405 



Abstract— Age and growth estimates 

 for the winter skate (Leucoraja ocel- 

 lata) were estimated from vertebral 

 band counts on 209 fish ranging in size 

 from 145 to 940 mm total length (TL). 

 An index of average percent error 

 (lAPE) of 5.8% suggests that our aging 

 method represents a precise approach 

 to the age assessment of L. ocellata. 

 Marginal increments were significantly 

 different between months (Kruskal- 

 Wallis P<0.001) and a distinct trend of 

 increasing monthly increment growth 

 began in July. Estimates of von Berta- 

 lanffy growth parameters suggest that 

 females attain a slightly larger asymp- 

 totic TL (L„=1374 mm) than males 

 (L_=1218 mm) and grow more slowly 

 (*=0.059 and 0.074, respectively). The 

 oldest ages obtained for the winter 

 skate were 19 years for males and 18 

 years for females, which corresponded 

 to total lengths of 932 mm and 940 mm, 

 respectively. The results indicate that 

 the winter skate exhibits the charac- 

 teristics that have made other elasmo- 

 branch populations highly susceptible 

 to exploitation by commercial fisheries. 



Age and growth estimates of the winter skate 

 (Leucoraja ocellata) In the western Gulf of Maine 



James A. Sulikowski 



Michael D. Morin 



Seung H. Suk 



W. Huntting Howell 



Zoology Department, Spaulding Hall 



University of New Hampshire 



46 College Road 



Durham, New Hampshire 03824 



E mail address (for J A, Sulikowski) |sulikow@hotmail com 



Manuscript accepted 17 December 2002. 



Manuscript received 31 December 2002 

 at NMFS Scientific Publications Office. 



Fish. Bull. 101:405-413 (2003). 



Little is known about the biology of 

 many elasmobranchs, including impor- 

 tant parameters such as validated age, 

 growth, age at maturity, reproductive 

 cycles and annual fecundity (Frisk et al., 

 2001). Difficulty in obtaining samples, 

 the large size of specimens, their high 

 mobility, and minor commercial value 

 are just a few of the problems that make 

 such studies complicated and in some 

 respects impractical (Cailliet et al., 

 1983; Cailliet et al., 1986). The recent 

 intensification in commercial fishing 

 of elasmobranchs (Cailliet et al., 1983; 

 Brown and Gruber, 1988; Kusher et al., 

 1992; Dulvey et al., 2000) has made the 

 collection of their life history informa- 

 tion essential to the realistic manage- 

 ment of their populations (Cailliet et al., 

 1983; Ryland and Ajayi, 1984; Dulvey 

 et al., 2000). Historically, batoids have 

 been of minimal commercial value 

 (Otwell and Lanier, 1979; Sosebee, 

 1998); hence the majority of research 

 on elasmobranchs has focused on com- 

 mercially valuable sharks (e.g. Holden, 

 1977; Natanson et al., 1995; Walmsley- 

 Hart et al., 1999). According to the 

 characteristics outlined by Winemiller 

 and Rose (1992) and the comparative 

 analyses of Frisk et al. (2001), skates, 

 like other elasmobranchs, fall into the 

 category of equilibrium strategists and 

 as such reach sexual maturity at a late 

 age, have a low fecundity, and are rela- 

 tively long-lived. These characteristics, 

 coupled with fisheries that select for the 

 removal of large individuals (especially 

 those over 100 cm total length), make 

 these particular fish highly susceptible 

 to overfishing (Hoenig and Gruber, 



1990; Dulvey et al., 2000; Frisk et al., 

 2001). 



Traditionally, skates caught by 

 ground fishing operations were dis- 

 carded (Martin and Zorzi, 1993; Jun- 

 quera and Paz, 1998; Sosebee, 1998). 

 New and expanding markets for skate 

 wings have made retention of these fish 

 commercially more lucrative in recent 

 years (Sosebee, 1998; New England 

 Fishery Management Council^. Skate 

 harvests in the U.S. portion of the 

 western North Atlantic are currently 

 unregulated. Moreover, biological infor- 

 mation on skate life histories is almost 

 nonexistent (Frisk, 2000). This combi- 

 nation of factors is believed to have led 

 to a depletion of common skates (Raja 

 batis) in the Irish sea (Brander, 1981). 



The winter skate (Leucoraja ocellata) 

 is a large species (total length over 100 

 cm) of skate of the family Rajidae (Big- 

 elow and Schroeder, 1953; Robins and 

 Ray, 1986; New England Fishery Man- 

 agement Council'). It is endemic to the 

 inshore waters of the western Atlantic, 

 from the Newfoundland Banks and the 

 southern Gulf of St. Lawrence in Can- 

 ada to North Carolina in the United 

 States (Bigelow and Schroeder, 1953). 

 Despite this wide range, little direct 

 biological data is available for this spe- 

 cies (Simon and Frank, 1996; Casey and 



' New England Fishery Management Coun- 

 cil. 2001. 2000 Stock assessment and 

 fishery evaluation (SAFE) report for the 

 northeast skate complex, 179 p. New 

 England Fishery Management Council, 

 50 Water Street, Mill 2 Newburyport, MA 

 01950. 



