State prisoners are being considered to do the low-paying work of crab picking. With temporary workers from Mexico in demand nationwide, only one of Maryland’s 21 seafood processing plants was able to secure visas this year. Women’s prison units in Jessup and Baltimore were toured this week by members of the Chesapeake Bay Seafood Industries Association. Corrections officials also have toured two Dorchester County crab houses. Maryland inmates already make furniture and butcher meat.