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Fishery Bulletin 107(1 ) 
cal data. The rate of increase for the cumulative prey 
curve of the current diet was 3.0%, indicating that 
the diet was well sampled. Conversely, the cumula- 
tive prey curve for the historical diet showed a rate of 
increase of 6.24%, indicating more sampling may have 
captured the diet breadth better (Fig. 4). Jackknife 
estimates of species richness were 16 and 36 prey spe- 
cies for the 2001-02 and historical diet, respectively. 
The two measures of niche overlap used to compare 
the historical and 2001-02 diet data revealed slight 
Table 2 
Current and historical diet data for the shortfin mako ( Isurus oxyrinchus) expressed as a percentage by number (%N), weight 
(%W ), frequency of occurrence (%FO), volume (%V); and the index of relative importance expressed as a percentage (%IRI). 
Prey item 
Current diet 
Historical diet 
%N 
%W 
%FO 
%IRI 
%N 
%V 
%FO 
%IRI 
Crustaceans 
10.60 
0.03 
0.83 
0.07 
0.96 
0.15 
1.79 
0.02 
Cephalapoda 
Ommastrephidae 
///ex illecebrosus 
2.54 
0.14 
1.67 
0.10 
6.71 
2.62 
4.93 
0.40 
Loliginidae 
Loligo pealeii 
2.96 
0.42 
4.17 
0.14 
0.72 
0.28 
1.35 
0.01 
Unidentifiable 
7.19 
2.81 
7.18 
0.34 
Elasmobranchs 
Carcharhinidae 
Prionace glauca 
0.24 
0.19 
0.45 
0.00 
Squalidae 
Squalus acanthias 
0.42 
0.02 
0.83 
0.00 
Teleosts 
Ammodytidae 
1.44 
0.02 
0.45 
0.01 
Clupeidae 
1.20 
0.02 
0.45 
0.01 
Brevoortia tyrannus 
0.85 
0.68 
0.83 
0.01 
0.48 
0.09 
0.45 
0.00 
Clupea harengus 
0.85 
0.35 
1.67 
0.02 
Gadidae 
0.24 
0.24 
0.45 
0.00 
Merluccius bilinearis 
0.24 
0.03 
0.45 
0.00 
Malacanthidae 
Lopholatilus chamaeleonticeps 
1.27 
1.07 
1.67 
0.03 
Pomatomidae 
Pomatomus saltatrix 
71.19 
92.62 
87.50 
99.21 
55.64 
86.90 
78.48 
97.24 
Scomberesocidae 
Scornberesox saurus 
10.07 
0.13 
2.69 
0.24 
Scombridae 
1.44 
0.88 
2.69 
0.05 
Auxis rochei 
0.48 
0.09 
0.90 
0.00 
Euthynnus pelamis 
0.85 
0.81 
1.67 
0.02 
0.24 
0.39 
0.45 
0.00 
Sarda Sarda 
0.24 
0.03 
0.45 
0.00 
Scomber scombrus 
3.80 
0.93 
6.67 
0.22 
2.39 
0.68 
4.04 
0.11 
Thunnus albacares 
0.85 
2.51 
1.67 
0.04 
1.20 
0.63 
1.35 
0.02 
Serrandiae 
Centropristis striata 
0.42 
0.08 
0.83 
0.00 
Sparidae 
0.24 
0.06 
0.45 
0.00 
Triglidae 
0.24 
0.05 
0.45 
0.00 
Xiphidae 
Xiphias gladius 
0.24 
2.58 
0.45 
0.03 
Zoercidae 
Macrozoarces americanus 
0.24 
0.06 
0.45 
0.00 
Unidentifiable remains 
3.39 
0.34 
5.83 
0.15 
7.19 
0.94 
8.52 
0.60 
Mammalia 
0.48 
0.14 
0.90 
0.01 
Plant 
0.24 
0.00 
0.45 
0.00 
