read as appears on gates page.
SAT San Antonio 0 139
RSW Fort Myers 0 129
(you ain't getting them back, they're in full use).
all other gates listed, 0-1 gates, 1 frequency min if owned as they don't appear on my 'select returnable gates' page.
edit: i threw the names of about 10 inactive, substantially negative cash value airlines based out of the very first one listed in a pm, due to other concerns.
edit2: here's a little help:
Barcelona: look at ID 320, they have 56 gates there, but only 26 listed flights from it (they appear to be using 64 slots out of 560 available to them). Also they're steeply negative, my guess is inactive (but that's not my decision).
341 123fly 123 pax €-29,400,000 549
342 SEMAIR SEY pax €-29,400,000 576
343 flyfun fly pax €-29,400,000 550
344 Sk LIN SKL pax €-29,400,000 551
345 Air Future AAI pax €-29,400,000 558
346 Air Walk AIX pax €-29,400,000 562
347 Airline 1 AXX pax €-29,400,000 564
348 Dicki Air DIC pax €-29,400,000 569
349 UMU UMU pax €-29,400,000 571
350 Johston Air JOH pax €-29,400,000 572
351 Joke Air JOK pax €-29,400,000 573
352 MirAir MRA pax €-29,400,000 574
353 AirCal CAl pax €-29,400,000 575
354 WALTAIR XXX pax €-29,400,000 578
10 of these are based on LCJ (the others seem to be based in problem cities primarily). they also all have 0 aircraft, and identical debts. (fishy?) that's 20 of the 50 gates at LCJ identified.
edit3: I realize southampton is not identified on your list, but ID=604 has 11 gates there, 0 flights anywhere.
Maxxline has 5 gates at rsw, uses 28 slots (note, if freed, i can and will expand further in RSW, likely returning it to 0 within 24 hours. mmm. planes.)
Manchester isn't on the list, but it has 0 flights anywhere, 0 planes, and 8 gates at manchester (plus a few misc.)