Abstract
This study supplements and builds upon the findings from Love et al. (2017a) on red rock crab behavior to increase our understanding of potential consequences that renewable energy projects may have to commercial harvest. Our primary objective was to verify the response of rock crab in the presence of energized cables associated with MRE installations, while also controlling for environmental conditions. To do this, we quantified and mapped local magnetic fields near an energized cable at the study site, determined if the energized cable altered crab responses, and described and quantified variables that were most likely to affect crab responses, including water current direction/velocity, magnetic field strength, and physical characteristics of each crab. Our experimental design specifically addressed three questions and the following null (H0) and alternative (Ha) hypotheses:
1) Will the requirement of crossing an artificial magnetic field from an energized power cable affect the rate at which crabs will enter a baited trap? HO: There is no difference in the rate crabs enter a baited trap with or without needing to cross an electromagnetic field HA: There is a difference in the rate crabs enter a baited trap with or without needing to cross an electromagnetic field
2) Does the presence of a submarine power cable and associated artificial magnetic field affect the direction of crab travel? HO: There is no difference in the direction of travel with or without the presence of a submarine power cable HA: There is a difference in the direction of travel with or without the presence of a submarine power cable
3) Does water current direction/velocity, magnetic field strength, or physical characteristics of the crabs influence the direction of travel or rate to which crabs will enter a baited trap? HO: There is no relationship between the rate crabs enter a baited trap or the direction they travel and water current direction/velocity, magnetic field strength, or physical characteristics of the crabs HA: There is a relationship between the rate crabs enter a baited trap or the direction they travel and water current direction/velocity, magnetic field strength, or physical characteristics of the crabs