Historical changes in age and growth of Atlantic croaker, Micropogonias undulatus (Perciformes: Sciaenidae)

Archaeological excavations near St Augustine, Florida, U.S.A. recovered 415 otoliths from Atlantic croaker, Micropogonias undulatus (Perciformes: Sciaenidae), which were caught by Native American and Hispanic peoples living in the area. Age determination using growth increments of otoliths and correlated size information were used to construct size distributions, age distributions, growth rates and season of capture. During a 3000 year time span, coastal Indians captured Atlantic croaker 1–10 years old ranging from about 13–39 cm total length. Marginal increments of otoliths revealed that most fish were caught from January to May, during or shortly after the period of annulus formation. Numbers and size ranges of otoliths in each archaeological sample were quite small, suggesting that Indian fishing was probably done by individuals or small groups. Gears and methods used by Indians were selective for small, young croaker or were inefficient in areas where large fish occurred. The absence of large, old croaker and nearshore coastal species in Prehispanic collections suggest that Indians fished predominantly in the estuary. Spanish interaction with coastal Indian tribes resulted in changes in the size and age composition of the Atlantic croaker catch. Post-contact, older (up to 15 years) and larger (up to 46 cm, tip of the jaw to the end of the caudal fin—TL) croaker formed a large portion (> 30%) of the catch, suggesting that fishing effort was more extensive throughout estuaries and nearshore coastal waters and may have employed other gears and methods. Marginal increments of otoliths suggest that fishing occurred primarily in winter and spring but may have extended year-round. Comparing information from these collections with modern studies indicates that age and growth of Atlantic croaker have changed dramatically, perhaps in response to exploitation or habitat alteration. In earlier centuries, Atlantic croaker grew more slowly, perhaps an indication of density-dependent growth, and lived much longer (15 years versus 7 years). Differences in age and size class composition of Prehispanic, First Spanish Period, and modern catches are consistent with those of a species whose rates of exploitation have increased. Future research of environmental conditions and the biology of Atlantic croaker and other fishes during these early periods may provide explanations for the dramatic changes in the biology of Atlantic croaker observed in this study.