Ground-truthing the ground-truth: reply to Garibaldi et al.'s comment on “Managing fisheries from space: Google Earth improves estimates of distant fish catches”

There has been a growing interest in the potential of Google Earth for scientific inquiries, and our previous paper (Al-Abdulrazzak and Pauly, 2014. Managing fisheries from space: Google Earth improves estimates of distant fish catches. ICES Journal of Marine Science, 71: 450–454) on weirs and their catch in the Persian Gulf is a case in point. Garibaldi et al. (2014. Comment on: “Managing fisheries from space: Google Earth improves estimates of distant fish catchs” by Al-Abdulrazzak and Pauly. ICES Journal of Marine Science), while agreeing in principle with using Google Earth for fisheries-related purposes, criticized the assumptions, data, methodology, and results of this paper. Here, we refute their criticisms, notably by showing that the “derelict weirs” that they thought they had “ground-truthed” are not weirs at all, but another type of fishing gear in one case, and debris from a boat anchoring system in the other. We develop the theme that ground-truthing requires local knowledge, and provide recommendations for using Google Earth images in fisheries management.