From vessel exposure to biological consequence

Traffic overlap, received sound, individual response, and population consequence describe different stages of an impact assessment. This evidence review compares two narwhal exposure studies with the Population Consequences of Disturbance framework to identify the evidence connecting those stages. It preserves the studies' small exposed samples, male or adult representation, and concurrent sound sources rather than converting their results into universal distance rules. Hypothetical comparisons show why identical animal-hours can distribute exposure differently and why a lower sound level over a longer passage need not reduce integrated exposure. No actual route impact or safe buffer is estimated. The review supports proportionate precaution while distinguishing measured responses, energetic assumptions, demographic inference, and unresolved mechanisms that additional observations would need to constrain.