Promoting conservation through the improvement of cod pots - a low impact fishing gear and alternative harvesting strategy for Atlantic cod (Gadus morhua) in Newfoundland and Labrador

Pots are baited fishing gears that are growing in use as a tool for harvesting Atlantic cod (Gadus morhua) in Newfoundland and Labrador (NL). To study how cod behaviours affect pot efficiency, I used underwater video cameras to assess two models of pot deployed in the Fogo Island fishery. Cod made few entry attempts relative to the number of approaches, and only 22% of entry attempts were successful. The majority of approaches, entry attempts, and successful entrances occurred from the down-current direction, and 25% of cod were able to escape following capture. Following video analysis, I made modifications to existing pots, and created a new design. I then collected catch and length data, across five models of pot, over two years, to determine the optimal design for a re-emergent cod fishery in NL. All five pots caught cod effectively, but the new and modified pots caught the most per deployment, and increasing mesh size was effective at reducing the number of undersized fish caught. This thesis demonstrates that modifications can have a substantial impact on catch rates, that potting gear is fundamentally sound, and fishermen can select a pot that is most appropriate to their needs

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

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

The Effect of Marine Acidification on Chemosensation in the Predatory Echinoderm Pycnopodia helianthoides

<p>Climate change is the leading cause in the acidification of marine ecosystems, which may influence the chemo-detection of prey by the sea star Pycnopodia helianthoides. Interference with predation may negatively impact marine food-web dynamics in P.</p> <p>helianthoides habitats. We explored how the detection of the blue mussel Mytilus edulis varied in 15 P. helianthoides specimens in lowered pH seawater and 15 specimens in current pH seawater. We observed that there was no significant difference in the number of prey detected by P. helianthoides between the treatments and that no significant difference was present between the durations of successful trials. These results indicate that future marine acidification may not have as large of an impact on Pycnopodia helianthoides foraging as expected.</p

Distributed under Creative Commons CC-BY 4.0 OPEN ACCESS Will you swim into my parlour? In situ observations of Atlantic cod (Gadus morhua) interactions with baited pots, with implications for gear design

ABSTRACT Pots (also known as traps) are baited fishing gears widely used in commercial fisheries, and are being considered as a tool for harvesting Atlantic cod (Gadus morhua) in Newfoundland and Labrador, Canada. Pots produce lower environmental impacts than many other fishing gears, but they will only be a viable fishing strategy if they are efficient and selective at catching their target species. To study the behaviour of cod in and around pots, and how those behaviours affect pot efficiency, we used longduration underwater video cameras to assess two models of cod pot deployed in the nearshore waters of Fogo Island, NL. We examined the number of cod that approached the pot, the number and proportion that successfully completed entries into the pot openings, and the number that exited, and related these factors to the direction of water movement. We observed very few entry attempts relative to the number of approaches by cod, and only 22% of all entry attempts were successful. We observed that 50% of approaches, 70% of entry attempts, and 73% of successful entrances occurred against the current, and 25% of cod were able to exit the pot following capture. Based on our observations, we suggest that future cod pots should have a greater number of entrances, or a mechanism to ensure that entrances rotate in line with the current, in order to maximize their catch efficiency for cod

Supplementary Video - NOR Cod Pot Underwater 2015.mp4

Underwater video recorded of a Norwegian (NOR) cod pot, deployed under water, off the coast of Fogo Island, Newfoundland, Canada, in August 2015.<div><br></div><div>https://peerj.com/articles/2953/<br></div

Estimated regression parameters, standard errors, z-values, and P-values for the negative binomial GLMM presented for catch-per-deployment from our 2016 field study.

<p>Estimated regression parameters, standard errors, z-values, and P-values for the negative binomial GLMM presented for catch-per-deployment from our 2016 field study.</p

Summary of cod caught per pot type from our 113 deployments.

<p>Summary of cod caught per pot type from our 113 deployments.</p

Supplementary Video: Cod potting in NL

This is the supplementary video associated with Meintzer, Walsh, and Favaro (2016), Data collection and performance assessment of Norweigan and Newfoundland cod pot

Summary of cod caught across all pot deployments for each pot style.

<p>N represents the number of pots deployed per pot type.</p

Bycatch comparison between the NL and NOR pots for our 2015 field study.

<p>Values represent the total number of individuals caught out of 41 NL and 72 NOR deployments. Species with total catch < 10 are excluded from the table.</p