picture of a salmon on a sign

Sign posted near the rearing shed at the side channel we toured in the Englishman River watershed.

One of the highlights from the PFLA 2014 field tour was a visit to the Englishman River watershed. Resource specialists were on hand to describe the programs and processes in place to successfully rebuild salmon populations in the Englishman River, as well as some fascinating new technology used to assess and measure fish stock levels.

Dave Davies, a community advisor with the Department of Fisheries and Oceans (DFO), works with over 30 different stewardship groups from Campbell River to Parksville. He describes his job as “helping people to help salmon”.

Dave provided information about fish populations in the river and some context for the construction and evolution of the side channel we visited.

According to Dave, the Englishman River watershed is a moderate size for Vancouver Island and fairly small by BC standards. The river is home to all five species of salmon — chinook, chum, coho, pink and sockeye — as well as, cutthroat and rainbow trout.

The development of cities and towns, during the early part of the century, along with historic forest harvesting and other industrial events, had lasting impacts on the river. In the mid 1990s, measures were taken to mitigate the declining salmon populations. The construction of the side channel, originally called the TimberWest side channel, was a major factor in rebuilding coho salmon populations in the river.

map of the Englishman River watershed

Dave Davies points out the location of the side channel on the map of the Englishman River watershed.

In the early 2000s, land donated by TimberWest and Island Timberlands created a network of protected parkland along the river that enables the river to rebuild itself. The side channel was extended in 2006 to reach 4.6 km in length, one of the longest side channels on Vancouver Island, and is now called the Clay Young side channel.

Dave describes the side channel as “incredibly productive” and explains that a 2009 through 2011 study determined 42 percent, almost half, of the coho smolt population for the Englishman River comes out of this side channel.

Unlike other salmon species, coho salmon spend an entire year in fresh water before heading out to sea as 6-inch smolts. Part of the problem with the main stem of the Englishman River is low-flows during the summer and high-flows during the winter make for unstable fish habitat. Because not many pools are left in the main stem of the river, the side channel provides protected habitat for coho salmon year round.

Of course, in order to know how well habitat restoration is working, you need some way to measure what you’re studying. Coho salmon are a federally governed species, so it’s the job of the Department of Fisheries and Oceans (DFO) to measure coho salmon populations in the Englishman River.

James Craig, from the British Columbia Conservation Foundation, described an interesting PIT tag trial project they offered the DFO in the fall of 2013 to help determine the effectiveness and efficiency of the annual DFO snorkel surveys (people with snorkels swim in the river and count the number of coho salmon they see).

James explains, “DFO uses expansion factors to calculate the actual numbers of fish in the river reported by the snorkelers each fall. The PIT tags program was a double check. It was also an effort to reconfirm the effectiveness of the side channel—see how many fish it does support, how many adults are coming back to the side channel vs. the rest of the watershed.”

What are PIT tags?

a container of PIT (passive integrated transponder) tags

Samples of PIT (passive integrated transponder) tags injected into the abdominal cavity of adult coho salmon.

PIT (passive integrated transponder) tags are small, glass-encased coils of copper, of various sizes, injected into the abdomen of fish to later track and record information about the fish.

How does the PIT tag program work?

In the fall, in the lower end of the river, angling and seining techniques were used to capture adult coho salmon. Once captured, PIT tags were injected into the abdominal cavity of the fish and they were tagged, on the dorsal surface, with a long spaghetti tag (a piece of plastic designed to show up easily). Then the fish were released back into the population to mix with the untagged fish.

Essentially, it’s an easy mark recapture study—you get a ratio of how many tags you put out, how many tags you see after, and you do the math to come up with a population estimate. It’s a simple technique, but the PIT tags are an added component.

Once the adult fish are tagged, they swim up the river and distribute naturally to wherever they might be going. The PIT tags allow you to detect the fish by simple antennas.

Using antennas to detect the PIT tags

James Craig showing an antenna used to track PIT tags

James Craig shows the rectangle shaped plastic frames used to detect the PIT tags.

A plastic frame, with extension cord wire going through it, is put in a small creek, horizontally. The wire is hooked up to a tuning box—essentially, some capacitors, and resistors and diodes and chips powered by a deep cell cycle 12-volt battery with a data logger. When the antenna detects the adult fish going by, the data is downloaded into a laptop and logged.

To summarize: fish are tagged in the lower river. Several antennas are set up in the upper river and in the side channel. Adults coming back in the fall pass the antennas, the PIT tags are detected and the information is stored.

The passive part (the P in PIT tags) is that it’s not battery operated. James explains, “The tags are inert, there’s no power. The antenna is what charges the tag. You’re charging the tag to identify itself, in a split second, when the fish swims through the antenna and releases a number that’s logged into the computer.”

What’s great about the technology?

Using the PIT tag technology to analyze and help guide habitat restoration efforts is an exciting application.

James explains, “The tags are inexpensive, 2 dollars, and they last forever. You can put them in a juvenile Chinook as small as 58 millimeters long, and they will stay in the fish and grow with the fish and come back in a 35 pound Chinook salmon, 5 years later, swim through an antenna and be detected.

equipment used to capture and log the data from the PIT tags

James Craig displays the equipment used to capture and log the data from the PIT tags.

Wherever you capture the fish, be that adult coho in the Englishman River or juvenile fish of any species, you know exactly where, when, what type of habitat it was in, how long it was there, and what condition factor it was.

When you get the fish back, as adults, you can do an analysis of how well each group of tags survived and identify which habitats were the most productive and generated the highest returns and help determine what restoration techniques are going to be the most effective at growing fish.”

Thanks to Morgan Kennah and Ken Epps from Island Timberlands for organizing this section of the field tour and thanks to Dave Davies and James Craig for interesting and engaging presentations.