NOAA has an answer according to this report from BairdMaritime. The short answer is “…the commercial fishing and seafood industry including imports generated US$153 billion in sales in 2014, an eight per cent increase from 2013, and supported 1.39 million jobs such as harvesters, processors, dealers, wholesalers and retailers…Domestic harvest without imports produced US$54 billion in sales, a figure similar to 2013, and supported 811,000 jobs…”.

You can see the full report here: Fisheries Economics of the United States, 2014 (pdf)

(Despite the 2014 date, the report was issued in May 2016.)