pontoon trap for salmon and trout equipped with a seal exclusion device catches larger salmons

Calamnius

Lundin²,

Fjälling

et al. 2018

PLoS ONE

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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.

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The Harbor Seal: The Most Ubiquitous Phocid in the Northern Hemisphere

Chudzińska

McConnell

Hastie

2022

Ethology and Behavioral Ecology of Marine Mammals

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Seal exclusion devices in cod pots prevent seal bycatch and affect their catchability of cod

Cited by 20 publications

References 32 publications

Comparing catch efficiency of five models of pot for use in a Newfoundland and Labrador cod fishery

Comparing catch efficiency of five models of pot for use in a Newfoundland and Labrador cod fishery

Pontoon trap for salmon and trout equipped with a seal exclusion device catches larger salmons

The Harbor Seal: The Most Ubiquitous Phocid in the Northern Hemisphere

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