Shipping line Hamburg Süd said Wednesday it would shift its container operations from the Port of Seattle to the Port of Tacoma at the end of July.

The announcement comes four months after the so-called "Grand Alliance" consortium of major shippers said its members would move from Terminal 18 on Seattle's waterfront to Tacoma's Washington United Terminals, shifting some 400,000 units of cargo to Tacoma.

Hamburg Süd's decision was not unexpected: It jointly operates the Mediterranean Pacific Service between Livorno, Italy and Pacific Rim ports with fellow German carrier — and Grand Alliance member — Hapag-Lloyd. The weekly service consists of eight Hapag-Lloyd and two Hamburg Süd vessels.

In a statement, the Port of Tacoma estimated that together, the two carriers would bring 32,000 container units a year to its terminals.

The last Hamburg Süd ships are expected to arrive at Seattle on July 27 and 29, and the first ones to call at Tacoma are due in early August.

Vessels from the other Grand Alliance lines — Orient Overseas Container Line of Hong Kong and Japan's NYK Line, as well as associated carrier ZIM Integrated Shipping Services of Israel — will begin calling at Washington United Terminals at the end of this month, the Tacoma port statement said.

Container operations generated nearly three-quarters of the Seattle seaport's 2011 net operating income of $60.7 million.

The seaport accounts for about 28 percent of the Port's total operating income, with Seattle-Tacoma International Airport generating most of the rest.

Drew DeSilver: 206-464-3145 or ddesilver@seattletimes.com