I'd like to know how they derived that margin of error, when DNA technology is promoted as virtually infallible. Maybe they took a bunch of short cuts.
100% sure of the individual fish. not so sure about every fish being sold as red snapper.
It is a function of sample size. Just like the +/- n% you see on polls. For all statistics, larger samples = smaller error; smaller samples = larger error. In this case they only have a sample size of 22 so the error bars are wider.