There have always been plenty in UK zoos- forming an increasingly important back-up population now perhaps.
I beg to differ actually. Aside and sadly, the interest and commitment from the ex situ captive-breeding / conservation breeding community as not always been that much of a significant deterrant to their continued decline in the wilds in north-eastern Sulawesi nor assisting in stabilising populations. At times, the program has been in a stalemate with no or no significant breeding in zoos. Nota Bene: One UK zoo that has stood apart in this - I must add - was Paignton Zoo where Dr. Melfi (now at Taronga) with the Whitley Trust set up the in situ Sulawesi conservation program that is still active in Tangkoko and Minahassa Province in northern Sulawesi. Right now, a local NGO Selamatkan Yaki has more or less taken over control, while still being supported by many individual zoos overseas.
I wasn't suggesting that to date there has been any real connection between the captive and wild populations. Free-breeders in zoos, there may also have been population controls on this species which is very well represented in UK zoos.(From memory there are groups, some of them sizeable; at Chester, London, Paignton, Jersey, Marwell, Newquay(?) Dudley, Thrigby(?) Drusillas, Howletts -and probably more) But maybe with the increasing rarity in the wild, this population might now become more important?
The captive population is now more important than ever. It would certainly help also if some more zoos would assist with rehousing and rehab programmes for confiscated macaques in situ. It is an open ... door at the moment in some of the rescue centers.