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Show bycatch. Most of the harvested cysts are used as hatch out feeds in the aquaculture of shrimp and fish which are reared for human consumption. Brine Flies Often considered " noxious and insidious creatures" ( Rawley et al., 1974) brine flies are actually harmless, do not bite or transmit disease and are a very important part of the overall ecology of GSL. Brine flies are the primary food source for many species of animals, spiders and birds living around the shores of the lake. A source of the misconception is their sheer numbers, reported to be over 370 million flies per mile of sandy beach, for a total of over 110 billion flies plus 10 billion pupae on approximately 300 miles of beaches around GSL. Brine fly abundance is variable from year to year, and depends upon changes in water chemistry and other environmental conditions. The lake's rise in the 1980s probably resulted in an enormous supply of brine flies when the bullrush was inundated and new pupation sites appeared. Wind direction and velocity seem to have a direct affect on their distribution. Brine fly numbers peak during July and August, and decrease as temperatures begin to drop ( Vorhies, 1917). There are two species of brine flies, Ephydra gracilis and the smallest and most abundant, Ephydra hians, the alkali fly. Brine flies play an essential role in converting organic material entering the lake into food for wildlife living along the lake's shoreline. By removing over 120,000 tons of organic matter each year from GSL, brine flies consume great quantities of algae, bacteria and organic refuse from brine shrimp and their own life processes. It would require a 78,000,000 gallon per day waste water treatment facility about the size of the Salt Lake City municipal treatment plant to remove this much organic waste from the lake. According to biology professor Dr. Robert N. Winget, " Without brine flies or additional water treatment, lake waters would become cloudy and foul smelling, sands would be clogged with algae and decomposing organic materials, and wild animals of the lake area would be starving." The life cycle of the brine fly consists of four stages, egg, larva, pupa and adult. Each female lays approximately 75 eggs on the surface of the water or on floating debris consisting of brine fly pupal casings, dead brine shrimp or cysts. The eggs sink to the bottom of the lake before they hatch into larvae. They obtain oxygen from the water by diffusion, and feed on blue- green algae. They become free swimming after emergence, until they find suitable habitat such as algal bioherms or other stationary objects in shallow areas of the lake on which to pupate. Nearly 10 percent of the lake bottom is covered with algal bioherms ( Cohenour, 1966). Larvae and pupae have been found in water depths of between one and 20 feet, and can obtain oxygen from the water by use of tracheal gills located in a long forked anal tube. During warm weather, the larval stage also may pupate on the surface of the lake on floating masses of algae. The pupal cases split open on the back and fully develop into adult flies. Flies emerging from the bottom of the lake float to the surface in a bubble of air. The life cycle can be completed in 21- 30 days, and may extend longer during cooler temperatures. Adult brine flies only live 3- 4 days. Brine fly 71 |