The Top 3 Questions to Consider when Growing Big, Healthy Fish - Q&A with Our Industry Experts

Typically, to grow trophy-sized fish, you need a healthy and abundant phytoplankton assemblage (phytoplankton are microscopic algae). However, similar to most things, there is an ideal range that is beneficial for fish production without causing other issues like fish kills. I would recommend having a water sample taken to assess water quality parameters and determine what species of algae are present. A fisheries biologist can then evaluate those results to determine if nutrient management or fertilization are needed. A trained fisheries biologist can help you promote beneficial green algae and prevent harmful blue-green algae, thus ensuring fish production is maximized and in-line with stakeholder goals.

Multiple factors play into when we stock, such as the source of fish and lake or pond location. For much of the country, the best timeframes are spring and fall, when surface water temperatures are as close as possible to ideal hauling temperatures, which is done in insulated transport tanks. Transporting fish is inherently stressful for them, so we employ several strategies targeted at minimizing the stressors wherever possible. Hauling water is kept cool for two important reasons: First, ammonia (produced by fish at higher rates while undergoing stress) becomes more toxic to fish as the temperature and pH of the hauling water increase. Second, colder water holds more oxygen than the same volume of warm water. Another stress associated with stocking is acclimation to the lake or pond water upon arrival; the larger the difference between hauling water and pond water, the more stressful the transition will be for the fish. In order to avoid long acclimation times and associated higher mortality rates, stocking is generally performed when temperatures are cool.

It depends on which species are overabundant and to what degree. For example, too many Bluegill can limit Largemouth Bass recruitment by consuming bass fry. Conversely, too many bass can quickly overgraze the available forage (like Bluegill) and cause the fishery to be comprised primarily of stunted bass—and with small insectivorous fish absent, nuisance insects like mosquitos can become a problem. Similarly, too many benthic fish such as carp can cause excessive foraging, destabilizing lake sediments, uprooting plants and causing high turbidity. Each pond has a healthy carrying capacity range and the density you manage for within that range is directly related to your goals for the fishery. If high catch rates are important, you may want to keep your gamefish density high and add forage annually. If trophy fish are more in line with your goals, then a lower density will likely be necessary.

Stocking baitfish into a lake can often improve growth of sportfish like Largemouth Bass. However, the decision of what to stock and when to stock should be determined by a fisheries biologist, preferably after an electrofishing evaluation to determine the current status of the lake. Additional considerations include the goals of the lake owner, whether the species will reproduce or not, what species of sportfish are present, and budget. Collectively, all of these factors can be used to determine if stocking is necessary and, if so, what species to stock. Stocking without these pieces of information may or may not be successful.

Non-native plants are characteristically adaptable to new habitats. They also tend to grow aggressively and have a high reproductive capacity. They are often introduced to a new location that is not characterized by the environmental checks and balances (such as seasonal weather, diseases, or insect pests) that kept them under control in their native range. Their vigor, combined with a lack of natural enemies, often leads to outbreak populations. Invasive plants often have negative effects on the ecosystem with high costs for control. While some anglers enjoy fishing near non-native plants, they typically are less desirable from an ecological standpoint. They are known for outcompeting native plants, reducing spawning areas, inhibiting other recreational activities such as boating and swimming, and affecting reservoir operations, and increasing so much that predator-prey interactions of fish are negatively affected.

Yes, habitat management should be addressed in a fisheries management plan. Essentially, stakeholder engagement and involvement for the HOA would help fisheries biologists discern any issues that stakeholders have, how they value the lake, and to clarify goals for management. One of the issues may be lack of habitat and a goal would then likely be to improve habitat. Then, steps could be taken to make habitat improvements that are aligned with not only stakeholder goals but also agree with HOA guidelines.

It goes without saying that road salt inputs of sodium and chloride (as well as other frequent inclusions like calcium, magnesium, and potassium chloride) are not ideal as they can cause numerous issues with freshwater ecosystems. In freshwater, fish are among the most salt-pollution tolerant organisms; especially compared to other more sensitive aquatic taxa such as invertebrates and amphibians. So, the short answer is – road salt inputs should be minimized as much as possible for the benefit of the entire aquatic ecosystem – but impacts are likely to be seen elsewhere before becoming evident in fish. To reduce these impacts road salt use should be minimized particularly near surface waters and wetlands as much as possible.

No, ponds do not need to be deep to produce excellent fish growth, as long as water quality is optimal fish can be successful in a variety of depths. In fact, most commercially operated fish grow-out ponds are 3-4’ deep. It is worth noting that ponds this shallow often require aeration due lower water volume with a given fish density (which is often based on surface acres). Fish also tend to be more vulnerable to predation in shallow ponds without a deep-water refuge. In the north, ponds need to be deep enough to allow fish to over winter, generally at least 6 feet deep.

When talking about incorporating the height of submersed plants, then you are looking at habitat on a 3-dimensional view. When Fisheries Biologist recommend 20 to 30% of cover, we are including surface coverage as well as submersed plants in that calculation. Another way to look at it, depending on the shape of your lake, if you have a lot of shoreline or if you have a lot of open water, the percentage of cover will vary. The 20 to 30% is not required but it is something to shoot for when building your fishery. For instance, if you have a lake that has a lot of open water, you may want to consider 20 to 30% of shoreline coverage compared to surface coverage. Having a conversation with a Fisheries Biologist or taking an aerial view of the lake can help you determine what and where the best habitat should be in order to get into that ideal 20 to 30% range.

Spring fed lakes often have superior water quality; therefore, they can potentially support a more diverse fishery. If you have a spring fed lake, even in southern climates, you may be able to support a cold-water species such as rainbow trout or brook trout longer through the year. Spring fed waters should be tested to find out what those water quality perimeters look like, however, there should not be any specific problems with spring fed lakes.

As fisheries managers, it’s important to aim for that balance between predator and prey. The rule of thumb has always been anywhere from five to ten pounds per acre of bait fish or forage fish for every pound per acre of sport fish. If you have a highly productive system where you have a healthy phytoplankton bloom, you may want to shoot for ten pounds per acre (10:1 ratio). However, if you are managing for trophy fish, you may want to increase that ratio to twenty to twenty-five pounds of bait or forage fish for every pound of sport fish. All in all, the ratio depends on your fishery goals. Though, if your ratio falls below five pounds per acre, you will run into an unbalanced ratio that will need to be improved.