Fish Behavior near Bottom Trawls

Winger, Paul D.; Eayrs, Steve; Glass, Chris R.

doi:10.1002/9780813810966.ch4

Cited by 64 publications

(83 citation statements)

References 57 publications

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“…Similar behaviour has been observed for other teleosts in codends where there were colour/contrast changes (Winger et al, 2010). While such a theory is plausible, there was no evidence of meshing, which might be expected among fish around 11 cm TL (Broadhurst et al, 2012).…”

Section: Tablesupporting

confidence: 55%

“…more acute netting angles and wider lateral mesh openings). Further, based on the data here and those presented in previous studies, the reactions of the three affected species were probably somewhat divergent (Watson, 1989;Winger et al, 2010).…”

Section: Discussionmentioning

confidence: 76%

“…In contrast to school prawns, southern herring selection was significantly related to both diel phase and diurnal cloud cover, with individuals only escaping from the short trawl during sunny days. Previous studies have identified that where there is sufficient light for fish to detect trawls (>10 −6 lx; Glass and Wardle, 1989) they display a range of species-specific behavioural responses that reflect a suite of intrinsic and extrinsic characteristics, including their size, schooling behaviour and abundance, physical condition, body shape, swimming ability, learning and experience and water temperature (reviewed by Winger et al, 2010). Considering these known characteristics, one hypothesis to explain the greater escape of southern herring from the short trawl is that given sufficient ambient light, individuals were more easily able to detect the steeper panels against the background as it approached, and some therefore avoided entry, possibly under the foot rope or around the wings rather than over the headline (since the shallow water meant that the trawls mostly fished the entire water column).…”

Section: Tablementioning

confidence: 99%

“…Considering these known characteristics, one hypothesis to explain the greater escape of southern herring from the short trawl is that given sufficient ambient light, individuals were more easily able to detect the steeper panels against the background as it approached, and some therefore avoided entry, possibly under the foot rope or around the wings rather than over the headline (since the shallow water meant that the trawls mostly fished the entire water column). This species forms close schools, and so density-dependant conspecific interactions could have provided additional impetus for escape (Winger et al, 2010).…”

Section: Tablementioning

confidence: 99%

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Effects of diel period and diurnal cloud cover on the species selection of short and long penaeid trawls

2015

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Section: Tablesupporting

confidence: 55%

Section: Discussionmentioning

confidence: 76%

Section: Tablementioning

confidence: 99%

Section: Tablementioning

confidence: 99%

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Effects of diel period and diurnal cloud cover on the species selection of short and long penaeid trawls

2015

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“…Although there have been various observations of target and nontargeted species' response to fishing gear in situ, (Watson, 2007;Winger et al, 2010) the use of laboratory-based behavioral observations and their application to bycatch problems has received less attention. While we were not able to simulate commercial towing speeds in a laboratory environment, red snapper were found to respond to hydraulic changes created by a flow blocking plate.…”

Section: Discussionmentioning

confidence: 99%

Applying Fish Behavior to Reduce Trawl Bycatch: Evaluation of the Nested Cylinder Bycatch Reduction Device

Parsons¹,

Foster²,

Osmond³

2012

mar technol soc j

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We used a laboratory flow chamber to examine the behavioral response of juvenile red snapper, Lutjanus campechanus, to hydraulic and illumination changes with the intention of exploiting these responses to devise a more effective bycatch reduction device (BRD). Snapper were observed to use slack water areas for flow refuge, and this refuging behavior increased the chance of the fish escaping from the flow chamber. Additionally, we observed that dark-adapted red snapper were more likely to exit the test chamber when the flow chamber was illuminated during nighttime hours. We also observed a significant effect of illumination intensity on the time required for red snapper to locate and exit the flow chamber. These behavioral observations were then used to design a BRD that was tested in the Gulf of Mexico shrimp trawl fishery on board a commercial fishing vessel. The Nested Cylinder Bycatch Reduction Device (NCBRD) employed flow blocking plates to encourage fish to move into an area of the trawl where they could more easily escape. The NCBRD reduced total fish bycatch by about 53% and retained 81% of shrimp. Modifications of the inner cylinder of the NCBRD provided higher shrimp retention rates (86.2%-96.6%) but lower bycatch reduction rates (37.2%-42.9%). Illumination of the NCBRD during field testing had no significant effect on total fish bycatch or shrimp retention. However, we found that red snapper bycatch was reduced by 50% when the NCBRD was illuminated. These results suggest that illumination may be effective for increasing the performance of a BRD's ability to exclude red snapper and perhaps other species.

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Simulated trapping and trawling exert similar selection on fish morphology

Thambithurai

Rácz

Lindström

et al. 2022

Ecology and Evolution

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Commercial fishery harvest can influence the evolution of wild fish populations. Our knowledge of selection on morphology is however limited, with most previous studies focusing on body size, age, and maturation. Within species, variation in morphology can influence locomotor ability, possibly making some individuals more vulnerable to capture by fishing gears. Additionally, selection on morphology has the potential to influence other foraging, behavioral, and life‐history related traits. Here we carried out simulated fishing using two types of gears: a trawl (an active gear) and a trap (a passive gear), to assess morphological trait‐based selection in relation to capture vulnerability. Using geometric morphometrics, we assessed differences in shape between high and low vulnerability fish, showing that high vulnerability individuals display shallower body shapes regardless of gear type. For trawling, low vulnerability fish displayed morphological characteristics that may be associated with higher burst‐swimming, including a larger caudal region and narrower head, similar to evolutionary responses seen in fish populations responding to natural predation. Taken together, these results suggest that divergent selection can lead to phenotypic differences in harvested fish populations.

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Fish Behavior near Bottom Trawls

Cited by 64 publications

References 57 publications

Effects of diel period and diurnal cloud cover on the species selection of short and long penaeid trawls

Effects of diel period and diurnal cloud cover on the species selection of short and long penaeid trawls

Applying Fish Behavior to Reduce Trawl Bycatch: Evaluation of the Nested Cylinder Bycatch Reduction Device

Simulated trapping and trawling exert similar selection on fish morphology

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