Sea surface temperature and the brown shrimp ( Farfantepenaeus aztecus) population on the Alabama, Mississippi, Louisiana and Texas continental shelves

Abstract

Analysis of the Southeast Area Monitoring and Assessment Program – Gulf of Mexico (SEAMAP-GM) summer and fall trawl survey data covering the Alabama, Mississippi, Louisiana and Texas continental shelves for the period 1987–2000 shows that the annual number n and weight w of the brown shrimp per trawl is positively correlated with annual sea surface temperature (SST) averaged over the continental shelves. Correlations of the monthly anomalous SST by calendar month with the annual shrimp data are highest in April and May. Past work has suggested a possible reason for this: juvenile brown shrimp, which mainly develop from postlarvae in coastal estuaries in April and May, grow faster in warmer water and are therefore more likely to escape predators. Since the juvenile shrimp population is a good predictor of the adult shelf shrimp population, and since the estuarine and shelf SST are closely linked, it is reasonable that April and May shelf SST should be positively correlated with the number and weight of brown shrimp per trawl. Shrimp are more numerous in the summer and the correlation of April and May SST anomaly is much higher for the number and weight per trawl in the summer than in the fall. Hindcasts are made using the simple linear statistical prediction model n = α + β · SSTA , where SSTA is the anomalous April–May departure of SST from the annual cycle. The cross-verified correlation between model and observed n is r = 0.77. A similar model for w gave r = 0.79. A prediction model for summer shrimp alone had cross-verified correlations r = 0.79 for n and 0.86 for w. Based on the 2004 April–May SST anomaly, annual and summer models predict that n and w should be close to average in 2004.