Precision of Hard Structures for Estimating the Age of Burbot

Burbot Lota lota are the only freshwater member of the family Gadidae and have a holoarctic, circumpolar distribution.  Throughout much of their distribution, burbot are declining.  Management agencies tasked with monitoring burbot populations often rely on age and growth data gleaned from calcified structures (e.g., otoliths, fin rays).  Although otoliths have been identified as reliable ageing structures for burbot, they require sacrificing fish.  Due to the status of many burbot populations, investigations on non-lethal ageing structures are warranted.  Brachiostegal rays, pectoral fin rays, and dorsal fin rays were compared to otoliths to evaluate the precision and readability of non-lethal structures for ageing burbot.  All structures were sectioned and independently read by two readers.  Between-reader precision, the relationship between readability and precision of age estimates (i.e., confidence ratings), and differences in age estimates among hard structures were evaluated.  Identifying the best non-lethal ageing structure will allow burbot conservation efforts to gain insight into age distribution and dynamic rate functions without sacrificing fish.