Unalaska High School Hatchery Revitalizes Local Silver Salmon Population
Around October every year for the last 19 years, Unalaska High School students have been wading into the Iliuliuk River, under science teacher Steven Gregory's guidance, to collect pairs of spawning salmon.
Last week, students in Gregory's fisheries class stretched a seine net from bank to bank, while another group waded upstream, rhythmically slapping large dip nets on the surface of the water.
"Two people go down and they scare the fish into the net and then a bunch of people stand on the net so the fish can't escape," said Natalie Buttner, a junior at Unalaska High School. "And then as the people come down, scaring [the fish] in, the net comes all the way around and catches the fish, hopefully males and females."
Buttner said she's excited to be in Gregory's class, and that it's something that seems unique to the region. As the course has progressed, she said she's gained more interest in the subject, as she's been able to observe the salmon daily, from counting silvers from the banks of the river to assisting with the fertilization process.
While the class struck out last Tuesday — only catching a single male silver — they caught two spawning pairs the day before.
After they catch the spawning pairs, Gregory said they collect the eggs in a bucket and fertilize them. They then add salt to water from the Iliuliuk River, which is added to the eggs. Gregory said his class started adding the extra salt about four years ago, and it has increased their fertilization success rate to about 90 percent — a percentage that he said is comparable to professional hatcheries.
Gregory encourages the students to actively participate, but he said the beginning of the harvesting process requires a delicate and experienced approach.
"What I do is I express the eggs from the female. I usually do that because it takes a certain amount of experience to be able to squeeze the eggs out," said Gregory. "You don't want to break the eggs, it's very bad if you break the eggs because the contents of a broken egg will interfere with the fertilization of the healthy eggs."
After fertilizing the eggs, they place them into incubation trays with running water to simulate the undergravel nest in the river — also known as a redd.
Gregory very carefully pulled out an incubation tray filled with about a thousand salmon eggs, directing pairs of students to gather around to get a closer look.
"The eggs can be exposed to the air for a short period of time," Gregory explained to the students. "You don't want them to be exposed to the air for too long because the mold spores will land on them and a fungus will start to grow on the eggs. The dead eggs will appear white. So anything that is white was not fertilized."
Gregory said the fisheries course covers a number of topics, ranging from basic biology to commercial fishing and salmon hatchery operation.
He tells the students that they are "the stewards of the river." And as part of their current unit, they've performed a salmon census and the eggs that they are now collecting will ultimately develop into young salmon and will be released into the Iliuliuk River.
Gregory and his students monitor the eggs until they become fry, which are small salmon that no longer have a yolk sac attached to them. Most of the fry are released into the river, but some, Gregory said, are kept longer in the hatchery.
"Once the alevins have turned into fry, we put them in the other part of the hatchery — it's called the raceway," said Gregory. "And the raceway simulates the flowing water part of the river. And so that's where the salmon go when they're fry and then they turn into what are called 'smolt'."
Gregory said they will keep 50 fry in the raceway and feed them and chart their growth.
"And this spring, May of 2021, [the smolt] will be about as long as your hand," said Gregory. "And we will let them go along with the fry from the eggs that we captured last week."
Along with some of the elementary students, Gregory's class will release last year's smolt into the river in the spring, and will nurture another group of salmon for next year's class to observe and then release.
In the meantime, Gregory uses the fish to teach students about a number of subjects, from the salmon life-cycle to analyzing and protecting the watershed.
Rodrey Sebastian, a senior in the class held up a murky vile of water and explained that they monitor the water in the raceway to ensure it has the correct amount of dissolved oxygen in it.
"So this right here is sodium thiosulfate," said Sebastian. "This is what we use to determine how much dissolved oxygen there is in the water. So right now the water is just super mucky. After we add this chemical, we have to mix it up and then after that we transfer it into this little tube, and then put it in this mixing jar. And what we'll do once this is a little bit mixed up and settled, is we'll drop as many drops of sodium thiosulfate that we need to make the water clear again."
Sebastian said the number of drops of sodium thiosulfate will tell them the number of units of dissolved oxygen in the water. He said they are aiming for about 9 to 11 drops.
As students fed the fry, cleaned the raceway, and gathered around a microscope to look at a fertilized egg while Sebastian excitedly explained this process, it was clear that Gregory’s class meant a lot to them.
And as Gregory discussed aspects of the course and detailed the life-cycle of a salmon, it was easy to see where that enthusiasm originated.
"Do not take the salmon that run in our river for granted," said Gregory. "The amount of urbanization that has taken place in this town — it's obvious that [it has] negatively impacted our watershed. And I'm very passionate about that."
While Gregory remains frustrated with some of the ways local streams and water quality are neglected, he said he's noticed a significant increase in the silver salmon population in the river since they began regularly offering the course and releasing salmon into the stream.
"Our operations here at the hatchery have done nothing but increase the silver salmon population," said Gregory. "It's been amazing to see that come back. When I was a kid here, there were hardly any of them spawning out there. And today, you can go out there for two or three straight weeks and see 100, at least, actively spawning at any one time. So it's been a success."
Gregory said the class will try again this week — weather permitting — to catch another spawning pair of silvers.