Weekend's Fishline reports will begin again on April 1, but there's many a thing for serious anglers to do before the fishing gets under way.

Start by cleaning your fishing reels. Before every one in your inventory receives a good scrubbing, remove the monofilament line and discard it unless it was only recently spooled onto the reels. Fishing line is the cheapest investment in your tackle. Good fishermen replace monofilament regularly, depending, of course, on frequency of use and type of terrain the gear was used in.

Surf anglers in particular need to replace line that receives constant abrasion as it rubs across sandy beach water. Bass hounds who frequent rocky, stump-laden territory are in the same boat and should replace their line at least once a year. And if you're among the few who still keep rods and tackle in a heat-soaked auto trunk, by all means, replace the string. What a shame to lose the trophy of a lifetime because of nicked, heat- or sun-damaged nylon.

If the reels still function, a simple scrubbing with an old toothbrush, a few baby cotton swabs and a soft cloth will suffice. Use a bit of cleaning solvent to loosen dirt, then oil every moving part with quality sewing- machine oil. Fill the oil receptacles of your trolling and casting reels, then wipe off the excess.

For spinning reels, curl a piece of jeweler's cloth into the reel bail where the line rests. Remove tiny bits of corrosion and rust, but be certain not to polish with rough-grained sandpaper. The cure, in that case, may be worse than the illness. Now you're ready to add fresh line.

Don't attempt to disassemble a reel unless you're qualified to do so. Phone area tackle shops that have reel-repair departments and ask how soon they can repair items. There's no sense in dealing with someone who intends to get around to fixing things when time allows. Check the warranty literature that came with your equipment. The battle for your fishing dollars is so intense among large tackle companies that many offer free or nearly free repairs just to keep you in their fold.

Metal fishing-rod guides also should get a thorough going-over. Use the same jeweler's cloth or fine emery paper and gently push a cigarette-shaped roll into the insides of the guides and work the metal back into shape. Get rid of cuts and grooves that will damage that new line. As far as bits of loose line wrappings go, brush a bit of model airplane dope around the wraps. It will do in a pinch.

Now to the tackle box. Dump everything onto a sheet of paper. Your neighborhood tackle shop sells little boxes of every type of hook imaginable. Replace rusty, bent and broken treble and single hooks immediately. More fish are lost to poorly conditioned hooks than any other cause. Look at your lures. Have they lost that new look? Repaint them with model-airplane paint or fingernail polish.

After gently sanding away the grime, dab on a new coat of clear polish for a shine that will last all year. Red fingernail polish will spruce up every lure. And the model- airplane paint is available in colors to match the rest of the lures in the box.

Now sharpen every hook -- even new ones -- with a good whetstone. You'll be glad you did when that eight-pound bass lands in the net instead of the water when it makes its last leap.

Finally, there's one fishing activity that requires advance reservations -- black drum fishing around the fabled haunts of Cape Charles, Virginia. Schools of huge, delectable drum (many weigh over 70 pounds) invade the lowest recesses of the Chesapeake Bay every April and May -- especially the first and second weeks of May. We hope it isn't too late to get a booking aboard one of the fine charter boats found in this Eastern Shore angling headquarters.

Here are the black drum captains and their phone numbers: Captain Donald Stiles, 804/336-5433. Captain Doug Carson, 301/968-2212. Captain Ben Walls, 804/331-2058. Captain Carl Lewis, 804/331-3069. Captain Monty Webb, 804/331-3235. Captains Ed Howard & Janine Hardy, 804/665-4889..