For products, rates are seen rising as Japan imports more diesel, gasoline and fuel oil to stave off power shortages after the devastating earthquake and tsunami.
The world's benchmark Very Large Crude Carrier (VLCC) export route from the Middle East to Japan fell to W63.03 from W68.91 last week despite unprecedented trading activity.
Demand for VLCCs shipping Middle East grades surged to a record in the spot market with more than 115 fixtures in March as OPEC pumped more supplies.
At least 97 of the cargoes were Asia-bound, with the rest going to the West, said shipbroker firm Meiwa International.
''Although March has been a record month in terms of demand for VLCC tonnage in the Middle East Gulf, the overcapacity of tonnage in this size is exerting a strong pressure and rates have again fallen,'' said broker firm BRS.
Tonnage lists were long for the balance of March, and April tonnage looked ample, said broker firm SSY.
The stoppage of Libyan oil exports due to escalating violence has also pressured rates, especially in the aframax market.
The Baltic Exchange's rate for 260,000-tonne crude tankers from West Africa to China fell to a three-week low of W63.67 from W72.89 last week.
West Africa rates were expected to rebound in the coming weeks with Japan turning to Nigeria and Angola crude to feed its refineries and supplement fuel for power.
Rates for 80,000-tonne aframax tankers from Southeast Asia to East Coast Australia rose to a fresh 2011 high of W105.83 from W103.75.
Medium range (MR) tankers travelling from Singapore to Japan rose to a 10-day high of W127.21 from W126.57 last week.
The market hit a 2011 low of W126.21 earlier this month.
''For the MRs, demand rose through the course of the week and is very tight for the rest of March,'' said BRS. ''A raft of short-haul voyages has kept the market busy.''
Japanese refiners are boosting output in the wake of the supply crunch following this month's massive quake.