Contents of one 19-ft. sealing dory, 6-ft. beam 1 qt. water, 1 signal flag, 1 pliers, 1 screw driver, 1 crescent 11--oars and oarlocks 12-- lifejackets 13--sticking knife 14--ammunition box, contains 100 rounds 00 buckshot 16--boat bailer (not shown) 17--flotation jackets(optional--not shown) can be used in place of lifejackets: 18--waterproof notebook, and Frontispiece--Dory equipped for pelagic sealing. Pelagic Fur Seal Investigations, 1965 By CLIFFORD H. FISCUS, Wildlife Biologist, and Bureau of Commercial Fisheries ABSTRACT Pelagic fur seal research as required by the Interim Convention on Conservation of North Pacific Fur Seals was conducted off Washington (2-24 April) and off California (11 April to 23 June). One hundred forty-seven fur seals (Callorhinus ursinus) were taken off Washington and 269 off California. Off Washington, seals were most numerous near Grays Harbor in mid-April. Off California, seals were concentrated off Monterey from late April to early June and near Cordell Bank west of Pt. Reyes in April and early May. Observation or transect lines extending from 10 to 80 miles offshore were established between Bodega Head and Pt. Sur, Calif., at 20-mile intervals, to study distribution and migration. Seals were most abundant from 30 to 40 miles offshore. Of the 387 female seals taken, 44 percent were pregnant; the youngest pregnant females were 5 years old. A squid, Moroteuthis robusta, is reported for the first time as fur seal food. By volume, the principal species of fish eaten by seals off California was Merluccius productus and off Washington was Engraulis mordax. INTRODUCTION The United States has engaged in pelagic research on fur seals intermittently since 1883. In that year James G. Swan (1883), U.S. Fish Commission, worked on seals brought into Neah Bay, Wash., by Indian sealers. Charles H. Townsend (1898) and A. B. Alexander (1892)' of the U.S. Fish Commission began pelagic studies in 1892 from the U.S. Revenue Marine Cutter Corwin in the Bering Sea and Gulf of Alaska. Townsend, Alexander, and Frederic A. Lucas continued ocean investigations in 1896 under a commission headed by David Starr Jordan (Jordan, 1899). Between 1896 and 1952 no large-scale investigations were carried out. Observations and collections made by many observers during this time are summarized by Taylor, Fujinaga, and Wilke (1955). As part of cooperative investigations by Canada, Japan, and the United States in 1952, Victor B. Scheffer collected seals offshore In Records of the United States Fish Commission, prepared by General Services Administration, The National Archives, Washington, D.C., 1953 (Record Group 22). (Manuscript report by A. B. Alexander concerning fur seals, 1892, 23 p.) 1 from California to Alaska (Taylor, Fujinaga, and Wilke, 1955). Wilke and Kenyon (1957) studied food habits of fur seals in the Bering Sea in 1955. Pelagic research under the Interim Convention on Conservation of North Pacific Fur Seals began in 1958. Members of the Convention are Canada, Japan, the U.S.S.R., and the United States. One objective of the Convention is to determine "what the relationship is between fur seals and other living marine resources and whether fur seals have detrimental effects on other living marine resources substantially exploited by any of the Parties, and, if so, to what extent." The first part of this objective will probably never be entirely satisfied, and though we have acquired detailed knowledge about the food of fur seals, the effects resulting from their feeding are obscure and likely to remain so indefinitely. Other research required by the Convention is partly completed. The migration routes of fur seals and their wintering areas are generally known, but relatively little information is available on far-offshore distribution and the movements of seal pups during their first months at sea. The age and sex of seals moving and feeding off the coast during different months are generally known, but little progress has been made on estimating the numbers of seals on migration routes and in wintering areas in the eastern Pacific. Sampling indicates, however, that few seals under age 8 originating from Robben Island or the Commander Islands migrate along the coast of North America. The most dependable data on pregnancy and mortality rates are obtained from seals collected at sea. These data are essential for population and recruitment estimates for the Pribilof seal herd. Investigations off California