D24—Lancaster Farming, Saturday, April 2,1983 UNIVERSITY PARK - When it comes to conserving energy, wild trout are among nature’s smartest creatures. Wild trout know how to save energy and only the most efficient ones grow year by year. For example, says Robert Bachman, fisheries biologist at Penn State, smart trout save their energy by intercepting food as close as possible to their feeding sites. Then they drop quickly to the stream bottom, where there is less current, in returning upstream to “home base.” Most food is in the drift, meaning it drifts with the current. Over three seasons, April through November, Bachman discovered that wild trout spent over 85 percent of their time in “sit and wait” feeding sites. He studied free-ranging wild brown trout from camouflaged towers at the Spruce Creek Fisheries Research Area in central Pennsylvania. World Record Bachman’s studies set something of a world record in Egg production rises HARRISBURG - February, 1983 egg production in Penn sylvania totaled 367 million ac cording to the Pennsylvania Crop Reporting Service. This was up seven percent from the 343 million eggs produced in February 1962. The February average of 18.1 million layers was seven percent above a year ago. Egg production per 100 layers was 2,032 compared Just how smart are those trout? observing a single group of wild trout - over 100 of them - without handling or marking the fish. He was supporting in his studies at Penn State by .the Cooperative Fishery Research Unit, now merged into the Cooperative Fish and Wildlife Research Unit. He claims the speed of a trout’s growth, and how big it gets, depends on the difference between the energy gained from the food and the energy spent in catching it. He noticed that hatchery trout, brought into the research site, used up more energy than they gained - mostly due to wasted movements. Thus, they didn’t survive well in the wild. Feeding sites used by any one trout, typically six to eight for each fish, changed very little with time of day, season, or even as the trout grew, he affirmed. The area en closing the trout’s home range averaged less than 200 square feet. These sites usually were established when the trout were six months to a year old. with 2,034 in February 1962. The nation’s laying flocks produced 5.35 billion eggs during February 1963, up fractionally from a year earlier. The number of layers on hand during February 1963 was 281 million, compared with 288 million a year earlier. Egg production per 100 layers during February was 1,899 compared with 1,850 a year earlier. “Home ranges of different in dividuals overlapped,” he said, “and we often found four or five trout using the same feeding site on a time-sharing basis. Such feeding sites became the focus of fights.” Fight for Feed Bachman explained that a trout usually tries to chase away another trout approaching its feeding site. It appears that each trout knows its neighbors, he added, since fighting between them is brief and not very costly in energy.- But fights between strangers or neighbors of nearly the same age and size are often long and burn off energy. “Trout seem to know in stinctively that energy costs can be reduced by quickly driving away competitors or by occupying less busy feeding sites," he stated. “Trout usually take only about one second to intercept food floating downstream but often take as long as eight to ten seconds in returning upstream," he added. “Then once again they take up Are You Feeding Properly? our Hay.Forage.Silage computer Analyzed ...In only 24 Hours! 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The larger trout gradually omitted more and more of the smaller food items from their diet. Bachman said the trout apparently were able to judge when a food item was large enough to warrant the energy needed to catch it. In general, the wild trout were very good at balancing their energy budgets. Growth stopped, or continued very slowly, when trout reached a size where the energy from food balanced the energy spent getting it. One such trout, named “Yellowfin,” was seen in the same area six consecutive summers. “Yellowfin" grew only two inches in a 50-month period - but was the most dominant trout in the study area during that time. Bachman said only one trout in a thousand grows to trophy size. He thinks that certain special areas of Distributor For FIBERGLASS ROLLS BLOWN IN Mw ■ I SALES One In Thousand Redwood, Yellow Pine & Outdoor Wood COMPLETE LINE OF REDWOOD LAWN FURNITURE • Glider * Picnic Table • Lawn Chair & Table • Porch Swings • Double Bench Lawn Swing JONAS S. EBERSOL Lancaster Intercourse WHEELING CHANELDRAIN ROOFING & SIDING Colors in Stock: • Red • Avocado Green • Plain Galvanized • Light Green • White • Gold • Brown • Tan • Silo Blue a stream provide a place where a trout can ambush small fish as they pass by. Such areas tend to grow big fish. However, most trout are drift feeders for all of their lives and never attain trophy size, regardless of their age. The hatchery trout brought into the stream were much less “cost conscious” than the wild ones. Hatchery trout changed position more than three times as often as wild trout and used energy-saving sites less often than wild trout. Moreover, hatchery trout were less likely to return to feeling sites after an encounter with another trout, wild or hatchery. As a result, hatchery trout failed to become part of the established “pecking order” and did not settle into a permanent home range. “With all their moving around, one might assume that the hat chery trout were seeking food more diligently that the wild trout. Our results showed, however, that hatchery trout fed only one-fourth to one-half as often as wild ones. So they use up more energy than they gain,” he added. DOUBLE BENCH LAWN SWIM Wholesale or Retail „ 1W MILES NORTH OF BIRO-IN-HAND ? 0n2689 Stumptown Road 3 Box 461. BW-in-Hand. PA 17505 | * DEALER INQUIRIES INVITED * 1 —SPECIAL—, Round Picnic I Tables I Underpass "Seechdak ★ 3rd house Distributor For ALUMAX ALUMINUM ROOFING & SIDING COMPLETE POLE & OTHER BUILDINGS TRUSSES
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