Data used to produce linear models of phototactic behaviour and light preference in Heatwaves and anthropogenic light may disrupt phototaxis‑based behaviours that regulate early-life migrations of fish' Roberts et al.

These data are from Y-maze experiments, used to characterise the progression of phototaxis and colour preference of a coregonine fish native to Lake Constance (Coregonus wartmanni) throughout larval ontogeny. We hypothesised that positive phototaxis and colour preference for mid-spectrum light (i.e. yellow/green) could act as a mechanism to lead fish to shallow nursery areas. Subsequent reduction in positive phototaxis and colour preference could also trigger fish to leave nursery areas and enter deeper, darker juvenile habitats. Based on observations of wild fish leaving a nursery site earlier in warmer years, we also hypothesised that a rapid temperature increase could disrupt innate phototactic behaviours, which retain fish in nurseries. The Y-maze experiments tested the positive phototactic behaviour of the larvae using the presence or absence of light in a Y-maze arm. Colour preference of fish towards blue, red or yellow light was also tested in the Y-mazes. In the later part of larval ontogeny, we also tested groups of fish which had and hadn't experienced a rapid temperature increase in the Y-maze experiments to examine the impacts of events such as heatwaves on phototactic behaviours. We found Coregonus wartmanni larvae to initially exhibit strong positive phototaxis and preference for yellow light, which reduced as larvae developed. Larvae which experienced a heatwave exhibited precocious reduced preference for mid-spectrum light. Our findings highlight the danger of the increasing frequency of heatwave events on freshwater fish species, as they may cause them to prematurely leave nursery areas. Full details of this study are available in the publication 'Heatwaves and anthropogenic light may disrupt phototaxis-based behaviours that regulate early-life migrations of fish', Roberts et al., which has been accepted for publication in the journal Freshwater Biology but is not yet published. Upon publication of the article, a link will be given here.