The wild brook trout is as delicate as the tissue-winged mayflies he loves. Careless handling while releasing one will send the fragile fish off to die.

But more threatening than mishandling by anglers is the destruction of the native trout's severely limited habitat. The wild trout have vanished from virtually every stream that can be reached by road.

Dump silt or sewage into his crystal home, flood his churning rapids, and the native brookie will flee toward the ever-narrowing headwaters. Finally, trapped in a tiny branch, his majesty will wane. His paunch will tighten as the food supply is exhausted. Then he dies.

He is the recluse of the trouts. The farther from "civilization" you venture, the better chance that he'll be found thriving in cold mountain waters. Virginia's Shenandoah National Park has one of the few remaining strongholds of the native brook trout. Some 40 spring-fed mountain headwater streams there are managed to provide quality fishing for strictly wild trout.

To the experienced angler there is no comparison, on the line or on the tale, between a hatchery trout and those inhabiting these cold, crystal waters. The hatchery fish has been domesticated. His wildness has all but vanished, his colors paled, his quickness and survival instincts lost.

And you will chuckle at restaurant menus offering "genuine mountain trout" after having tasted the firm, salmon-pink flesh of a true native brookie. The pale mushiness of a lazy hatchery trout, hand-fed on pellets all his sterile life, does not remotely resembly the bright meat of a native brook trout fattened on insects, crustaceans and minnows.

But tasting the flesh of a native brookie is a reward the Shenandoah Park angler does not abuse. Few of the fish he catches are killed. Most are handled with extreme care as the hook is gently twisted free. They are admired for the beauty of their tiny, streamlined bodies and their awesome will to live, then supported gently in the water until they scurry away.

The native brookies of Shenandoah Park have been there for thousands of years and are the only trout (char) native to the eastern United States. Once abundant here, they are now confined to remote backcountry waters were their demanding habitat needs are still met.

Where mountains stop, brookies disappear. In the flatlands the streams no longer tumble and splash and so are less charged with oxygen. And once the steepness of the mountains eases, man's presence makes itself felt all too heavy-handedly. Sewage seeps into the water, trees that shaded and stabilized the banks are cut, silt smothers the clean gravel necessary for spawning.

Special park regulations help keep the angling harvest in check. Only five trout a day over eight inches may be creeled, and only single-hook artificial lures are permitted.

Most anglers who frequent these waters admire their quarry and are aware of its precarious existence. They usually keep less than a limit and often release all. The best use barbless hooks.

But it's primarily the lack of easy access that protects the native brook trout. Most of the streams require a hike of one to three hours to reach, from the heights of Skyline Drive downward on steep, sweat-inducing trails that make one wish he were 10 pounds lighter and 10 years younger.

This tough access rules out heavy pressure on the mountain brookie waters, since few will trek that far to catch a trout. Most stop instead along the roadside waters were pale and listless hatchery fish are dumped in a few days before the season opens. It is difficult for the average fisherman to appreciate the subtle beauty of a glistening brook trout that may measure only eight inches, so obsessed have we become with bigness. Rarely will the natives exceed a foot, and most park regulars are delighted to do battle with a 10-incher.

Shenandoan's streams should be at a peak for fishing during the next few weeks. Abundant rains have kept water levels up and caddis and mayflies are hatching on some creeks. Fishing will continue through the summer, but as the water volume drops, approaching the skittish-fish without spooking them becomes a challenge.

Backcountry camping is permitted in Shenandoah Park, but you must first obtain a permit from a ranger at one of the visitor centers or by mail from Robert R. Jacobsen, Superintendent, Shenandoah National Park, Luray, Va. 22835.

Three maps showing all the park's trout streams and their trails are available from the Shenandoah Natural History Association, Box 387, Luray, Va. 22835, for $4.50.