Dive to survive: effects of capture depth on barotrauma and post-release survival of Atlantic cod (Gadus morhua) in recreational fisheries

Atlantic cod (Gadus morhua) caught in recreational fisheries are commonly released, often with barotrauma after rapid decompression. Mouth-hooked, non-bleeding cod kept in a floating net pen showed mortalities ≥40% when angled from >50 m depth, likely because of cumulative stress from ongoing bar...

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Published in:ICES Journal of Marine Science
Main Authors: Ferter, Keno, Weltersbach, Marc Simon, Humborstad, Odd Børre, Fjelldal, Per Gunnar, Sambraus, Florian, Strehlow, Harry Vincent, Vølstad, Jon Helge
Format: Article in Journal/Newspaper
Language:English
Published: Oxford University Press 2015
Subjects:
Online Access:http://hdl.handle.net/1956/10091
https://doi.org/10.1093/icesjms/fsv102
id ftunivbergen:oai:bora.uib.no:1956/10091
record_format openpolar
spelling ftunivbergen:oai:bora.uib.no:1956/10091 2023-05-15T15:27:29+02:00 Dive to survive: effects of capture depth on barotrauma and post-release survival of Atlantic cod (Gadus morhua) in recreational fisheries Ferter, Keno Weltersbach, Marc Simon Humborstad, Odd Børre Fjelldal, Per Gunnar Sambraus, Florian Strehlow, Harry Vincent Vølstad, Jon Helge 2015-06-26T12:47:54Z application/pdf http://hdl.handle.net/1956/10091 https://doi.org/10.1093/icesjms/fsv102 eng eng Oxford University Press Catch-and-release of Atlantic cod (Gadus morhua) in recreational fisheries urn:issn:1054-3139 http://hdl.handle.net/1956/10091 https://doi.org/10.1093/icesjms/fsv102 cristin:1247234 Copyright International Council for the Exploration of the Sea 2015 http://creativecommons.org/licenses/by/4.0 ICES Journal of Marine Science barotrauma signs catch-and-release containment study gas embolism post-release mortality recreational fishing swim bladder rupture Peer reviewed Journal article 2015 ftunivbergen https://doi.org/10.1093/icesjms/fsv102 2023-03-14T17:41:20Z Atlantic cod (Gadus morhua) caught in recreational fisheries are commonly released, often with barotrauma after rapid decompression. Mouth-hooked, non-bleeding cod kept in a floating net pen showed mortalities ≥40% when angled from >50 m depth, likely because of cumulative stress from ongoing barotrauma and exposure to warm surface water. In a natural setting, however, cod have the opportunity to descend after release and are not restricted to the surface. In a follow-up study, 97.8% of similarly selected cod managed to dive following immediate release, whereas 2.2% were floaters. No mortality was observed for divers kept in cages, which were lowered to capture depth for 72 h. While the floaters would likely have died in a natural setting, no mortality was observed when they were recompressed and kept at capture depth for 72 h. The occurrence of swim bladder ruptures, swollen coelomic cavities, venous gas embolisms, and gas release around the anus was significantly influenced by capture depth (range 0–90 m). A supplementary radiology study showed inflated swim bladders in 87% of the cod after 72 h, and most barotrauma signs had disappeared after 1 month. This study encourages investigation of survival potential for physoclistous species when high mortalities are assumed but undocumented. Matching natural post-release and containment environment is essential in the experimental setup, as failure to do so may bias survival estimates, particularly when a thermocline is present. Assuming minimal predation, short-term mortality of cod experiencing barotrauma is negligible if cod submerge quickly by themselves and are otherwise not substantially injured. Survival of floaters may be increased by forced recompression to capture depth. Sublethal and long-term impacts of barotrauma remain to be studied. To ensure that cod have sufficient energy to submerge, anglers are encouraged to avoid fighting the fish to exhaustion and to minimize handling before release. publishedVersion Article in Journal/Newspaper atlantic cod Gadus morhua University of Bergen: Bergen Open Research Archive (BORA-UiB) ICES Journal of Marine Science 72 8 2467 2481
institution Open Polar
collection University of Bergen: Bergen Open Research Archive (BORA-UiB)
op_collection_id ftunivbergen
language English
topic barotrauma signs
catch-and-release
containment study
gas embolism
post-release mortality
recreational fishing
swim bladder rupture
spellingShingle barotrauma signs
catch-and-release
containment study
gas embolism
