Abstract

Analysis of vermilion snapper (Lutjanidae: Rhomboplites aurorubens) spawning and fecundity from the U.S. Gulf of Mexico provided accurate length-specific estimates of fecundity (batch fecundity, frequency of spawning, and annual fecundity) formature vermilion snapper in order to enhance stock assessment of this species. Fisheries-dependent sampling began off Panama City in northwest Florida (FL) in the northeastern Gulf of Mexico in 1991 and continues with greatly expanded sampling-coverage from off southwest FL to south Texas. Our main fisheries independent sampling began in 2000 and continues with day/night hook and line fishing as a necessity to determine length at first spawning, time of oocytehydration, spawningtime, and location/depth/temperature of spawning. Maximum oocyte diameter, gonadosomatic index and histology indicate that vermilion snapper mainly spawn from April through September. We found at least to probable spawning sites offwest Florida in depths of 30 10 114 m. The smallest female with hydrated oocytes found thus far is 159 mm total length (11.). Most vermilion snapper spawned at approximately 2230 hours: most (90%) hydrated oocytes occurred from 1300 to 2230, with none occurring between 2230 and 0905. Most (91 %) new postovulatory follicles occurred from 2230 to 0815, withnone occurring between 0815 and 1320. Batch fecundity estimates for 1993 - 1994 ranged from 27,000 to 415,000 for 44 fish from 21510 375 mm TL, for 2000 were 15,032 to 88,471 for 59 fish from 189 to 288 mm TL, and for 2001 were 7,385 10 377,226 for 20 fish from 159 to 510 mm TL. Average frequency of spawning for 2000 was 93 using the hydrated oocyte method. Average spawning periodicity for 2000 was 1.6 days. Annual fecundity estimates ranged from 1.4 to 8.2 million for 2000 (n = 59) and from 0.7 to 35 million including a few smaller and larger females for 2001 (n = 20), if the same spawning frequency estímate is used for both years.

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