yielded age-specific-survival fractions (/, ) for 

 females of each year class. Ro* for each year class 

 ranged from 7,100 to 25.800 (Table 3). The recip- 

 rocal of these numbers, 0.000141 and 0.000039, 

 respectively, indicate a survival rate ranging from 

 39 to 14 1 females, or 78 to 282 fish of both sexes, for 

 each 1,000,000 eggs spawned. 



Any estimate based in turn on a series of rather 

 imprecise and arbitrary estimates must be viewed 

 with caution, and this one is no exception. Yet it is 

 in line with current knowledge that the survival 

 rate of pelagic fish eggs is extremely low. 



Table 3.— Net reproductive rates (/?„*! and their reciprocals 

 (1/ffo*) for the 1954-63 year classes of Atlantic menhaden. 



Literature Cited 



Bagenal, T. B. 



1967. A short review offish fecundity. In S. D. Gerking 

 (editor). The biological basis of freshwater fish production, 

 p. 89-111, Blackwell Sci. Publ,. Oxf , Engl 

 DRYFOOS. R, L., R. P, CHEEK, AND R. L. KROGER 



1973, Preliminary analyses of Atlantic menhaden, Bre- 

 voortia tyrannus, migrations, population structure, survi- 

 val and exploitation rates, and availability as indicated 

 from tag returns. Fish, Bull., U.S, 71;719-734. 

 HIGHAM, J, R., AND W. R, NICHOLSON 



1964. Sexual maturation and spawning of Atlantic 

 menhaden. U,S, Fish Wildl. Serv., Fish, Bull. 63:255- 

 271. 

 JUNE, F, C AND J, W. REINTJES 



1959. Age and size composition of the menhaden catch 

 along the Atlantic coast of the United States, 1952-55; 

 with a brief review of the commercial fishery. U.S, Fish 

 Wildl, Serv,, Spec. Sci, Rep, Fish, 317. 65 p. 

 NICHOLSON. W. R. 



1971. Coastal movements of Atlantic menhaden as in- 

 ferred from changes in age and length distributions. 

 Trans, Am, Fish, Soc, 100:708-716, 



1972, Population structure and movements of Atlantic 

 menhaden, Brevoortia tyrannus, as inferred from back- 

 calculated length frequencies. Chesapeake Sci, 13:161- 

 174, 



1975, Age and size composition of the Atlantic menhaden, 

 Brevoortia tyrannus, purse seine catch, 1963-71, with a 

 brief discussion of the fishery. US, Dep, Commer,, 

 NOAA Tech. Rep, NMFS SSRF-684, 28 p. 



1978, Movements and population structure of Atlantic 

 menhaden indicated by tag returns. Estuaries 1:141- 

 150, 

 NICHOLSON, W, R., AND J, R, HiGHAM, JR 



1964. Age and size composition of the menhaden catch 

 along the Atlantic coast ofthe United States, 1959, with a 



brief review ofthe commercial fishery, U,S. Fish Wildl, 

 Serv,, Spec, Sci. Rep. Fish 478, 34 p, 

 ODUM, E. P, 



1971. Fundamentals of ecology, 3d ed W B, Saunders Co,, 

 Phila,, Pa,, 574 p 



REINTJES. J, W, 



1962. Development ofeggs and yolk-sac larvaeofyellowfin 

 menhaden. U.S.Fish Wildl, Serv., Fish, Bull, 62:93-102, 

 SCHAAF W. E., AND G. R, HUNTSMAN 



1972. Effects of fishing on the Atlantic menhaden stock: 

 1955-1969. Trans, Am, Fish, Soc 101:290-297, 



CHARLES S, DIETRICH. jR 



Southeast Fisheries Center Beaufort Laboratory 

 National Marine Fisheries Service, NOAA 

 PO Box 570, Beaufort, NC 28516 



ROLE OF LAND AND OCEAN MORTALITY 



IN YIELD OF MALE ALASKAN FUR SEAL, 



CALLORHINVS URSINVS 



The annua! commercial harvest of male fur seals 

 has fluctuated widely and declined since the early 

 1950's, This has occurred despite a fairly stable 

 harvesting regime and efforts to maintain the 

 population near the level believed to be consistent 

 with maximum sustainable productivity (Chap- 

 man 1961, 1964, 1973). Variations in early 

 natural mortality are mainly responsible for these 

 changes in the harvest of males which occurs at 

 ages 2-5 yr (mostly 3-4 yr). Kenyon et al. (1954) 

 and Chapman' emphasized that natural mortal- 

 ity between birth and age 3 yr is high and that 

 most of it probably occurs during the first winter 

 just after weaning. 



This report gives estimates of male survival 

 from natural mortality of pups on land and from 

 the first 20 mo of life at sea, a total interval of 

 approximately 2 yr. The importance of pup num- 

 bers and early survival rates in determining an- 

 nual variations in abundance at age 3 yr is quan- 

 tified also. 



Methods 



Data for survival estimates are in Table 1. The 

 age composition of annual kills before 1950 cannot 

 be determined accurately because an aging 

 technique was not available until then (Scheffer 



'Chapman, D. G, 1975, Methods of forecasting the kill of 

 male seals on the Pribilof Islands. Background paper for the 

 19th Annual Meeting ofthe North Pacific Fur Seal Commission, 

 10 p- (Unpubl. rep.) 



FLSHERY BULLETIN VOL 77, NO 1, 1979. 



311 



