Most of those 'gray hairs' had been there since the beginning (1970s) meaning they had been working the field for around 40+ years and assuming they were at least 15 years old when they started, we're near retirement age when oil prices crashed three years ago.  Like any smart business, BP offered a nice retirement package to high wage employees.  Many of those experienced employees, who rightly were earning some serious cash, chose to go enjoy the retirement they earned. It's not just BP but every long standing North Slope employer are facing a related issue which is predicted to get worse over the next 5 to 7 years with the 'graying' of the workforce as a significant and important part of the workforce who have been there since the beginning head south for the last time.