Understanding the Sunfish Spawning Process
By: Steve Quinn
As water temperature approaches 70°F, male bluegills begin to clear nests in shallow protected areas with side-so-side tail sweeps. (Photo courtesy of In-Fisherman.com)
Understanding biological basics fosters fishing success. That mantra was one of the cornerstones of In-Fisherman philosophy that changed the world of fishing in the late 1970s. This approach continues to be particularly pertinent when it comes to finding and catching fish during the sunfish spawn.
Scientific observations of the timing and activities of sunfish species in various regions assist the process. Spawning in clear shallow water, they’re a natural for fishwatchers, amateur and professional. And with planning and help from Mother Nature, you may catch the biggest fish of the year.
Bluegill Spawning Biology
Bluegills are the most widely distributed sunfish, thriving in waters large and small and coast to coast, since their popularity among eastern anglers led to western introductions in the late 1800s. In the southern fringe of their range in South Florida, bluegill may start spawning in late February as water temperatures rise toward 70°F. Populations farther north spawn progressively later, but at similar water temperatures.
As with black bass and crappies, northern fish often begin to spawn at lower water temperatures than fish in more temperate areas. It’s as though they want to get the deed done as soon as possible, knowing the summer growing season is short for offspring and parents alike. Moreover, large bluegills tend to spawn first, occupying the best areas.
Nest building and defense of eggs and fry improve survival of hatchlings but make adults more vulnerable to attack by predators as well as harvest. The spawn can be broken down into 5 stages: male establishes a territory; he constructs nest; male courts one or more females with lateral displays and fin movements, chasing, and nipping; egg laying and fertilization; male defends developing eggs, larvae and fry from predators and fans the nest to oxygenate it and prevent silt buildup.
A combination of increasing day length, warming water, and an internal biological clock seems to cue male sunfish to move shallow and start building nests. Because this species nests in colonies, there may also be some involvement of pheromones from males and females that draws more fish to the colony, where over 100 adults may be in various phases of the spawn.
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