ARTIFICIAL HYBRIDS BETWEEN 



PIKE AND PICKEREL 



Crossing Which Is Possible Artificially Appears Sometimes to Occur in Nature 



— Peculiar Specimens Which Are Occasionally Found Are 



Probably not Mutants, but True Hybrids 



G. C. Embody 



Cornell University, Ithaca, N. Y. 



THOSE who have collected and 

 studied the northern pike {Esox 

 luciiis) from Cayuga Lake, New 

 York, have occasionally come 

 across specimens showing, in one char- 

 acter at least, a condition intermediate 

 between the typical pike and pickerel 

 {Es».v rcficiilatiis). The question has 

 arisen, whether this is a mutation or 

 has been brought about by natural 

 crossing of the two species. In order to 

 shed some light on the question the 

 writer has studied the spawning be- 

 havior of both forms, has determined 

 the spawning time and lastly has 

 crossed the two artificially, rearing the 

 hybrids to a sufficient size to show 

 their principal characters. 



In the southern end of Cayuga Lake, 

 the pike begin to enter the marshes 

 and temporarily submerged fields as 

 soon as the ice leaves, which is usually 

 towards the middle of March. Spawn- 

 ing seldom occurs, however, imtil a 

 week or more later when the tempera- 

 ture of the water approaches 8° C. The 

 pike are accompanied, or closely fol- 

 lowed, by the pickerel both in migra- 

 tion and time of spawning. It happens, 

 therefore, that the two species may be 

 spawning over the same area and at 

 the same time. 



spawning pickerel cross male 

 pike's path 



Pike and pickerel are practically 

 identical in their spawning behavior. 

 This may be described briefly as fol- 

 lows : A female accompanied by one 

 or more males swims about in a mean- 

 dering path. Eggs and milt are cast 



during widely varying intervals, and at 

 each emission violent lashings of tails 

 tend to distribute both eggs and milt 

 over a comparatively large area. Spawn- 

 ing pickerel have been observed cross- 

 ing the paths of spawning pike. Should 

 this occur at the proper moment, it is 

 conceivable that a few eggs of one form 

 might come into the area clouded with 

 milt of the other and an accidental 

 cross impregnation take place. No 

 direct matings of pike with pickerel 

 have been observed. 



On March 30. 1917, the eggs from a 

 30.5 cm. pickerel having typical char- 

 acters were artificially pressed into 

 a moistened pan and covered with milt 

 from a male pike likewise typical of its 

 species. The reciprocal cross was not 

 attempted. About 70% of these eggs 

 developed normally, and those not pre- 

 served for future study, hatched in 

 from six to ten days. A few of the 

 young were reared in an aquarium to 

 lengths varying from 3.8 cm. to 6.4 cm. 

 after which they were transferred to a 

 small newly made artificial pond of 

 stagnant water. When six months old 

 three specimens were captured and gave 

 lengths of 15.2, 13.8, and 9.1 cm.;: re- 

 spectively. 



RECOGNITION CHARACTERS OF PIKE AND 

 PICKEREL 



The more obvious external differ- 

 ences between the pike and pickerel are 

 found in the scalation of the opercula 

 and the body color pattern. The ex- 

 tent of the scale covering of the oper- 

 cula ["gill plates"] has long been con- 

 sidered the best character for the identi- 



253 



