Aquatic surveys involving hand picking from the underside of stones, logs, and debris were undertaken in the Aleutian Islands, southern Alaska (Cook Inlet and Susitna River basin, Kodiak Island, Kenai Peninsula, and Prince William Sound and Copper River basin), Alexander Archipelago, Gwaii Haida, and Vancouver Island in British Columbia and Alaska.  These surveys and examination of specimens from the Canada Museum of Nature and the United States National Museum of Natural History identified four widespread  leeches: Erpobdella punctata and Haemopis lateromaculata (Nearctic),and Glossiphonia complanata and Helobdella stagnalis (Holarctic). Three Nearctic species (Erpobdella parva, Nephelopsis  obscura, and Haemopis marmorata) were not found. The first group of leeches represent a more ancient North American distribution, while glacial and sea level barriers blocked the post-glacial movement of continental leeches to the coastal islands. The conclusion is reached that coastal leeches occupied freshwater refugia throughout the Last Glacial Maximum. A similar conclusion was reached in the study of eastern Canada Newfoundland Island leeches (Madill and Hovingh 2007: Zootaxa 1657: 1-21).