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Home > Resources & Publications > Newsletters & Magazines > Fact Sheets > Bull Reds

Resources & Publications: Fact Sheets

by Jerald Horst

Late summer and early fall usually signal the time for Louisiana’s annual run of large redfish, or “bull reds” as they are usually called. During this period, the offshore schools of large redfish move nearer to the coast, especially to areas near passes, for their annual spawn. Redfish spend the first years of their lives in inshore estuaries, feeding and growing rapidly. By 4 or 5 years of age, almost all of them have left these waters and joined the offshore schools of adult redfish.

Age and growth research done in the late 1980s by LSU biologists on redfish captured from offshore schools provides interesting information. In this study, the biologists read the growth rings in the otoliths (ear bones) of 1,690 redfish taken offshore by purse seine, gill net and hook and line. The fish were taken from waters between northeast Texas and western Ala-bama, with most of the fish being captured off the Louisiana coast. The fish ranged in size from 22 to 42 inches in length. The oldest female was 36 years old (40 inches and 26.3 pounds) and the oldest male was 37 years old (38 inches and 23.1 pounds).

Female redfish were significantly larger than males, not because they lived longer, but simply because they grew faster throughout their lives in offshore waters. They found a few 2-year-old redfish in their samples from offshore. At that age, females averaged 27.6 inches and about 9 pounds. Males at that age averaged 26.8 inches and a little over 8 pounds. The size gap between the sexes remained fairly small until 9 years old. At that age, females averaged 33.2 inches and 16.7 pounds and males averaged 32.4 inches and 15.1 pounds. Then the gap widened.

By age-15, the growth rate for both sexes began to slow, but the growth rate for males slowed even more than for females. At that age, females averaged 36 inches and 22 pounds, and males averaged 34.4 inches and 18.7 pounds. By 30 years old, the average size for females was calculated at 39 inches and 29.3 pounds. Males averaged 35.6 inches and 22.2 pounds and their growth rate had become extremely slow.

The biologists noted that it was impossible to determine the age of a fish by its size, be-cause the high variation in size of fish at any age provides a great deal of overlap. For example, at age 21, the largest fish was a female at 42.4 inches and 34 pounds and the smallest fish was a male at 31.2 inches and 15 pounds.

Download: bullreds.pdf (625KB)


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