Tiny coho get better start thanks to study
Published: Friday, March 19, 2010
A Campbell River based plankton study now in its fourth year is getting down to the bottom of the food chain and helping to give tiny coho a better start in life.
The Discovery Passage Plankton Monitoring Program was initiated in 2007 in an effort to determine the timing of spring plankton blooms in local waters – to maximize the availability of food when coho smolts are released from the Quinsam River Hatchery.
Just back from a major fish conference in Nanaimo, Dave Ewart, Campbell/Quinsam watershed enhancement manager, said more and more attention is focusing on the first weeks of fish life.
“Everybody’s talking about the same thing, the same idea,” he said. “It’s food abundance, early in the life cycle, the first month, to get those fish growing. They have to hit a certain growth rate or they will not survive. That’s where things are heading right now.
“It’s all that environmental condition that leads up to that phytoplankton bloom in the spring that starts everything. If it’s good at the right time that salmon can use it, they do really well. They have to hit the ocean and begin feeding and growing really fast. That gets them enough energy to swim away.
“In the last four years it’s amazing how much science has changed in the Strait of Georgia. You’ve got IOS (Institute of Ocean Sciences) and PBS (Pacific Biological Station) and UBC and Simon Fraser and UVic, everybody’s got this on their plate and they’re really starting to look at the Strait of Georgia to see what is impacting it as far as productivity.”
That’s where the Campbell River-based BC Centre for Aquatic Health Sciences (BCCAHS) comes in. Working with funding from a variety of sources including the Campbell River Salmon Foundation, BCCAHS has been collecting data along the Campbell River waterfront. That data includes the types and timing of zooplankton – the fish food, as well as phytoplankton – the zooplankton food.
Members of the A-Tlegay Fisheries Society do the zooplankton and phytoplankton sampling just off the cruise dock. Coho smolts are also seined off the beach near the ferry terminal to see what types of zooplankton they’re eating.
“What we’re trying to do is look at the fish in the near-shore environment,” explained BCCAHS research assistant Elan Downey. “We’re trying to get them when they come out of the estuary, where they’re spending maybe their first few weeks. That’s where they’re getting their first taste of marine environment food. We’re also doing complete fish health on them, disease screening, parasite, size, length, weight. We try and maximize what we can get out of that fish.”
Ultimately, the goal is to better understand the most basic – and therefor most influential – rungs of the aquatic food chain in relation to ocean survival.
“The environment that we’re studying, it’s not just the salmon that it affects,” says Dr. Alexandra Eaves, BCCAHS research scientist. “It affects everything, all the fish, all the invertebrates, which feeds the birds, it feeds the seals.
“The timing of the plankton bloom varies every year. The composition of the plankton changes. If they don’t have enough of the food they want out there, the fish have to go look for it. When they’re really small, they just don’t have the energy reserves to sustain them as long as a large fish would.”
Data collected since the plankton monitoring program started suggests the hatchery may be on the right track.
The annual spring release of smolts has been spread out over a wider period in an effort to hit peaks in the plankton blooms. Fish tag analysis to date appears to show the best survival rates among smolts released close to plankton blooms.
Ewart said the data could help to better manage salmon enhancement efforts in years to come.
“If you had crystal ball and you knew that this year the conditions were going to be fantastic, you could maybe ramp production up and put more fish out there,” he said.
“If there’s more food there, why not take advantage of it? Or, if you know that things are really going down the tube, you’d have to adjust the program, maybe reduce the amount of fish that you’re putting out there or change a strategy – move everything earlier, or later, or spread them out. It just gives us way more tools to work with if we have that information ahead of time.
“We’ve got this lab here and it should be used for doing stuff like this.
“We’re pretty lucky and people don’t know it’s here in Campbell River.”