Bluegill Backbone or Bane? North Vs. South
June 23rd, 2010
AS SEEN IN POND BOSS MAGAZINE, May/June 2010: Written By Industry Expert David Beasley, Lead Fisheries Biologist
From America’s southern deserts to the vast timbered landscape along our northern border reside millions of private ponds and lakes. Each pond is a little different than the next, with regional climates and micro-climates giving ponds unique character. But, when it comes to ponds, the country has been placed into two stereotypical categories basically divided by the Mason-Dixon Line. When it comes to bluegill, that mythical boundary offers a distinct difference of opinions and strategies when it comes to managing this most basic of panfish. Of all the freshwater forage pond fish species in America, bluegill are one of few who prosper throughout both climates. Should bluegill be classified as the backbone to the forage base within both climates?
That’s a big question that offers a fair debate…depending on which side of that fabled line you live.
No matter where in the country they reside, bluegill definitely play the same role—they are forage for larger game fish as well as a highly sought-after sport fish in their own right. As a forage species, at their prime they have the ability to reproduce multiple times annually, laying thousands of eggs each spawn. Under ideal conditions, they grow fast and can reproduce before turning age one, maturing sexually as small as three inches long.
Their deep, compressed shape allows adults to avoid most predators and their diverse feeding habits allow for large numbers to live in harmony. Bluegill are warm water species, so they grow best when water temperatures are between 60 and 80 degrees Fahrenheit. Knowing this, it would make sense that they do better in warmer climates.
The climate in the south provides ideal water temperatures for bluegill growth throughout two extended periods of the year separated by a cold and a hot season. For example, bluegill in Alabama may have as many as 325 ‘perfect’ growing days, while upstate New York may only offer 70-120 of those same days.
In the south, bluegill have adapted to this split growing season, utilizing their ability to develop eggs in phases throughout both of these periods lending to multiple spawns. This important characteristic provides ponds with multiple size classes of young bluegill to fuel the food chain. That’s a key to largemouth bass management in the south. Warm water is conducive to plenty of plankton throughout most southern regions, supplying young bluegill with the nutrition needed to reach reproductive size by age one in some cases. The bass size class a couple months older than the latest bluegill hatch takes full advantage, providing young bass with great growth rates. This food chain works in harmony with these warm water species. The southern climate may not have perfect growing conditions year round, but multiple time periods of ideal temperature and available plankton draws out the annual growing season and exposes the good characteristics of bluegill as forage.
But what about pondmeisters in the northern third of the country stuck with warm water forage in a cooler climate? Are bluegill to blame for northern largemouth bass taking up to four years to reach 12 inches when, in the south, these bass can reach that in two years? Many people turn to blaming bass genetics and the short growing season to justify this reality. Is it possible that bluegill serve as an insufficient backbone for the food chain for predator fish in the north?
Well, a lesser known fact about the north is that they have a comparable number of growing days for largemouth bass. Many parts of the north have180 days of ‘ideal’ warm water temperature, it just all happens in sequence. Many parts of the south have 250 days of prime water temperatures with interruptions by a hot and cold season. Although bluegill in the north have a decent number of growing days, the sequence of these days and the different climate alters the dynamics of the food web.
Like many other species of wildlife throughout the world have evolved to make best of their current climate, bluegill have as well. The many spawns spread out over 9 or 10 months in the south don’t occur naturally in the north. Bluegill in the north often spawn only once or twice in the spring…or actually in the summer. This spawning habit is often related to food availability and the fact that spawning temperatures aren’t reached until June.
In unmanaged northern ponds expect one, possibly two size classes each year. Since bluegill spawn later in northern ponds, there’s often a gap in the food chain for largemouth bass.
And then, to complicate matters, perfect bluegill temperatures and fewer numbers of young allow for faster growth of individual fish. So, those bluegill which can survive immediate predation are often too large for the dominant size ranges of the predators we count on to eat them.
