rasps its victim with its tongue to obtain nourish- 

 ment in the form of blood and other body fluids 

 (Everhart 1976). Secretions from a pair of rela- 

 tively large salivary glands below the tongue 

 retard coagulation of host blood and also dissolve 

 tissue (Lagler et al. 1977). Bigelow and Schroeder 

 (1953) reported that in saltwater, lampreys have 

 been found preying on mackerel, shad, cod, had- 

 dock, pollock, salmon, basking sharks, various 

 anadromous herrings, swordfish, hake, sturgeons, 

 and eels. 



Piscine erythrocytic necrosis (PEN), a condi- 

 tion characterized by cytoplasmic inclusions and 

 nuclear abnormalities in erythrocytes, has been 

 shown to be of viral etiology in the Atlantic cod, 

 Gadus morhua, and Atlantic herring, Clupea 

 harengus harengus, from the Atlantic coast and 

 the chum salmon, Oncorhynchus keta, pink salm- 

 on, O. gorbuscha, and Pacific herring, Clupea 

 harengus pallasi, from the Pacific coast of North 

 America (Walker 1971; Appy et al. 1976; Walker 

 and Sherburne 1977; Philippon et al. 1977; Reno 

 et al. 1978; Evelyn and Traxler 1978; MacMillan 

 and Mulcahy 1979). In addition, PEN has been 

 reported in 15 other marine teleost species from 

 the Atlantic coast of North America, but confir- 

 mation as to viral etiology has not been made 

 (Laird and Bullock 1969; Walker and Sherburne 

 1977; Sherburne 1977; Sherburne and Bean 1979). 

 PEN has also been evident in the Atlantic mack- 

 erel, Scomber scombrus, (Sherburne, unpubl. 

 data). 



This report documents the first finding of PEN 

 in a host from the most primitive group of fishes, 

 the Agnatha. 



Materials and Methods 



A total of 142 lampreys, Petromyzon marinus, 

 was obtained for blood analysis from 5 Maine 

 localities (Table 1). Live lampreys were measured 

 for total length and sexed. Slides were prepared 

 by severing the caudal peduncle and taking the 

 blood into a heparinized capillary tube, from 

 which a small drop of blood was placed on a 

 microscope slide and the smear made. Air-dried 

 smears were Giemsa-stained and thoroughly 

 examined for PEN using light microscopy at 

 1000 x magnification. 



Results 



Of the total lampreys sampled in this study, 

 50.7% (72/142) had red cell lesions characteristic 

 of PEN (Table 1). By light microscopy, PEN 

 lesions of lamprey red cells often showed the 

 nuclear chromatin condensed into round blebs, 

 and there was evidence of nuclear vacuolization 

 (Fig. 1). Red acidophilic cytoplasmic inclusions 

 were occasionally seen in an infected cell (Fig. 

 2). 



Individual infections were light, with only one 

 or two infected cells evident in most smears. 

 Among the 72 infected lampreys, the severest 

 infection involved 2% of the red cells and it 

 occurred in a 69 cm male from the Coopers Mills 

 Fishway on 26 May 1980. 



From a total of 139 lampreys sexed, 47.9% of 

 the males and 53.0% of the females had PEN. The 

 smallest infected lamprey was 62.4 cm (24.6 in) 

 long; the largest was 81.5 cm (32.1 in). 



TABLE 1. — The occurrence of piscine erythrocytic necrosis (PEN) in the sea lamprey, Petromyzon 



marinus, from several Maine localities. 



542 



