By Jenny Neyman
File photo by Patrice Kohl, Redoubt Reporter. A computer monitor displays images of fish swimming in the Kenai River in July as recorded by a new sonar device being tested for counting king salmon. The Alaska Department of Fish and Game predicts a weak sockeye salmon run in Upper Cook Inlet this season.
Redoubt Reporter
Kenai River sockeye salmon fishermen still stinging from the memory of last year’s poor return of fish have another weak year ahead of them, according to the Alaska Department of Fish and Game’s 2010 Upper Cook Inlet sockeye salmon forecast.
Biologists are estimating a below-average total run of 3.6 million sockeye in 2010, in a range of 2.3 million to 5.8 million fish, with an escapement of 1.3 million and harvest of 2.3 million fish. The forecast continues a trend of below-average runs, and is even lower than the 2009 upper Cook Inlet run was expected to be, at 4.3 million total fish, with an escapement of 1.3 million and harvest of 3.0 million. When all was said and done, last year’s run ended up even worse than was forecasted, with 3.7 million fish returning and 2.6 million being harvested.
Secondary streams are predicted to do just fine this year, with Fish Creek expected to see 142,000 fish, 2 percent more than the 20-year average run of 139,000 sockeyes, and Crescent River forecast for 148,000 salmon, 47 percent greater than its 20-year average run of 101,000.
But for the Kenai River the outlook is in the red, meaning less reds to go around for sport, commercial, subsistence, educational and personal-use fishermen.
“The most dominant stock in Upper Cook Inlet sockeye salmon runs is the Kenai River stock, and our forecast for the Kenai River for 2010 is much below average,” said Pat Shields, assistant area management biologist for Fish and Game’s commercial fisheries division. “The forecast is not good for (the Susitna River) and the forecast is not good for the Kenai River, and it’s about average for the Kasilof, and then your other systems are all minor. So the outlook for the 2010 sockeye salmon run is for a much below-average return. How that impacts the different components — commercial fisheries definitely will expect a much lower harvest than average.”
This continues the trend of below-average Upper Cook Inlet runs in 2008 and 2009. In 2009, the harvest among all user groups was about 1.7 million fish below the 20-year average of 4 million sockeyes.
While it’s not much consolation for fishermen this summer, Upper Cook Inlet sockeye runs are expected to improve in future years. In the Kenai, escapement goals were met or underachieved in 2007, 2008 and 2009, which means the return runs of fish spawned those years should be back up around the average run strength.
“We hope that it bodes well for future years,” Shields said. “In 2012, 2013 and 2014, we can hope that sockeye salmon runs begin to build again.”
As with almost everything in the fisheries world, there is debate about what’s causing the decline in sockeye returns, and with the Kenai River being the system’s biggest sockeye salmon producer, it takes center stage in determining what’s going wrong. The 2010 sockeye run forecast is for 1.7 million, 42 percent less than the 20-year average of 3.1 million.
“There are multiple factors that affect salmon return. There are factors in the freshwater phase in their life cycle that affect salmon survival and, thus, adult returns,” Shields said. “And then once the smolt leave all of these systems and head out to sea, it’s not a black hole, but our understanding of what’s going on in the marine environment is much less than our understanding of the freshwater environment.”
Fish and Game’s stance is the problem is likely occurring in the freshwater habitat, and that three successive years — 2004, 2005 and 2006 — of having too many spawning salmon make it up the Kenai River is now resulting in fewer-than-normal fish coming back.
“We know that during those three years we overescaped the system. We put more spawners into the system than the escapement goal called for,” Shields said. “Did that cause the poor return? Some would believe that it did. Some would believe that it didn’t. We know that we get lower returns on average when we exceed the escapement goal.”
A glut of sockeye salmon made it past commercial nets, personal-use dipnets and sportfishing hooks and lines to spawning areas in the Kenai watershed those three years, with an estimated 1.3 million spawners in 2004, 1.1 million in 2005 and 1.3 million in 2006, Shields said. That’s about double Fish and Game’s ideal escapement goal.
“The escapement goals are set around the best data that we have and our understanding of the data,” Shields said. “For the Kenai River, we believe that you will get the highest yields on average when you put between 500,000 and 800,000 spawners into the system.”
Shields said that when too many fish make it back to spawn, there aren’t enough nutrients in the rearing grounds to support all their offspring.
