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Fishery Bulletin 107(1) 
over time in response to warming of the coastal 
waters (Oviatt et al., 2002; Collie et al., 2008), 
and to determine whether similar oceanic pro- 
cesses are dominant in structuring the species 
composition in these two areas by examining the 
similarity in abundances of warm-water faunal 
assemblages. 
Methods and materials 
Data sources 
Fish abundances were obtained from numerous 
long-term sampling programs in Narragansett 4 
Bay and Long Island Sound (Table 1). Concomitant 
environmental data were obtained when avail- 
able, including surface temperature, bottom tem- 
perature, and salinity. Average water temperature 
(mean of surface and bottom temperature) was 
calculated for each week of the year. 
Warm-water fishes (also called Carolinian, 
tropical, subtropical, transient, exotic species, ; 
in other literature) were identified by means of 
several regional ichthyofaunal guides (Smith, 
1899; Bigelow and Schroeder, 1953). Important 
identifying characteristics included a significant 
portion of the life cycle, and usually the time 
and area of spawning (south of Cape Hatteras 
and only in late summer and fall months). It should 
be noted that northern puffer (Sphoeroides maculatus) 
were included because of the timing of their occurrence 
and their southerly distribution (Able and Fahay, 1998). 
In addition, the warm-water fishes that are caught in 
Narragansett Bay and Long Island Sound are generally 
found as juveniles. 
Data analysis 
Timing, location, and frequency of sampling were differ- 
ent among the surveys considered here. Only the years 
in which sampling took place in all locations and during 
which consistent sampling methods were formed the 
data for the study. Sampling effort was not calculated 
for the different surveys but was consistent through each 
individual time series; therefore the accumulated data 
set represents internally consistent relative measures 
of the abundance of warm-water fishes. For area-spe- 
cific analyses, data from 1987-2001 were included from 
surveys in Narragansett Bay, and data from 1984-2000 
were included from surveys in Long Island Sound. For 
comparison between estuaries, only the data from over- 
lapping years were used (1987-2000). 
Describing and comparing warm-water fish fauna 
Lists of warm-water species were generated for each 
area by using the sum of the species abundances during 
the different surveys. A rank correlation was calculated 
Map of Northwest Atlantic region between Cape Hatteras 
and Nova Scotia. Note the location of Narragansett Bay and 
Long Island Sound, which represent the sample sites for this 
study. 
between total abundance of warm-water fish and year to 
evaluate whether species have increased in abundance 
through time. Correlations were then calculated between 
annual fish abundances in Narragansett Bay and Long 
Island Sound for all years, excluding 1994, during which 
extremely large catches of Atlantic moonfish (Selene 
setapinnis) were found in Narragansett Bay (59% of 
total Atlantic moonfish catch, 80% of 1994 catch, 29% of 
overall Narragansett Bay fish catch). Correlations were 
also calculated for the five most abundant individual 
species (representing 85% of the total catch): Atlantic 
moonfish, northern puffer, crevalle jack ( Caranx hippos ), 
planehead filefish ( Steplianolepis hispidus), and bigeye 
( Priacanthus arenatus). 
The observed species richness (S), or the number of 
different species present, was derived for both loca- 
tions. Next, a jackknife estimation of species richness 
was conducted for both the Narragansett Bay and Long 
Island Sound data sets to estimate the number of spe- 
cies that were present but not sampled, following the 
method described by Krebs (1999). This estimation was 
made because, although the list of warm-water species 
was based on a large number of trawls and seine hauls, 
there are numerous species of warm-water fishes that 
have been observed by SCUBA divers and aquarists 
