By Andrew Safer: 215 Atlantic salmon smolts were fitted with archival tags and released into the ocean from Campbellton River near Lewisporte this past May. This is the first time that such small, juvenile fish packed miniaturized tracking devices on their migration from a river to the ocean and back.

Lotek Wireless developed these tiny electronic tags in collaboration with Dr. Ian Fleming, a professor of marine and freshwater ecology at the Ocean Science Centre at Memorial University, and with the Department of Fisheries and Oceans (DFO) “This would be among the earliest studies to get an idea of what small fish are doing at sea,” Dr. Fleming said. “The ocean has been a huge black box for salmon management.”

During the year the smolts will be at sea, the archival tags will be continuously logging their location as well as three full days’ temperature and depth data—the maximum amount of information the tiny battery in the archival tag can record.

Dr. Fleming estimates that five per cent of the fish tagged and released will survive the year and return next spring. If those 10 – 15 fish make it they are expected to be recovered from DFO’s Campbellton River counting fence. Scientists already have this information for adult Atlantic salmon because tracking devices from Lotek and other companies have been available for larger fish since the early 1990s. If the project is successful, it is believed this will be the first time scientists will have information on the full migratory pattern of a species of fish that migrates from freshwater to saltwater and back to freshwater. The information would help researchers better understand the Atlantic salmon’s migratory patterns, habitat, and survival.

Advent of the Archival Tag

PHOTO:The electronics for Lotek Wireless’ tiny 2-gram archival tag.

When Lotek (formerly Lotimer Technologies) set up shop in Aurora, Ontario 27 years ago, they started out designing and manufacturing collars for terrestrial animals. In 1994 they started developing ocean tracking devices. Since GPS doesn’t work underwater, the maximum range for data transmission via acoustic transmitter is 1 kilometre, which greatly limited applications of the technology. “We realized one of the primary technologies of choice for the oceans was an archival [data storage] tag” recalls Lotek’s General Manager, Mark Ploughman who set up the manufacturing for Lotek’s operation at the St. John’s office in the Tooton’s building on Cabot Street in 1996. The ability to store information would obviate the need for long-range data transmission.

With the advent of light-based geolocation, an innovative technology that establishes geographical positioning underwater, the archival tag was developed.  In 2000, Lotek partnered with Northwest Marine Technology, Inc. of Shaw Island, Washington, one of the early developers of light-based geolocation, and the Centre for Environmental Fisheries and Aquaculture Science (Division of Fisheries and Aquaculture) in the UK, the designer of Lotek’s first archival tag. The longitudinal estimate of the location of the tag at any point in time is determined with reference to the time of mid-day (as determined as the mid-point between sunrise and sunset), and the latitudinal estimate is determined with reference to the length of the day. An optic fibre on the tag, positioned outside the fish, collects light and sends it into the electronics inside the tag. The light detector can detect sunlight from a depth of 400 metres.

In 2004, Lotek started designing their own archival tags in collaboration with the Lotek office in Newmarket, Ontario. In 2005 and 2006, tags that were recovered on sooty shearwater seabirds contained one of the largest bird tracks ever recorded. The tag provided scientists with a window into the overwintering behaviour of this seabird, tracking its movements from New Zealand to the Aleutian Islands, through North and South America, and back to New Zealand, for the first time. “It was revolutionary, groundbreaking research,” says Padraic O’Flaherty, Lotek’s director for the ocean segment who has been with the company since 1998.

Development of a Tag for Juvenile Fish

84PHOTO: Lotek production assembler, Marg Hayward, does the final assembly on an archival tag.

The work that led to the development of the tag used on Atlantic salmon smolts began in 2006. Looking to develop a method for tagging smolts, Lotek contacted researcher Dave Reddin, a salmon expert at DFO, who had been involved in the archival tag deployment on Atlantic salmon kelts (adults) before he retired from DFO. Reddin brought Dr. Fleming into the project. Dr. Fleming had recently returned to the Ocean Sciences Centre after spending 10 years in Norway and 4 years in Oregon conducting research on the wild salmon populations there. Lotek had been involved in a project of Dr. Fleming’s in 1998 concerning the conservation of an endangered fish species in Italy.  “We work really closely with key groups of researchers to develop the products,” said Ploughman. “The technology doesn’t evolve without a really strong connection with the market.”

As the principal investigator, Dr. Fleming worked with Lotek to develop the attachment mechanism by working through several iterations of a system that keeps the electronics outside the fish by feeding a tether under the dorsal fin. Using the tanks at the Ocean Sciences Centre, Dr. Fleming tagged smolts and monitored their survivorship over a year to ensure that the tags will survive the fish’s growth, from 15 centimeters to 70 centimeters, from the time they were released until they return.

For Lotek, the challenge was to design and assemble a miniaturized version of the tag they had developed for adult fish, and to develop a viable means of attaching it to the smolt. “Following work done in Alaska in 2006,” recalls O’Flaherty, “we realized that, because we were doing something that had never been done before, we had to do some fundamental science to determine how to design a tag to ensure retention on the animal.”

They reduced the size of the tag from 5 grams to 2 grams, which is the smallest light- based geolocation archival tag that has been developed for fish to date, according to Ploughman. He says since Pacific salmon are a lot smaller, the tags for those smolts will have to be ½  gram. “We can produce tags at close to 1 gram now,” he says. “We plan to be the first ones with a ½ gram tag”.

Mining the Past to Plan for the Future

A staff of 25 work out of Lotek’s St. John’s 12,000 square foot location where R&D, testing, and validation takes place on the second floor, with manufacturing and assembly on the main level. In addition to designing and producing archival tags, the St. John’s operation also builds acoustic transmitters and radio transmitters. The company annually invests between 15 and 20 per cent in R&D, and has no product on the floor that’s older than three years. Exports to 30 countries account for 90 per cent of revenues. Their client list includes the National Oceanographic and Atmospheric Administration (NOAA), US Army Corps of Engineers, Commonwealth Science and Industrial Research Organization (CSIRO) (Australia), and Department of Fisheries and Oceans.  

Lotek’s archival tag technology development over the years has been supported by the Atlantic Canada Opportunities Agency’s Atlantic Innovation Fund, NRC Industrial Research Assistance Program, and the Government of Newfoundland and Labrador’s Department of Innovation Trade and Rural Development. Lotek’s collaboration with Dr. Fleming and DFO was supported by the Ocean Tracking Network through the Canadian Foundation of Innovation and Natural Sciences and Engineering Research Council.

Meanwhile, as Ploughman, O’Flaherty, their design engineers, and the rest of the Lotek staff were setting their sights on the next technological challenge, in June a package containing two dataloggers from another era landed on Ploughman’s desk.  Two Alaskan sable fish that had been fitted with Lotek archival tags 10 years ago had been caught. The researcher is currently mining the 20 years of archived data.  “We’re pretty sure that’s a first”, says Ploughman, who is looking forward to learning what sort of secrets are being revealed by this “message in a bottle.”