IMR_2025_Cod-Tag

Forty years of Atlantic cod tag-recapture data from Norway

Dataset Creator	Dataset Title	Dataset Release Date	Dataset Publisher	Dataset DOI	Online Resource
Kathrine Michalsen, Ove Djupevåg and Terje Svåsand	Forty years of Atlantic cod tag-recapture data from Norway	2025-01-27T00:00:00:00Z	Institute of Marine Research	10.21335/NMDC-308042590	http://metadata.nmdc.no/metadata-api/landingpage/a55036b6be83f65af170578192518e15

Role	First Name	Last Name
Investigator	Kathrine	Michalsen
Technical Contact	Terje	Svåsand
DIF Author	Arnfinn	Morvik
Technical Contact	Ove	Djupevåg

Category	Topic	Term	Variable Level 1	Variable Level 2	Variable Level 3
EARTH SCIENCE	BIOLOGICAL CLASSIFICATION	ANIMALS/VERTEBRATES	FISH	RAY-FINNED FISHES	CODS/HADDOCKS
EARTH SCIENCE	OCEANS	AQUATIC SCIENCES	FISHERIES

Oceans

Atlantic cod,Gadus morhua L.,distribution,population structure,migration,fisheries management,mark-recapture,tagging

Start Date	Stop Date
1946-01-01	1991-12-31

Complete

Location Category	Location Type	Location Subregion1
Ocean	Atlantic Ocean	North Atlantic Ocean

unrestricted

Institute of Marine Research

Data Center Name	Personnel	Data Center URL
Institute of Marine Research, Norwegian Marine Data Center Institute of Marine Research, Norwegian Marine Data Center	Datacenter Arnfinn Morvik
NO/IMR Institute of Marine Research	Originating institution Kathrine Michalsen	http://www.imr.no

Distribution Media	Distribution Format
ftp	excel

Anon. A guide to fish marks. J Cons Int Explor Mer 1953; 19: 241-289. Dannevig G. Tagging experiments on cod, Lofoten 1947–1952: Some preliminary results. ICES J Mar Sci 1953; 19: 195-203. Jakobsen T. Coastal Cod in Northern Norway. Fish Res 1987; 5: 223-234. https://doi.org/10.1016/0165-7836(87)90042-7 Svåsand T, Michalsen K, Fall J, et al. Analysis of long-term Atlantic cod tag-recapture data from Norway reveals insights into historical migration patterns and mortality rates of Norwegian coastal cod. ICES J Mar Sci 2025; 82. https://doi.org/10.1093/icesjms/fsaf137

The IMR tag-recapture dataset comprises a total of 50 304 recaptures from the releases of 175 200 tagged cod along the Norwegian coast and in the Barents Sea during the period 1946-1991. The Atlantic cod were caught using different methods depending on the location of tagging, prevailing conditions, and the expertise of the fishermen involved. In some areas, cod were caught in shallow water (~25 m) by rod or longline, while in other areas cod were caught using bottom trawl, Danish seine and purse seine (Jakobsen 1987). All fish were marked with various external conventional tags, primarily Lea tags (Anon. 1953, Dannevig 1953). All tags used, contained a unique number and an information letter, and were fastened to the fish with nylon gut in front of the anterior dorsal fin (Anon. 1953). All tagged fish were measured to the nearest centimetre before being released at locations identified by their latitude and longitude. Advertising, educational programs and different reward schemes have been used during this period to ensure as high reporting rate of recaptured tags as possible. In cases where it was not possible to identify the exact geographic coordinates for recaptured fish, primarily for individuals captured offshore, the midpoint of the grid location in which the capturing vessel had operated was used, as defined by the Norwegian Directorate of Fisheries. The grid locations extend 1° eastward and 0.5° northward (1.0x0.5° grid). The distance in the northward direction is constant at 55.6 km, while the distance in the eastward direction depends on latitude but is 38.0 km at 70°N, and 55.6 km at 60 °N. When near the coast, the grid locations are adjusted to the coastline. A subset of this data set has been used to look into on mortality rates and displacement distances of Norwegian coastal cod (NCC). This study included 23,231 cod released between 1954 and 1983 across four specific release zones north of 62°N, along with 7,010 recaptures (Svåsand et al. 2025).

URL Content Type	URL
GET DATA	https://ftp.nmdc.no/nmdc/IMR/Cod/tag_recapture_all_final.csv
GET DATA	https://ftp.nmdc.no/nmdc/IMR/Cod/tag_recapture_Svaasand_et_al.csv
VIEW RELATED INFORMATION	https://ftp.nmdc.no/nmdc/IMR/Cod/tag_recapture_all_description.xlsx
VIEW RELATED INFORMATION	https://ftp.nmdc.no/nmdc/IMR/Cod/tag_recapture_Svaasand_et_al_description.xlsx

Norwegian Marine Datacentre

CEOS IDN DIF

9.7.1

2025-01-27T00:00:00:00Z

CC BY 4.0

POLYGON((68.15100000000001 47.891999999999996,-54.900999999999996 47.891999999999996,-54.900999999999996 79.35,68.15100000000001 79.35,68.15100000000001 47.891999999999996))