Jesse Brinkhof

Performance of the Nordmøre Grid in Shrimp Trawling and Potential Effects of Guiding Funnel Length and Light Stimulation

AbstractThe introduction of the Nordmore grid to shrimp trawls has reduced the issue of bycatch to that of small-sized species and juveniles that are able to pass through the grid and enter the small-meshed cod end together with the targeted shrimp. This study estimated the size- and species-selective performance of the Nordmore grid in the configuration most often applied by fishermen and made a preliminary exploration of the effects of reducing the length of the guiding funnel in front of the grid and mounting light-emitting diodes (LEDs) around the escape exit. Experimental fishing trials were conducted in the Barents Sea to assess the size-selective properties of a 19-mm bar spacing Nordmore grid, mandatory in this Norwegian trawl fishery targeting deepwater shrimp Pandalus borealis (also known as northern shrimp), and its potential improvement. Results were obtained for the target species and four bycatch species: redfish Sebastes spp., Haddock Melanogrammus aeglefinus, Atlantic Cod Gadus morhua, and...

Escape rate for cod (Gadus morhua) from the codend during buffer towing

The high abundances of Northeast Arctic cod (Gadus morhua) in the Barents Sea have led to 9 the development of a new fishing tactic called buffer towing. On factory trawlers, the trawl is 10 deployed immediately after taking the catch onboard, a tactic used to ensure a continuous 11 supply of fish is being processed. If the desired amount of fish is caught before the catch from 12 the previous haul has been fully processed, the trawl is lifted off the seabed and towed at a given 13 depth at low speed. This is called buffer towing. Cod that escape from the codend when the 14 trawl is shallower than the initial fishing depth are exposed to an increased likelihood of 15 barotrauma-related injuries, increased disease susceptibility, and predation, which could be 16 lethal, or affect growth and reproduction capability. Therefore, this study quantified the escape 17 rate and size selectivity during buffer towing of cod. A new analytical method was applied that 18 allows using the same trawl configuration as applied during commercial fishing and avoids 19 potential bias in the assessment of buffer towing size selection. Our results demonstrated a 20 significant size selection for cod during buffer towing where cod measuring up to at least 42 21 cm in length were proven to escape. In particular, at least 60% of cod measuring 20 cm were 22 estimated to escape during buffer towing. For cod measuring 30 cm and 40 cm, at least 53% 23 and 45% were estimated to escape during buffer towing, respectively. 24

Combination of a sorting grid and a square mesh panel to optimize size selection in the North-East Arctic cod (Gadus morhua) and redfish (Sebastes spp.) trawl fisheries

Combination of a sorting grid and a square mesh panel to optimize size selection in the North-East Arctic cod (Gadus morhua) and redfish (Sebastes spp.) trawl fisheries Manu Sistiaga*, Bent Herrmann, Eduardo Grimaldo, Roger B. Larsen, Leonore Olsen, Jesse Brinkhof, and Ivan Tatone SINTEF Ocean, Brattørkaia 17C, N-7010 Trondheim, Norway The Arctic University of Norway UIT, Hansine Hansens veg 18, 9019 Tromsø, Norway SINTEF Nord, Storgata 118, N-9008 Tromsø, Norway *Corresponding author: tel: þ479 166 3499; e-mail: manu.sistiaga@sintef.no.

Sequential codend improves quality of trawl-caught cod

Trawl-caught fish are frequently associated with deteriorated catch quality. This study presents a new dual sequential codend concept with the aim of improving the quality of trawl-caught fish by minimizing the frequency and severity of catch damage. During towing, the fish are retained in an anterior codend segment with the legislated mesh size. A quality improving codend segment, is attached to the aft part of the first codend segment. Its entrance is closed during the towing phase and opened at a predefined depth during haul-back. Comparing the quality of cod (Gadus morhua L.) retained in the sequential codend with cod caught in a conventional codend, demonstrated a significant improvement in the catch quality, i.e. reduction in catch damages. Cod caught in a conventional codend had only a 3.6% probability of being without visually detectable catch damage. The probability for catching cod without catch damage was five times higher when using the dual sequential codend. Furthermore, cod caught in the sequential codend had a significantly reduced probability of incurring specific catch damage, such as gear marks, poor exsanguination, ecchymosis, and skin abrasions.

New approach for modelling size selectivity in shrimp trawl fisheries

New approach for modelling size selectivity in shrimp trawl fisheries Roger B. Larsen*, Bent Herrmann, Manu Sistiaga, Jesse Brinkhof, Ivan Tatone, and Lise Langård The Arctic University of Norway UIT, Hansine Hansens veg 18, 9019 Tromsø, Norway SINTEF Fisheries and Aquaculture, Brattørkaia 17C, N-7010 Trondheim, Norway Norwegian Directorate of Fisheries, Postbox 185 Sentrum, 5804 Bergen, Norway *Corresponding author: tel: þ4777644536; fax: þ4777646020; e-mail: roger.larsen@uit.no These authors equally contributed to this study.