The small, sleek, silver bodies glisten as the clear water catches the sun; as they glide quickly, in the same direction, they become a blur of gray. An occasional drifter tags behind the rest; others seem to be hugging the sides of the round concrete pond.
``We want to raise lean, mean, fighting fish,`` says Tom Schwartz, who manages the Mixsawbah State Fish Hatchery just north of Walkerton, Ind. ``We make them work harder by creating a stronger current in the ponds when they are bigger. Those that you see dragging behind, they get picked on by the others and pretty soon they can`t get their share of food. Eventually they will be too small to survive.``
It is Schwartz`s job to be concerned about the survival rate among each of 100,000 two-month-old salmon or slightly older trout that are housed in 1 of 15 10,000-gallon outdoor rearing ponds.
Over a year`s time more than 750,000 chinook and coho salmon, and brown and steelhead trout are hatched and raised at the hatchery. Their survival is constantly put to the test in water temperatures ranging from a brisk 46 degrees to 56 degrees and a diet of high-protein fish food. Schwartz calls the environment ``as close to natural as we can get.``
Those that survive the peer competition in the ponds and are not swept up by the visiting raccoons, minks, possums, great blue heron and kingfishers that occasionally dine at the hatchery are cast off into the waters of the Trail Creek in LaPorte County and the East Arm of the Little Calumet River in Porter County, both of which feed into Lake Michigan. The chinook salmon are stocked directly into the Michigan City harbor.
Because of the hatchery, fishermen all over the Great Lakes are telling stories that, though hard to believe, may be true. A 3- to 5-pound salmon is a common catch in the lakes from March until September. The luckier anglers make it to the list of Indiana records, catching steelhead trout weighing in at 23 pounds or chinook salmon at 35 pounds.
Salmon are native only to the western United States but were added to the Great Lakes in 1966 by the state of Michigan as an experiment. Biologists watched eagerly to see how they would survive in the unfamiliar waters.
``People in Indiana started catching these funny-looking brown fish,``
Schwartz says. ``They didn`t know they were catching Michigan-bred coho.``
When reports of the ``funny-looking fish`` made it back to the biologists, the experiment was declared a success. In 1970, Indiana also began stocking coho, and in September, 1971, 25 Indiana-bred cohos were trapped by biologists in Trail Creek, examined and let go. In 1974 the Mixsawbah Hatchery was built to meet the demand for a permanant Great Lakes salmon population.
The hatching process begins with staff members catching fish in the late summer just before they lay their eggs. Adult salmon (3 or 4 years old) work their way upstream to lay their eggs in embankments.
``You can tell when they are about to spawn. Coho get dark and ugly,``
Schwartz says. ``In order to catch them in the stream, someone has to stay 24 hours a day. We sort of camp out in a trailer for a few days.`` The staff uses a simple temporary low dam set-up, called a weir, to catch the fish.
The reason for all this trouble: Eggs laid in the muddy, foggy bottoms of Midwestern streams have less than a 1 in 100 chance of survival. ``Indiana`s stream quality is just not high enough to ensure a natural cycle. The eggs get covered with silt and suffocate,`` Schwartz says.
Eggs, about the size of a pea, are collected or, to meet the quota for a year`s stock, are traded between hatcheries. The annual quota is more than 2 million eggs; each fish generally lays about 5,000 eggs.
The eggs are hatched in incubation trays, where they remain for about two months before they are transferred to one of Mixsawbah`s 18 inside rearing tanks. To make room for the newcomers, larger fish are transferred to the outside ponds. The whole process is kept on a tight production schedule, Schwartz says. ``It`s incubator, then inside, then outside and then out of here.``
Mixsawbah is a cold-water hatchery. The species raised here are accustomed to low water temperatures and remain outside even in cold winter weather. The crew`s daily winter watch often includes removing wind-driven snow from the automatic feeders and keeping ice from accumulating on the ponds.
``It`s definitely not glamorous to be walking around in waders cleaning out the tanks when it`s 20 below,`` Schwartz says. ``It`s much harder on us than it is on the fish.``
Indiana`s two other cold-water hatcheries are:
-- Twin Branch State Fish Hatchery in Mishawaka, where chinook salmon and steelhead trout are produced for the St. Joseph River.
-- Curtis Creek State Trout Station near Howe, in the northeast corner of the state, which raises primarily trout for stocking in inland streams, but also some muskie, tiger muskie, hybrid striped bass and walleye.