Salmon Management

Why can’t more yearling salmon and trout be reared?

Anglers often ask why state fish hatcheries can’t produce more steelhead or coho salmon yearlings (or for that matter brown and rainbow trout) if they are producing less Chinook salmon. The reason we can’t make this switch is based on the hatchery life cycle of these species and the rearing abilities of our hatcheries. Chinook salmon are reared indoors for six months, and they don’t typically use outside raceway space that could be used by coho salmon and steelhead. Producing fewer spring fingerling Chinook salmon does not open up more rearing space for the other yearling species.

Studies across the country and in Michigan have shown that coho salmon and steelhead both need to obtain a certain size in order to smolt and survive. For years Michigan stocked fish that were not as large as they are today, and survival of those fish was considerably less than those fish stocked today. Obtaining an appropriate size for smolting is a directly correlated with the temperature of the rearing water. Because of these limitations, fish such as steelhead and salmon cannot be reared to sufficient size at hatcheries with colder water supplies.

The fishery managers of the Michigan Department of Natural Resources have the utmost concern for maintaining viable sport fisheries, but they are limited in the tools that can be used. Hatchery systems have clear limitations on the number and type of fish that can be reared at any given facility, and work over the last 150 years has produced a system that is very effective and efficient at rearing the fish needed by fisheries managers. Changing the amount or locations of fish produced by the DNR’s fish production system would require large-scale disruptions in production or great increases in capital funding to modify existing hatcheries or construct new ones.

There is a more efficient way to increase the production of the key fish of interest to anglers—through improving the production of wild fish. Department management goals and objectives call for protection and rehabilitation of aquatic habitat which is key to improving wild fish production. While hatchery limitations place caps on the ability to rear increased numbers of certain species, fisheries managers look for opportunities to work with interested constituent groups to improve the natural rearing environment for sport fish. Increasing the ability of our streams to produce wild fish will continue to be a focal point for fisheries managers working to maintain and improve the fantastic sport fisheries that Michigan anglers enjoy.