An assessment of the immediate effect of the Braer oil-spill on the growth of herring larvae using otolith microstructure analysis

Herring larvae were sampled around the Shetland Isles as part of an environmental monitoring programme in the immediate aftermath of the wreck of the oil tanker Braer on 5 January 1993. Otolith microstructure analysis was used to investigate the short term effect of the oil pollution on the growth rate of the larvae. The results failed to detect any differences in growth between larvae sampled at stations heavily affected by oil and those outside the affected area. Otolith growth was also very similar before and after the spill, and to growth rates measured in January 1990 in the same area. However, the oil concentrations to which the larvae were exposed exceeded the threshold concentration for sublethal effects on larval fish in laboratory experiments. Longer term effects cannot therefore be ruled out.