Tuesday, October 3, 2017

Must be October

The TAG team had one of the most incredible runs in their 10 year plus Port Hood tagging history...six days straight on the water is almost unheard of in The Maritimes this time of year...and tagging Canadian bluefin in shorts and flip flops was previously incomprehensible. The best part was the fish were biting and we were able to deploy 25 electronic tags on multiple cohorts of giants.

The weather has kept the team on shore for a bit, allowing us to catch up on data entry, tag programming and most importantly laundry. We did manage a half day and discovered that the fish are still close by and still biting as we hooked four more fish in under 6 hours!

Troy Cameron cranks on a giant bluefin tuna

Capt. Dennis Cameron locks eyes with a bluefin

Capt Lloyd MacInnes positions the Bay Queen IV for tagging

Capt Dennis and his nephew Troy Cameron battle a bluefin

Natalie Arnoldi takes a fin clip from a fish for DNA analysis

Dr. Steve Wilson, Tom Horton and Lloyd MacInnes get ready to release a tagged bluefin back into the Gulf of St. Lawrence

First 72 hours

We arrived in Port Hood on the 19th September to kick-off the 2017 giant bluefin tagging season in the Gulf of St Lawrence, Canada. This year we are pop-up tagging to study movements and habitat use over periods of up to a year, as well as acoustic tagging. Acoustic tags have a life span of up to 10 years and emit an acoustic signal every minute or so. These signals can be “heard” by any listening stations that are in range (within half a kilometre or so) and can provide unrivalled data documenting repeat fidelity of Atlantic bluefin tuna to areas where acoustic receivers are present, such as the Gulf of St Lawrence. As these tags stay active on the fish for such long periods, we can estimate natural mortality rates for the species, which have been previously very tough to estimate. Once incorporated into fisheries models, by combining with ‘F’ (fishing mortality), our hope is that this will further bolster efforts to accurately define annual population losses to help inform management.  

Although the tags are slightly different, our goal on the water is the same; catch and release bluefin tuna. Robbie Schallert and Tom Horton met with Dennis Cameron and Lloyd MacInnes on the morning of the 20th to get the Canada 2017 field season going, this was after hearing that the previous day there were 30 hook-ups in the fleet before 7am. The herring had already begun spawning near Port Hood. 

charter boat gets hooked up as some of the rest of the fleet look on.  

Dennis Cameron looking on as one of the herring boats hauls a net laden with fish just after dawn.

Craig Cameron has been a part of our tagging team in the past; this year he's knee deep in herring on his own boat

This means that bluefin arrive in the early hours to pick off herring that escape as the fleet haul their nets. It usually means good bluefin fishing, and our first day was no exception. We had our first bite at 9:30am and by the close of play we had lost one and released three with acoustic and pop-up tags. This included a 299cm fish, the third largest we have ever tagged. It’s always a real privilege to see a fish that has run the fisheries gauntlet and won for nearly two decades, and we were very happy to see it go back out the transom door with an acoustic tag.

Robbie, Tom, Dennis and Lloyd haul a 299cm bluefin aboard for electronic tagging.

After day three we are 9 fish tagged for 10 hooked up. So, a good start but plenty more work to do. We’ve certainly been blessed with some very un-Nova Scotia – like weather and were even on the boat in shorts yesterday. We’re sure that will change……  

A rare glint of sun off a bluefin tuna prior to tagging in the Gulf of St. Lawrence. 

Friday, August 18, 2017

'Tis the Season of the Giant Bluefin Pop-Ups!

Summer Recovery Season Begins:

The tuna tagging team from the TRCC put out over 30 pop up satellite archival tags in 2016 on large bluefin tunas built by Wildlife Computers in collaborations that took the team from the waters off California, Canada, Israel and Ireland. These tags are unique instruments  that ride on a giant bluefin tuna externally, and release at a preprogrammed time. The tags float up to the surface and send via radio transmissions to Earth orbiting satellites summaries of position, behavioral diving and environmental data from the sensors on board (depth, temperature, time, light). From these data the scientific team can reconstruct the behavior  of how bluefin tuna use our oceans. TRCC, TAG and affiliate team members are busy this month collecting some of these tags put on over a year ago on Atlantic bluefin in Canada, Ireland, and on Pacific bluefin tuna off the west coast of North America. The team has fanned out this past week to pick up some of the tags on the ocean as they have high resolution data sets archived in the memory. 

First up was the longest ever pop up satellite tag on any tuna in the Atlantic or Pacific. This 13+ month tag and a few others of similar length and archival data quality were on very large Pacific bluefin tuna tag- put out over a year ago on the large Pacific bluefin tuna “ The fish were - about 7 years of age- part of the great bite last July off San Clemente of 200-300 lb fish” Dr. Block said.  These bluefin were caught aboard the F/V Shogun using flying fish as baits, and trolling a kite a long way back. Barbara and the team tagged these fish with the pop up  satellite tag placed on the outside and internal archivals sewn inside the peritoneal cavity. The fish which were approximately 7 years of age (as determined by length measurements) a year ago (last July) are still at large with the internal tags. The bluefin tuna’s  satellite tag  popped up to the south of where we tagged the fish. I was pleased that we were able to keep the tag on this long. Recovering the tags can be challenging as the scientists are looking for a  small 25 gram instrument floating at the surface. Luckily there is w a locator that can “identify” the tag’s radio signature. The team hopes to get out again shortly to potentially recover a few tags in the Pacific.

-Barb Block