Release of unwanted flat-bodied fish from a horizontal-bar grid system as revealed through comparative fishing trials and underwater video observations
Grid systems separate fish species primarily through physical means: fish size and body shape. On Georges Bank off the northeast USA, many species of flounders are overfished, and their catch needs to be reduced. Flat-bodied skates are also often discarded. We tested a European style horizontal-bar...
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2021
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Online Access: | https://doi.org/10.1016/j.aaf.2020.05.010 https://doaj.org/article/b9924e55814544bfb9f88a7f4d9c447c |
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ftdoajarticles:oai:doaj.org/article:b9924e55814544bfb9f88a7f4d9c447c 2023-05-15T15:27:25+02:00 Release of unwanted flat-bodied fish from a horizontal-bar grid system as revealed through comparative fishing trials and underwater video observations Christopher B. Rillahan Pingguo He 2021-07-01T00:00:00Z https://doi.org/10.1016/j.aaf.2020.05.010 https://doaj.org/article/b9924e55814544bfb9f88a7f4d9c447c EN eng KeAi Communications Co., Ltd. http://www.sciencedirect.com/science/article/pii/S2468550X20300678 https://doaj.org/toc/2468-550X 2468-550X doi:10.1016/j.aaf.2020.05.010 https://doaj.org/article/b9924e55814544bfb9f88a7f4d9c447c Aquaculture and Fisheries, Vol 6, Iss 4, Pp 348-358 (2021) Trawl Bycatch Selectivity Flounder Skate Haddock Aquaculture. Fisheries. Angling SH1-691 article 2021 ftdoajarticles https://doi.org/10.1016/j.aaf.2020.05.010 2022-12-31T06:47:46Z Grid systems separate fish species primarily through physical means: fish size and body shape. On Georges Bank off the northeast USA, many species of flounders are overfished, and their catch needs to be reduced. Flat-bodied skates are also often discarded. We tested a European style horizontal-bar grid system to reduce these flat-bodied low quota species in a trawl targeting the haddock (Melanogrammus aeglefinus), whose population is robust. The grid system consisted of 4 grid sections, two on each side, with horizontal bars 70 mm apart. The alternating tow method was used to compare the catch characteristics between a trawl with a grid section and the same trawl without a grid section. A video camera was used to observe fish escape in the grid section. The results indicate that the grid system reduced the flounder catch rate (mainly winter flounder, Pseudopleuronectes americanus) by 51.3%, and skates (mainly winter skate, Leucoraja ocellata and little skate, Leucoraja erinacea) by 29.4%, while there were no differences in the catch of Atlantic cod (Gadus morhua). While haddock was reduced by 37% by weight, the reduction was primarily small undersized individuals. There was no reduction in large haddock greater than 50 cm. Video observations indicates that flounders and cod mainly escaped from the bottom half of the grid while haddock were from the top half. These finding suggest that this system reduced low quota flounders, as well as discarded skates and small haddock, while retaining Atlantic cod and large size haddock. Underwater observations indicate that differential spacing (narrower on the top and wider on the bottom) may improve the system performance by releasing more flat-bodied fish, that were observed to escape from the bottom part of the grid, while retaining more haddock, which typically escape from the top part of the grid. Article in Journal/Newspaper atlantic cod Gadus morhua Directory of Open Access Journals: DOAJ Articles Aquaculture and Fisheries 6 4 348 358 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Trawl Bycatch Selectivity Flounder Skate Haddock Aquaculture. Fisheries. Angling SH1-691 |
spellingShingle |
Trawl Bycatch Selectivity Flounder Skate Haddock Aquaculture. Fisheries. Angling SH1-691 Christopher B. Rillahan Pingguo He Release of unwanted flat-bodied fish from a horizontal-bar grid system as revealed through comparative fishing trials and underwater video observations |
topic_facet |
Trawl Bycatch Selectivity Flounder Skate Haddock Aquaculture. Fisheries. Angling SH1-691 |
description |
Grid systems separate fish species primarily through physical means: fish size and body shape. On Georges Bank off the northeast USA, many species of flounders are overfished, and their catch needs to be reduced. Flat-bodied skates are also often discarded. We tested a European style horizontal-bar grid system to reduce these flat-bodied low quota species in a trawl targeting the haddock (Melanogrammus aeglefinus), whose population is robust. The grid system consisted of 4 grid sections, two on each side, with horizontal bars 70 mm apart. The alternating tow method was used to compare the catch characteristics between a trawl with a grid section and the same trawl without a grid section. A video camera was used to observe fish escape in the grid section. The results indicate that the grid system reduced the flounder catch rate (mainly winter flounder, Pseudopleuronectes americanus) by 51.3%, and skates (mainly winter skate, Leucoraja ocellata and little skate, Leucoraja erinacea) by 29.4%, while there were no differences in the catch of Atlantic cod (Gadus morhua). While haddock was reduced by 37% by weight, the reduction was primarily small undersized individuals. There was no reduction in large haddock greater than 50 cm. Video observations indicates that flounders and cod mainly escaped from the bottom half of the grid while haddock were from the top half. These finding suggest that this system reduced low quota flounders, as well as discarded skates and small haddock, while retaining Atlantic cod and large size haddock. Underwater observations indicate that differential spacing (narrower on the top and wider on the bottom) may improve the system performance by releasing more flat-bodied fish, that were observed to escape from the bottom part of the grid, while retaining more haddock, which typically escape from the top part of the grid. |
format |
Article in Journal/Newspaper |
author |
Christopher B. Rillahan Pingguo He |
author_facet |
Christopher B. Rillahan Pingguo He |
author_sort |
Christopher B. Rillahan |
title |
Release of unwanted flat-bodied fish from a horizontal-bar grid system as revealed through comparative fishing trials and underwater video observations |
title_short |
Release of unwanted flat-bodied fish from a horizontal-bar grid system as revealed through comparative fishing trials and underwater video observations |
title_full |
Release of unwanted flat-bodied fish from a horizontal-bar grid system as revealed through comparative fishing trials and underwater video observations |
title_fullStr |
Release of unwanted flat-bodied fish from a horizontal-bar grid system as revealed through comparative fishing trials and underwater video observations |
title_full_unstemmed |
Release of unwanted flat-bodied fish from a horizontal-bar grid system as revealed through comparative fishing trials and underwater video observations |
title_sort |
release of unwanted flat-bodied fish from a horizontal-bar grid system as revealed through comparative fishing trials and underwater video observations |
publisher |
KeAi Communications Co., Ltd. |
publishDate |
2021 |
url |
https://doi.org/10.1016/j.aaf.2020.05.010 https://doaj.org/article/b9924e55814544bfb9f88a7f4d9c447c |
genre |
atlantic cod Gadus morhua |
genre_facet |
atlantic cod Gadus morhua |
op_source |
Aquaculture and Fisheries, Vol 6, Iss 4, Pp 348-358 (2021) |
op_relation |
http://www.sciencedirect.com/science/article/pii/S2468550X20300678 https://doaj.org/toc/2468-550X 2468-550X doi:10.1016/j.aaf.2020.05.010 https://doaj.org/article/b9924e55814544bfb9f88a7f4d9c447c |
op_doi |
https://doi.org/10.1016/j.aaf.2020.05.010 |
container_title |
Aquaculture and Fisheries |
container_volume |
6 |
container_issue |
4 |
container_start_page |
348 |
op_container_end_page |
358 |
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1766357855849414656 |