I was one of the only vets in the world that specialized in poison dart frogs. This type of specialization is such a tremendous pain in the @$$, that I could not come close to describing the endless agony - of dealing with the dart frog enthusiasts.
Actually, depending on how loosely you define neutering, you can extend the life span of some cephalopods by removing the gland that controls ovarian development and brooding behavior. In a classic paper by Wodinsky (Science, 1977), he demonstrated that in Octopus hummelincki, the removal of the optic gland "... after spawning results in cessation of broodiness, resumption of feeding, increased growth, and greatly extended life-span."
NO actually it's the addition of the lubricating slime of the steppes cuttlefish to the monks diet . Apparently the secretions enable the cuttlefish to get around on the grasses etc found on the steppes!
But seriously folks.....I wouldn't want to muck around with removal or destruction of the optic gland unless I was VERY familiar with the anatomy of the octopus. I know approximately where it is but my exerience is with DEAD octopus!!!! Plus there's the issue of appropriate anaesthesia PLUS in NZ it's illegal to carry out such work without the correct ethics approval (per the Animal Welfare Act)!!!!