8-15 



In New Haven Harbor Crangon was collected most abundantly at 

 the inner and middle harbor stations and least abundantly in the outer 

 harbor (Stations 19 and 20) (Table 8-3) . Total annual abundance of this 

 species has fluctuated, with highest numbers found during 1975 (101,000 

 individuals) and the 9-month survey of 1977 (93,000 individuals) , while 

 lowest abundances were observed during 1974 (31,000 individuals) and 

 1976 (68,000 individuals) (Table 8-3). Variability in catch-abundance 

 was also evident on a monthly basis; however, no clearly defined sea- 

 sonal pattern was observed (Figure 8-2) . In the outer harbor (Stations 

 19 and 20) , where Crangon abundances were low, a trend of decreasing 

 abundance during summer and early fall was apparent. However, no such 

 trends were apparent at inner and middle harbor stations where abun- 

 dances and variability in abundance was high. In New Haven Harbor, 

 variations in abundance between months and stations were as high as four 

 orders of magnitude, indicating the extreme spatial patchiness of the 

 Crangon population. In a study of the benthic epifauna of Long Island 

 Sound, Richards and Riley (1967) similarly found the abundance of Crangon 

 to be highly variable due to patchiness , thus obscuring seasonal abun- 

 dance patterns. 



Variability in the abundance data of Crangon is to some degree 

 a result of the inability of the trawl to quantitatively sample this 

 species. Under normal circtomstances the 1-3/8-inch mesh of the trawl's 

 wings and body is too large to effectively sample small individuals. 

 Clogging of the trawl, however, can increase the nvunber of small indi- 

 viduals collected, thereby providing an additional source of variability 

 in the abundance data. Variability in the abundance of Crangon may also 

 be attributed to its mode of existence. Crangon utilizes both infaunal 

 and epifaunal habitats, spending much time foraging on the bottom and 

 occasionally among the plankton, while at other times burrowing into the 

 bottom sediments (Price, 1962). Such behavior can greatly affect the 

 pattern of abundance as determined by epibenthic trawls . Epibenthic 

 densities estimated from trawl data may not reflect actual densities 

 since many individuals may be inhabiting burrows. Because of the 

 observed similarity in catch abundance between duplicate tows, however. 



