Ottiida I.aki- /-islus 449 



Enemies and Disease. Wall-eyed Pike in (Jneida Lake apiieared to \)e very 

 free from disease during the time of our field investigations. The fish seen apinrared 

 healthy, with bodies well formed. \'ery few were found dead anion},' the many 

 carcasses of fish of various kinds seen floating; or on the shore. In .Xpril, 1927, 

 Dence made two visits to the hatchery at (."onstantia durinjj the height of the I'ike 

 Perch sjmwninj; season. The tanks were filled to capacity with fish waiting to be 

 stripjied. AI)out 5 per cent of the fish contained wart-like excrescences in the 

 skin ami on the fins, particularly the latter. The fins of some Pike Perch were 

 literally covered with these growths, which in some cases were also found on the 

 head about the eyes and mouth. In spite of this affliction the fish api>eared healthy 

 and were apparently yielding a normal amount of spawn. This disease was found 

 on two s|)ecimens ( Nos. 146 and 4215) collected from the lake in other years. 



The predacious enemies of the species in the lake are ])rol>ably almost entirely 

 other fishes, although they do to some extent |)rey upon each other (Clemens and 

 others, '24, p. \2(j). No definite information was obtained by us on the vertebrate 

 enemies, other than man, of this sjiecies, except through observations of Hankin- 

 son, who saw many young perch on the spawning beds of the species, and these are 

 known t(» feed upon its eggs ( liean, '12. p. joi ). Pratt ('2^. p. 67) re|K)rts that 

 eight of the nine ( )neida I-ake fisli examined contained parasites. ( )f these eight, 

 seven contained Acanthocei)hala, seven contained cestoiles, and one contained a 

 single tremato<le. No ncmatcMles were found by Pratt, but in one fish (No. 498) 

 ij4 inches long we found a mass of thread-woniis or nematixlcs in the stomach. 

 A large sjH-cimen found dead (No. 456) h.i<l 15 large leeches in its gill chamber. 



While the literature on the Pike Perch reveals names of many parasites, no 

 account has l)een found of a thorough study of these parasites in the sjiecies, 

 although C"ole ('05. p. 579) mentions excrescences in the skin of s|)ccimens he 

 found in I-»ke Krie as due to .some sjKjrozoan iiarasitc. Whether or not this in- 

 fested Ixith the Blue and the Yellow Pike is not stated. 



.S|>ace will ]»ermit only a mere mention <if the parasitic wurnis given in the 

 literature on the Pike Perch so far as known t<> the authors. 



Tkkmatodi s 

 Azyijia sp. Pratt, '2},, j). 67, Oneida I^ike. 



.hyuia aeiiniituita (ioldberger. Pearse. '_•.». p. 171 ; Mauler, 'jd. p. Ci2. 

 .■/rv</iii anguslicauda .StafTord. .Stafford, 'o.|. p. 108: Manter. 'jii. ji. M. 

 Azyifia Innga ( I.eidy ). Pcarso, '-'4. p. 171, as ./. hdhosa. 

 Diploslomum sp. Pearse, 'J4, p. 17J. 



Cenlrmvriuiii loholes ( M.icCallum ). Ward ;md Whi]>ple. "iS, p. 401. 

 Cref'idoslomum lourealuni Ze«ler. .'stafTord. '04, p. 40.V 

 C,islrr,>Kt,>iit!ir- *..•■" <tatT'.ril. .'Stafford, '04, i>. 41)4. 



Cf-STODF-S 



n«tli>io(,f<luiliis sp. Piatt. "J.V p. 67; Oneida Ijike. 

 nolhrioeefluilus cuspidalus C<K)i>cr. Pearse, '24. p. 4. 

 Proteoeephalus sp. Pear.sc, '24, p. 174. 

 Proteocephiilus anihloplitis I^idy. IVarsr, '.'4. p. 175. 



