Determinación de las diferentes fases del desarrollo sexual de Octopus vulgaris Lamarck, mediante un índice de madurez | Determination of the different stages of the sexual development of the common octopus by a maturity index

20 páginas, 11 figuras, 5 cuadros

[EN] In order develop a more precise method for the knowledge of some aspects of the sexual development of Octopus vulgaris Lamarck, a series of observations have been made during twelve months on the stock exploited in the Catalonian shelf within coordinates: 41º 10' N, 1º 52' W and 41º 30' N, 2º 27' W and between 25 and 100 meters deep. To numerically the different stages of maturity, the following indexes of maturity have been used, adapted from HAYASHI, in accordance with the formulae: M= PN/PN + PT; M = Povd/Povd + Pov, where PT is the testis weight, PN Needhanis sac mass weight; Pov the weight of the ovary and Povd the weight of the oviducts and their glands. These indexes of maturity clearly define the different phases of sexual development; the calculated values being for males, 0<=M<=0,29 (M1) inmature; 0.27 <=M <=0.63 (M,) with spermatophores; and M>0.63 (M') after mating; for females, 0.36> M>=0.14 (M,) inmature; 0.14 > M> 0.07 (M2) pre-spawning; 0.07>= M>0.01 (M.) maturated and 0.36 <= M after brooding (M,). The observated values of the indexes have been compared with the gradual changes in the aspects of the gonads: in females, with the development and external morphology of the oviductals glands, oviducts and ovary, and with the size of the eggs]" in males, with the development and external morphology of the testis, Needham's sac mass and number of spermatophores. Some aspects of the resulting values of the indexes are discussed; among others: a) the boundary between inmature males and males with spermaiophores is ill-defined both found in the interval 027<=M<=029; b) the minimal number of spermatophores requiered for fecundation seems to be very small; c) and the possibiüty of only a fraction of the number of actual spermatophores being used in copulation. It has been established that, from October to January all observed females were inmatures; that spawning period in this area stretches from March to September: that the bulk of mature females and males is found from April to June; and that the period of greater sexual activity is from May to July. However, the whole year there were some inmature individuals, both male and females. The usual weight of females at the time of reproduction is around 1.000 g, althoush one individual weighted only 200 g and in prespawning stage weights between 590 and 680 g were also observed. Males are more precocious than females; 150 g specimens weigh were showing spermatophores in their Needham's sacs. Finally, the possibility of more than one spawning on the life of some common octopus lemales is discussed. [...] Todarodes pacificus, Eledone aldrovandi

[ES] La importancia comercial de las pesqerías del pulpo común y de otros Cefalópodos del banco sahariano queda patenfizada por el gran número de pesqueros de distintas nacionalidades que faenan en el banco; y los numerosos trabajos publicados en los últimos años son indicio del interés por el estudio de dicha área. Actualmente se cuenta con abundante información sobre la evolución de la pesquería a partir de 1967, así como sobre diferentes aspectos de la biología de Octopus vulgaris Lamarck, pero quedan cuestiones por dilucidar; entre otras: la elaboración de criterios que permitan determinar la edad, sobre la que se tienen estimaciones imprecisas; la distribución de individuos en distintas fases de maduración sexual a lo largo del ciclo biológico; y determinados aspectos del desarrollo sexual. […]

Peer reviewed