BY KEVIN G. HALL - Knight Ridder News Service

CALLAO, Peru - In a squalid fish market near Peru's largest seaport, blood drips from the morning's fresh catch of ''chancho marino,'' or sea pork. It's actually dolphin of the Flipper variety, a protected mammal under Peruvian law. In practice, dolphin remains widely available under the counter from Peruvian fishmongers. At 40 cents a pound, it's a popular protein for the poor. Horsemeat, by comparison, costs 70 cents a pound; beef, $1.85. The realities of this miserable market, coupled with meager money for enforcement, are contributing to the depletion of dolphin species throughout the eastern tropical Pacific Ocean from Southern California to northern Peru.

3,000 A YEAR By conservative estimates, 3,000 dolphins a year are trapped in Peruvian fishermen's nets, harpooned as they feed in shallow water or trapped, hauled to the beach and clubbed to death for human consumption. Fishermen kill many more for shark bait. Although there are no reliable figures on the region's dolphin population or its losses, thousands more die throughout the eastern tropical Pacific in the nets of deep-sea tuna and marlin fishermen.

POPULATION UNKNOWN ''We have no idea what the population was,'' said Stefan Austermuhle, a German biologist who heads Mundo Azul (Blue World), a Lima-based Peruvian conservation group that is working to halt the illegal slaughter of dolphins. 'But many people say, `I used to see dolphins and porpoises and now I don't.' '' Artist Maria Serena Matteucci knows how that can happen. She and her children were walking on the beach in front of their home in Pulpos, south of Lima, in February when they spotted dolphins close to shore. ''We were happily watching them swimming when suddenly fishermen started circling the dolphins and throwing them bait,'' she recalled. ``When the dolphins came close, the fishermen fired their harpoons. Then two fishermen jumped in, swam to the dolphin and lifted it into their rowboat.

SQUEALING DOLPHIN ``The dolphin was squealing as they massacred him with clubs. You could hear how the animal suffered. I have never heard anything like that. All I could do was pray the dolphin didn't suffer long before dying.'' Among the varieties hunted and eaten in Peru are the bottlenose dolphin, dusky dolphin, Burmeisters porpoise and two breeds of the common dolphin. Only three countries hunt dolphins for human consumption, according to Randall Reeves, the chairman of a specialist group for dolphins and whales for the World Conservation Union, based in England. In Peru and Sri Lanka the meat is sold to the poor, while in Japan it is considered a delicacy. Preservation of dolphins, which are actually small whales, will be on the agenda at The International Whaling Commission's annual meeting in Berlin, which begins Monday. Researchers want to reduce the ''bycatch'' of dolphins netted or caught in other devices by large-scale tuna and marlin fishermen. Mundo Azul, with help from Ripley, a large Peruvian department-store chain -- but with almost none from international environmental groups -- tries to enforce a 1996 Peruvian law against hunting, catching, transporting, selling or eating dolphins.

POLICE RAID In one recent effort, Mundo Azul sent an informant to a Callao market to confirm the sale of dolphin for police in the environmental crimes division. The police then obtained warrants for a raid. Mundo Azul found a car for the raiding party, which was too big for the Lima-based unit's single squad car. The police swept in on the dusty, smelly market and arrested two vendors, seizing their fresh dolphin meat and some protected seabirds. But word traveled fast. When officers arrived at an indoor market nearby, vendors hurled insults and threats. The dolphin meat the informant had seen a day before was gone. Outnumbered, police opted against a search and beat a hasty retreat. Col. Carlos Herrera, the chief of the environmental crimes division, said he wanted to do more enforcement but couldn't. ''I have no budget. I don't receive money to pay informants or conduct inspections,'' Herrera said. To weigh the bloody dolphin seized in the raid, the raiders carried it to a nearby shopkeeper who sold staples by the pound and asked to use his scale. It came to 90 pounds.

`CHEAPEST THING' ``As long as I can remember I have eaten dolphin,`` said vendor Nicanor Espinoza Alvino, 56, who was arrested in the raid. ``It's the cheapest thing out there.'' He told police that fishermen paid him $3 for every 60 pounds of sea pork he sold. Fines are minimal and the justice system overburdened. The real deterrent to Espinoza probably was the loss of the day's wares.

DOWNWARD TREND ''For the most part, the trend is downward for the dolphin,'' Reeves, the World Conservation Union's top marine mammal specialist, said in a telephone interview. Dolphins found along coastal regions and inland rivers are the most threatened, he said. Deep-sea populations face greater threats but have healthier numbers. The scientific journal Nature reported in mid-May that 90 percent of large fish, including tuna and marlin, have disappeared from the world's oceans because of over fishing.