The influence of towing speed and fish density on the behaviour of haddock in a trawl cod-end

Jones, Emma; Summerbell, K.; O’Neill, Fiona

doi:10.1016/j.fishres.2008.06.010

Cited by 45 publications

(40 citation statements)

References 17 publications

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“…Studies of fish escape behavior from cod ends in the North Sea showed that more strikes or approaches to nets yield more escapes (Jones et al, 2008;Kim et al, 2008). Fish that show approaching or striking behaviors are exhibiting erratic responses, in contrast to the optomotor response of maintaining swimming speed and position (Wardle, 1993;Kim and Wardle, 2006).…”

Section: Resultsmentioning

confidence: 99%

Effects on the Escapement of Juvenile Bastard Halibut Paralichthys olivaceus of Actively Stimulating Devices Inside a Model Cod End

Kim¹

2011

Fisheries and aquatic sciences

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The effects of actively stimulating devices (ASD) on juvenile flatfish escape were studied to increase escape rates from the cod end by encouraging fish to approach the net wall. Two kinds of ASD were designed: a fluttering net panel, i.e., a free-end flag-like net panel, and a double conical rope array. Escape responses of juvenile bastard halibut were observed in a circulating water channel using two model cod ends, one made with diamond-shaped 43-mm-mesh-size polyethylene (PE) as a high-contrast cod end and the other with polyamid (PA) mono-ply as a low-contrast cod end. Retention rate was significantly lower with the double conical rope-array ASD in the PE cod end than with conventional PE cod ends only or the fluttering net-panel ASD inside the PE cod end. Mean retention rate with the low-contrast PA cod end was also significantly lower than that with the high-contrast PE conventional cod end. Therefore, active fluttering devices using a double conical rope array together with less visible low-contrast netting in the cod end could help to reduce the bycatch of juvenile flatfish by weakening their optomotor response and actively driving fish to the side net panel.

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Section: Resultsmentioning

confidence: 99%

Effects on the Escapement of Juvenile Bastard Halibut Paralichthys olivaceus of Actively Stimulating Devices Inside a Model Cod End

Kim¹

2011

Fisheries and aquatic sciences

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“…The development of a new trawl responds to the need to improve the poor performance and selectivity of the trawls traditionally used in the fisheries targeting nylon shrimp (Heterocarpus reedi), red royal shrimp (Haliporoides diomedeae) and squat lobsters (Pleuroncodes monodon and Cervimunida johni). In this respect, it has been reported that the selectivity of fishing gear depends on the behaviour of the fish towards different components of a trawl net (Wardle, 1989(Wardle, , 1993Watson, 1989;Engås, 1994) and is influenced by mesh size and shape (Robertson, 1989;Halliday et al, 1999;Broadhurst et al, 2006), towing speed (Jones et al, 2008), catch rate and volume (Robertson and Ferro, 1988;Dahm et al, 2002), twine diameter and codend circumference (Broadhurst and Kennelly, 1996;Broadhurst et al, 2006;Graham et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Comparison between dynamic simulation and physical model testing of new trawl design for Chilean crustacean fisheries

2009

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“…Jones et al (2008) observed that the fluttering of square mesh windows or slack nets in the cod end improved juvenile fish escape, although they did not provide any specific data about escape ratios, etc. The experimental rope kite used in the present study was more changeable in its rotating period and has a wider range of action, so it acted as a very active stimulating device to evoke fish escape response from the cod end.…”

Section: Resultsmentioning

confidence: 97%

“…Fish escapement from the cod end was greater when mesh nets were used in North Sea trawls, where movement was very erratic and prevented fish from maintaining position as an optomotor response (Kim et al, 2008). In addition, Jones et al (2008) found that rates of netting strikes of fish during North Sea trawling were generally higher at higher towing speeds and lower catch densities. They hypothesized that opportunistic contact occurred during netting, perhaps as a result of the pulsing motion of the cod end and water turbulence rather than any active change in behavior.…”

Section: Introductionmentioning

confidence: 99%

Performance of an Active Stimulating Device Using a Rope Kite or Array in the Cod End to Reduce Juvenile by-catch

Kim¹

2010

Fisheries and aquatic sciences

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An active stimulating device (ASD) using a rope apparatus may operated by the flow of turbulence inside a cod end, generating variable stimuli in addition to flow-related effects to minimize the bycatch of juvenile fishes. Preliminary testing involved a hydrodynamic effect inside the cod end with a rotating rope kite or conical rope array to generate variable stimuli (visual stimuli, water flow, or physical contact with fish) to change fish position. The experimental rope kite offered more choice in rotating period and range of sweeping action; adjusting the towing line or flow velocity helped to drive fish toward the net panel and encouraged escape. The conical shape of the rope array in the cod end helped to clear a path for fish by disturbing the rigging and providing more contrast between objects, preventing an optomotor response. This enabled more black porgy to be herded toward the net at an early stage of towing. Therefore, either a conical rope array or a rotating rope kite can be used as an effective ASD to prevent juvenile by-catch.

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The influence of towing speed and fish density on the behaviour of haddock in a trawl cod-end

Cited by 45 publications

References 17 publications

Effects on the Escapement of Juvenile Bastard Halibut Paralichthys olivaceus of Actively Stimulating Devices Inside a Model Cod End

Effects on the Escapement of Juvenile Bastard Halibut Paralichthys olivaceus of Actively Stimulating Devices Inside a Model Cod End

Comparison between dynamic simulation and physical model testing of new trawl design for Chilean crustacean fisheries

Performance of an Active Stimulating Device Using a Rope Kite or Array in the Cod End to Reduce Juvenile by-catch

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