NOTES Uchiyama and Sampaga' Age estimation and composition of Pseudopentaceros wheelen 



221 



Table 4 



Mean fork lengths (FL) of pelagic armorhead Pseudopentaceros wheeleri age groups at the Southeast Hancock Seamount. 



Sample date 



Aug.-Oct. 1981 

 July 1984 



Age 



1.5 

 2.5 



1.5 

 2.5 



Range 



267-320 

 304-304 



247-330 

 285-326 



Male FL (mm) 



Female FL (mm) 



Mean 



SD 



N 



Range 



Mean 



294 

 304 



301 

 307 



14.07 



15.57 

 13.96 



37 



2 



37 

 13 



285-325 

 283-329 



295-331 

 290-342 



307 

 310 



308 

 315 



SD 



N 



9.54 68 



14.08 8 



8.22 39 



10.89 27 



Figure 2 



Length-frequency distribution of Pseiidopei^taceros wheeleri sampled 

 at the Hancock Seamounts, 1 August-15 October 1981. 



Figure 3 



Length-frequency distribution oi Pseudopentaceros wheeleri sampled 

 at the Southeast Hancock Seamount, 24 July 1984. 



We could not determine when the opaque zone formed 

 because specimens were not obtainable throughout the 

 year and the edge always appeared translucent. 



Pelagic armorhead from the summer trawl fishery 

 at the Southeast Hancock Seamount consisted of fish 

 approximately ages 1.5 and 2.5, and yearlings were 

 dominant in both 1981 (96%) and 1984 (66%) (Table 4). 

 Yearling females appeared to be larger than males in 

 both 1981 and 1984 samples (Figs. 2 and 3; Table 4). 

 Differences between male and female mean lengths 

 were significant in 1981 (P<0.001) and in 1984 

 (P = 0.025), but difference in mean lengths for year-2 

 females and males in 1984 was not significant 

 (P = 0.107). The latter could have been due to small 

 sample size; hence, larger samples should be examined 

 before requiring separate growth curves for males and 

 females. Our samples were not perfectly suited for 

 group comparison because sex and age were unknown 



when the random samples were taken. Thus, unequal 

 group size and unequal variances occurred. Due to our 

 small sample size, slight skewness and kurtosis were 

 encountered in comparing central tendencies of some 

 age-sex groups. However, only the unequal variance 

 between groups was serious enough to have affected 

 the analyses. 



Pelagic armorhead may attain sexual matiuity before 

 they reach the seamount. We base this on the age- 

 length relationships of the three oceanic specimens 

 (Table 2). After pelagic armorhead settle on the sea- 

 mount, it appears that little growth occurs. Length- 

 frequency distribution reported by other investigators 

 (Sasaki 1986, Wetherall and Yong 1986) tends to con- 

 firm this observation. The lack of older (>age 3) indi- 

 viduals on the seamounts suggests that pelagic armor- 

 head may spawn only one or two seasons and then die. 

 Indeed, the presence of emaciated individuals suggests 



