VANCOUVER, British Columbia (Reuters) - Canada will launch an investigation into why far fewer sockeye salmon than scientists had predicted returned to the Fraser River on the Pacific Coast this summer. Prime Minister Stephen Harper announced the judicial inquiry on Thursday, saying the federal government was concerned about the declining sockeye population. Federal government scientists had predicted that as many as 13 million sockeye salmon would return to the river this year to breed, but it is now estimated that only about 1.4 million fish actually returned. The collapse gutted the commercial Fraser sockeye fishing season, and prompted the government of the West Coast province of British Columbia and federal opposition parties to ask...