Ditidaht First Nation is expanding their monitoring of Hobiton River bi?aat (sockeye salmon) with the introduction of a rotary screw trap (RST) into their data collection approach.
The RST will enable the nation, and partners Uu-a-thluk and Fisheries and Oceans Canada (DFO South Coast Stock Assessment Unit and Nitinat River Hatchery) to monitor and assess juvenile bi?aat out-migrating from the Hobiton River. This will complement the work already taking place that tracks adult bi?aat returning to the river using a fish fence and counter box.
“To assess the health of the population and to forecast adult returns, you need to know juvenile production out (RST data) and adults back (adult escapement),” said Jim Lane, Uu-a-thluk Deputy Program Manager.
“The lack of juvenile production data essentially leaves us blind as to what is happening to the sockeye in the lake,” he added. “To rebuild a population, you need to know what is happening in both their lake and marine environments.”
According to huu-yiik, Sabrina Crowley, Uu-a-thluk Southern Region Biologist, there haven’t been any recent projects looking at the fish populations leaving the Hobiton system, and collecting the information again is a positive step.
Rebuilding Hobiton bi?aat is a priority for Ditidaht as the nation has seen really low escapement rates for several years (much like other west coast Vancouver Island bi?aat populations). This has hampered the nation’s ability to harvest the number of food and ceremonial (F&C) fish required to feed their community, and to provide security for future generations.
To put things into perspective, the highest recorded escapement rate for Hobiton bi?aat is 80,000 fish, whereas the 2021 season saw less than 5,000 returning fish recorded through the fish counter box.
In response to these low return rates, the harvest of Hobiton bi?aat has been restricted for everyone except Ditidaht First Nation.
“The fisheries team will harvest for the nation at 10 per cent of escapement,” said sa?iix?ab (Paul Tate), Ditidaht c?aabat (hereditary chief) and Fisheries Manager, adding that restrictions are updated in-season.
His long-term goal is to see returning bi?aat numbers “back to near historical records.”
Lane would like to see the Hobiton rebuilt to levels that can at least support consistent F&C harvests, and potentially some economic opportunities.
Monitoring the resource is a critical step in achieving both goals, and the RST will assist in building a more robust data set for scientists to analyze.
In its second year of use, and still considered a trial, the RST consists of a large rotating cone suspended between two floating pontoons. River flow rotates the cone and funnels a portion of the migrating fish into an underwater holding tank at the back of the trap.
Ditidaht fisheries representatives monitor the trap throughout the migrating season to count, measure, weigh and collect scale samples from the juvenile fish, as well as to remove any debris that gets caught in the trap. Once evaluated, fish are released back into the system.
Monitoring will take place from the end of March through to June using an RST provided by DFO, and stored by Nitinat Hatchery in the off-season. Annual installation of the trap is a collaborative effort between Uu-a-thluk, Ditidaht Fisheries and DFO staff, as is monitoring data collection, input and analysis.
For Ditidaht’s Josh Tate, a fisheries technician with the nation’s fisheries department, the RST monitoring work is also a capacity building opportunity.
“This is additional training for Josh, so that he’s familiar with juvenile sampling and capturing; the methods, and handling the fish, and being able to take scale-smear samples off of them,” said Crowley.
Ditidaht has a long record of collaborative work with partners in the public and private sector, including DFO, Nitinat Hatchery and biological consultants M. C. Wright and Associates Ltd. The nation has several projects currently on the go, or under consideration, including a First Nations guardianship program, and establishing kelp stands by seeding bare substrate areas.