SEX DIFFERENCES IN BODY SIZE AND BODY CONDITION OF CALIFORNIA SEA LION (ZALOPHUS CALIFORNIANUS) PUPS FROM THE GULF OF CALIFORNIA |
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Authors: | Sebastián P Luque David Aurioles-Gamboa |
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Institution: | Departamento de Pesquerías y Biología Marina, Centro Interdisciplinario de Ciencias Marinas–Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional s/n, Col. Playa Palo de Santa Rita, Apdo. Postal 592, La Paz, Baja California Sur, 23096 Mexico E-mail: |
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Abstract: | The Gulf of California harbors about 15% of the total California sea lion ( Zalophus californianus californianus ) population. We studied pup morphometrics from eight Gulf of California rookeries during the 1996 and 1997 reproductive seasons to describe sex differences in body size and body condition indices. Newborn pup body size was not different from previous reports. Male pups were heavier and larger than female pups in terms of all linear dimensions. Morphometric relationships, however, showed that males were 3%-4% denser, and that after removing the effects of length, they were about 2% heavier than females. Sculp depth adjusted for length was 12% larger in female than in male pups. Our data provide further evidence that male otariid pups may allocate a larger fraction of milk energy to muscular and skeletal growth compared to female pups. |
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Keywords: | body size body condition California sea lion growth Gulf of California morphometry sexual dimorphism Zalophus californianus |
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