582 
Fishery Bulletin 96(3), 1998 
well as the numbers, locations, and shapes of the 
processes. The majority of the cleithra described here 
have a gently sloping curvature along the dorsoven- 
tral axis, whereas others are clearly more sharply 
curved. Most families examined here possess cleithra 
with dorsal and ventral processes that end sharply; 
others possess varying numbers and shapes of pos- 
terior and anterior processes. 
The cleithra of silver hake and red hake are gen- 
tly curved along the dorsoventral axis and each has 
two posterior processes located directly ventral to the 
dorsal process (Fig. 2, A and B). The ventral process 
of the red hake ends in a sharper point and is not as 
broad as that of silver hake, and the posterior pro- 
cesses are broader than those of silver hake. Atlan- 
tic cod and haddock have gently curved cleithra with 
a general shape similar to that of the cleithra of sil- 
ver and red hake (Fig. 2, C and D). However, the 
cleithra of Atlantic cod and haddock contain only one 
posterior process that is broader than the posterior 
processes of the hake cleithra, and the dorsal pro- 
cesses of Atlantic cod and haddock cleithra end 
sharply and are much more pronounced than those 
of the hake cleithra. The main difference between 
the cleithra of Atlantic cod and haddock is in the 
shape of the posterior process; the process is distinctly 
more hook-shaped in Atlantic cod than in haddock. 
The cleithra of alewife and Atlantic herring are each 
sharply curved and possess an anterior process lo- 
cated medially along the dorsoventral axis, which is 
Table 3 
Least squares regression equations relating measurements of opercle length (OP), cleithrum length (CL), and dentary length 
(DN) to total length (TL) and fork length (FL) for ten prey species in the Northwest Atlantic. All measurements are in millime- 
ters. s b = standard error of the regression coefficient; r 2 = coefficient of determination; %PE = mean percent prediction error; n = 
number of fish measured; Range = size range in total length. Fork lengths were not measured for red hake, silver hake, or 
Atlantic cod. 
Total length Fork length 
Species 
Equation 
S 6 
r 2 
°lc PE 
Equation 
s b 
r 2 
%PE 
n 
Range 
Alewife 
TL = 9.8510P- 1.119 
0.126 
0.99 
2.80 
FL = 8.6170P + 0.307 
0.118 
0.99 
3.15 
66 
73-282 
TL = 7.115CL - 3.450 
0.097 
0.99 
2.80 
FL = 6.217CL - 1.579 
0.097 
0.98 
3.22 
66 
73-282 
TL = 11.610DJV- 23.205 
0.163 
0.99 
3.23 
FL = 10.144LW - 18.824 
0.163 
0.98 
3.74 
66 
73-282 
Blueback herring 
TL= 10.0140P + 6.641 
0.547 
0.90 
3.07 
FL = 9.1980P + 4.259 
0.555 
0.88 
3.46 
38 
83-134 
TL = 7.491CL + 0.161 
0.354 
0.93 
3.09 
FL = 6.893 CL - 1.863 
0.362 
0.91 
3.40 
38 
83-134 
TL = 11.743LW- 11.125 
0.653 
0.90 
2.96 
FL= 10.87 1DN- 12.840 
0.621 
0.90 
3.04 
38 
83-134 
Atlantic herring 
TL = 11.732OP-0.427 
0.168 
0.99 
2.30 
FL = 10.4050P + 2.028 
0.168 
0.98 
2.65 
71 
97-269 
TL = 8.752 CL - 10.804 
0.126 
0.99 
2.19 
FL = 7.771CL - 7.353 
0.117 
0.98 
2.41 
71 
97-269 
TL = 10.692LW- 17.263 
0.180 
0.98 
3.02 
FL = 9.495LW - 13.112 
0.164 
0.98 
3.10 
71 
97-269 
Atlantic mackerel 
TL= 1 1.1 140P + 0.379 
0.179 
0.99 
2.01 
FL = 9.867 OP + 7.462 
0.163 
0.99 
2.06 
44 
158-330 
TL = 7.789 CL - 6.990 
0.067 
0.99 
1.26 
FL = 6.916CL + 0.889 
0.062 
0.99 
1.27 
44 
158-330 
TL = 12.564LW - 30.649 
0.212 
0.99 
2.53 
FL = 11.148DA - 19.970 
0.201 
0.99 
2.44 
44 
158-330 
Butterfish 
TL = 7.9560P + 5.184 
0.299 
0.92 
7.64 
FL = 6.5980P + 9.279 
0.266 
0.91 
8.48 
63 
54-193 
TL = 5.583 CL - 27.802 
0.091 
0.98 
3.23 
FL = 4.653 CL - 18.698 
0.081 
0.98 
3.43 
63 
54-193 
TL = 13.643ZW + 6.884 
0.484 
0.93 
7.49 
FL = 11.309LW + 10.725 
0.436 
0.92 
8.25 
63 
54-193 
Sand lance 
TL = 18.903 OP + 25.655 
1.042 
0.82 
5.46 
FL = 18.352 OP + 24.729 
1.044 
0.81 
5.60 
75 
109-209 
TL = 18.487CL- 1.156 
0.719 
0.90 
3.81 
FL = 17.938CL - 1.228 
0.741 
0.89 
4.12 
75 
109-209 
TL = 2Q.785ZW- 33.880 
0.772 
0.91 
3.89 
FL = 20.300LW - 34.146 
0.752 
0.91 
3.92 
75 
109-209 
Red hake 
TL = 27.956 OP - 4.679 
0.612 
0.98 
4.53 
45 
108-340 
TL = 9.061CL- 12.185 
0.123 
0.99 
2.81 
45 
108-340 
TL = 13.870ZW - 11.769 
0.291 
0.98 
4.37 
45 
108-340 
Silver hake 
TL = 17.6660P- 11.964 
0.212 
0.99 
3.20 
60 
75-300 
TL = 7.87501-5.271 
0.071 
0.99 
2.57 
60 
75-300 
TL = 8.427LW - 5.149 
0.087 
0.99 
2.63 
60 
75-300 
Haddock 
TL = 23.0400P- 15.425 
1.053 
0.91 
5.52 
FL = 22.3510P- 16.804 
0.984 
0.92 
4.78 
47 
79-202 
TL = 6.567 CL - 2.688 
0.176 
0.97 
3.25 
FL = 6.2150,-1.202 
0.258 
0.93 
4.87 
47 
79-202 
TL = 12.348PW - 3.688 
0.496 
0.93 
5.07 
FL= 11.680OV- 2.075 
0.606 
0.89 
6.29 
47 
79-202 
Atlantic cod 
TL = 19.019OP + 7.733 
0.705 
0.96 
5.43 
31 
52-140 
TL = 6.590CL + 1.118 
0.101 
0.99 
2.50 
31 
52-140 
TL = 10.458LW - 5.592 
0.181 
0.99 
2.29 
31 
52-140 
