major wintering area. Although visibility was excellent during both surveys, only 21 seals were seen on the first cruise (28-29 May) and 1 on the second (21-22 June).

A concentration of seals was located north of Pt. Sur in and near the Monterey seavalley from late April to early June. Seals were on the Farallon grounds southwest and west of the Farallon Islands throughout the survey period. Concentrations of seals were also observed on or near Cordell Bank west of Pt. Reyes in April and in early May.

Seals off California seldom come close to land; however, during a severe storm on 14 April we saw an adult female about a half mile from shore at the western approach to Drakes Bay. Seals were abundant offshore at this time.

Seven observation or transect lines were established between Bodega Head and Pt. Sur at 20-mile intervals as a basis for a systematic study of the distribution and migration of fur seals off California. These lines, which extended from 10 to 80 miles out from shore (figs. 2 and 3), were cruised once each month, and the seals seen were recorded (table A-1). Because of the annual northward migration, the number of seals seen per month decreased from 264 in April to 72 in June. Seals were most abundant from 30 to 70 miles offshore (figs. 2 and 3). The greatest concentration was from 30 to 40 miles offshore; abundance decreased rapidly toward shore and gradually between 40 and 80 miles out. The largest number of seals seen in 1 day in each month were: 16 April 101, 26 May - 66, and 14 June 46. Thirty seals were seen on the last day (23 June) in the area.

Surface water temperatures off California ranged from 10° to 14° C. in the areas surveyed. Temperatures were mostly 110 to 12° C. in April and May and 12° to 13° C. in June.

Relative Abundance of Seals and Size of Groups

The number and relative abundance of seals seen and collected, by 10-day periods, are shown in tables A-2 and A-3. The decreasing number of seals seen per boat-hunting day off California in April, May, and June, is a result of the annual northward migration to the Pribilof Islands breeding grounds. This decrease was not apparent off Washington, where the survey ended at about the peak of migration.

A group of seals is defined as one or more seals that are feeding, traveling, or resting in close association with each other. A single seal is recorded as a group of 1. Seals separated from each other by more than 100 yards are recorded as separate groups. The percentage of seals in each group for Washington and California combined (table A-4) did not change greatly from that observed in 1964

1/ Table does not include seals born in years when no tagging was done, or year classes from which no tagged seals were taken.

Reproductive condition. -- Of the females collected off California and Washington in 1965, 45 percent were nulliparous, 12 percent were nonpregnant primiparous and multiparous, and 44 percent were pregnant (tables A-12 and A-13). The youngest pregnant females taken were three primiparous 5-year-olds.

Pregnancy rate.-- The number of female seals (and the percentage pregnant) collected in the eastern Pacific from 1958 to 1965 are shown in table 4; records for 1965 are given by area and month in table A-14.

Data on pregnancy rates are necessary for making population estimates and for determining the effects of a reduction in size of the herd. For example, the low pregnancy rates of 3- and 4-year-old females may increase now that killing of females on the Pribilof Islands has reduced the herd to the approximate level of maximum sustained yield. Pregnancy rates representative of the population cannot be accurately determined from animals taken on the Pribilof Islands because the females segregate by reproductive condition when on land (Roppel, Johnson, Anas, and Chapman, 1965). Therefore, knowledge of variation in rates among females taken at sea, by year, season, and area, is important as a basis for determining pregnancy rates representative of the total population.

Regardless of area or season of collection, the total annual samples show little variation in pregnancy rates among females in ages

7-13 during the period 1958-65. The variation increased among 6-year-old females, and at age 5 the pregnancy rate in different years ranged from 21 to 56 percent (mean 39 percent). These variations are unexplained.

Uterine horn of conception and fetal sex ratio.--The uterus of the female fur seal is bicornuate. One uterine horn carries a conceptus one year and the other horn carries a conceptus the following year unless the female fails to conceive one or more years. Examination of 5,057 pregnant females collected since 1958 shows that 51.3 percent of the fetuses were carried in the left uterine horn. This difference, together with the necessity of alternating horns in order to conceive each year, means that the first conception, or conceptions that occur following an interruption, must be most frequently in the left uterine horn.

Of 4,369 fetuses collected in 1958-65, 49.2 percent were males and 50.8 percent were females.

Attached Organisms (Commensals)

Algae and gooseneck barnacles are commonly found on the guard hairs of seals that have been at sea for an extended period. Of 270 seals collected off California in 1965, algae were attached to the guard hairs of 42.2 percent, barnacles 33.3 percent, and both algae and barnacles on 18.1 percent (table 5). The amount of algae ranged from a few spots to almost complete coverage of the animal.