Life history of anadromous burbot (<i><scp>L</scp>ota lota</i>,<scp> L</scp>inneaus) in the brackish <scp>B</scp>altic <scp>S</scp>ea inferred from otolith microchemistry

Abstract

Abstract Strontium to calcium ( S r: C a) and barium to calcium ( B a: C a) ratios were quantified in 74 otoliths of brackish water‐living burbot Lota lota , collected from two regions in the eastern B altic S ea. Considerable amount of life history plasticity was observed. Ninety‐six per cent of analysed burbot were of freshwater origin; only three specimens displayed signs of hatching in low‐salinity (1–2) estuarine environment. Most of the juveniles emigrated from freshwater during late winter and spring the next year after birth, while nine individuals did so at the age of 2–3 months. Age and length at maturity (as determined by first freshwater spawning migration) varied from 2–6 years and 189–540 mm, respectively, with most of burbot maturing during the second or third year of life. It is hypothesised that the bulk juvenile downstream migration is triggered by high‐flow conditions as evidenced by B a: C a peak around the point of freshwater exit. This study provides new information on burbot life history.