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Fish and Game’s many ways to track sockeyes all add up to weak run forecast

Losing count

Posted: Monday, July 24, 2006

Editor’s note: This is the first in a series of stories examining how restrictions of Kenai River sockeye salmon fishing affect diverse user groups.

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  Suzanne Maxwell points last week at fish as they register on a new dual frequency identification sonar the Alaska Department of Fish and Game is testing on the Kenai River. The new model, which is already in use on some Alaska streams, will replace an existing machine the department uses to maintain salmon escapement goals. Sonar has been used to track fish on the Kenai since 1968. At top, red salmon are an important resource to different user groups. Keeping track of their numbers is an important job in Alaska. Photo by M. Scott Moon

 

Suzanne Maxwell points last week at fish as they register on a new dual frequency identification sonar the Alaska Department of Fish and Game is testing on the Kenai River. The new model, which is already in use on some Alaska streams, will replace an existing machine the department uses to maintain salmon escapement goals. Sonar has been used to track fish on the Kenai since 1968. At top, red salmon are an important resource to different user groups. Keeping track of their numbers is an important job in Alaska.

Photo by M. Scott Moon

Each year, Alaska’s five species of salmon return from the deep ocean to spawn in the rivers feeding Cook Inlet, presenting a challenge to fishermen of all sorts and a shot in the arm to the region’s economy.

They’re called chinook, sockeye, coho, pink and chum (also respectively called king, red, silver, humpback or humpies and dog). They end up filleted, lathered in butter, showered with lemon, barbecued and bitten on backyard decks and campsite beaches, shipped to market as wholes, steaks or in cans, smoked or hung to dry on open-air racks — pick your preference.

 

Bill Glick monitors an oscilloscope on the Bendix sonar the department now uses.

Photo by M. Scott Moon

All five species of fish are harvested commercially, but sockeye are far and away the most valuable, according to the Alaska Department of Fish and Game.

A good argument could be made that with the number of users competing for a finite number of fish, few would harvest any were it not for those managing Alaska’s fisheries. That job falls to Fish and Game biologists and members of the Alaska Board of Fish, where biology and politics often cross paths.

There are three primary user groups vying for portions of the salmon runs — commercial harvesters that fish either drift or setnet gear in Cook Inlet, sportfishermen who ply the waters of the inlet’s river system, and personal use/subsistence users.

 

Photo by M. Scott Moon

In 2005, the Alaska Department of Fish and Game issued 405 resident drift permits and 166 nonresident permits, for a total of 571. Another 609 resident setnet permits were issued, along with 128 to nonresidents, for a total of 728, according to department data.

For sportfishing, license numbers are not broken down by area, because a license acquired in, say Fairbanks, would be good all over the state. However, in 2005, the state issued 191,022 resident sportfishing licenses, while issuing 335,327 to nonresidents.

Personal-use anglers (for salmon) must fish either the Kasilof or Kenai rivers. Two gear types for personal use are allowed in the Kasilof — setnets and dipnets. Kenai allows only the dipnet. The Upper Cook Inlet management district includes only two subsistence fisheries, in Tyonek and Skwentna.

Fish and Game biologists utilize a variety of methods to count fish. None are perfect, but together they provide figures useful for deriving estimates accurate enough to make critical decisions about which user groups get what (allotment) and how many fish should be allowed to move upriver to spawn (escapement).

The sonar fish counter, which emits sound energy into the water column and reads reflected echoes, is one. The biggest challenge, said Pat Shields, assistant area management biologist for Upper Cook Inlet, is differentiating which echoes represent which species. Another is which sounds represent fish and which have bounced off other things in the water.

“Most fish will be moving upstream,” Shields noted. “Most non-fish will be moving downstream.”

Newer sonar gear can tell what is moving up- or downstream, and in some cases even see the profile of a fish.

Sonar counters, typically placed on each side of a river, are used primarily for counting sockeye. They are employed for commercial fish purposes on the Crescent, Kenai, Kasilof and Yentna rivers in the Upper Cook Inlet management area. A sonar station on the Anchor River supplies data used by Fish and Game’s Sport Fish Division.

Another way to count salmon is by using a fish wheel, a device similar to a waterwheel that scoops up fish headed upstream and deposits them in a holding pen or tank where they can be counted and differentiated by species, perhaps even tagged, before being released back into the river stream. In the Upper Cook Inlet area they are used to determine species composition — that is, how many of each type are there. They are positioned at the same sites as the sonar gear.

Still another method for enumerating sockeye is the weir, a kind of trap once used to harvest salmon, but employed today as a management tool. Fish are diverted from their upstream migration into a pen or confined gate where they can be visually counted as they pass through. Of all the counting methods, weirs are the most accurate.

Only one is consistently used for Upper Cook Inlet management purposes, and that is at Big Lake. But more weirs are planned, Shields said.

Counting fish in the inlet is more involved, and final figures are largely dependent on equations using several somewhat esoteric factors.

The Commercial Fish Division runs a drift boat along the southern boundary of the Upper Cook Inlet area, a line stretching west across the inlet from Anchor Point. Each day, a 200-fathom driftnet fishes six stations along the line for a half hour each, fishing east to west one day, and west to east the next during every day of July.

“We enumerate all species, but we’re primarily interested in the sockeye run timing and strength of the run,” Shields said.

The catch is converted to something called the Catch Per Unit of Effort (CPUE). Fish and Game converts the catch to numbers of fish caught in 100 fathoms of gillnet in one hour.

“We sum those up for the six stations and report the data to the public as index points for that day,” Shields said.

For instance, say an estimate of 1 million fish is arrived at through harvest numbers and escapement figures. If the CPUE were 500, you would divide that into 1 million. Each resulting index point would represent 2,000 sockeye.

Shields called it “a rough way of estimating,” but said those numbers and run-timing curves from past years give biologists a way to estimating where the total run would end up in the current year to within a quarter of a million fish or so.

“There are just too many variables to be accurate to the fish, but it is helpful to us for management,” he said. “Both commercial and sport look at that.”

Armed with such data, Fish and Game biologists allocate sockeye among the users, guided by policy set by the Board of Fish, a public process.

The Board of Fish develops management plans that give the department direction about how to conduct fisheries to harvest salmon surplus to escapement goals.

Determining the right escapement for each river system is a balancing act between the needs of the users groups and the long-term health of the fisheries. Commercial fishermen want to catch as many fish as they can before they hit the rivers, while sports interests would prefer to see as many fish coming into the river as possible. Atop that is the fact that too much escapement may be detrimental to spawning and rearing success, though that is a matter of scientific debate.

“The board gives us the plans we follow,” Shields said. “Within that, there is some discretion when to open or close fisheries.”

In normal years, commercial fishing occurs regularly from 7 a.m. to 7 p.m. on Mondays and Thursdays. Other openings or closings are done by “emergency orders,” typically announced over the radio. If the run to a river is strong, the department may authorize extra fisheries. When weak, they may close fishing down.

That’s exactly the problem Fish and Game is facing now with the Kasilof and Kenai Rivers. Shields noted that while the Kasilof run is strong, the Kenai’s has been weak, leading to orders restricting some fishing of Kasilof-bound fish in some areas and ordering outright closures in places where fishing is known to target Kenai-bound fish.



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