This is disturbing (boldface mine):
Astudy published Tuesday in the journal Nature Communications suggests that the national data many countries have submitted to the UN’s Food and Agriculture Organization (FAO) has not always accurately reflected the amount of fish actually caught over the past six decades. And the paper indicates that global fishing practices may have been even less sustainable over the past few decades than scientists previously thought.
The FAO’s official data report that global marine fisheries catches peaked in 1996 at 86 million metric tons and have since slightly declined. But a collaborative effort from more than 50 institutions around the world has produced data that tell a different story altogether. The new data suggest that global catches actually peaked at 130 metric tons in 1996 and have declined sharply — on average, by about 1.2 million metric tons every year — ever since…
Scientists had previously noticed, for instance, that when nations recorded “no data” for a given region or fishing sector, that value would be translated into a zero in FAO records — not always an accurate reflection of the actual catches that were made.
Yes, the absence of data was recorded as a value of zero.