Post-spawn transition and dietary changes are factors Louisiana anglers should consider when trying to hunt down a limit of trout in September.
For people, most of whom are detached from agriculture, the profound impact nature’s rhythmic patterns bring to life on earth goes largely unnoticed.
What we do notice are the seasonal changes in temperature and weather, and while this is significant, Gulf coast anglers will do well to look deeper into the patterns of nature for clues that can lead to increased success catching species such as speckled trout.
This is especially true during periods of the year when major biological patterns change, such as September.
September: month of change
In coastal Louisiana, September roughly marks the arrival of a new pattern for the inshore fishery. For anglers targeting speckled trout, it is not a pattern that typically helps them catch these fish.
September is generally an easier month to be on the water, because cooling temperatures have diminished the violent and dangerous thunderstorms characteristic of summer. The slight decrease in water temperature could be perceived to result in better fishing than in August, when trout generally feed in low-light conditions and retreat to cooler water during the heat of the day. However, it is the tapering-off of the speckled trout spawn that makes September a challenging month to fish.
A fundamental characteristic of September is that there are roughly 2 hours less daylight per day than in mid-summer, and this physical change is a dominant force informing the speckled trout that the spawn is ending. During the spawn, speckled trout form large schools in high-salinity water because they are a broadcast spawning species. Biologists say that most spawning activity occurs at night, so anglers rarely fish schools of trout engaging in the spawning function. However, the necessity to gather near the time of spawning makes locating trout easier for anglers and thus increases the catch.
Of course, speckled trout are fundamentally a schooling species, forming schools as a feeding strategy. So certainly, for small and mid-sized fish, schools will still exist in September. However, when female trout have stopped producing eggs, they are released from the necessity to form spawning schools and the need for high-salinity water. Male trout, which also school during the spawn and drum to attract females, will follow the same patterns of post-spawn behavior as females. Thus, trout transition from the requirements of spawning to a purely survival mode, which makes finding large schools of trout more difficult. This gives September the reputation of being a difficult month to catch speckled trout.
One bright spot for Louisiana anglers is that a new generation of female trout have reached 12 inches, the minimum size for harvest. These trout were spawned in the previous year’s spawning season and are forming shoals of hungry fish. Sometimes, schools of 12- and 13-inch trout form that are large enough to allow a relatively continuous bite for a few hours.
Where to find trout
Most of Louisiana’s spawning trout have spent the summer in the high-salinity water of coastal sounds, the mouth of coastal bays, around barrier islands and around nearshore rigs. Even though spawn ends in September, there is no rush for trout to leave these areas.
Since survival is now the primary objective, trout will be motivated to inhabit areas where they can moderate their metabolic rate with cooler water and where there is ample bait. A third consideration is areas where predators can be avoided, although this must be a lesser motivating factor than the other two. When considering areas during pre-tip planning sessions, start with areas where these three conditions intersect. Water turbidity and water flow remain important factors, since they are foundational to areas holding feeding speckled trout.
A type of area that often has the three conditions are the edges of deep channels and passes. The presence of rock armoring on channel banks seems to create a more-desirable habitat than sediment banks. In September, large schools of 12- and 13-inch trout take up residence in the MRGO channel. Oriented north/south, the channel provides continuous habitat stretching from where the trout spent the summer, to where they will be in October. Anglers fishing somewhere along this path in September will find success in waylaying trout that are on the move.
Speckled trout will also be found around structure in open bays, including oil and gas rigs and on the hardbottoms of oyster beds and shell pads. These areas easily supply two of the three critical conditions: moderated water temperature and protection from predators, but they must also hold a large amount of bait. The presence of bait is not assured, however, so don’t spend much time there if you don’t find trout.
As September progresses, trout will begin to appear in Lake Pontchartrain, more often around shorelines than bridges. Shorelines featuring submerged aquatic vegetation are a particularly attractive habitat for speckled trout, which cruise shallow flats with eelgrass beds, feeding on baitfish until the sun rises high. In shallow water, you can see the eelgrass growing like a carpet on the water bottom, but it will also grow in depths of 5 or 6 feet, so it’s worth canvassing areas to locate deeper eelgrass beds. Widgeon grass can also provide adequate habitat, so these areas should not be overlooked. Fortunately, the vegetation serves to clean particles from the water, so water quality is typically very good around the grassbeds in Lake Pontchartrain.
A trout’s September diet
For several months preceding September, most of the legal-sized trout have been eating a diet consisting largely of white and brown shrimp. According to biologists from the University of Southern Mississippi’s Gulf Coast Research Laboratory, a diet high in shrimp is beneficial for optimal reproduction.
Adult shrimp are plentiful in high-salinity areas where trout have been spawning, but the numbers of shrimp decrease by September due to predation and human harvest. Shrimp are destined for a short lifespan in modern times. They can grow quite large, up to 12 inches, but very few have the chance to do so. Almost everything in the water eats shrimp, and humans harvest them in large numbers. In Louisiana, annual harvests are in the range of 100 million pounds. While early in the summer, most speckled trout are primarily eating shrimp; with the spawning period over and the shrimp population diminished, trout will turn to schools of finfish like mullet and menhaden.
This transition, from trout feeding on massive groups of shrimp to feeding on schools of finfish will reduce the number of fish in a shoal of trout. There must be a relationship between the number of trout in a school and the size of a school of baitfish they target. If there are too many trout for the amount of bait, some fish will expend energy to feed without gaining an adequate caloric intake, and this could cause some trout to leave a large shoal. Observations generally supports this theory, because many anglers catch more trout in a short period of time when the trout are feeding on shrimp than when they are feeding on mullet or menhaden. If the average number of trout in a school is reduced due to the available food, it could explain why “run-and-gun” is a commonly used fishing strategy for limiting out in September.
For September success, target structures along a path from the lower estuary to the inside waters. Expect to find fewer trout at each spot you fish, so you often fish more spots and spend less time at each spot. There are certainly exceptions to this, but the size of the trout in these large September shoals are juveniles and just legal fish.
Artificial baits that are effective in September are not much different from July and August, but tight-lined swimbaits on jigheads are often more useful in September than in previous months, especially when targeting less-aggressive trout located in deeper water.
Hard baits for September are typically suspending or deep-diving jerkbaits and suspending twitchbaits, plus 3-inch paddletails on 1/8- to 3/8-ounce jigheads. The swimbaits should be fished on the bottom with firm twitches to lift the bait. For fishing grass beds in September, floating jerkbaits are often better choices.