post-release mortality
recreational fishing
swim bladder rupture
Ferter, Keno
Weltersbach, Marc Simon
Humborstad, Odd Børre
Fjelldal, Per Gunnar
Sambraus, Florian
Strehlow, Harry Vincent
Vølstad, Jon Helge
Dive to survive: effects of capture depth on barotrauma and post-release survival of Atlantic cod (Gadus morhua) in recreational fisheries
topic_facet barotrauma signs
catch-and-release
containment study
gas embolism
post-release mortality
recreational fishing
swim bladder rupture
description Atlantic cod (Gadus morhua) caught in recreational fisheries are commonly released, often with barotrauma after rapid decompression. Mouth-hooked, non-bleeding cod kept in a floating net pen showed mortalities ≥40% when angled from >50 m depth, likely because of cumulative stress from ongoing barotrauma and exposure to warm surface water. In a natural setting, however, cod have the opportunity to descend after release and are not restricted to the surface. In a follow-up study, 97.8% of similarly selected cod managed to dive following immediate release, whereas 2.2% were floaters. No mortality was observed for divers kept in cages, which were lowered to capture depth for 72 h. While the floaters would likely have died in a natural setting, no mortality was observed when they were recompressed and kept at capture depth for 72 h. The occurrence of swim bladder ruptures, swollen coelomic cavities, venous gas embolisms, and gas release around the anus was significantly influenced by capture depth (range 0–90 m). A supplementary radiology study showed inflated swim bladders in 87% of the cod after 72 h, and most barotrauma signs had disappeared after 1 month. This study encourages investigation of survival potential for physoclistous species when high mortalities are assumed but undocumented. Matching natural post-release and containment environment is essential in the experimental setup, as failure to do so may bias survival estimates, particularly when a thermocline is present. Assuming minimal predation, short-term mortality of cod experiencing barotrauma is negligible if cod submerge quickly by themselves and are otherwise not substantially injured. Survival of floaters may be increased by forced recompression to capture depth. Sublethal and long-term impacts of barotrauma remain to be studied. To ensure that cod have sufficient energy to submerge, anglers are encouraged to avoid fighting the fish to exhaustion and to minimize handling before release. publishedVersion
format Article in Journal/Newspaper
author Ferter, Keno
Weltersbach, Marc Simon
Humborstad, Odd Børre
Fjelldal, Per Gunnar
Sambraus, Florian
Strehlow, Harry Vincent
Vølstad, Jon Helge
author_facet Ferter, Keno
Weltersbach, Marc Simon
Humborstad, Odd Børre
Fjelldal, Per Gunnar
Sambraus, Florian
Strehlow, Harry Vincent
Vølstad, Jon Helge
author_sort Ferter, Keno
title Dive to survive: effects of capture depth on barotrauma and post-release survival of Atlantic cod (Gadus morhua) in recreational fisheries
title_short Dive to survive: effects of capture depth on barotrauma and post-release survival of Atlantic cod (Gadus morhua) in recreational fisheries
title_full Dive to survive: effects of capture depth on barotrauma and post-release survival of Atlantic cod (Gadus morhua) in recreational fisheries
title_fullStr Dive to survive: effects of capture depth on barotrauma and post-release survival of Atlantic cod (Gadus morhua) in recreational fisheries
title_full_unstemmed Dive to survive: effects of capture depth on barotrauma and post-release survival of Atlantic cod (Gadus morhua) in recreational fisheries
title_sort dive to survive: effects of capture depth on barotrauma and post-release survival of atlantic cod (gadus morhua) in recreational fisheries
publisher Oxford University Press
publishDate 2015
url http://hdl.handle.net/1956/10091
https://doi.org/10.1093/icesjms/fsv102
genre atlantic cod
Gadus morhua
genre_facet atlantic cod
Gadus morhua
op_source ICES Journal of Marine Science
op_relation Catch-and-release of Atlantic cod (Gadus morhua) in recreational fisheries
urn:issn:1054-3139
http://hdl.handle.net/1956/10091
https://doi.org/10.1093/icesjms/fsv102
cristin:1247234
op_rights Copyright International Council for the Exploration of the Sea 2015
http://creativecommons.org/licenses/by/4.0
op_doi https://doi.org/10.1093/icesjms/fsv102
container_title ICES Journal of Marine Science
container_volume 72
container_issue 8
container_start_page 2467
op_container_end_page 2481
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