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Volume 40 - Number 1 - 2005
Nota Científica 

Variation of gonadal, muscle yield and digestive gland indexes of Spondylus princeps (Gray, 1825) (Mollusca: Bivalvia) at Isla Cedros and Punta Eugenia, Mexico

Marcial Villalejo-Fuerte, Arturo Tripp-Quezada y Federico García-Domínguez

CICIMAR-IPN, Av. Instituto Politécnico Nacional, S/N, Col. Playa Palo de Santa Rita. La Paz, Baja California Sur, México. CP 23096




The variation of the gonadal, muscular yield and digestive gland indexes was studied in Spondylus princeps from Punta Eugenia and Isla Cedros, Mexico. Specimens were collected from March to July 1997 and from August to December 2003. Gonadal indexes from 2% to 4% suggest reproductive inactivity from March to May and from October to December. The sustained increase in the index from May to July suggests gonadal maturity (10% of the soft tissues weight in July); the index decreased from 10% to 2% from July to October, corresponding with the spawning period. The muscular yield index showed high values (45-50%) from March to June and diminished sustainedly until August, when the lowest value (37%) was attained. Muscular yield index recovered during September and October with values of 45% staying around 40% during November and December. The muscular yield suggests that during the gonadal maturity, the energy stored in the abductor muscle is not used until the spawning season. The digestive gland index showed the highest value in March and decreased lightly until June, indicating that the energetic substances stored in the digestive gland sustain together with the external food, the gonadal development from July up to September when a fast decrease of the index occurs, suggesting that reserve substances in the digestive gland and in the muscle are used during the spawning period.

Key words: Spondylidae, reproduction, spawning period



1Laboratorio de Zooplancton, Instituto de Ciencias del Mar y Limnología,Universidad Nacional Autónoma de México. A. P. 70-305, 04510 México, D. F. México
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