Govoni et al : Early life history o\ Xiphias gladius in the western North Atlantic 



781 



Table 1 



Summary of models evaluated for describing growth of larval swordfish. Models 1-6 were preserved standard length (PSD as a 

 function of estimated age from hatching (AFH); model 7 was lower jaw fork length (LJFL) as a function of AFH. There were three 

 model types; linear regression (models 1 and 2), 2"'' order polynomial (models 3 and 4), and piecewise regression (models 5-7). 

 Y-intercepts (model parameter a) were estimated by the regression in Equations 1, 3, and 5 but were fixed at an observed length 

 at hatching of 3.2 mm from Yasuda et al. (1978) in Equations 2, 4, 6, and 7 ("ns" denotes that a was not significantly different from 

 an assigned a of 3.2 at a=0.05; * =y-intercept significantly different from 3.2 at a=0.05; na = not applicable; b and c are slopes; and 

 d is the inflection point). 



Model 



1. PSL = a + 6AFH 



2. PSL = 3.2 +6AFH 



3. PSL = a +6AFH+ fAFH2 



4 . PSL = 3.2+6AFH + c AFH^ 



5. PSL = a + 6AFH + c(AFH - d) x (AFH d) 



6. PSL = 3.2 + 6AFH + c(AFH-d)x(AFH>d) 



7. LJFL = 3.2 + 6AFH+C (AFH- d)x (AFH >d) 



hence PSL=LJFL) and 3.4 mni/d for the second segment 

 (Fig. 2B). 



The fit of the piecewise regression for PSL and LJFL was 

 unchanged by inclusion or exclusion of the estimated age 

 of the largest larva. 



Diet 



The diet of larvae is limited and transitional. Larvae 

 <8.3 mm PSL ate copepods exclusively, primarily a single 

 cyclopoid genus, Corycaeus spp., but also another cyclopoid, 

 Oithona spp., and the calanoid Eucalanus (Table 2). Larvae 

 9.0 to 11.0 mm PSL ate copepods (Fig. 3A) and chaeto- 



