FISHERY BULLETIN: VOL. 72. NO. 1 



and Robben Island, USSR. Small breeding 

 colonies are found in the Kurile Islands, Japan, 

 and on San Miguel Island, Calif. During winter 

 and sjiring, fur seals are pelagic and migrate 

 as far south as southern California and Japan. 

 Fur seals feed principally on fishes and squids 

 in offshore areas. 



Harboi- seals are a nonmigratory species 

 found in the northern hemisphere in both the 

 Pacific and Atlantic Oceans. Those collected for 

 this study (subspecies )-icli(irdi) are found from 

 Mexico to the Bering Sea. Harbor seals feed 

 principally on fishes, s(iuids, and octoi)uses near 

 coastlines. 



METHODS 



The liver and kidneys were selected as the 

 principal tissues for this study because heavy 

 metals tend to accumulate in these organs 

 (DuBois and Ceiling, 1959; Curry, 1969). 

 Sami)les of muscle were collected from fur seals 

 but not from harbor seals. 



Collection of Samples 



In general, the sampling was conducted as 

 follows: From a seal liver weighing about 1.8 

 kg. a kidney weighing about 0.5 kg, or muscle 

 from the shoulder area, a sample of about 75 g 

 was placed in a new unwashed glass bottle or 

 l)olyethylene bag and stored at — 23°C. 

 Analyses were made about 5 mo after initial 

 sami)ling. 



Samples included liver and muscle from 3-mo- 

 old pups and 2- and 3-yr-old male fur seals from 

 the Pribilof Islands; liver, muscle, and kidney 

 from fur seals (mostly adult females) from 

 Washington; and liver from harbor seals from 

 California, Oregon, Washington, and the Bering 

 Sea. Tissues from fur seals taken on the Pribilof 

 Islands were kept in jjolyethylene bags; all 

 other tissues were kei)t in new glass bottles. 



Analyses of Samples 



For the analysis of mercury, four rei)licate 

 20-mg samples were taken from a piece of 

 tissue in the sam])le bottle and analyzed. The 

 mean of these four replicates was taken as 

 representative of the i)articular tissue for that 

 analysis. The analytical procedure for mercury 



involves introduction of the weighed sample 

 into a tubular furnace from which the products 

 of combustion and vaporized mercury are 

 drawn. After scrubbing and filtering to remove 

 interfering components, the mercury vapor is 

 passed through a cell and read by atomic 

 absorption spectrophotometry.'' 



For lead, cadmium, and arsenic analyses, a 

 separate 2-g sami)le was taken for each metal. 

 The lead analysis was carried out by digesting 

 the sample in a 5:2 nitric-sulfuric acid mixture 

 followed by dry ashing in a muffie furnace at 

 550° C until all organic material was removed. 

 Following dissolution in 5 ml of hydrochloric 

 acid, lead content was determined by the 

 double extraction, mixed color dithizone method 

 (Committee on Chemical Procedures of the 

 Occupational Health Section, American Public 

 Health Association, 1955). 



For cadmium, the .sample was wet ashed in a 

 2:1 nitric-perchloric acid mixture, and the 

 re.sultant solution diluted to a known volume 

 with water. The cadmium was extracted into 

 methyl isobutyl ketone (MIBK) by means of 

 chelation with sodium diethyldithiocarbamate 

 (NDDC) and measured by atomic absorption 

 (Berman, 1967). 



For arsenic, the sami)le was wet ashed in an 

 8:4:1 nitric-perchloric-sulfuric acid mixture to 

 oxidize organic matter and release organically 

 bound arsenic. Following digestion, the sample 

 was diluted to 25 ml volume with water and 

 arsenic determined by the silver diethyldithio- 

 carbamate method (American Public Health 

 Association, 1971). 



Detection limits of the analyses were 1 i)pb 

 for mercury, 0.1 ppm for lead, 0.01 ppm for 

 cadmium, and 0.2 i)i)m for arsenic. Recoveries 

 were over 90% for mercury and cadmium where 

 mercury was added as elemental mercury 

 dissolved in nitric acid and cadmium was added 

 as cadmium sulfate. Lead and arsenic recoveries 

 wei"e over 95% with lead added as lead nitrate 

 and arsenic added as arsenic trioxide. 



All of the tissue samples were analyzed by 

 Environmental Health Laboratories Inc., 



! Hermann, W. J., Jr., J. W. Butler, and R. G. Smith. 

 1468. A dynamic system for the rapid microdetermination 

 of mercury in undigested biological materials. Presented 

 at Applied Seminar on Laboratory Diagnosis of Diseases 

 Caused bv Toxic Agents, Washington. D.C., Nov. 8-9, 

 1968. Wayne State Univ.. Detroit. Mich., Dep. Med., 

 14 p., 1 fig. (Processed.) 



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