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Nov. 21, 2005

Inland Fisheries Biologists Tag and Stock 20,000 Budweiser Sharelunker Offspring

ATHENS, Texas — Will the potential next world record largemouth bass please raise a fin?

Texas Parks and Wildlife Department Inland Fisheries biologists tagged and stocked 20,000 6-inch largemouth bass the week of November 14 as part of an ongoing effort to produce a new world record.

Operation World Record (OWR) evolved as a result of the Budweiser ShareLunker program. Now in its 20th year, the ShareLunker program has accepted 391 largemouth bass donated by anglers and used them for spawning in an effort to increase the number and size of trophy largemouth bass caught in Texas.

But until OWR, the program was based mostly on faith and common sense, which hold that bigger-than-average fish stand a better-than-average chance of producing offspring that will also grow large. Like cattle or deer, fish need three things to reach their maximum growth potential: good genetics, good nutrition and plenty of time to grow.

Recent advances in the ability to detect genetic differences among fish are expected to enable scientists to confirm their belief that big fish have genes that make it possible for them to grow bigger, and that these genes can be passed on to their offspring.

After extracting DNA from ShareLunker tissue samples, TPWD geneticist Dijar Lutz-Carrillo looks for short repetitive sequences of DNA known as microsatellites. At locations along the chromosomes where microsatellites exist — known as microsatellite loci — the DNA sequence is highly variable, providing elevated levels of variation among individuals. Variation is expressed in the form of different sized alleles at these microsatellite loci. Different sized alleles in different individuals can then be used to identify or exclude possible offspring at a later date. “We will be using up to 17 microsatellite loci to monitor these fish,” said Lutz-Carrillo. “We have DNA from the ShareLunker fish and their male mates. Taken together, the combinations of alleles at these 17 loci are virtually unique to these individuals. This allows us to use a technique analogous to fingerprinting to identify specific fish except that the alleles, unlike fingerprints, are passed on to their offspring. When fish are collected from these reservoirs at a later date, we will examine their DNA to determine if they are possible offspring from these ShareLunker crosses.”

“The study reservoirs were selected by considering a variety of factors,” said Mukhtar Farooqi, a principal investigator in the study along with Michael Baird, Timothy Bister and Thomas Hungerford. “The most important criteria were habitat, water quality, reservoir size and sampling conditions. We also considered the trophy history of the lake as well as its forage base and harvest regulations.”

Coded wire tags, tiny pieces of stainless steel wire 0.25 mm in diameter and 1.1 mm long, are inserted using a tag injector. The fish are then run through a device that magnetically detects the tag. If a tag is present, the fish falls into a holding tank. If no tag is detected, the device swings a gate inside to shunt the fish into a net so it can be retrieved and tagged.

“The fish we tagged last week will be sampled by electrofishing in April 2009,” Farooqi explained. “At the same time, we will sample wild fish of the same age from the reservoirs. Differences in length and weight of the ShareLunker offspring and wild fish will provide insight into the effectiveness of TPWD’s OWR largemouth bass selective breeding program.”

“Ultimately we will be able to take a DNA sample from a Budweiser ShareLunker and determine that fish’s parents,” said Allen Forshage, director of TFFC.

Forshage also praised the TFFC hatchery staff that raised the fish. “The survival rate of the fingerlings was high, which reflects the months of careful work of the biologists and technicians at TFFC,” he said.

The Budweiser ShareLunker program is made possible through support from Anheuser-Busch, Inc. Since 1991, Anheuser-Busch, in partnership with the Texas Parks and Wildlife Foundation, has contributed millions of dollars in funding to support conservation causes and fishing, hunting and outdoor recreation programs in Texas.

LH 2005-11-21

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