Collection of canine teeth, recovery of tags, and recording of checkmarks were done midway between the sprinklers and the grinder. Standing on a platform 3 feet high, one man used a hack saw to remove the snouts just anterior to the eyes (fig. 5). From this position, the snouts passed the worker at eye level. Twenty percent or more of the seals were sampled daily for right upper canine teeth by taking the snouts from carcasses 1 and 2, 11 and 12, 21 and 22, etc., until all seals killed that day had passed. Another man examined left front flippers for tags and checkmarks as he walked in a direction opposing that of the moving line of carcasses (fig. 6). When he reached the sprinklers, the worker inserted a marker into the last carcass examined, crossed to the other side of the line, and examined the right front flippers as he returned to the carcass with which he began. Examination of about 100 seals in 10 minutes was followed by a wait of 15 minutes, after which the worker repeated the procedure, beginning with the last carcass he had marked. During the 15-minute interval, the tag-recovery man examined loose flippers at the carcass dumping site or assisted the tooth collector.

Bull counts.-- The number of harem bulls (adult males holding females) counted on the Pribilof Islands has decreased each year since

1961 (fig. 7). The number of harem bulls depends on the numerical strength of two other herd elements--idle or reserve bulls (males age 7 and older without females) and producing females. Decreases in the number of harem bulls, however, are believed to be the result of the reduction in the number of producing females.

The number of idle bulls counted on land has also been decreasing, following a sharp rise from 1952 to 1960 (fig. 7). The decline in idle bulls has been caused by extensive killing of recent year classes through longer seasons and increases in the maximum size of seals taken.

The counts of bulls in 1965 are given by island and by rookery in appendix table 10, and all counts of bulls since 1911 are presented in appendix table 11.

Females

The maximum sustained yield of sealskins should occur when the number of breeding females is at some level below its natural peak. For this reason, large numbers of females were purposely killed on the Pribilof Islands from 1956 through 1963 to reduce the population from the peak reached by about 1940 to a lower and more productive level. Additional females were taken in 1964 and

1965 to maintain the population at the level achieved.

A total of 10,432 females were taken from the hauling grounds of the Pribilof Islands in 1965. Of these, 3,868 were taken during the kill of male seals 7 July to 9 August and 6,564 during the special kill of females 16-27 August. The female seals killed in 1965 are classified by age in appendix tables 12, 13, 14, and 15. Year class contributions to the kill of females are given in table 4, and the percentage age composition of females sampled from the kills on the Pribilof Islands in 1958-65 are presented in table 5.

Once the females attain sexual maturity and join the breeding element of the herd, they are subjected to bite wounds from the harem bulls. The resulting scars lessen the commercial value of their skins. Most of the females are initially exposed to scarring at age 5 or 6, when they enter the rookeries to give birth to their first pup. The skins from females age 5 and

younger, therefore, are more valuable than those from females age 6 and older.

In addition to being relatively free of scars, females age 5 and younger usually have black or a mixture of black and white vibrissae. By comparison, most females age 6 and older have white vibrissae. Thus, females having the most valuable skins can be selected for killing on the Pribilof Islands on the basis of vibrissal color. In 1965, selection was practiced on St. Paul Island 23-27 August; 88 percent of the females taken were age 5 and younger. On St. George Island, where selection was not practiced 16-27 August, only 64 percent of the females killed were age 5 and younger.

Tag Recoveries and Tagging

Tagging provides marked seals needed for making estimates of the population and furnishes seals of known age and origin of birth for studies of age and growth, distribution at

for killing all seals. The limits for taking males on both Islands were from 42.0 inches (106.7 cm.) long to, but not including, those with manes. All females driven with the males were taken. During the special kill of females on St. Paul Island 23-27 August, only those with black or mixed black and white vibrissae were killed. All females driven during the special kill of females on St. George Island 16-27 August were taken, regardless of vibrissal color. Possibly a few of the 65 tagged seals taken on St. Paul for studies of fur value by age and were outside the prescribed limits.

sex

A total of 2,736 tags were recovered from male seals in ages 2-10, and 1,508 checkmarks were recorded from males that had lost their tags (table 6).

A total of 463 tags were recovered from females in ages 2-17, and 240 checkmarks were recorded from females in ages 2-6. Checkmarks from females age 7 and older were not recorded because each of the four front flipper marks used since 1953 (app. table 18) has been repeated every fourth year. Thus, the location and type of checkmarks on females age 7 and older may be identical on animals of different ages. Checkmarked females (as well as males) 2 and 6 years old can be separated on the basis of body size.

