Joanne Lyczkowski-Shultz

Age and Growth of Red Drum Larvae in the North-Central Gulf of Mexico

Abstract Otolith growth increments were used to estimate the age of 113 larval red drum Sciaenops ocellatus collected in the north-central Gulf of Mexico in October 1983, October 1984, and September 1985. Larval growth, as estimated by correlating age with length and dry weight measurements, was exponential and positively associated with water temperature. Mean growth in length of larvae smaller than 4 mm was relatively slow (≈0.3 mm/d), but at sizes larger than 4 mm, length increased rapidly. Based on growth equations, the mean increases in length of 4–6-mm larvae in October 1984, October 1983, and September 1985, were 0.4, 0.5, and 0.6 mm/d, respectively. These increases in larval growth were associated with increasing water temperature at time of capture; ranges in temperature during the three periods were 24.5–25A, 25.5–26.5, and 27.8–29.0°C, respectively. Larvae that developed in October 1984 grew to a length of 6 mm in about 15.0 d, whereas in September 1985, at the warmest temperatures, larvae grew...

Red Snapper Larval Transport in the Northern Gulf of Mexico

Abstract This study examines the advection of red snapper Lutjanus campechanus larvae in the northern Gulf of Mexico. The potential for repopulating the eastern Gulf stock through larval transport from the more populous western stock is addressed. Transport pathways across topographic features that inhibit alongshelf flow (e.g., the Mississippi River delta, DeSoto Canyon, and the Apalachicola peninsula) and interregional larval transport are considered. An advective field of currents is developed from a large database of drifter and moored currents, augmented by an operational model to fill gaps. The starting points for larval transport are the locations and day of the year of larval captures from the Southeast Area Monitoring and Assessment Program ichthyoplankton surveys. Because the field of currents is derived from near-surface observations and the depth distribution of larvae is uncertain, findings are expressed in terms of maximal transport pathways. Transport pathways were principally vectored towa...