Fishermen are tough to satisfy. No matter how many fish a particular body of water produces, those who enjoy catching them are seemingly always wanting more. Every angler young or old has one thing in common; they all want to catch lots of fish and big ones too!
Fishermen approach life with a "have their cake and eat it too" attitude. Anything less just isn't satisfactory.
Now, just for a moment imagine what it must be like to be a fisheries biologist who's job is to insure fish populations keep pace with angler demand. Talk about a thankless job, biologists are constantly under pressure to improve fishing success in the face of increased pressure, poor fish habitat, unpredictable weather and other factors out of their control.
Some of the hardest fish species to manage are those that are the most popular. Walleye are a good example. Often walleye are caught and kept almost as quickly as they reach legal size.
In many ways being a fisheries biologist is like being a politician. To have any chance at success you have to tell people what they want to hear. It's also essential to get the job done with limited public funding.
A body of water can only support so many fish. Even in ideal conditions there are limits to any food chain. Unfortunately, the environmental conditions in our lakes, rivers and impoundments are rarely ideal for fish production. Biologists are faced with the complex job of getting the maximum return in fish flesh for their limited budget dollars.
Dollars allocated for fisheries projects are spent in a wide range of areas. Projects aimed at increasing natural reproduction are a popular way to spend "fish dollars". Efforts to improve habitat or structure so fish can avoid predation is another way these funds are spent. Stocking is yet another way that management dollars can help improve sport fishing.
UNDERSTANDING NATURAL REPRODUCTION
Fish populations naturally fluctuate. Spawning success, the amount of available forage, fishing pressure, natural predation, water levels, weather and disease all play a role in determining fish populations from year to year. When spawning conditions are good most species of fish have little trouble perpetuating their species. If spawning conditions are poor, an entire year class of young fish may be lost forever. Two or three bad spawning seasons in a row can destroy a fishery.
In the real world, spawning conditions are rarely ideal or catastrophic. Instead, spawning success tends to average out over time yielding middle of the road results.
When natural reproduction doesn't fulfill the demand for fish production, biologists can either wait and hope for better spawning success in the future or use supplemental stocking efforts to help level out population fluctuations.
Natural reproduction can't always insure fish populations are near their peak, but it does have one important benefit. Because natural reproduction is "free" any recruitment gained is achieved without costing biologists or licensed anglers dollars.
Because funding in fisheries projects is nearly always limited, stocking efforts are most often used to periodically supplement natural reproduction. Only in certain situations where the private sector helps to finance stocking efforts are annual planting efforts common or practical.
STOCKING
Stocking is becoming an increasingly popular way of supplementing game fish stocks. New fish rearing and hatchery technologies have made stocking certain species a more desirable alternative than ever before. Stocking popular species like walleye can quickly make fisheries biologists into heroes. Not only can these fish be readily grown in shallow ponds, the cost per fish produced is surprisingly modest and the return for the investment is a bargain.
The walleye eggs are fertilized and hatched in the controlled environment of the hatchery, then the tiny fry are released into the plankton rich ponds. Organic fertilizers like sheep manure are used to insure that the plankton levels are high and growing walleye have plenty to eat. When the fish reach fingerling size in about two or three months, the water in the pond is dropped and the fish collected. The young walleye are then transported to the stocking location.
A single pond can support hundreds of thousands of walleye fingerlings! In Michigan's Saginaw Bay upwards of one million walleye fingerlings are stocked annually, thanks to a cooperative effort between the state DNR and private sector funds. The whole key to this unique stocking system is insuring the walleye have plenty of plankton to feed on and that the fish are removed from the ponds before they become big enough to literally eat one another.
As many as 60% of the fingerlings raised in these ponds live to adulthood. That's amazing compared to natural reproduction which typically struggles to achieve a 2% recruitment! The cost required to raise walleye fingerlings is pennies per fish, making them one of the best candidates for stocking efforts.
Other species of fish are much more difficult and expensive to stock. Coho salmon, steelhead and brown trout are three highly sought after salmonids. Unfortunately, these species must remain in the hatchery environment for more than a full year. Because of the extra care and feeding, these species can cost upwards of .75 cents each to raise and stock!
