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Fishing lessons
By JULIANNE WU, Times Staff Writer SEMINOLE -- For the next few months, students in Heather Judkins' marine science classes at Seminole High School will be in the aquaculture business. They are raising tilapia, a freshwater fish also known as Nile perch. The job of the students -- about 100 in the Marine Science I, and 27 in the Marine Science II honors classes -- will be to feed the tilapia daily, make sure their 500-gallon tank is cleaned periodically (one-third of the water being changed per week) and to record the length and weight of the fish biweekly. "We picked tilapia because they are an easy-to-maintain, hardy and edible fish," said Judkins, 30, a teacher at the school for over eight years. The fish-raising experiment at Seminole High is funded by a $2,000 grant Judkins received from the Southwest Florida Water Management District. It will continue until the end of May. Last Friday, about 50 fish were delivered to the school's science lab from a vendor in Myakka City. Over the weekend, however, three of the fish died. Monday, biologists Brent Winner and Cindy Armstrong helped the students in the advanced class divide the tilapia into three different groups: those to be tagged with numbers, external T-anchor or dart tags, and a control group without tags. Also, students assigned random numbers to the fish to determine which would be tagged and to keep records of their growth. Winner is an associate research scientist with the Florida Marine Research Institute of St. Petersburg and Armstrong is a staff biologist at the FMRI's Stock Enhancement Resource Facility (SERF) at Port Manatee. Winner told the kids that either method of tagging would work on the tilapia and would not affect their growth. FMRI experiments with both kinds of tags to see which stay on the fish longer. The T-anchor tags were inserted in the belly cavity of the fish, while the dart tags were inserted in the dorsal fin. The first step in the process was to scoop up the fish from the 500-gallon tank, a few at a time. Then, they were transferred to a smaller tank filled with water and a mild anesthetic, MS222. "Their breathing will be slowed down just enough so you can tag the fish and then measure and weigh them," Winner told the students. The anesthetic also reduced the stress to the fish as they were handled and tagged. "It's hard to catch the fish," said Aaron Kalwa, 17, a junior from Redington Shores, who helped transfer the fish. "But, it's good for us to learn how this stuff works." Junior Brittany Runyan, 16, from Seminole, was a tagger. "At first, it felt like it wasn't going to go in," said Runyan. "But, then it was fun." She described the fish as "real slimy." Other kids measured each fish -- which now range between 3 to 5 inches and will eventually grow to 8 to 10 inches -- while still others weighed them before gently throwing them back into the 500-gallon tank. But the kids are learning to measure the fish in millimeters. (One inch equals 25.4 millimeters.) "That's how it's done in the scientific community," said Armstrong. Senior Kristalyn Heliker, 18, from Seminole, volunteered to assign the random numbers instead. "I'm afraid I might hurt or kill the fish," she said. Tilapia, native to Africa, were introduced to Florida in the early 1960s by biologists as a new freshwater game fish and because they were supposed to control the growth of algae. It was soon discovered that mature tilapia, gray-brown in color, are bottom-feeding vegetarians that do not bite a baited hook. Because they are very prolific breeders, they soon turned up in Florida lakes in great quantities. By the 1980s, some fishermen were selling them to consumers. "I wanted to make this a real-life experience for these kids," said Judkins. "Aquaculture is one of the things they might do later on. Such things as depleted fish supplies and pollution make it necessary to have more marine research and fish farming." Judkins expects the population of the tank to grow soon, as it is spawning season for the tilapia. She hopes to save the juveniles for a continuing project next year. At the end of May, the students have to decide what to do with their tilapia. Either they will sell the fish to a local market, release them back into the wild or host a fish fry for the class members. -- Information from Times files used in this report.
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