With the help of a seamer-friendly surface and a good serving of patience, the 30-year-old was rewarded with four for 36 from 21 overs to help dismiss the Volts for 232.
Bates, who played two one-dayers and three twenty20s for the Black Caps two years ago, was then asked to play a role with the bat as well, coming in as nightwatchman when Martin Guptill was brilliantly caught at first slip by Jesse Ryder.
He held his end up for 24 minutes before nicking to Bradley Scott. It was just long enough to protect the next man in, Jeet Raval. At stumps, Auckland was seven for two.
Otago's bowling attack has been severely depleted in recent weeks and the home team suffered another setback with Jacob Duffy limping off after one over.
Volts coach Vaughn Johnson said the pace bowler had injured his ankle and it was unclear whether he would bowl again in the match.
''We won't know until the morning but I'm over all these ... injuries,'' he said.
''We'll treat it with ice overnight and see how he wakes up in the morning. But it is not looking great, obviously.''
If Duffy cannot bowl, Otago will have to rely on all-rounder Sam Wells and veteran left-armer Scott to spearhead the attack.
Wells has been in good form this summer and Scott has been a wonderful performer for Otago in the past. But it will be a big ask for the pair who are more suited to bowling first and second change.
While the bowling is of more immediate concern, Otago's batting display was below par.
''I thought he [Bates] bowled quite well,'' Johnson said.
''He showed if you bowl a good line it is doing enough. But one or two of our guys just lost patience ... and 230-odd wasn't enough, really.''
Judging by the dents left the pitch at lunch, the surface was certainly softer than usual. The ball, though, did not seam around alarmingly.
And wickets tended to come through mistakes rather than any demons in the pitch.
Neil Broom (0) might beg to differ. The opener got a decent ball from Bates which he edged.
Aaron Redmond should have followed him into the dressing room in the next over but he was dropped in the slips on four.
Michael Bracewell showed patience initially but he was lured into a drive and bowled by Matt Quinn for 5 leaving Otago 17 for two.
Ryder has been in marvellous form all summer and looked at ease on the surface. He combined with Redmond in an 89-run partnership for the third wicket to help ease the nerves in the camp.
He flourished where others had trouble just surviving but flashed hard at a wide delivery from Colin de Grandhomme. Ryder hit six fours in his knock of 44 and his edge was probably the first time he did not middle the ball.
Redmond continued to give opportunities at the other end. He was lucky not to be run out on 15, survived a confident lbw appeal on 65 and found a gap in the slips on 69.
But for all his good fortune he also knuckled down and fought his way through to a valuable 74 before edging a delivery from Bates. He next claimed Nathan McCullum, who was tempted into chasing a delivery he would have been better served to let pass harmlessly well outside off.
His fourth wicket was the result of a mistake by Derek de Boorder, who tickled the ball through to wicketkeeper Gareth Hopkins. He ended up with five catches in a tidy display behind the stumps.
