Subscribe to PB mag ! If you do then you read this article below. I don't post whole articles often but this one is a reminder that things aren't as they seem on first analysis. Cull underperforming fish all year long - don't wait for the problem to manifest. Fix the wheel before it starts squeaking. IMO its better to harvest underperforming LMB before fall (cull in summer). See the article below about harvesting LMB before fall so that the fish to be culled don't use up part of the fall feeding frenzy. That way your better LMB get all of the food rather than letting fish that should be culled use up resources.


The Cutting Edge - Science Review

Fall Frenzy , Winter Soon

Fall followed by Winter is an interesting time at the lake from a biological perspective. Many people think of Fall as a quiet time of year. In reality for many pond creatures Fall is a period of frenzy followed by Winter survival struggles . A good way to view the workings of a pond or for that matter a fish is like that of an engine. An engine that is dependent on sunlight for power and nutrients for growth. Add to that , fish are cold blooded making water temperature a critical factor in all metabolic aspects. Because fish are cold blooded they have optimum growth in warm spring and early summer waters , then growth slows and can stop or even reverse in extremely hot summer temperatures. Then as the water starts to cool in Fall metabolism ramps back up as optimum temperatures occur again. Then metabolism slows when temperatures cool more into Winter and feeding and growth slows substantially and stops. If not enough energy reserves of the right type are stored going into Winter fish may have a difficult time. Lack of adequate food resources is the most common reason for lack of energy reserves in many fisheries. Increasing food intake with very little energy use during the optimum Fall feeding frenzy period is good. More energy acquired and less used equals more energy reserves. Obviously in Fall and Winter the sun’s energy reduces to low levels so the pond and fish engine slows. However, in the optimum temperature Fall lead up to Winter there is a frenzied attempt by fish to secure energy reserves.

Fish energy sources are mostly carbohydrates, fats (lipids), and proteins (muscle). The amount of energy actually obtained and stored is lower than the amount present in the food as some energy is used in catching food and in the fish’s digestion, metabolism, and thermogenesis. Understanding the role of energy as it works through biological seasons of the year is fundamental to management. This was noted in Energy Partitioning in Largemouth Bass under Conditions of Seasonally Fluctuating Prey Availability by S. Marshall Adams R, . B. McLean and J. A. Parrotta, Transactions of the American Fisheries Society 111:549-558, 1982. Here, in order to maintain condition Largemouth Bass maximize caloric growth in the Fall, store visceral fat, and minimize active metabolic demands in preparation for Winter. This study site was in Tennessee which like many freshwater systems of the United States, particularly in temperate areas, have threadfin and gizzard shad as a primary prey source of several predators. These prey species have large fluctuations in abundance due to heavy Winter mortality thus the growth and mortality of a largemouth bass population were indirectly influenced by temperature effects on prey availability. Shads reach optimum size and abundance in early Fall when temperatures are perfect for Largemouth metabolism and the Largemouth need energy reserves, so the feeding frenzy begins.
This study notes that growth of females was highest in June following the May peak in consumption (post spawn feeding) and then gradually declined through a summer depression in growth and consumption. Males had high growth levels in the summer and Fall. More importantly both male and female bass added fat during the Fall. Both sexes built up their fat reserves in the Fall when consumption (Fall feeding) was high as evidenced by a Fall increase in the visceral-somatic index (VSI). Decreases in VSI in both sexes during the Winter and early spring probably were due to utilization of stored fat to meet metabolic demands when feeding and prey abundance was low, which is also reported for other fish species.

Obviously, different species of fish differ in their ability to use fat deposits. This in turn affects the temperature range in which different species can grow and survive. For example, Nile tilapia do not store excess lipids in the muscles but rather rely on visceral deposits which it is incapable of using at low temperatures, resulting in high mortalities when water cools. However, many pond species which are capable of using lipids (fat) from muscular and visceral deposits are able to survive much colder temperatures under the same conditions. It is believed that the lipid composition in the fish muscle plays a vital role in the ability of fish to adapt from one temperature to another. Variations in the liver weight of largemouth bass reflect storage of glycogen, fat, and water, which vary with consumption rate. Consumption was high during the late spring and summer, yet the liver-somatic index (LSI) of both sexes declined. This decline may have been related to utilization of energy for reproduction and temperature-induced metabolic demands. Other studies have found this same pattern in the LSI for field-collected bluegill over a year and attributed the low summer LSI to spawning and temperature.

Fall is the period when many species accumulate these fat deposits while adjusting to a lower metabolism. Of course, it depends on a pond’s location and the type of fish involved. Bluegill in one report consumed at higher rates in the Fall like bass and very little food during the Winter in more northern climates. Whereas Yellow perch (a cool water fish) ate much more food than did bluegills during the Winter and did not have to indulge in the Fall feeding frenzy to the same degree.

So, as you watch the Fall changes around you also look for Falling fish as they eat away packing on fat in preparation for Winter.