Atlantic herring use a time-compensated sun compass for orientation
Lisa Spiecker1,*,‡, Malien Laurien1,*, Wiebke Dammann1, Andrea Franke2,3, Catriona Clemmesen4 and Gabriele Gerlach1,2
ABSTRACT
Atlantic herring (Clupea harengus), an ecologically and economically important species in the northern hemisphere, shows pronounced seasonal migratory behaviour. To follow distinctive migration patterns over hundreds of kilometers between feeding, overwintering and spawning grounds, they are probably guided by orientation mechanisms. We tested whether juvenile spring-spawning Atlantic herring, caught in the western Baltic, use a sun compass for orientation just before they start leaving their hatching area. Fish were randomly divided into two groups, one of them clock-shifted 6 h backwards, to investigate whether they shift their orientation direction accordingly. Individual fish were placed in a circular bowl and their orientation was tested multiple times with the sun as a sole visual orientational cue. Our results show for the first time that juvenile Atlantic herring use a time-compensated sun compass during their migration. Their swimming direction was impaired, but still present, even when the sky was very cloudy, indicating additional orientation capabilities.
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Editor’s Remark
Our hero Tristan Gooley has navigated across Crete proving that your brain can calculate direction from the sun’s bearing over the day and its altitude. I am certain that this is how most mammals navigate so it is exciting that this paper says the Herrings do it too. Perhaps this explains why people are terrified by Dark Forests as the sun is obscured so they get lost.