from April to June 1965 expanded studies carried on in the spring of 1964. A collection of seals on the salmon trolling grounds off Washington provided information about these animals in an area where a salmon population was present during the time of the study. EQUIPMENT, METHODS, AND PERSONNEL Vessels, boats, equipment, and methods used in hunting and in collecting data were described by Fiscus, Baines, and Wilke (1964). Equipment and methods are now standardized, although specialized equipment and techniques are used dependent on collecting requirements. The frontispiece shows a dory equipped for sealing. Equipment carried in dories has been selected on the basis of experience at sea since 1958. Seals are taken from the vessel, or from a dory, with 12-gage shotguns, loaded with buckshot. Seals are weighed, measured, and skinned, and the stomachs, reproductive tracts, and right upper canine teeth are saved for examination in the laboratory (ages are determined from longitudinal sections of the canine teeth). A study of the accuracy of determining age from upper canine teeth of fur seals is in progress at the Marine Mammal Biological Laboratory. Preliminary results in reading the ages of sectioned teeth of seals of known age indicate the following percent error: males age 2 through 5, error by three readers (33 teeth) ranged from 9 to 24 percent with the greatest error of 1 year; females age 1 through 7, error for three readers (93 teeth) ranged from 9 to 25 percent with 99 percent differing by no more than ±1 year and a greatest error of 12 years; females 8 through 13, error for two readers (39 teeth) ranged from 41 to 59 percent with 91 percent within ±1 year and a greatest error of -4 to +2 years. The sample of known-age males age 6 and females age 14 and older was too small to use in this study. The method of handling skins described by Fiscus and Kajimura (1965) was modified in 1965 to include blubbering (the act of removing fat, muscle, and connective tissue from the skin) prior to salting. This was done to determine if differences in quality of curing existed between skins blubbered soon after collecting and those blubbered several weeks to several months after they were taken. After a skin was stripped from the seal carcass and washed, it was soaked in clean sea water overnight, then blubbered on a portable fleshing beam, drained, and cured in salt for 2 weeks before barreling. Observations of marine mammals and collections of fur seals in 1965 were made off Washington from the chartered purse seiners M/V St. Michael' 2-4 April and M/V Harmony 6-24 April; the St. Michael was also used off central California 11 April to 23 June. Records for three female seals are not complete. These three animals are included in the sections on distribution of seals by date and locality, and relative abundance and size of groups, only. Biologists aboard the St. Michael were Clifford H. Fiscus and Hiroshi Kajimura. Biologists on the Harmony were Raymond E. Anas, Alton Y. Roppel, and Ford Wilke. Assistants on the vessels and in the Seattle laboratory were Richard K. Stroud and James A. Wood. Allan H. Vogel assisted in the Seattle laboratory. Hiroshi Kajimura observed pelagic research in Japan from 10 April to 10 May 1965 (app. B). RESEARCH IN 1965 In 1965, fur seal research was carried out at sea off the coast of Washington between lat. 46° N. and 49° N., in April, and off the coast of California between lat. 360 N. and 39o N., from April to May. Distribution off Washington Seals were widely scattered and scarce off Cape Flattery and the northern Washington coast in early April; however, in mid-April concentrations of seals were located 10 to 20 miles off Grays Harbor (fig. 1). For example, 96 seals were seen 15 April and 145 on 22 April in water from 30 to 100 fathoms (55 to 182 m.) deep. Surface water temperatures off Washington ranged from 8° to 12° C. in the survey areas. Off Cape Flattery, temperatures were mostly 10° to 11° C. Distribution off California With two exceptions, investigations were carried out between Bodega Head (lat. 38° 18' N.) and Pt. Sur (lat. 36° 18' N.) from shore to about 100 miles out. Two cruises were made south from Pt. Sur to Morro Bay (lat. 35° 23' N.) to survey what in the past has been a 2M/V St. Michael: registered length 72,5 feet, 107 gross tons, 380 horsepower, cruising speed 10 knots. M/V Harmony: registered length 70.5 feet, 90 gross tons, 220 horsepower, cruising speed 9 knots. |