If the Allies have poison gas, they could gas the German soldiers "covering" the mine-fields and then clear them out.
(Assuming the gas is successful in killing the Germans or suppressing attacks on the mine-clearing units.)
I think that'd be more effective than masses of conventional artillery or air raids, since many Pacific islands were bombarded thoroughly pre-invasion and the Japanese were still able to inflict lots of losses on the Allies.
A good point especially if using non-persistent agents, ie limited risk of contamination when advancing into previously held enemy territory. Also very limited risk of collateral damage as not much in the way of civilian population.