By Jenny Neyman
Photos courtesy of Tim McKinley, Alaska Department of Fish and Game. An Alaska Department of Fish and Game technician takes a tissue sample from a monster king salmon at the Fish and Game test-net site on the lower Kenai River. Samples are run through genetic testing to determine which spawning stock the fish is from.
Redoubt Reporter
As much as we might wish them to, fish simply don’t talk. Though biologists and fishery managers in Cook Inlet are constantly trying to learn more about king salmon, especially those from the Kenai River, pulling a chinook alongside a boat and asking it, “Where you from?” “Been here long?” or “Where you headed?” does not elicit a response. At least, not in so many words.
But advances in genetic testing make it just about that easy to get much better acquainted with king salmon.
“It’s pretty simple anymore,” said Tim McKinley, research biologist with the Alaska Department of Fish and Game Sport Fish Division. “In this business, when there’s a change in technology there’s rapid learning that goes on about your critter of interest. It’s kind of like when they put the Hubble Telescope up there. It was a whole new leap in technology for the astronomers and physicists and everything else.”
The leap for fishery biologists came with improvements in genetic testing that led to much easier and cheaper ways to derive information from tissue samples. Twenty-five years or so ago, genetic sampling of salmon was a time-intensive, technical, expensive and deadly process.
“If you were going to take genetic samples from fish you had to kill the fish because you were taking all kinds of weird stuff — like heart tissue or kidney or liver and blood. And then, once you took that sample, it had to be preserved using stuff like liquid nitrogen,” McKinley said.
Running the genetic testing lab work could cost a couple hundred dollars per sample.
“If you needed to run dozens or hundreds or thousands of samples, it gets ridiculous,” McKinley said.
Nowadays, sampling is as quick and easy as snipping off the axillary process — a long, pointed piece of tissue in front of the pelvic fin
Sampling involves removing the axillary process, at the pelvic fin.
— putting it in a small vial filled with ethanol, shipping it to the lab in Anchorage, and running a test that costs about $25 a sample.
“Taking this little thing off a fish does not kill them. They do not even wiggle,” McKinley said.
Fish and Game technicians started amassing a repository of genetic samples from Kenai kings in 2002 and have been adding to it ever since. There are two types of sampling — baseline and mixture. For baseline collections, kings are sampled in their spawning locations, whereas mixture sampling involves collecting samples from kings outside their spawning grounds — in the river, in Cook Inlet, or even in the Gulf of Alaska — where they could be headed to any number of spawning locations.
The project began by archiving mixture samples from kings caught in Fish and Game’s test net near its sonar site in the lower river. Mixture sampling expanded to sampling sport-caught kings in the lower river in about 2005, and to sampling sport-caught kings above the Soldotna bridge in 2007.
In 2005, baseline sampling began, with technicians collecting samples from spawning kings in the Kenai River watershed tributaries that
A Fish and Game technician records information from baseline sampling of spawning king salmon in Quartz Creek.
support king spawning — Slikok Creek, Funny River, Killey River, Benjamin Creek, Russian River, Juneau Creek, Quartz Creek, Crescent Creek, Dave’s Creek and Grant Creek.
Technicians also have been sampling spawning kings in spawning areas in the main-stem Kenai River, from the outlet of Kenai Lake to Skilak Lake, from the outlet of Skilak Lake to Bing’s Landing, from the confluence of the Moose River to the Soldotna bridge, and from the Soldotna bridge through the lower river.
The baseline sampling from spawning kings creates a genetic map, of sorts. Kings spawning in one location are genetically distinct from those spawning in another. There are some caveats to this, for instance kings spawning in Slikok Creek are genetically somewhat similar to those spawning in Funny River, so those two stocks get lumped together in analysis. But by and large, genetic testing can accurately distinguish between stocks, assigning them to their specific spawning location, about 90 percent of the time, McKinley said.
It takes 100 to 200 samples to establish a reliable genetic profile for each spawning location, and sampling is best done over two to three seasons, McKinley said. Some sites still need more sampling, such as Grant Creek, but most of the Kenai already is mapped. And it is important to have baseline data established from all spawning locations in order to have confidence in being able to assign kings in mixture samples to the spawning locations they came from and are headed to.