A total of 238 seals selected as yearlings on the basis of body length and double-tagged on St. Paul Island in 1961 (M-series), 1962 (N-series), and 1963 (O-series) were recovered on the Pribilof Islands in 1965 (table 7).

Thirty-six seals tagged by the U.S.S.R. were killed on the Pribilof Islands in 1965 (table 8 and app. table 16).

Tagging and marking of pups.--Pups were not tagged or marked on St. George Island in 1965.

On St. Paul Island, 30,000 pups were tagged and marked, or marked only, as follows: (1) Tags were attached to the left front flipper of 10,000 pups between the fourth and fifth digits, and a V-notch checkmark was cut into the leading edge of the same flipper with veterinary ear-notching instruments; (2) 10,080 pups were marked only by removing the tip of the first digit (big toe) of the right hind flipper at the web; and (3) 10,007 pups were marked only by cutting a V-notch into the leading edge of the right front flipper. The tagging and marking were completed in 8 days by 11 men. Example of tag and mark locations used on fur seal pups are illustrated in figure 8. The veining chisels formerly used to make the V-notch checkmarks were replaced in 1962 with veterinary ear-notching instruments. The latter tool is superior because it is easier to use, does not require a surface such as wood to cut against, is adjustable for horizontal depth of cut, and remains sharp during thousands of cuts; furthermore, it makes consistently good marks such as that shown in I figure 9, whereas the veining chisels tended to slip off the edge of the flipper and leave only a faint and unrecognizable checkmark. Figure 10 illustrates a few of the checkmarks made by veterinary ear-notching instruments in 1962 and recovered from tagged 3-yearold males in 1965. Of 279 tagged seals examined, 266 had checkmarks that were easily recognizable; only 13 of the tagged seals did not have recognizable checkmarks.

All tags used since 1952 have been attached to front flippers, and most have been attached

to the front flipper at the hairline (fig. 8); however, in 1964, a new tagging site located between the fourth and fifth digits (fig. 8) was used for half (10,000) of the pups tagged. The new site was used on all pups tagged in 1965 to lessen damage by tagging. The effectiveness of the new tagging site is not yet known.

The number of pups tagged in 1965 is listed in appendix table 17 by rookery, and a record of pups tagged on the Pribilof Islands since 1941 is given in appendix table 18.

Tagging of yearlings.-- The methods used to select and tag yearlings in 1965 were nearly the same as in 1962 and 1963. The upper length limit was reduced from 37.5 inches (95 cm.) to 35.0 inches (89 cm.) for females after the second day of tagging in 1965 to prevent selection of females older than age 1 for tagging. Body length has proved to be a good basis for selecting yearling males; it is not suitable for identifying yearling females, however (see section on estimates based on recoveries of tags applied to yearlings), because of the greater overlap in lengths among 1-, 2-, and even 3-year-old females. An upper body-length limit of 39.5 inches (100 cm.) has been used successfully to separate yearling males from older males. The length-frequency distributions of known-age yearling males tagged as pups and males selected as yearlings on the basis of body length are similar (fig. 11); the mean lengths of the two differ by only 1 cm. (table 9).

The surveys for known-age yearlings tagged as pups, begun in 1963, were discontinued in 1965 because it was impossible to tag yearlings and make surveys during the same period. Also, no apparent way existed to standardize the survey work from year to year.

Most of the yearlings found in 1965 were on hauling grounds on Zapadni Reef and south of Sea Lion Neck.

In previous years, the hauling ground areas most used by yearlings were examined in 1 day. In 1965, however, seals were so abundant on the hauling grounds that it was impossible to examine all areas in less than 2 days. Possibly weather caused more animals to be on the hauling grounds in 1965 than in other years. The weather during tagging was windy with occasional snow. The relation between weather and the location of yearlings, however, is not clear.

Six men tagged 991 yearlings in 7-1/2 days in 1965 (app. table 19).

Pup Mortality

The number of dead pups counted in 1965 was 181 percent of the number counted in 1964 on St. Paul Island and 219 percent on St. George Island. The counts for both Islands are illustrated in figure 12 for 1950-65 and given in detail in appendix table 20 for 1941-65.