Poker Stars, $0.25/$0.50 No Limit Hold'em Cash, 6 Players
Poker Tools Powered By Holdem Manager - The Ultimate Poker Software Suite.

SB: $69.78 (139.6 bb)
Hero (BB): $50 (100 bb)
UTG: $62.46 (124.9 bb)
MP: $51.74 (103.5 bb)
CO: $55.54 (111.1 bb)
BTN: $37.88 (75.8 bb)

Preflop: Hero is BB with 2 Q
UTG raises to $1.08, 2 folds, BTN calls $1.08, SB calls $0.83, Hero calls $0.58

Flop: ($4.32) 3 J 6 (4 players)
SB checks, Hero checks, UTG bets $1.56, BTN calls $1.56, SB folds, Hero calls $1.56

Turn: ($9.00) 7 (3 players)
Hero bets $4.75, UTG raises to $10.53, BTN calls $10.53, Hero calls $5.78

River: ($40.59) 9 (3 players)
Hero checks, UTG bets $49.29 and is all-in, Hero?

UTG 29/24 WTSD/W$SD/WWSF (30/45/48) agg 2.3 OR% EP-19%
BTN 47/23 (24\20\32)

I have a flush but opponent has a lot of better flushes and I'm not sure he would be bet Allin with small flushes like 89d or T9d. Also including weak player OTB I think UTG don't have any bluffs here. How to play better here?