By MICHAEL GERSTEIN
Capital News Service
LANSING — Researchers based in Marquette have potentially grave news for Michigan anglers: Hundreds of shallow basins dug into riverbeds to collect trout- and salmon-harming sediment might be more like fish coffins than protectors. After two reportedly successful experiments in the 1980s, sand traps were constructed worldwide in an attempt to save fish populations hurt by excessive sand in freshwater streams. Michigan has more than 250. But now, researchers from the Department of Natural Resources (DNR) say they doubt whether these measures have had any benefit. In some cases, sand traps could even harm river ecosystems, experts say. Popular species like salmon and brook trout need coarse riverbeds of gravel or small pebbles.