Our
Pacific bluefin tuna tagging and collecting trip is out in the Pacific
aboard the Shogun a recreational long Range fishing boat we've used annually to
do this trip. The objective of the cruise is to electronic tag Pacific bluefin
tuna and study their migrations to the spawning grounds in the western Pacific.
In addition we hope to collect 15 to 20!bluefin tuna for the TRCC lab to
conduct feeding studies. For tagging we use two types of electronic tags
each with their target size of fish and story we hope to tell with the data
One type of electronic tag is a Pop up satellite tag that is programmed
to stay on the fish for one year and potentially show us where the largest year
classes go after foraging in the eastern Pacific hot spots. This is a hot
question in current Pacific bluefin tuna science. The other type of tag is
called an archival tag. These tags are programmed to last six years and will
provide in depth data in what a bluefin does over the entire period In 10-20
second intervals. That would be immense data and to far we've successfully used
these techniques up to three years in the Pacific and five years in the
Atlantic. These tags are brand new and when we put them in fish off the shores
of North America we hope to see them five to six years from now recaptured.
They have the potential to record the daily position, thus the journeys and
behavior in high resolution for the entire six years. They carry three
languages and all say Return for Big reward.bit takes a fisher person to
get the tag back. But we know this works to date we have 53 percent returned in
the Pacific and about twenty percent in the Atlantic. It takes a lot of
international cooperation but we are hopeful as this type of tagging has given
Atlantic and Pacific bluefin tuna researchers the most detail required to
increase our knowledge of when and where tuna spawn a critical question
essential to life history and management questions. In addition these tags
provide oceanography and behavioral data essential for better understanding the
fish.
Slow
Bite but Big Fish😎
Today
the first of July l, we got off to great start with the pop up satellite
tagging of our first fish which by measurement is the largest fish we ever have
tagged on the Shogun. The bluefin tuna was caught by a crew member and measured
177 cm in curved length. We estimate the fish was close to 190-200 lbs.
We caught the
fish using innovative techniques by the Shogun crew and met the challenge of
lifting it on board from a swim step and satellite tagging the fish. If
the tag stays on (a problem for these fast moving fish) we hope to get a year
of data on where the bluefin tuna go to spawn. Fish of this size class
are very hard to catch as bluefin tuna vision is extraordinary. We were able to
catch two more bluefin tuna of a smaller size class well above the size we
intend to collect and for our first day we ended with two archival tags and the
largest fish ever in twenty years of TRCC tagging. Great start!
- Barbara Block
