A cull of 400 wild boar is "needed" in the Forest of Dean but the Forestry Commission said it lacks the resources.
The commission, as part of a management plan, agreed to a population of 400 but the latest thermal imaging survey shows there are 819 wild boar in the forest.
Kevin Stannard, from the commission, said: "There needs to be a significant cull but we're not setting a 419 target because we need to increase resources."
But David Slater, from Friends of the Boar, said numbers were "sustainable".
In 2012 the cull was suspended over concerns the numbers were too low and the species could be eradicated.
But last year, despite a cull of 135 wild boar, the population increased by 284 and is now double the 400 target agreed by the commission.