Alaska concluded that poor management by Exxon Shipping Co. is to blame for the nation’s worst oil spill. “Exxon Shipping’s failures and lapses in management were so numerous and pervasive that it is a wonder the Exxon Valdez was the first tanker grounded,” said Robert LeResche, head of the state inquiry into the spill. LeResche said in a 110-page report to the National Transportation Safety Board that the response to the spill by the Alyeska Pipeline Service Co. was a failure. The report follows NTSB hearings in Anchorage in May into the March 24 spill. The ship spewed 11 million gallons of oil when it hit a reef in Prince William Sound.