Comment on "Slow adaptation in the face of rapid warming leads to collapse of the Gulf of Maine cod fishery".

Pershing et al (Reports, 13 November, p. 809) concluded that failure to account for temperature in the assessment and management of Gulf of Maine Atlantic cod caused overfishing. We argue that the "extra mortality" calculation driving this conclusion is an artifact. Environmental factors affect all stocks, but attribution of additional mortality to temperature alone by Pershing et al is unsupported by the data.