OLYMPIA– New technology is changing decades-old procedures the Washington Department of Fish and Wildlife (WDFW) uses to collect data from anglers' chinook salmon catches.
Because of the changes, WDFW soon will hold the last cash prize drawing for anglers who turn in the heads from chinook caught last November and December.
In the past WDFW held the drawings to encourage anglers to turn in fish heads that contained coded wire tags bearing information about the fish's hatchery or stream of origin.
Now instead, WDFW samplers will contact salmon anglers in the field, passing electronic "wands" over chinook catches to detect the presence of the small (1/25th of an inch) coded wire tags. When tags are detected, those salmon heads will be collected and sent to WDFW laboratories for data recording.
The same technique already is being used to detect coded wire tags in coho salmon catches. The reward system for voluntary coho salmon head recovery was discontinued in 1998.
In the past, anglers could identify which salmon heads to turn in because fish implanted with coded wire tags were marked by the removal of the small adipose fin on the fish's lower back. WDFW laboratory technicians removed the coded wire tags from fish heads that were returned, read the tag data under microscopes and collected the information to reconstruct a "snapshot" of the size and composition of a particular year's returning salmon run.
In recent years, however, fin-clip marking has been much more broadly used. Instead of being reserved only for fish implanted with coded wire tags, now millions of hatchery-produced chinook and coho are marked for future selective fishing– allowing anglers to distinguish catchable, hatchery salmon from protected wild stocks that must be released.
Mass marking of state hatchery chinook began in 1999, with coho mass marking starting several years earlier. Last year, WDFW marked some 30 million of each species. The first mass-marked chinook will return to Washington waters this year, necessitating the change in the way chinook heads are checked for coded wire tags.
With millions of marked salmon in the water, the task of checking all fin-clipped fish for the presence of coded wire tags would be overwhelming. WDFW biologists would have had to process thousands, rather than hundreds, of fish heads— the vast majority of which would not contain the coded wire tags they sought. With the electronic wand detection method, however, only those salmon heads containing the tags will be collected.