(CNN) -- Nearly 7,000 more square miles of fishing waters were reopened in the Gulf of Mexico on Friday, leaving only 7 percent of federal waters in the region still closed to fishing operations, authorities said.
The ninth reopening since July 22 reflects continued progress on the cleanup in the aftermath of the April BP oil spill. Officials, however, caution much work remains.
"We are guardedly optimistic," said Roy Crabtree, Southeast regional administrator for the National Oceanic and Atmospheric Administration's Fisheries Service.
The commercial and recreational waters reopened Friday are nearly 200 nautical miles south of the Florida Panhandle, between the Florida-Alabama state line and Cape San Blas, Florida, federal response officials said.
Federal testing of seafood from opened fishing areas has not shown any problems.
"Tourists and consumers should know most Gulf waters are open for fishing and seafood from these waters is safe to eat," said Jane Lubchenco, NOAA's administrator.
At its peak, the area covered by the fishing closure was 88,522 square miles, or 37 percent of Gulf waters, NOAA said. A little more than 16,000 square miles remain closed.
For the most part, NOAA first concentrated on testing waters farthest from the well, believing they would be the soonest to reopen for fishing, Crabtree said.
"We also took into account the economic importance," of fishing to a community, he said, indicating that was most vital on the western side of the Mississippi River in Louisiana and off the coasts of Mississippi and Pensacola, Florida.
The overriding concern, however, was the number of days an area was exposed to the oil, he said.
Four "blocks" of gulf waters remain closed, he said. Their close proximity to the well may mean it will take longer for them to be deemed safe. Crabtree said he is confident all areas will be reopened to fishing, but some waters may not get the all-clear until 2011.
"It's too soon to draw conclusions about the long-term impact of this," he said, citing continued testing on fish eggs and larvae near the ocean surface, sub-surface oil and oil in Louisiana's marshes.
Christine Patrick, also of the NOAA Fisheries Service, told CNN that more than 2,700 seafood samples went through rigorous sensory and chemical testing, and none came up positive for the presence of oil or dispersants.
"No samples have been taken from opened fishing areas that haven't passed those tests," Patrick said earlier this week.
In September, NOAA reported that scientists found a decline in oxygen levels in the Gulf of Mexico following the BP oil spill, but did not find any "dead zones" connected to the spill A dead zone in Chandeleur Sound off Louisiana appears to be unrelated to the spill, federal officials said.
CNN's Vivian Kuo contributed to this report.