Not all salmonids are expensive to raise in hatchery situations. King salmon are a fisheries biologists dream fish. Kings spawn in the fall like their cousins the coho. Eggs collected in the fall are fertilized are kept in oxygen rich hatchery waters until the following April. Once the eggs hatch into fry, the young king salmon are ready for stocking.
Some king salmon are stocked directly into rivers as fry. Others are stocked into special rearing facilities known as net pens. Young salmon fry are released into nets that are anchored near the mouth of natal spawning streams. Inside the nets the young salmon can feed on plankton and grow freely, while being completely protected from predation. Also, the longer the fry remain in the net pens, the better their odds of survival becomes once they are released to the open waters of the Great Lakes.
It's important to note that salmon kept in net pens tend to imprint strongly on the stream mouth where the pens are located. As adults three years down the road, these very fish will return to exactly the same stream making it easy for anglers to find and catch them. The methods used to raise king salmon is one of the biggest success stories in fish management.
STOCKING ISN'T FOR EVERY SPECIES
Unfortunately, not every species of fish is a good candidate for stocking. Certain species like northern pike do not do well in hatchery situations. Pike are so aggressive that in a hatchery environment the fish tend to prey upon one another. Instead, fisheries biologists manage pike by providing suitable spawning habitat and letting nature take its course. Ideal pike spawning habitat consists of shallow and weedy marshes adjacent to natural lakes and rivers. Adult pike migrate into the marshes and spawn. When the pike eggs hatch, the young remain in these marshes feeding on plankton, other fry and aquatic insects until they grow large enough to feed and survive in open water.
Both largemouth and smallmouth bass are other species that aren't good candidates for stocking. Because both of these species provide parental care to their young, predation is lower than with other species of fish. The male bass guards the nest until the eggs hatch and the young fry are big enough to hunt for food on their own. This unique spawning ritual makes bass among the most successful species at natural reproduction.
Bass also enjoy another benefit that makes stocking efforts unnecessary. Because the majority of bass captured by anglers are returned unharmed to the water, natural recruitment doesn't have to be exceptionally high to sustain quality fishing.
STOCKING ISN'T ALWAYS THE ANSWER
Every angler wants his home lake to be stocked, but not every waterway is a good candidate for stocking. If a body of water has a limited forage base, adding additional fish into the system can defeat the whole purpose for stocking. Most species of fish grow quickly in forage rich environments. In waters where forage is limited, fish grow painfully slow. Also, because these fish grow slowly, they are also more susceptible to natural predation.
In this situation, stocking does little to improve fishing conditions. Not having adequate forage is one of the major reasons many waters are not good candidates for stocking. Having too many of a particular predator species is another reason stocking may not be a good idea.
Stocking trout for example into a lake that has an abundant population of northern pike makes little sense. The aggressive pike simply eat the young trout as quickly as they are stocked.
It's often necessary to control the population of certain species before other more desirable species can be stocked. Liberal harvest regulations are often used to help reduce the numbers of undesirable fish, so planting efforts can be conducted more successfully.
Biologists are often faced with the difficult decision of rejecting stocking requests for these and other good reasons. Saying no to stocking requests is never an easy or popular decision, but it is a decision that must be made for the greater good.
As long as anglers demand quality fishing experiences, stocking will continue to be in demand. Unfortunately, stocking isn't a fix all that applies to every species or body of water. Used properly, stocking can be a powerful fisheries management tool. It's tough to keep fishermen satisfied, but stocking is one way to keep the peace.
The walleye eggs are fertilized and hatched in the controlled environment of the hatchery, then the tiny fry are released into the plankton rich ponds. Organic fertilizers like sheep manure are used to insure that the plankton levels are high and growing walleye have plenty to eat. When the fish reach fingerling size in about two or three months, the water in the pond is dropped and the fish collected. The young walleye are then transported to the stocking location.
are so aggressive that in a hatchery environment the fish tend to prey upon one another. Instead, fisheries biologists manage pike by providing suitable spawning habitat and letting nature take its course. Ideal pike spawning habitat consists of shallow and weedy marshes adjacent to natural lakes and rivers. Adult pike migrate into the marshes and spawn. When the pike eggs hatch, the young remain in these marshes feeding on plankton, other fry and aquatic insects until they grow large enough to feed and survive in open water.