“Some people say it’s akin to putting hundreds of cows on one acre of grass in a field. The field can’t support the cattle and obviously some of them die. Systems for fish are limited. You can’t put an infinite amount of fish into a system and expect them all to survive,” he said.
Every fall, Fish and Game runs sonar counts to estimate the number of rearing juvenile sockeyes in Kenai and Skilak lakes. They use tow nets to capture samples and look at the age structure of the population and length and weight of the fish, and compare that to the number of spawners that produced that brood. In the spring, if the ice leaves the lakes before the fish do, Fish and Game again takes samples, does a population estimate and compares the length and weight of the fish. Research has shown that when an overabundance of spawners produce an overabundance of fry in the lakes, survival rate drops, Shields said.
“We have seen that when you put large numbers of fry into Skilak Lake, they are smaller and weigh less. They don’t survive as well over the winter,” Shields said. “The primary food resource for them in Skilak Lake is zooplankton, and as they crop down the zooplankton, what happens is the next year’s fry, when they come out in the lake, there’s not enough food available.”
The effect is compounded where there are successive years of overescapement, as there were in 2004-06, because each year’s hatch of overabundant eggs leaves less food for the next brood year of juvenile fish. But being able to determine at what specific point the system is overloaded is difficult to do.
“The question begging to be answered is, did those overescapement events cause the poor return? In other words, did the fish not survive as well during the freshwater phase of their life cycle? We have data that would indicate that that has happened in the past,” Shields said. “At what point have you overescaped the system? That’s what the Department of Fish and Game is tasked with discovering. That’s what our research is aimed at.”
One piece of evidence the department is trying to definitively substantiate on the Kenai is whether overescapement causes less smolt to survive their juvenile lives in the river to begin the ocean phase of their life cycle.
“We’re attempting to count smolt as they leave the Kenai, also, but we’re finding that to be a challenge. You have multiple sizes. The smolt coming out of Hidden Lake are larger, and smolt from Russian Lakes are also emigrating, along with the Skilak and Kenai smolt and the main stem. It’s been quite a challenge for us to make that program a success. We’re still attempting to do so,” Shields said, adding that the department has been working on the count for three years now.
Photo by Patrice Kohl, Redoubt Reporter. Alaska Department of Fish and Game technician Bob Zeyer tethers a king salmon caught in the Kenai River in July in a sonar station test net until it can be measured. Fish and Game repeatedly drifts a catch and release net past the station six hours a day to help gauge the accuracy of sonar-based counts.
And the equation could soon change, as the department is undergoing a review of escapement goal numbers, as it does every three years, in advance of the Alaska Board of Fisheries meeting next February to discuss Cook Inlet finfish issues.
“As we speak, there are people speaking in Anchorage and Juneau about the very same thing. Right now, (the escapement goal) is the best data we have, our best analysis,” Shields said.
“Are we saying that overescapement will cause a stock to go extinct? No. What we’re saying is as you exceed the upper level of your escapement goal, the more you exceed it, the higher the likelihood is of diminished returns. We’re not saying you’re going to wipe out the stock as you’ll get less bang for your buck. The Department of Fish and Game is charged with managing to the highest sustained yield that we can. That’s what we’ve spent an inordinate amount of time and money determining, is what is the best number of spawners to put into a system to maximize the yield?”
Determining appropriate escapement numbers is one part of the equation of managing to a maximum sustained yield. Hitting that number is another, as shown in the 2005-06 overescapement years. From 1990 to 2009 in the Kenai River, Shields said that five years saw an underscapement of sockeyes, nine years saw an escapement within the 500,000 to 800,000 range, and six years saw an overescapement.
Part of the reason for missing escapement targets is predicting salmon runs is an inexact science.
“They don’t tell you how many are going to enter a river on a certain date, and so there’s error in management,” Shields said. “You either didn’t know it was going to happen or you weren’t prepared for that large of an event to occur at that period in time.”
The other factor is that management plans and allocation decisions set by the Board of Fish can tie the hands — and nets — of Fish and Game managers and commercial fishermen. But Shields said that issue has been improved by Board of Fish decisions at the 2008 meeting where Fish and Game got permission to step outside of management plans that restrict when and where the commercial fishery may operate.
“The Board of Fish was made aware of some of these difficulties. They did clarify that managing to escapement goals was to be the department’s top priority. They directed the department to do what they needed to do to be able to meet that goal. In other words, they could step outside the plan. That flexibility is very helpful,” Shields said.
However, liberalizing fishing opportunities likely won’t be the case this summer. Instead, fishing opportunities will probably be restricted in order to ensure the forecasted diminutive run meets escapement in the Kenai.
