Police said on Saturday that nine men, believed to be Moroccans, were detained at Fuerteventura island on Thursday while a dozen more adults were discovered there on Friday along with 23 others on the neighbouring island of Lanzarote.
More patrols off both islands turned up the remainder, including 16 from Mali and one from Mauritania.
In the mainland town of Tarifa, Spain’s nearest point to Africa, police said on Saturday they had intercepted two further boats carrying 84 would-be North African immigrants, including two children.
Maritime police intercepted the craft in the early hours, locating the first, with 58 people on board, some three kilometres out to sea and the second an hour later just several hundred metres from the coast.
The second boat had 26 people aboard, including the two children and four pregnant women. Officials said six of them were from sub-Saharan Africa.
On 1 August, six people drowned off the Canary Islands when the small boat in which they were trying to reach the Spanish territory, the chief point of entry for would-be African immigrants, capsized.
At least 71 immigrants have drowned this year attempting to reach Spain, according to an AFP count.
Meanwhile Italian police used tear gas to foil an attempted breakout by around 40 illegal immigrants from a holding centre near the Sicilian city of Catanzaro overnight, officials said on Saturday.
Many immigrants have drowned trying to reach Europe
They said the immigrants, of various nationalities, attempted to scale a fence around the Lamizia Terme centre in the early hours of Saturday morning.
Wardens alerted police who faced a hail of rocks thrown by some of the immigrants before resorting to tear gas to quell the trouble.
Police said no-one was injured in the incident.
The immigrants are awaiting deportation under Italy's strict anti-immigration laws.
It was the sixth attempted breakout from the centre in the past four months. Recently, 10 immigrants who succeeded in getting away were recaptured after a police search.
The Lamezia Terme centre is one of several temporary holding facilities set up by the Italian government to deal with an influx of illegal immigrants, the majority of whom arrive by boat from north Africa.
Italy recently signed an agreement with Libya to increase cooperation on stemming illegal immigration from the region.