Males will last much longer than females, even if they look darker. Their energy is needed to fight other salmon for the chance to pair up and spawn, so the meat retains nutrients. Females, on the other hand, put all of their energy into their eggs, so the meat degrades much more quickly. Chinook last longer than chum and pinks, but not quite as long as coho - at least in my experience. If you catch a decent male that isn't black (and you have a smoker), I'd say go for it. The bonus is that removing a male from the population will have minimal impact on the future population as one male can fertilize many redds.