Using underwater video observations to improve capture efficiency of fishing gear

• Main Author: Folkins, Maggie
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2019
• Subjects: Greenland; Somniosus microcephalus
• Online Access: https://research.library.mun.ca/13932/; https://research.library.mun.ca/13932/1/thesis.pdf

High incidental catches of Greenland shark (Somniosus microcephalus) in Greenland halibut (Reinhardtius hippoglossoides) longline fisheries has led to studies on the feasibility of capturing halibut with baited pots. In this study I compare catch data among six experimental pots and examine video of halibut interacting with pots. Catch rates of halibut did not differ among treatments and pots did not produced substantial amounts of bycatch. Video observations revealed that halibut become entangled by their teeth significantly more often in entrance funnels constructed with 50 mm than with 19 mm netting, resulting in 45% higher entry rates in the latter. Most (80%) halibut approached pots against the current following the scent of the bait. I recommend that future studies consider a four-entrance pot to ensure an entrance is aligned with bottom currents. To reduce likelihood of entanglement, I recommend 19 mm netting for entrance funnels, 100 mm polyethylene for exterior panels, and 19 mm polypropylene for parlour entrances for pots targeting halibut.