TY - JOUR
T1 - Short-term tagging mortality of Baltic cod (Gadus morhua)
AU - Haase, Stefanie
AU - McQueen, Kate
AU - Mion, Monica
AU - Andersson, Magnus
AU - Hilvarsson, Annelie
AU - Olesen, Hans Jakob
AU - Svenson, Anders
AU - Casini, Michele
AU - Hüssy, Karin
AU - Radtke, Krzysztof
AU - Krumme, Uwe
PY - 2021
Y1 - 2021
N2 - Tagging-induced mortality experiments are an important component of mark-recapture studies, as they can be used to assess the appropriateness of the tagging methodology, and to improve the reliability of estimates of recapture rates used for calculations of mortality rates and population size. Here, short-term tagging mortality of Baltic cod was estimated through containment experiments in the southern Baltic Sea. Experimental cod were selected from trawl catches, and approximately half were tagged externally with T-bar tags and received an intraperitoneal injection of tetracycline-hydrochloride. The rest of the experimental cod formed the control group, and received neither tag nor injection. The tagged and control cod were mixed evenly within submersible cages, and held for 5−8 days. The experiments were conducted in different regions and during different months by different tagging teams. Overall mortality rate was 16 % (n = 324), with the mortality rate of the tagged group 19 %, and the mortality rate of the control group 13 %. A general linear mixed model was fit to assess the effect of tagging, month, experiment duration, fish length and tagging site (i.e. the combined effect of region and tagging team) on mortality. Tagging had no effect on mortality, indicating that mortality can be attributed mainly to the capture and handling procedure. There was a significantly negative relationship between fish length (range: 20−55 cm) and mortality. Mortality did not differ between the months tested, but there was a significant effect of tagging site on mortality. Tagging-related mortality should be accounted for in analyses of data from mark-recapture studies of Baltic cod, and some variability in mortality between tagging sites can be expected.
AB - Tagging-induced mortality experiments are an important component of mark-recapture studies, as they can be used to assess the appropriateness of the tagging methodology, and to improve the reliability of estimates of recapture rates used for calculations of mortality rates and population size. Here, short-term tagging mortality of Baltic cod was estimated through containment experiments in the southern Baltic Sea. Experimental cod were selected from trawl catches, and approximately half were tagged externally with T-bar tags and received an intraperitoneal injection of tetracycline-hydrochloride. The rest of the experimental cod formed the control group, and received neither tag nor injection. The tagged and control cod were mixed evenly within submersible cages, and held for 5−8 days. The experiments were conducted in different regions and during different months by different tagging teams. Overall mortality rate was 16 % (n = 324), with the mortality rate of the tagged group 19 %, and the mortality rate of the control group 13 %. A general linear mixed model was fit to assess the effect of tagging, month, experiment duration, fish length and tagging site (i.e. the combined effect of region and tagging team) on mortality. Tagging had no effect on mortality, indicating that mortality can be attributed mainly to the capture and handling procedure. There was a significantly negative relationship between fish length (range: 20−55 cm) and mortality. Mortality did not differ between the months tested, but there was a significant effect of tagging site on mortality. Tagging-related mortality should be accounted for in analyses of data from mark-recapture studies of Baltic cod, and some variability in mortality between tagging sites can be expected.
KW - Marc-recapture
KW - T-bar
KW - Teracycline hydrochloride
KW - Baltic sea cod
KW - Post-release survival
U2 - 10.1016/j.fishres.2020.105804
DO - 10.1016/j.fishres.2020.105804
M3 - Journal article
SN - 0165-7836
VL - 234
JO - Fisheries Research
JF - Fisheries Research
M1 - 105804
ER -