Locomotor and other behaviorisms are of interest vitien trap- 

 ping operations are considered. Sea lampreys observed arri-ving 

 on the doivnstream side of the Carp Creek weir and trap did not 

 lead immediately along the wings of the weir. In general, they 

 tended to prod and explore both downstream and upstream along the 

 barrier, seeking some small aperture through which to pass; 

 eventually the trap entrance tb.s alv/ays discovered and entered. 

 As a result of this searching behavior, these lampreys had phenom- 

 enal success in finding and passing through the smallest of aper- 

 tures in a weir face„ When in a trap or a live-crate, the same 

 behavior was noted — ^an almost ceaseless searching for some means 

 of escape. In 19k7 , I tested the ability of sea lampreys to find 

 an opening large enough to permit their passage through a barrier 

 screen. Eighteen migrating adults ivere placed in the lower of two 

 compartments of a large live-crate that was situated in a moderate 

 ivater current. The crate measured 3 feet by 3 feet by 6 feet and 

 Tra.s made of l/2-inch mesh hardware cloth on a light wooden frame. 

 The depth of the ivater within the live-crate ivas approximately 20 

 inches. A small hole, one inch in diameter, vras made in the center 

 of the har-dware cloth partition dividing the live-crate. T/Vithin 

 four hoirrs, all but two of the sea lampreys had found, and passed 

 through, this hole into the upstream half of the box. For this 

 reason, great care must be exercised in the construction and main- 

 tenance of weirs, traps, and holding pens. 



The physical characteristics of the lampreys and many of their 

 natural responses make them extremely difficult to handle during 

 trapping operations. All nets used for removing trapped specimen^-; 

 must have deep bags since the lampreys tend to jump and thrash 

 violently when removed from the v/ater. Unless considerable practice 

 has been had, it is almost impossible to hold on to an adult sea 

 lamprey with bare hands. l/Vhen held out of the water they -sveave and 

 tvo-st violently and attempt to fasten by their mouths to the nearest 

 solid object» Specimens which succeeded in attaching themselves 

 to my hand or arm did nothing more than hold on — they never harmed 

 me with either teeth or tongue. In handling live specimens ^^ they 

 d.re best grasped just behind the last gill opening in a finger lock 

 between the middle finger and the index and fourth fingers. They 

 may also be held by grasping them strongly betTreen the furinel ana 

 first gill opening with the thumb and forefinger. 



Data relative to the differential migration of sexes during 

 the spawnijig run and changes in its generally nocturnal nature 

 have been presented in a preceding section (p. ^h and pp. I|.7-U9). 



The negative response of migrating sea lampreys to light is 

 particularly marked dur-ing the first half of the run in streams. 

 In the Ocqueoc River watershed a period of six to eight iveeks 

 elapses betroen the entrance of the first migrants into the river 

 snd the beginning of spawning activity. Although towards the end 

 cf this period a great number of sea lampreys are present in the 



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