Date With Me....Mate With Me: A Courting Story

The Role of a Male Bluegill in Reproduction

Male bluegills play an extraordinary role in the reproduction process!  As soon as the water nears 67 degrees Fahrenheit, males gather in shallow water (Holtan, 1990).  The nesting spots are usually free of vegetation, which makes males vulnerable to predation.  It must be noted that these colonies are not always seen in other related fish species.  The exact population of a colony varies. In general, about 50 males gather at each spawning site (Spotte, 2007). Using their tails, the males make a small nest for females to lay their eggs.

A Female Bluegill Searching for a Mate

Females eventually move into the spawning beds.  They are picky, however!  As a natural defense mechanism from predation, they lay their eggs in the center of the nesting site.  Once towards the middle, females scan the area for potential mates.  They choose males with larger bodies and ears.  Thus, large ear size is a desirable trait for males to have.  Once a female finds a suitable male, the courtship process begins. 

The Courtship Process in Bluegills

As a female approaches, the male begins quickly circling his nest.  Soon after, the male acts aggressively towards the possible mate.  The female either stays or finds a more suitable partner.  The fertilization process is completely external.  Females touch bellies with males; meanwhile, eggs and sperm are released and fall into the nest.  A female caught in the Mississippi had 12,000 eggs! (Spotte, 2007). As soon as females release all of their eggs, they leave the nesting site.  In contrast, males stay to defend their nests.  Many intruders attempt to consume the eggs; however, aggressive activity allows the males to fend off predators.  After about ten days, these precious eggs hatch (Spotte, 2007).  The male stays for a couple more days until the recently hatched bluegills, known as fry, swim to more vegetated areas.  Here, the fry find possible food items. They feed constantly in hopes of reaching reproductive maturity. 

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A Bluegill Reaching Reproductive Maturity

Food resources, predation pressures, and competition all play roles in the rate at which bluegills reach reproductive maturity.  In Wisconsin, a bluegill may not engage in reproduction until their fourth spring.  In contrast, bluegills in Florida may reach maturity at one year of age (Spotte, 2007). This difference is due to increased foraging in warmer waters.  Regardless of geographic location, bluegills travel to nesting sights during the spring they reach maturity.  On average, adults weigh 6 to 8 ounces and reach 9 to 12 inches in length (Holton, 1990).

Mature Mississippi Bluegill (Image taken by Author)

 

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