Sulikowski et al.: Age and growth estimates of Leucorqa ocellata 



407 



The marginal increment was calculated as the ratio of the 

 distance between the last and penultimate bands (Brans- 

 tetter and Musick, 1994; Cailliet, 1990; Simpfendorfer, 

 1993; Simpfendorfer, 2000). Mean average increments by 

 month of capture were plotted to identify trends in band 

 formation by using a Kruskal-Wallis one-way analysis of 

 variance on ranks. (Simpfendorfer, 1993; 2000). 



Results 



Morphological measurements 



A total of 230 specimens were used for this study. Males 

 (;!=98) ranged between 147-932 mm TL, 82-601 mm 

 DW, and 0.015-6.2 kg. Females (/i = 132) ranged between 

 145-940 mm TL, 82-635 mm DW, and 0.015-7.5 kg. A 

 linear relationship existed between the total length, disk 

 width, and mass relationships for male, female, and the 

 sexes combined (all r- values were greater than 0.85). Two 

 skates (one male: TL=147 mm, DW=82 mm, weight=0.015 

 kg; and one female TL= 145 mm,DW=82 mm, weight=0.015 

 kg) hatched from egg cases during May 2001 in the CML 

 after gestating 18 months. One wild male specimen (age-0, 

 TL=175 mm, DW=100 mm, weight=0.027 kg) was also cap- 

 tured and incorporated into the results of this study. 



the centra) were easily distinguished from complete bands. 

 Of the 230 processed vertebrae, 209 (91%) were readable. 

 These 209 vertebrae (males=88;females=121) had annular 

 count estimates that agreed within two years, resulting in 

 an TAPE of 5.8%. Mean total length and disk width at age 

 for male, female, and sexes combined are given in Table 1. 

 The relationship between TL and centrum diameter was 

 linear {r~=Q.92\ P<0.05; Fig. 2) and there were no signifi- 

 cant differences (ANCOVA, P<0.05) between males and 

 females. Because no significant difference existed for TL 

 and centrum diameter between the sexes, the data were 

 combined (Fig. 2). 



Marginal increments were averaged from five speci- 

 mens for each month, except June when skates belonging 

 to the 4 and 5 year age classes were unavailable. Marginal 

 increments were significantly different between months 

 (Kruskal-Wallis P<0.001) and a distinct trend of increas- 

 ing monthly increment growth began in July (Fig. 3). Maxi- 

 mum marginal increment measurement occurred in May. 

 Minimum marginal increment measurement occurred in 

 July Two recently hatched males (one from the laboratory 

 (147 mm TL) and one from field collections (175 mm TL)) 

 had opaque zones on the distal edge of their vertebral cen- 

 tra. Reviewing this information, we suspect that a single 

 opaque band may be formed annually on the vertebral 

 centra during June-July in the winter skate. 



Vertebral analyses 



No difficulty was encountered in estimating the age of L. 

 ocellata. False bands (bands that do not completely encircle 



Age and growth estimates 



We assumed that opaque-translucent band pairs were 

 formed annually, and we fitted von Bertalanffy growth 



