In its role as a breeding-ground for oysters it is natural for the Lucrine to be designated stagnum rather than lacus.
Circeis nata forent an Lucrinum ad stagnum Rutupinoue edita fundo ostrea callebat primo deprendere morsu.(18)
From stagnum to saxum is palaeographically an easy change; the error might have been perpetrated by a scribe whose understanding of oyster-culture was no more precise than vague notions of collecting molluscs off the rocks at low tide.(19)
But if stagnum is right for the context, it remains to determine whether it is right for Juvenal's tone.
ist anzunehmen, dass stagnum im technischen Sinn als Teich fur Fische oder Austern ...
16 Columella concludes 8.16 with the programmatic statement 'sed iam de situ piscinarum dicendum est'; the first sentence of 8.17 begins 'stagnum censemus eximie optimum, quod sic positum est, ut ...'.
18 If 'Lucrinum ad stagnum' is the correct reading, this is an instance where ad is used loosely instead of in with the ablative, as is occasionally attested with the names of cities, countries, and islands: see L-H-S ii.