That’s because genetic testing will assign the kings somewhere, and if baseline profiles from all the stocks represented in the sample aren’t
Technicians with the Alaska Department of Fish and Game take tissue samples from a sportfisherman’s catch on the middle Kenai River.
complete, some of those fish will be misidentified. Say, for instance, 100 kings are mixture sampled in the Kenai king test-net site, and 50 of them are from Benjamin Creek, 25 are from Killey River and 25 are from Juneau Creek. If the genetic baseline profile for Juneau Creek hadn’t been established, the 25 kings in that sample would be mistakenly assigned to another baseline profile, such as Russian River or Crescent Creek.
“If you don’t have a baseline in there for an area, the analysis don’t comeback saying, ‘20 percent unknown area,’” McKinley said. “It always allocates 100 percent of the sample.”
The genetic information has many uses, and can be especially important in determining escapement goals. With a comprehensive map of genetic profiles, biologists can determine where king salmon are coming from.
“We can see, as an example, how many fish coming into the Kenai are from, let’s say, the Killey River, and/or how many of the kings that are harvested in the Kenai are from the Killey River,” McKinley said.
The stock profiles are a way to distinguish early run from late-run kings, since early run kings spawn in tributaries, and late-run kings spawn in the main stem. For management purposes, the early run ends at the end of June, with the late run starting July 1. But that doesn’t mean there’s a clear divide between the two. Through the end of June and early July, there’s a mixture of early run and late-run kings in the river, which can make it difficult to get an accurate count of escapement numbers if managers don’t know how many of the fish caught in that time frame should be attributed as early run or late-run kings.
“You’ve got to have a date, and we call July 1 the start of the late run, but the fish don’t read the calendar,” McKinley said. “We’ve always known that some fish that come in June are late-run fish and some fish that come in July are early run fish.”
The genetic sampling allows managers to tell the kings apart. Test results aren’t turned around quickly enough to be used for in-season management decisions, but are factored into season-end escapement reviews.
“It’s all very useful information for escapement goal analysis,” McKinley said.
The information can be useful outside the river, as well. For the last two years Fish and game has been mixture-sampling kings caught in east side set nets, to determine where those fish would be headed. At this point the data can’t be analyzed definitively until all potential stocks those fish could be from in Cook Inlet have baseline profiles established. Because, again, stocks may be misidentified if all the spawning locations represented in a sample aren’t profiled.
“More baseline studies need to be done. We haven’t started analyzing them. We’re waiting for other potential baselines to be collected.
Spawning locations in the main-stem Kenai River and its tributaries are profiled by the king salmon stocks they produce.
Although we expect the vast majority of the harvests in the set nets would be from Kenai and Kasilof kings, we need to do due diligence on it,” McKinley said.
Kasilof and Kenai stocks have been profiled, and work is ongoing to profile the rest of the stocks in Cook Inlet, such as the Anchor River and west-side stocks. Once that baseline work is done, the information could settle some of the thornier issues of fishery management in Cook Inlet, such as debate over the utility of restricting central district commercial fishermen in order for them to avoid catching kings headed to northern district streams. In the future, testing will be able to show whether kings caught by those commercial nets really are headed to the Susitna River, for example, or whether they’re Kenai kings.
This data could be useful even beyond Cook Inlet, with the issue of bycatch in the Gulf of Alaska. Again, all the potential king stocks of origin would need to be profiled before biologists could determine with certainty what stocks are ending up as bycatch. But that day may soon come.
“The Anchorage lab and other offices are collecting tissue from some of the other king salmon stocks on the peninsula and around the inlet to fill in the holes in the baseline, so the future of it is reaching farther and farther out in the gulf to see if and where our fish show up in other fisheries,” McKinley said. “It’s very important to have all the stocks, basically in the North Pacific, to have baselines from all of them. For a number of years there’s been this big movement to sample all the king stocks up and down the coast.”
Of course, research takes funding. Testing may be a bargain at $25 a sample, compared to the hundreds of dollars it used to cost, but $25 a sample for 100 to 200 samples per baseline profile still adds up. As do the costs of collecting the sampling. The Kenai River Sportfishing Association has been helpful in securing Alaska Sustainable Salmon Fishery funding for the genetic sampling in the past, McKinley said, but changes in program eligibility requirements have cut off that source of funding for the last few years, meaning funding has come from existing department funding.
“Which has been dropping the last few years,” McKinley said.
Provided continued funding is secured, continued testing will continue. Getting better acquainted with the fish is too important to pass up.
“The big thing here is making people’s fishing better,” McKinley said. “The more information we have on things and the finer scale that it is, means a better job that we can do.”
