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Detection of Passive Integrated Transponder Tags from Juvenile Salmonids on Piscivorous Bird Colonies in the Columbia River Basin
Author(s) -
Ryan Brad A.,
Ferguson John W.,
Ledgerwood Richard D.,
Nunnallee Edmond P.
Publication year - 2001
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(2001)021<0417:dopitt>2.0.co;2
Subject(s) - transponder (aeronautics) , antenna (radio) , fishery , endangered species , structural basin , juvenile , drainage basin , environmental science , geography , ecology , telecommunications , geology , cartography , habitat , biology , computer science , meteorology , paleontology
We modified 400‐kHz passive integrated transponder (PIT) tag detection equipment, previously used in water, to detect PIT tags in piscivorous bird‐nesting areas in the Columbia River basin. Two land‐based recovery mechanisms were developed: a flat‐plate antenna that was drawn over the surface of bird‐nesting areas with a four‐wheel‐drive vehicle and a pole‐mounted antenna that was passed by hand over smaller nesting areas. In 1998 and 1999, we detected more than 100,000 unique PIT tag codes by the use of the flat‐plate antenna, and in 1999, we detected more than 10,000 unique PIT tag codes by the use of the pole‐mounted antenna. Codes were detected for every release year since 1987, the first year that salmonids were marked with PIT tags in the Columbia River basin; however, the majority of tag codes came from juveniles marked for the 1999 migration year (>50,000 tag codes recovered). In 2000, researchers in the Columbia River basin changed to a 134.2‐kHz PIT tag, in accordance with guidelines from the International Standards Organization (ISO). We are adapting the land‐based apparatus to detect ISO tags, which will provide information on management issues critical to recovering salmonid stocks listed under the Federal Endangered Species Act.