Want to win a halibut derby here? Better bring a 300-pounder to the docks.

Want to set a state (and world) record? You'll need 460 pounds of flatfish.

Want to impress your fishing friends? Don't bother unless you're in triple digits.

While monster halibut continue to win derbies here, most anglers are seeing smaller and smaller fish on the ends of their lines.

For the first 11 days of June, for instance, the biggest derby fish across Homer's docks was a relative pipsqueak, a 78-pounder.

"I can remember years ago, anything under 30 pounds you wouldn't keep," said Wayne Bentler, a member of the 2010 Homer Jackpot Halibut Derby Committee. "Now you better hang onto it."

It's more than an impression. Today, a 12-year-old female halibut -- all huge halibut are females -- weighs half as much as it did two decades ago, according to Scott Meyer, a Homer-based groundfish biologist with the Alaska Department of Fish and Game.

Why?

"That's the million-dollar question," said Steven Hare, a biologist with the International Pacific Halibut Commission, which manages halibut off Alaska. He has at least three theories:

• Steady removal of the larger and typically fastest-growing halibut by commercial and sport fishermen reduces those traits in the population over time.

• There are more halibut in the seas than there were in the 1960s or 1970s. At the same time, the rarely fished arrowtooth flounder, which occupies similar terrain, has seen a huge growth in its population size. The resulting crowding and competition for food has driven down halibut size.

• Some unknown problem has harmed the quality or quantity of halibut food.

"They're definitely quite a bit smaller than they were 25-35-years ago," Hare said. "Back then, a 15-year-old female could be 100 pounds. Now it's 30."

Hare says there's no proof which, if any, of the theories is correct.

MILLIONS OF FISH

Halibut can live more than 50 years and older females are particularly productive, releasing up to 4 million eggs. That leads to what biologists call "exploitable biomass." In Southcentral alone, there are some 131 million pounds of that biomass, with sport and commercial fishermen allowed 26 million pounds this year. Anglers are expected to take about 4 million pounds.

But the declining growth rate of the big flatfish -- rather than fishing derbies -- "is the reason halibut are smaller than they were a couple of decades ago," Meyer said.

Charter boat captains frequently hear the debate over whether halibut are smaller today.

"My opinion is that the size has come down, but not that drastically," ace charter skipper Keith Kalke of Homer said on Sunday. "I had one load in May with a 65-pound average, but we had to run out to the Barren Islands to get them.

"I had one on yesterday I guarantee you would be very high up there on the (derby) board. I had to throw my anchor and chase the fish. But we lost it when it wrapped the line around a rock or something."

Kalke, in his seventh year out of Homer, has built a reputation for big halibut. His Ocean Hunters charter website is headlined, "Hard Core Fishing -- For serious fishermen only; not a pleasure cruise." Two years ago, a California angler on his boat caught the 2008 derby winner, a 348-pound fish. Elmendorf angler Jesus "Skip" Torres, fishing with Kalke in May, leads this year's derby with a fish 100 pounds lighter.

"I love big halibut, and I target them. I give you a derby ticket if you book with me, but I don't want to kill a big fish for a photo. If it's going to win the derby and you're going to eat it, that's different."

THROW BACK THE BIG ONES?

Kalke's not the only one who values big fish.

Commercial processors pay more per pound for fish in the higher weight classes and are required to toss back halibut under 32 inches, about 15 pounds.

In an effort to conserve large fish, the Homer derby established a new released-fish category four years ago in which anglers can earn $1,000 monthly and $5,000 over the summer by releasing a halibut weighing at least 60 pounds.

But some months have seen as few as two entries in the released-fish category. All of last year, just 58 halibut were entered in that category.

"Really, what we're trying to do is conserve and get people to release fish," said Henry Baldauf, chairman of the derby. "The first year it was really slow, the second year went gangbusters, then it went down again -- and we're not sure why.

"You can't force somebody to turn back a 60-pound fish. People come here to catch the biggest fish of their life, and it's a dream."

Meyer, the state biologist, has another halibut-conserving suggestion. He's seen anglers release one 30-inch halibut after another, "looking for a 32-incher."

And even though halibut tend to be hardy, there's some mortality.

"I've seen people probably release 10 fish looking for the big one."

He suggests taking the initial 30-incher and enjoying the filet, comforted by knowing that a halibut didn't die needlessly.

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Reach reporter Mike Campbell at mcampbell@adn.com or 257-4329.