Searching for causes of Southern Elephant Seal populations decline
Stanganelli, Z.B. (1996). Searching for causes of Southern Elephant Seal populations decline. MSc Thesis. VUB: Brussel. 57 pp.
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Document type: Dissertation
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| Abstract |
In the present studies, to better understand causes of population decline re-analysis of life tables from the three stocks of southern elephant seals and statistical analysis of their growth patterns from the Atlantic ones were carried out. Concerning life tables the number of female offspring born in each time interval Vx, net reproductive rate Ro, survival-fecundity rates of increase rs, finite rate of increase lambda, potential to double the population Y, and mean generation time T, was calculated. Values obtained indicated the better condition of Atlantic stock. Analysis of growth rates in pups from Patagonia and Antarctica belonging to the Atlantic stock showed significant differences in birth weight, the higher value corresponding to Antarctica. As a consequence of that, analysis of adult length frequency showed that these differences were retained in the adult stages. Relationship between mother size, pups' growth and milk composition were analysed and an index for monitoring interannual changes in growth rate was presented. Possible link of the decline with food availability are discussed. |
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