432 
Fishery Bulletin 96(3), 1998 
Table 3 
Relative food importance, measured by frequency of occurrence (%FO), numerical proportion (%Num), and proportion of total 
mass (%Mass), in the diet of noncalf harbor porpoises during autumn in the Gulf of Maine (present study) and summer in the Bay 
of Fundy (Recchia and Read, 1989). 
Prey 
Gulf of Maine 
Bay of Fundy 
%FO 
%Num 
%Mass 
%FO 
%Num 
%Mass 
Alosa pseudoharengus 
0 
0 
0 
3 
<1 
— 
Bathypolypus arcticus 
1 
<1 
<1 
3 
<1 
<1 
Clupea harengus 
78 
7 
44 
88 
44 
64 
Gadus morhua 
4 
<1 
<1 
14 
14 
14 
Illex illecebrosus 
10 
<1 
<1 
6 
1 
<1 
Loligo pealei 
4 
<1 
<1 
1 
<1 
<1 
Macrozoarces americanus 
0 
0 
0 
2 
<1 
— 
Maurolicus weitzmani 
38 
67 
3 
0 
0 
0 
Meganyctiphanes norvegica 
12 
— 
— 
— 
— 
— 
Merluccius bilinearis 
68 
16 
22 
41 
33 
19 
Myxine glutinosa 
7 
— 
— 
— 
— 
— 
Peprilus triacanthus 
12 
1 
1 
0 
0 
0 
Pollachius virens 
7 
1 
2 
0 
0 
0 
Pleuronectes americanus 
0 
0 
0 
<1 
<1 
— 
Scomber scombrus 
9 
<1 
1 
6 
1 
2 
Sebastes spp. 
11 
<1 
<1 
0 
0 
0 
Urophycis spp. 
29 
7 
26 
13 
3 
2 
Unknown fish 
1 
<1 
<1 
26 
4 
— 
for silver hake was 163 mm (±95 
SD), with the length-frequency 
distribution showing a strong peak 
between 30 and 55 mm and an- 
other peak between 180 and 205 
mm. The mean length of pear- 
Isides was 50 mm (±4 SD), rang- 
ing from 40 to 62 mm. 
Diet of sex and 
maturity categories 
The stomach contents of calves 
differed substantially from those 
of nutritionally independent por- 
poises. Pearlsides, silver hake, and 
euphausiids each occurred in more 
than half (7/13) of the calf stom- 
achs (Table 4). Pearlsides (72%) 
and silver hake (26%) were the 
most numerous prey in calf stom- 
achs and accounted for 53% and 
27% of the calf diet by proportion 
of total mass, respectively. Only 
11% of the ingested mass in calf stomachs comprised though euphausiids and milk were common in the 
Atlantic herring (<1% of numerical abundance). Al- calf diet, they were excluded from the analyses of 
o 
o 
O 
140 
120 - 
100 - 
80 
60 
40 - 
20 - 
Clupea harengus. n = 316 
I '////A Merluccius bilinearis, n = 149 
m Maurolicus weitzmani, n = 136 
30 55 80 105 130 155 180 205 230 255 280 305 330 355 380 405 
Fork Length (mm) 
Figure 2 
Length-frequency distributions of Clupea harengus (Atlantic herring), Merluccius 
bilinearis (silver hake), and Maurolicus weitzmani (pearlsides) eaten by harbor 
porpoises during autumn (1989-94) in the Gulf of Maine. 
