Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coast
Abstract Dramatic and persistent reductions in Atlantic cod (Gadus morhua) are common in many coastal areas. While offshore cod stocks still were abundant and productive, the Swedish west coast showed signs of diminishing adult cod abundance at the beginning of the 1980s, where the local cod compone...
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Online Access: | http://dx.doi.org/10.1093/icesjms/fsy166 http://academic.oup.com/icesjms/article-pdf/76/2/418/31238363/fsy166.pdf |
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croxfordunivpr:10.1093/icesjms/fsy166 2024-05-12T08:00:56+00:00 Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coast Svedäng, Henrik Barth, Julia M I Svenson, Anders Jonsson, Patrik Jentoft, Sissel Knutsen, Halvor André, Carl Secor, David Swedish Agency for Marine and Water Management Gothenburg University Centre for Marine Evolutionary Biology 2018 http://dx.doi.org/10.1093/icesjms/fsy166 http://academic.oup.com/icesjms/article-pdf/76/2/418/31238363/fsy166.pdf en eng Oxford University Press (OUP) https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model ICES Journal of Marine Science volume 76, issue 2, page 418-429 ISSN 1054-3139 1095-9289 Ecology Aquatic Science Ecology, Evolution, Behavior and Systematics Oceanography journal-article 2018 croxfordunivpr https://doi.org/10.1093/icesjms/fsy166 2024-04-18T08:15:40Z Abstract Dramatic and persistent reductions in Atlantic cod (Gadus morhua) are common in many coastal areas. While offshore cod stocks still were abundant and productive, the Swedish west coast showed signs of diminishing adult cod abundance at the beginning of the 1980s, where the local cod component was considered to be extirpated. To survey the present cod spawning activity and stock composition, we initiated egg trawling over two consecutive years (203 hauls in total) in combination with population genetic analyses (425 individually genotyped eggs). Here, we provide evidence of cod spawning at the Swedish Skagerrak coast, suggesting recolonization or that local cod has recovered from a nearly depleted state. Early stage eggs were found inside fjords too far to have been transported by oceanic drift from offshore spawning areas. The cod eggs were genetically similar in early to late life-stages and cluster mainly with the local adult cod, indicating that eggs and adults belong to the same genetic unit. The cod eggs were genetically differentiated from adult North Sea cod, and, to a lesser degree, also from the Kattegat and Öresund cod, i.e. indicating a possible recovery of local coastal stock. The patterns of the genetic structure in the inshore areas are, however, difficult to fully disentangle, as Atlantic cod in the North Sea-Skagerrak area seem to be a mixture of co-existing forms: local cod completing their entire life cycle in fjords and sheltered areas, and oceanic populations showing homing behaviours. The egg abundances are considerably lower compared with what is found in similar studies along the Norwegian Skagerrak coast. Nevertheless, the discovery of locally spawning cod along the Swedish west coast—although at low biomasses—is an encouraging finding that highlights the needs for endurance in protective measures and of detailed surveys to secure intraspecific biodiversity and ecosystem services. Article in Journal/Newspaper atlantic cod Gadus morhua Oxford University Press Kattegat ENVELOPE(9.692,9.692,63.563,63.563) ICES Journal of Marine Science 76 2 418 429 |
institution |
Open Polar |
collection |
Oxford University Press |
op_collection_id |
croxfordunivpr |
language |
English |
topic |
Ecology Aquatic Science Ecology, Evolution, Behavior and Systematics Oceanography |
spellingShingle |
Ecology Aquatic Science Ecology, Evolution, Behavior and Systematics Oceanography Svedäng, Henrik Barth, Julia M I Svenson, Anders Jonsson, Patrik Jentoft, Sissel Knutsen, Halvor André, Carl Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coast |
topic_facet |
Ecology Aquatic Science Ecology, Evolution, Behavior and Systematics Oceanography |
description |
Abstract Dramatic and persistent reductions in Atlantic cod (Gadus morhua) are common in many coastal areas. While offshore cod stocks still were abundant and productive, the Swedish west coast showed signs of diminishing adult cod abundance at the beginning of the 1980s, where the local cod component was considered to be extirpated. To survey the present cod spawning activity and stock composition, we initiated egg trawling over two consecutive years (203 hauls in total) in combination with population genetic analyses (425 individually genotyped eggs). Here, we provide evidence of cod spawning at the Swedish Skagerrak coast, suggesting recolonization or that local cod has recovered from a nearly depleted state. Early stage eggs were found inside fjords too far to have been transported by oceanic drift from offshore spawning areas. The cod eggs were genetically similar in early to late life-stages and cluster mainly with the local adult cod, indicating that eggs and adults belong to the same genetic unit. The cod eggs were genetically differentiated from adult North Sea cod, and, to a lesser degree, also from the Kattegat and Öresund cod, i.e. indicating a possible recovery of local coastal stock. The patterns of the genetic structure in the inshore areas are, however, difficult to fully disentangle, as Atlantic cod in the North Sea-Skagerrak area seem to be a mixture of co-existing forms: local cod completing their entire life cycle in fjords and sheltered areas, and oceanic populations showing homing behaviours. The egg abundances are considerably lower compared with what is found in similar studies along the Norwegian Skagerrak coast. Nevertheless, the discovery of locally spawning cod along the Swedish west coast—although at low biomasses—is an encouraging finding that highlights the needs for endurance in protective measures and of detailed surveys to secure intraspecific biodiversity and ecosystem services. |
author2 |
Secor, David Swedish Agency for Marine and Water Management Gothenburg University Centre for Marine Evolutionary Biology |
format |
Article in Journal/Newspaper |
author |
Svedäng, Henrik Barth, Julia M I Svenson, Anders Jonsson, Patrik Jentoft, Sissel Knutsen, Halvor André, Carl |
author_facet |
Svedäng, Henrik Barth, Julia M I Svenson, Anders Jonsson, Patrik Jentoft, Sissel Knutsen, Halvor André, Carl |
author_sort |
Svedäng, Henrik |
title |
Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coast |
title_short |
Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coast |
title_full |
Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coast |
title_fullStr |
Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coast |
title_full_unstemmed |
Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coast |
title_sort |
local cod (gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the swedish skagerrak coast |
publisher |
Oxford University Press (OUP) |
publishDate |
2018 |
url |
http://dx.doi.org/10.1093/icesjms/fsy166 http://academic.oup.com/icesjms/article-pdf/76/2/418/31238363/fsy166.pdf |
long_lat |
ENVELOPE(9.692,9.692,63.563,63.563) |
geographic |
Kattegat |
geographic_facet |
Kattegat |
genre |
atlantic cod Gadus morhua |
genre_facet |
atlantic cod Gadus morhua |
op_source |
ICES Journal of Marine Science volume 76, issue 2, page 418-429 ISSN 1054-3139 1095-9289 |
op_rights |
https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model |
op_doi |
https://doi.org/10.1093/icesjms/fsy166 |
container_title |
ICES Journal of Marine Science |
container_volume |
76 |
container_issue |
2 |
container_start_page |
418 |
op_container_end_page |
429 |
_version_ |
1798842998035841024 |