The Alaska Revenue Department reports that crude oil production declined to around 546,000 barrels per day last month, about 5.7 percent less than in April 2012.
That's a faster pace of decline than in March. A spokeswoman for BP told Bloomberg News that part of that decline was because of problems with a compressor unit at its facilities there.
Oil production in Alaska peaked more than 20 years ago with slightly more than 2 million barrels of oil produced per day, state figures from last year indicate.
Alaskan lawmakers said they were working to overhaul tax laws to encourage investors to look at the state's oil reserve potential.
Last month, Spanish energy company Repsol said it had "encouraging results" from its recent campaign there. The company said Alaska is one of the more promising areas in the United States.
The U.S. Energy Department, in a 2012 assessment, nearly all of the state's oil production takes place on the North Slope.