Missing Sea Lions of Eastern of Alaska

Stellar Sea Lions of Eastern Alaska

Sea Lions of Eastern Alaska

B) 9,600 I estimated the 2004 population of Steller Sea Lions to be 2800, as indicated on the Y-axis of the graph. Plugging this figure into Trites' and Larkin's formula, I calculated as follows: Total population = 3.43 x 2800 = 9604.

E) 15 years Figure 3 shows the relative population changes for pollock, herring, and Western stock sea lions. The pollock population shows steady growth from 1985 to 1995. Assuming that the population number on the Y-axis are in thousands, the pollock population roughly 50,000 to 138,000 in southwest Alaska during that period. Growth of the pollock population appears to have increased slightly following the Pollock fishing ban, rising to roughly 58,000 in 1975. However, a pollock population decline was seen 10 years after the ban, and at the 15-year mark, the pollock population was approximately what it had been at the time the ban was instituted. Fifteen years of controlled fishing and an associated change in the ecosystem of southwest Alaska resulted in a significant increase in the pollock population.

3. C) 23 years Figure 2 shows the estimated growth rate of Eastern stock Steller sea lions from 1956 to 2000, a period of approximately 44 months. Without knowing the lifecycle of the Stellar sea lions and the death rate due to predation, I assumed a steady growth rate of the historical 3%. My calculations show that the Steller sea lion population would double in 23 years. Given:

5469 = Steller sea lion total population in Eastern Gulf of Alaska

5469 x 2 (doubling the population) = 10,938

5469 x .03 (historical growth rate) = 164.07

10793.54463 = Compounding for 23 years

See Excel Worksheet Calculations below:

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10938

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10173.95101

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10479.16954

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10793.54463

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11117.35097

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4. F) Central and Western Aleutian Islands The proportion of pups to adults in the Central and Western Aleutian Islands is higher than any of the other population regions at roughly 2.5 adults to each pup (13888/5493 = 2.528 or 2.5:1). For whatever reason more pups are born or survive in this population.

5. D) low 8.4 kg The change in body mass for each day of a pollock-only diet resulted in an average loss of 0.5 kg per day. After 14 days, the approximate change in body mass would be 7 kg/d. However, the data is provided in a box and whisker format that indicates some outlier data about one standard deviation (SD) below the mean. This indicator could logically push the body mass change to 8.4 kg/d.

6. D) 405 Given 100 grams of pollock contains 1% fat, 20% protein, and 79% carbohydrates, we will need to calculate and sum the products of each percentage with its standardized energy equivalent. Thus, 9 kCal/g x .01 = 9; 4 kCal/g x .20 = 80; 4 kCal/g x .79 = 315. 9 + 80 + 315 = 405

7. A) 10% vs. 1% Table 1 provides the both the kCal/g and the percentage values for fat as it is found in herring and pollock.

8. D) 100g of herring and 100g of pollock contain the same number of calories of carbohydrate. The numbers 9, 4, and 4 - respectively for fat, protein, and carbohydrates - are standardized energy equivalents. So, 1 gram of herring would have 4 calories and 1 gram of Pollock would have 4 calories. This relation holds true as long as the number of grams of each type of fish is the same.

9. D) With the exception of one outlier, sea lion counts are similar in Kodiak and in PWS. The correlation between sea lion counts and herring biomass in Kodiak is r = 0.83 and in Prince William Sound it is r = 0.79. Both are substantive ratios indicating a strong positive correlation, and the values are not likely to be significantly different given that they are based on counting sea lions and estimating herring biomass, both processes subject to considerable error. Moreover, only one data point could be considered an outlier in this scatterplot.