Red Drum - Reproduction and Growth

Reproduction and Growth

Mature red drum spawn in near shorelines from mid-August to mid-October. The red drum's eggs incubate for 24 hours. A female lays about 1.5 million (with a range of 200,000 up to more than three million) eggs per batch. Scharf (2000) reported that in the first year, young red drum in Texas estuaries grew about 0.6 mm per day, though the rates varied with location and year and were higher in more southerly estuaries. After the first year they may be 271 – 383 mm long. About half of red drum are able to reproduce by age 4 years, when they are 660-700 mm long and 3.4 – 4 kg in weight. Red drum live to be 60 years old unless caught.

• Adults mature by 3 – 5 years of age; approximate length at maturity: males – 28 inches, females – 33 inches.
• Spawn during late summer and fall. Spawning aggregations occur near estuary inlets and passes along barrier island beaches. Males produce drumming sounds using muscular contractions to vibrate the swimbladder, to attract females.
• Larval red drum use vertical migrations to ride high salinity tidal currents into tidal creeks and shallow salt marsh nursery habitats.

As red drum grow longer, they increase in weight. The relationship between length and weight is not linear. The relationship between length (L) and weight (W) for nearly all species of fish can be expressed by an equation of the form:

Invariably, b is close to 3.0 for all species, and a varies between species. Jenkins (2004) reported slightly different weight-length relationships for red drum caught in the spring and the fall off the western Gulf Coast of Louisiana:

where weight is in grams and length is total length measured in millimeters. For example, these relationships predict that a 600 mm red drum (just under two feet long) would weigh about 2300 grams (just over five pounds). These relationships can be used more specifically to determine how healthy a sample of red drum are by comparing their actual weights to weights predicted by these relationships for the same length.