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

• Main Authors: Calamnius, Linda, Lundin, Mikael, Fjälling, Arne, Königson, Sara
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2019
• Subjects: Seal exclusion; pontoon trap; mitigating conflict fishers vs seals; coastal fisheries; Salmo salar; Halichoerus grypus; grey seal
• Online Access: https://doi.org/10.5061/dryad.dm2v1bk

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. Salmon and trout catch 2012 and 2016 Catch from 2012 and 2016 from a pontoon trap equipped with two different types of Seal Exclusion Devices. Each caught fish was weighed individually at every harvest occasion. Total catch, number of harvest occasions, Catch Per Unit Effort (CPUE) - total numbers of fish per soak day in one trap and Weight Per Unit Effort (WPUE)- weight of the catch per soak day in one trap, can be calculated from this data. Seal visits 2012 and 2016 Filmed number of hours and seal visits in pontoon traps equipped with two different types of Seal Exclusion Devices, compared to a Control. The study took place in 2012 and 2016.