Hi mate, I,ve never used them for cod but we use them regularly for smoothounds we take the claws off and just crack the shell with the back of a knife wether this would work for cod or not but must be worth a go normally use squid/cuttle and lug worm for cod and if you can get them fresh clams whipped on to the trace above the squid. tight lines.
every cod iv ever gutted was full of them but they were all tiny 1-1 1/2 inch max
if you got apier or seawall near ,you get adropnet put some mackrel in it & it should be full of hermits in no time,in my opiniom these r better than lug,stay on the hook better,(if u hook em right) you can use multiples or 1 big un (theres a bit of anack to getting em out the shell,or u can freeze em ,when thawed the slide out easy.o n iv always took the 2 big claws off em ,,,iv never tried hard shorecrabs
ps- fillet the mackrel first ,just use the carcase