The equipment necessary for this type of capture is a hoop net 0.75 

 m in diameter, having a 1 .5 m deep net with 10 cm mesh, and a han- 

 dle 4 m long made of aluminum tubing. The hoop should be wrapped 

 with cloth or rubber to reduce noise when hitting rocks. Captures 

 using a net depend on stalking a sleeping seal until the workers are 

 within 5 to 6 m, and then making a sudden, short dash to the animal. 



The workers must approach slowly, remain hidden at all times, and 

 make no noise. The approach phase of such a capture is often more 

 prolonged than with a noose capture. Do not try to outrun seals over 

 large boulders while holding a net. Furthermore, stalk a specific seal: 

 do not alarm a group hoping to make an instant choice during the 

 chase. If the target seal is in the center of a group, the seals at the edge 

 of the group can be moved out of the way by tossing pebbles onto the 

 rocks near them and making sudden hand and arm movements that 

 only they can see. 



Try to net from directly behind a fleeing seal, placing the hoop 

 over the head and neck so that the seal steps over the front edge of the 

 hoop into the net. Then lay the hoop flat on the ground and stand on 

 the ring. The head can be held immobile with a hold-down fork, or by 

 grasping large folds of skin just behind each ear using bare hands. To 

 transfer a netted seal to a cage or restraint bar, first place a choker on 

 the seal while it is still under the net. Adult males are not a factor in 

 this type of capture since they either are not present or are not territo- 

 rial after 1 August. No bamboo poles are needed for defense against 

 males here. 



3) Mass captures.— It is possible to capture 50 to 100 females in a 

 group after the first of August. These captures obviously cause great 

 disturbance to the rookery, so they must be well justified. The princi- 

 ple is that a group of females and pups is cut off from escape to the sea 

 by workers holding moveable fences. By advancing the fences away 

 from the water the seals can be removed from the rookery to flat 

 ground where the fences can be formed into a corral. From the corral 

 females can be handled individually with a choker. We have made 

 mass captures while adult males are on territory. However, this proce- 

 dure is exceedingly dangerous and should not be attempted by inex- 

 perienced handlers. 



At least six workers holding three sections of fence between them 

 are required. These fence sections may be similar to those described 

 for use with subadult males. The workers move the fences as close to 

 the back of the rookery as possible without detection. Two teams sta- 

 tion themselves together at least 25 m from the third single team. At a 

 signal, the teams dash forward holding the fence between themselves 

 and the seals and attempt to form a U-shaped enclosure on the sea- 

 ward side of the seals with the open arms of the U facing inland. Sur- 

 prise and speed are essential. The females will quickly collect against 

 this fence in a pile and must be forced to move away from the water 

 by prodding them through the fence with bamboo poles, by shaking 

 noise makers, and by physically pushing them with the fence. 

 Females in a mass are very difficult to drive in a desired direction. 

 However, it is imperative that they be moved immediately; other- 

 wise, pups are likely to be killed by suffocation. Once females are 

 moving they must not be allowed to stop because they are difficult to 

 start again. When the animals are in the desired location for further 

 handling a fourth fence section is added and tied with ropes to com- 

 plete the corral. 



Pup Captures 



Individual pups may be captured during the first 2 or 3 d postpar- 

 tum using the method described under noose captures for females. 



Later in the season pups may be captured independently of their 

 mothers as they wander the peripheral areas of the rookery. The area 

 covered by wandering 2-mo-old pups is considerable, and the 

 chances of any given pup being on the inland border of the rookery at 

 some time during the day are good. These animals are also captured 

 with a long bamboo pole with a noose of light cord on the end. Sleep- 

 ing pups are by far the easiest to capture. A pup running to escape 

 capture can move down into the rookery faster than can a person car- 

 rying a long pole and who is trying to avoid causing a disturbance. 

 Late in the season when disturbance is less important a small long- 

 handled hoop net may be used for capturing pups. 



When the rookery structure has largely broken down late in the 

 season, large numbers of pups may be rounded up with portable 

 fences in a manner similar to that used for subadult males, or for mass 

 captures of females. Adult males and females on the rookery at this 

 time ofyearcanbedrivenoff quite easily. To minimize the number of 

 pups escaping into the water, plan carefully before the roundup 

 begins. Two persons can handle a roundup and marking operation. 



Pups up to 2-3 mo of age can be safely held up in the air by their 

 hind flippers at arm's length. For longer trips place the free hand 

 under the animal's chest, but still with arms outstretched. Pups have a 

 surprisingly long reach, and if carried close to the chest can severely 

 bite a persons shoulders, upper arms, or face. 



Heavy gloves are required. Teams that mark large numbers (thou- 

 sands) of pups extend their protection to the shoulder using a sleeve 

 cut from a leather jacket. While marking 25 or more animals, minor 

 nips are almost inevitable. 



Short poles (1.5 to 2 m) are useful for herding groups of pups. 

 Rigid sections of low fencing (1.5m high) can be arranged in a U- 

 shaped corral to hold groups of up to 25-30 pups. Inside these corrals 

 the pups will crawl atop one another. This may allow some to escape 

 over the top of the fence, and may cause some to suffocate at the bot- 

 tom of the pile during the roundup. The animals should be driven 

 back from the fence, or physically pulled off the top of the pile at fre- 

 quent intervals. In extreme cases, lift the fence up and let the pups go 

 toward the water 



During the peak of pupping, northern fur seals will not flee from 

 humans moving over their heads. For years wooden walkways (cat- 

 walks), elevated 2.5 to 3 m off the ground, have given researchers 

 access to the centers of breeding groups to census, photograph, or 

 collect animals for autopsy (Keyes 1965). We have recendy used 

 them as a platform to capture live pups for sexing, tagging, and 

 growth studies. 



Captures are made using a bamboo choker about 4 m long. From 

 the squat position on the catwalk (to reduce alarm among females) 

 lower the noose of the choker straight down. If the cord is so limp that 

 the noose will collapse in this position stiffen the cord by wrapping 

 tape around it. Using the end of the choker to move the pup around, 

 arrange the noose so that it includes the pup's neck and one front flip- 

 per, and tighten by twisting. This placement of the noose encircles 

 part of the rib cage and prevents closure of the trachea when the pup 

 is lifted off the ground. With hand-under-hand motions lift the pup 

 straight off the ground. This must be done very quickly to get the pup 

 (and possibly its dangling placenta) out of the mother's reach before 

 she can bite it. Quickly place the pup on the catwalk or have a second 

 person catch it; dangling pups unwind the chokers and may fall. 



Adult males often interfere with captures from a catwalk. Some 

 will aggressively chase the choker and prevent the pup from being 

 noosed. These animals can be distracted with a second choker, or by 

 tossing pebbles as described in the section on female captures. Very 

 few males will bite and toss dangling pups; simply avoid working 

 near such males. 



14 



