154 



Fishery Bulletin 91(1). 1993 



Table 1 



Summary, by location, of Kruskal-Wallis one-way nonparamet- 

 ric significance tests for monthly differences in Spanish mack- 

 erel Scomberomorus maculatus catches in 1989. n = number of 

 records at one location, df+1 = number of months sampled. 



Spatial distribution 



Results 



Spanish mackerel become widely distributed in sum- 

 mer throughout Virginia waters of the Chesapeake Bay. 

 In 1989, we observed large catches, at least on occa- 

 sion, at Lynnhaven, off the lower York River, on the 

 Eastern Shore, and at Reedville (Fig. 2). Catches were 

 consistently large in June, July, and early August off 

 Lynnhaven and apparently off the lower York River, 

 although records were not as complete there. Com- 

 paratively low catches were consis- 

 tently made at Reedville and on the 

 Eastern Shore. We formed the dis- 

 tinct impression from our data and 

 observations that Spanish mackerel 

 were much more abundant in the 

 summer along the lower Western 

 Shore of Chesapeake Bay in 1989 

 than either along the Eastern Shore 

 or upbay at Reedville. 



Our interpretation of spatial pat- 

 terns in Spanish mackerel abun- 

 dance is supported by significance 

 tests that evaluate the null hypoth- 

 esis, within months, of no difference 

 in C/f between areas. Kruskal- 

 Wallis non-parametric tests for 1989 

 showed significant differences in 

 C/f between areas in June and July 

 (Fig. 4), when peak abundance 

 occurred, but there were no sig- 

 nificant differences in the other- 

 months when abundance was lower 

 (Table 3). Tukey's multiple compari- 

 sons tests (Table 4) showed signifi- 

 cantly higher C/f in July at 

 Lynnhaven and the lower York 

 River than at Reedville or the East- 

 ern Shore. In June, these tests 

 showed significantly higher C/f at 

 Lynnhaven than on the Eastern 

 Shore. Reedville C/f in June was in- 

 termediate and not significantly dif- 

 ferent from either Lynnhaven or the 

 Eastern Shore; data from the Lower 

 York River were not included in the 

 Tukey's test presented because only 

 one data contact was made there in 

 June. 



Discussion 



Spanish mackerel primarily occur 

 in the lower Chesapeake Bay, i.e., 



