A MERISTIC AND MORPHOMETRIC COMPARISON OF 

 THE HAKES, UROPHYCIS CHUSS AND U. TENUIS 



(PISCES, GADIDAE)i.2 



J. A. MUSICK^ 



ABSTRACT 



Urophycis chiiss and U . tenuis are shown to be statistically different for several meristic 

 and morphometric characters. The ranges of the number of lateral line scales are 

 distinct, U. chiiss having 95 to 117 and U. tenuis having 119 to 148. The numbers of gill 

 rakers on the epibranchial of the first gill arch are distinct, U. chuss having three and 

 U. tenuis having two. The number of abdominal vertebrae and the regression of head 

 length on standard length can be used to distinguish between the two species, with 

 certain reservations. Two characters previously used in the literature to distinguish between 

 the two species are not valid. These are: the relation of upper jaw length to the distance 

 from the snout to the posterior margin of the orbit, and the relation of the distance 

 from the origin of the pelvic fin to the anus to the length of the pelvic fin. Samples of 

 U. tenuis from off New England and Nova Scotia appear to be morphometrically different 

 from those from the Gulf of St. Lawrence. 



The genus Urophycis Gill (1963) includes at 

 least seven species of gadid fishes endemic to the 

 western Atlantic Ocean (Svetovidov, 1948:105). 

 The most abundant of these in the area north 

 and east of Delaware Bay are U. clutss (Wal- 

 baum, 1792) and U. tenuis (Mitchill, 1814) 

 which are difficult to distinguish (Figures 1 

 and 2). These two species have been repeatedly 

 confused since U. tenuis was first described by 

 Mitchill (1814), who recognized the meristic 

 differences between them but apparently did 

 not always recognize the species by sight, be- 

 cause he gave the maximum weight for Gadus 

 longipes {— U. chuss) as 18 lb. U. chuss rarely, 

 if ever, exceeds 6 lb, whereas U. totuis may 

 reach 40 lb or more, and often exceeds 18 lb 

 (Musick, 1969). Among the long list of confused 

 and misnamed accounts in the literature, the 

 outstanding ones are Rafinesque-Schmaltz 

 (1818), Storer (1839), Kaup (1858), Cornish 

 (1907, 1912), and Vladykov and McKenzie 



' Virginia Institute of Marine Science Contribution 

 No. 518. 



^ Based on part of a doctoral dissertation presented 

 to Harvard University. 



^Virginia Institute of Marine Science, Gloucester Point, 

 VA 23062. 



(1934) who placed U. tenuis within the syn- 

 onymy of U. chuss, after a "study of the 

 literature." 



Both U. tenuis and U. chuss are taken 

 commercially throughout their ranges. The 

 International Commission for the Northwest 

 Atlantic Fisheries (ICNAF) has the responsi- 

 bility of reporting the annual catch statistics 

 for all major species, including U. chuss and 

 U. toiuis, taken in the ICNAF area. Musick 

 (1967)^ pointed out that the statistics for 

 Urophycis frequently were in error because of 

 misidentification. Recently, Leim and Scott 

 (1966:217) were compelled to discuss the biol- 

 ogy, distribution, and commercial value of 

 U. chuss and U. tenuis together because of the 

 confused treatment of species in earlier Cana- 

 dian literature. 



The purpose of this paper is to test the 

 validity of certain characters previously used 

 in the literature to distinguish between U. chuss 

 and U. tenuis and to examine additional char- 

 acters of potential diagnostic value. Seven 



Manuscript accepted November 1972 

 FISHERY BULLETIN: VOL. 71, NO. 2, 1973. 



^ Musick, J. A. 1967. Designation of the hakes, Vro- 

 phvcis chuss and U. tenuis in I.C.N.A.F. statistics. Int. 

 Comm. Northwest Atl. Fish., Res. Doc. 67-76, No. 1872, 

 5 p. (Unpubl.) 



479 



