Reasons Cromwell data superior to at Sea Cromwell 1. More limited number of observers over course of project - (lessening effects of subjective variabilities) 2. Constant # of observers 3. Consistently greater experience of Cromwell observers 4. Precise navigation + hence same areas consistently visited month by month 5. Larger grid, more observation 6. Constant observation conditions (same ship) 7. Hydrographic data available At Sea 1. Greater number of observers over course of project 2. Variable # of observers 1-5, 6 3. Lesser + more variable experience 4. Very poor navigation, variable grid 5. Smaller grid, less observation 6. Inconstant observation conditions (N ships) 7. Hydrographic data not available [illegible]