Selection of External Tags for Marking Atlantic Herring (Clupea harengus harengus)

Abstract

Of seven external tags (carlin, disc and disc, disc and dangler, anchor, short anchor, dart, streamer) applied to Atlantic herring (Clupea harengus harengus), the anchor tag is the best to use when tagging rate, recovery rate, and persistence of tagged fish in the population are considered. A high recovery rate for carlin tags was more than compensated by the higher application rate exhibited by anchor and dart tags. Anchor tagged fish had a lower sustained mortality and reduced time in setting up the tags for application compared to dart tags. Tagged herring suffered higher short and apparent long-term mortalities than the unmarked population regardless of which external tag type was applied. Long-term tag loss may have been due to tag induced mortality and/or tag shedding. Consequently, studies requiring data beyond 2 yr after release would need another type of tag. Initial mortalities of herring increased with holding and handling time for all tags tested. This result confirms that herring should be tagged immediately after capture to reduce initial mortalities.