In Puerto Cabello, near the El Palito refinery -- the scene of a spill last year -- tarry ooze marred the sandy beaches, AFP journalists saw.
Environmental researcher Eduardo Klein said the oil slick has so far caused 225 square kilometers (87 square miles) of damage, according to a post on X that included satellite images.
State oil company PDVSA did not immediately comment on the situation.
"It's now been eight days that we're practically unemployed because we can't go out to fish," fisherman Antonio Giusti told AFP.
"There is still oil" off the coast of Puerto Cabello, he added.
Last year, when the El Palito refinery caused a spill, PDVSA said it was "not heavy crude oil, but a discharge of hydrocarbons, wastewater or effluents that were directed to the coastal marine environment."
Venezuela, which has one of the world's largest oil reserves, saw production plummet from three million barrels per day more than a decade ago to 400,000 barrels per day in 2020 due to corruption, mismanagement and US sanctions.
Now, production is back to about one million barrels a day, but numerous experts say that Venezuela's equipment is in bad shape.
