On 5–8 October 2017, the second one this year, and the fourth since the beginning of the TABACOD project, tagging of the Baltic cod was carried out. Cod were tagged on board the NMFRI research vessel Baltica in the Gdańsk Bay area according to the assumptions of the international research project TABACOD, co-implemented by research institutes from Denmark, Sweden and Germany, and financed by the BalticSea2020 foundation. The cruise should be considered successful for several reasons. The difference in water temperature between the surface of the sea, to which cod returned, and the bottom where they dwelled before their catching, was only 1°C, which meant that the cod did not experience thermal shock – a factor significantly deteriorating the survivability of tagged cod. Good catch per unit effort has been achieved, resulting in a record number of tagged fish of this species – 1386 individuals.
In addition, the cod were found relatively shallow – 55 m, so the barotrauma associated with taking cod out from greater depths occurred to a lesser extent. A factor favouring tagging was the semi-storm conditions at sea. They were not difficult enough to prevent tagging, and at the same time stopped fishing boats in ports while tagging, which reduced the risk of too fast catching of the tagged cod. The project aims to keep the tagged cod in the sea for as long as possible so that we can get more information about migration routes and the growth rate of these fish. It is worth mentioning that during the cruise we re-caught eight cod previously tagged by us, which to a certain extent confirms the good condition and survivability of the tagged fish.
The NMFRI Director, Dr. Emil Kuzebski, also participated in the tagging cruise. The TABACOD project is of great scientific importance for him, especially in the context of the present problems of cod fisheries. Bearing in mind the above-mentioned circumstances accompanying the tagging, one may be tempted to say that the Director’s presence favours tagging 🙂 .
We kindly ask all users of the sea – fishers, anglers, and processors to return the tagged cod, as only then will we be able to consider the tagging as fully successful.