stranded for 1984-90 by state is illustrated in Figure 1 and listed in Appendix II. From 1984- 

 89, more animals were reported stranded aimually along the Texas coast than in the rest of 

 the U.S. Gulf. However, during 1990, the number of animals reported stranded on the Texas 

 coast was less than that reported in the remainder of the U.S. Gulf (161 vs 200). The rate 

 of increase in strandings during 1990, expressed as January through June 1990 

 strandings/prior 4-year average, varied by state (Appendix II). The highest increase was 

 observed in Alabama (9.68 times), and the lowest was observed in Texas (1.80 times). For 

 the U.S. Gulf as a whole, strandings during 1990 were 2.62 times the 1986-89 average. 



Historically, strandings of bottlenose dolphins 

 in the U.S. Gulf of Mexico have shown a seasonal 

 trend. The greatest number of dolphins strand during 

 March, with February and April also showing an 

 increase over the rest of the year (Figure 2). Overall, 

 the 1990 strandings by month showed a pattern similar 

 to that previously observed. Some deviation from this 

 pattern was observed in Alabama, Lx)uisiana and 

 Texas. However, the stranding reporting and recovery 

 effort in Alabama and Louisiana was considerably 

 greater during 1990 than in prior years, and the 

 degree and duration of increases observed in those 

 states may, in part, be an artifact of increased effort. 

 The Texas strandings deviated from the 1984-89 trend 

 during January, with more strandings occurring during 

 that month than during February (Figure 3). However, 

 if the anomalous mortality that occurred in Matagorda 

 Bay, Texas, during January is excluded, the pattern is 

 similar to that previously observed. Although it may be 

 reasonable to exclude the Matagorda Bay strandings, 

 it should be noted that the 1990 pattern for the U.S. 

 Gulf exclusive of Texas shows the same pattern of a 

 higher proportion of strandings during January (Figure 

 4). 



With the exception of August, strandings were 

 higher in all months during 1990, and were outside of 

 the upper 95% confidence interval about the mean for 

 the period 1986-89 (Figure 2), and were generally 

 greater than the maximum monthly reported for that 

 period. Strandings in Texas were above the 95% 

 confidence interval for January-March and October- 

 November (Figure 3). Strandings in the remainder of 

 the Gulf were above the 95% confidence interval for 

 all months except August and November (Figure 4). 



1*0 

 120 

 100 

 BO 

 60 

 40 

 20 



CULF OF MEXICO 



• 1990 



V 1984-89 HIGH 



ERROR BARS 9SS 



un^ 



J F M A M J 



A S N D 



Figure 2 Comparison of northern Gulf of Mocioo 

 1990 monthly bottlenose dolphin strandings with 

 1986-89 mean, with 1986-89 95% conndence 

 interval High monthly from 1984-89 data. 



70 



60 



50 



40 - 



30 - 



20 



10 



JFMAMJJASONO 



Figure 3: Comparison of Texas 1990 monthly 

 bottlenose dolphin strandings with 1986^ 

 mean, showing 1986-89 95% confidence interval 

 High monthly from 1984-89 data. 



During January-June 1990, Texas 



16 