Another difference between Dixie and the snow covered north is the simple fact that largemouth bass are king of southern waterways. In the north, largemouths are a warm water fish often out of place with their cool water cousins, smallmouth, walleye and yellow perch.
These facts also affect what we think about bluegill and how we use them.
Throughout early and late winter months, cool water fish find the ice covered environment ideal for foraging. They gorge themselves on the shivering, young, lethargic warm water species…such as bluegill. By the time spring rolls around, forage is often scarce, creating a significant lull in the forage base. With the lack of abundant food, warm water fish simply don’t have the tools to put on the pounds. As temperatures rise, cool water fish spawn, then bluegill and other warm water fish. That’s a disadvantage to these warm water fish vying for a living in northern waters. Plankton blooms can be slow to start and only last 4-5 months.
But, those months of plankton growth can be intense. That intensity grows bluegill, fast. Each spring, or early summer in the north, bass and bluegill are hatched around the same time. This gives bluegill a distinct advantage over newly hatched bass. In this process, bass get off to a slower start in life than their southern cousins. Come July and August, young bass are only an inch or two long and most still rely on plankton and invertebrates for food. By mid-summer, the growing season is half over and food availability is finally reaching its peak. Young bluegill serve as a good source of forage now that they are around an inch plus in length.
But, this food chain is trying to support bass from several years past. For several months the environment provides a productive warm water fishery. When fall rolls around, young of the year bass are usually 3-4 inches in length and bluegill range between 1-2 inches. While young bluegill may be abundant, the metabolism of bass and bluegill slows to a crawl as fall yields to winter. Without hesitating, the cool water species continue to consume, taking advantage of the summer’s productivity and lethargic tendencies of the young bluegill. Come spring, temperatures rise, but one problem, those bluegill that were the backbone of the food chain are few and far between.
This annual lull in available food takes the reasonable 180 day growing season for warm water species and turns it into 80-120 days due to the lack of availability of food in the spring. Throw in the fact that, in the north, bluegill are age two before reaching reproductive size and things look more grim for those warm water predators awaiting a key component of the food chain. That’s the main reason largemouth bass don’t grow rapidly in the north and further adds to their overcrowding, even when in the presence of fish more suited to that climate.
So, although northern ponds struggle with bass growth, bluegill are not necessarily at fault. Bluegill continue to serve as a great source of forage. They can be depended on to reproduce annually and they have a large number of young, they just don’t have the same synergy with their key predators in northern waters as they do in the south.
So, what do we do?
In the south, feeding and fertilizing are key. Feed the bluegill and they will respond. With many, many more growing days, a southern pond can produce a much larger crop of bluegill. But, in the north, exercise care. If you tell a biologist you plan to feed or fertilize, that scientist-thinker is likely to tell you not to do it. Too big a risk, due to the complications of fertile water under snow-covered ice. Winter fish kill is a big issue. But, with cutting edge aeration systems and new management technologies, managers are re-thinking that advice.
So, are bluegill the backbone of the food chain in the south and north? Well, “Yes” to different degrees. In the south, they provide the basis for largemouth bass to grow fast and large. In the north, they assist in survival of predator fish, but are not adequate stand-alone forage fish for largemouth bass. Toss in their saucer-shape and they are less than ideal for other game fish with smaller mouths than largemouth bass, such as smallmouth.
In order to successfully grow large fish in the north with bluegill, you will need to provide for seasonal voids in the food chain. So, for those throughout the country questioning the decision to put bluegill in your pond, definitely do, just know how their characteristics mesh with your climate and adjust accordingly.
Contact the experts at 888-480-LAKE (5253) for all of your lake, pond and fisheries management needs.
David Beasley is a Lead Fisheries Biologist and Regional Manager with SOLitude Lake Management. Since 1998, SOLitude Lake Management has been committed to providing full service lake and pond management services that improve water quality, preserve natural resources, and reduce our environmental footprint. Services are available throughout the Eastern United States. Fisheries management consulting and aquatic products are available nationwide. Learn more about SOLitude Lake Management and purchase products at www.solitudelakemanagement.com.