By JoNel Aleccia, msnbc.com health reporter

While we're waiting for the sniffing to begin, let's address a question that several posters already have brought up:

Why use humans rather than chemical tests?

Using human assessors rather than chemical tests for first screening is a matter of efficiency and practicality, according to Steven Wilson, chief quality officer for NOAA's inspection program. Seafood that has a noticeably oily smell or taste is considered unfit for human consumption and can't be sold.

"If you actually smell oil in there, even though the chemical may be low and safe to eat, it won't be marketable," he said. "There are times when even it fails sensory, it passes chemical."

And suspect samples are chemically tested for PAHs – polycyclic aromatic hydrocarbons, the primary components of oil and tar. But that process is expensive and time-consuming. It can cost between $400 and $800 and take four days to test a batch of fish. Better to test only the fish that seem, well, fishy, Wilson said.

Click here to read the next post in the series: Deep sea fish on the sniffing menu