Goldman and Musick Growth and maturity of Lamna ditropis 



285 



the oviducal glands sampled from ma- 

 ture females contained spermatozoa. The 

 smallest mature male observed was 155.4 

 cm PCL, and the largest immature male 

 was 91.0 cm PCL. Based on age estimates 

 from vertebral sample data, ages at MP- 

 CL range from 6 to 9 yr for females and 

 from 3 to 5 yr for males. Ninety-five per- 

 cent confidence limits (for percent mature) 

 were very narrow for females <155 cm 

 PCL and >172.5 cm PCL and for males 

 <107.5 cm PCL and >132.5 cm PCL. The 

 wide vertical confidence intervals around 

 the calculated estimates of MPCL (Fig. 6) 

 were caused by not having many observa- 

 tions for lengths around the estimated 

 MPCL in the sample. 



Age-length composition in the 

 Eastern North Pacific 



The mean age and length composition of 

 ENP salmon sharks was latitude depen- 

 dent (Table 3). Sharks between and 7 

 yrs old, ranging from 62.2 to 153 cm PCL, 

 were collected from southern California 

 to southeast Alaska, with smaller indi- 

 viduals found in the southern part of that 

 range. Sharks between 5 and 20 yrs old, 

 ranging from 144.8 to 213.4 cm PCL, were 

 collected from southeast Alaska up into 

 the Gulf of Alaska, Prince William Sound, 

 and the Bering Sea. 



Discussion 



Vertebral growth significantly increased 

 with somatic growth (Fig. 2), which, along 

 with the reliability of the RMI analysis 



30 



25 :■ 

 20 :■ 

 15 :■ 

 10 :■ 

 5  



O Dahl-Lea 



□ Dahl-Lea linear-modified 

 • Dahl-Lea quadratic-modified 

 O Fraser-Lee -modified 



190 200 210 220 



Sample mean precaudal length-at-age (cm) 



Figure 5 



Mean deviation, from mean sampled precaudal length, of four pro- 

 portional back-calculation methods for (A) female, and for (B) male 

 eastern North Pacific salmon sharks (Lamna ditropis). Data points 

 represent mean back-calculated lengths-at-age. An x-axis point on the 

 zero line extending from the y-axis would represent zero deviation 

 from the sample mean length-at-age. 



