Royal Dutch Shell Plc’s (RDSa.L) decision last week to walk away from its $7 billion drilling effort in the Alaska Arctic could have a negative impact on the state’s already struggling economy, Moody’s said in a note released on Monday. Although the exploration and drilling would have occurred in federal water and would not have directly contributed to state revenues, the decision to stop the project is still “credit negative” for Alaska, the ratings agency said.