Abstract

The Gulf of Mexico (GOM) serves as an important habitat for many pelagic species of substantial ecological and economic value, including billfishes such as the Atlantic blue marlin (Makaira nigricans). The purpose of the present study was to examine the early life ecology of blue marlin from a presumed spawning/nursery ground in the northern GOM. Icthyoplankton surveys were conducted using neuston nets in 2005 and 2006. Blue marlin accounted for a significant fraction of the billfish collected and larvae were often present in high numbers near the western margin of the Loop Current. Otoliths were extracted from a subset of blue marlin collected (n = 166) and microstructure analysis was implemented to determine age, growth, and hatch-date distributions. Standard lengths (Ls) of blue marlin larvae ranged from 3 to 17 mm with corresponding ages varying from 7 to 21 days. Hatch-date calculations indicated that larvae hatched from early June to late July, peaking in mid July of both years. An exponential model was fit to size at age data and instantaneous growth coefficients (gL) ranged from 0.10 to 0.12, with some evidence of cohort-specific variation. Abundance and growth data suggest that the northern GOM serves as critical spawning/nursery habitat of blue marlin and this region may play an important role in the overall sustainability of the Atlantic stock.

PDF Preview