Better news for area fishermen is that the Kasilof River’s forecasted sockeye run is about on average with 901,000 fish, only 6 percent less than the 20-year average run of 958,000.
Shields said that some would contend the Kasilof suffers from past overescapements, as well, but that the effect of too many spawners in the Kasilof is different than in the Kenai. While the Kenai is rearing limited, where too many juvenile fish overcompete for food resources, Tustumena Lake at the headwaters of the Kasilof River is spawning habitat limited, meaning too many sockeye spawners in the system result in fish not being able to find suitable habitat in which to spawn.
The other big monkey wrench torqueing down the 2010 Upper Cook Inlet sockeye run forecast is the Susitna River. That stream again is expected to have a dismal return of 542,000 sockeyes, 41 percent less than the 20-year average. In 2009, the Susitna run was estimated at 196,000. It ended up getting about 669,000 sockeyes, but that’s still under the average run of 913,000 fish.
The Susitna run has been of increased concern in recent years as run strength has seemed particularly weak, causing a conservative approach to fisheries management. That’s caused argument between central peninsula-area fishermen and residents of the Matanuska-Susitna Borough, who lobby for more restrictive fisheries management approaches in the central district, under the idea that fishermen in the Kenai area are catching fish bound for the Susitna River.
A new cause of heartburn in the ongoing saga comes from Fish and Game’s realization that its escapement counts on the Susitna and Yentna River, which drains into the Susitna, have not been accurate.
“The department believes that, likely there were more sockeye salmon escaping the Susitna than we originally believed,” Shields said. “We just can’t quantify that with any degree of certainty. We are in the process of doing that.”
Fish and Game estimates the Susitna sockeye escapement based on the Yentna River escapement, figuring for every sockeye that makes it up the Yentna, one sockeye makes it up the Susitna. The problem is, the escapement for the Yentna appears to be inaccurate.
The department operates a sonar counting program on the Yentna, which estimates the number of all species of salmon entering the river. To determine how many of those are sockeyes, Fish and Game operates a fish wheel on the Yentna, where it samples the population of fish and extrapolates how many recorded by the sonar are sockeyes. But the fish wheel results now seem to be skewed.
Fish and Game did a mark-recapture study and installed weirs on two lakes that drain into the Yentna. The weir data, which tends to be quite accurate, indicates there are more sockeyes in the river than the fish wheel let on.
“The weirs on the two lakes had nearly as many sockeye salmon swimming just in the two lakes as we had estimated for the entire river. What it shows us was that we were underestimating the number of sockeye salmon swimming up the river,” Shields said. “We’re doing a very intensive review of the sonar program on the Yentna River, focusing much of our research on the fish wheels’ capture. We believe the fish wheels are not truly representative, that they are capturing a lower percentage of sockeye salmon than are actually swimming up the river.”
As a result, the in-river escapement goal for the Yentna has been removed and replaced with escapement goals for two lakes on the Yentna and one on the Susitna that are monitored by weirs. That gives an accurate count of sockeye escapement, but it doesn’t allow for flexibility with in-season fisheries management, because once the fish reach the weirs, it’s too late to expand fishing opportunities to reduce their numbers.
The Board of Fish enacted the Susitna River Salmon Action Plan.
“That directs the department to conduct their commercial fisheries at a conservative level on the Susitna River stocks until we can finish our research on the Yentna River. It means gear reductions — from three nets to one net — while fish are swimming through the northern district, and restrictions on the drift fishery in central district,” Shields said.
Without an accurate count, it’s difficult for Fish and Game to accurately assess whether sockeye runs have, indeed, been as weak as have been estimated, and to what extent other factors — such as invasive northern pike and beaver dams — may be hurting the Susitna and Yentna sockeye stocks.
“There were years where we believed we had missed the escapement goal on the bottom end, that we had failed to achieve it, when in reality we may have achieved it,” Shields said. “We also know there are other factors. … You put all these together — escapement levels, beavers, pike, environmental factors — and they all can play a role on salmon production, and they all do. It’s just difficult trying to quantify each one and say, ‘Yeah, this one caused 32.1percent of the problem.’
“We’re not ignoring what’s going on, we’re spending proportionately more money per fish in trying to understand sockeye salmon production in the Susitna drainage than we are in the Kenai-Kasilof. It’s important to the department, it’s important to everybody to try and understand what’s going on there.”
