Reproductive biology of the cockfish, Callorhinchus callorynchus (Chondrichthyes: Callorhinchidae), in coastal waters of the northern Argentinean Sea

Abstract

The cockfish, Callorhinchus callorynchus, is a widely distributed holocephalan in the south-western Atlantic and an important resource for Argentinean fisheries. The reproductive characteristics of this species were studied in northern Argentinean coastal waters, where specimens arrive seasonally (winter-spring). Sexual dimorphism in maximum precaudal length (PCL) and total body mass (TM) was found, being females (PCL=630 mm; TM=3330 g; n=167) larger and heavier than males (PCL=482 mm; TM=1630 g; n=19). Maturity size for females was 466.22 mm PCL, representing 74% PCL of the largest female sampled. The mean number of ovarian follicles was 8.37 (± 4.84). The highest values of ovarian follicles diameter, gonadosomatic and oviducalsomatic indices were found in spring. A high proportion of mature females (44%) had atretic ovarian follicles, suggesting that they were in the resting stage of their reproductive cycle. The low number of mature males recorded and the absence of mature females with spermatophore masses or egg cases indicate that the study area would not be a reproductive zone. The seasonal presence of C. callorynchus in this region could be related to trophic movements. These results, obtained in an area with high fishing pressure on chondrichthyans, will be useful for implementing conservation and management measures.Keywords: Holocephalans, Maturity, Ovarian fecundity, Seasonality, South-western Atlantic.El pez gallo, Callorhinchus callorynchus, es un holocéfalo con amplia distribución en el Atlántico Sudoccidental y un recurso importante para las pesquerías en Argentina. Las características reproductivas de esta especie fueron estudiadas en aguas costeras al norte del Mar Argentino, adonde se acercan estacionalmente (invierno-primavera). Se observó dimorfismo sexual en los valores máximos de longitud precaudal (LPC) y masa corporal total (MT), siendo las hembras (LPC=630 mm; MT=3330 g; n=167) más grandes y pesadas que los machos (LPC=482 mm; MT=1630 g; n=19). La talla de maduración para las hembras fue de 466,22 mm LPC, representando el 74% de la LPC máxima observada. El número promedio de folículos ováricos fue 8,37 (± 4,84). Los valores más altos del diámetro de los folículos ováricos, índice de la glándula oviductal e índice gonadosomático fueron hallados durante primavera. Una gran proporción de hembras maduras (44%) presentaron folículos ováricos atrésicos, sugiriendo que se encontraban en la etapa de reposo de su ciclo reproductivo. El bajo número de machos maduros registrados y la ausencia de hembras maduras con espermatóforos o cápsulas de huevos indican que las aguas costeras del norte de Argentina no serían una zona reproductiva. La presencia de C. callorynchus en el área de estudio podría estar relacionada con movimientos tróficos. Los resultados, obtenidos en un área con una gran presión pesquera sobre los condrictios, serán útiles para implementar adecuados planes de manejo y conservación de esta especie.

Observations of follicle cell processes in a holocephalan

“…This size is, to a greater or lesser extent, larger than those recorded for other Holocephali species and for the same species in other locations (Alarcón et al . , ; Barnett et al ., ; Chierichetti et al ., ; Finucci et al ., ; Malagrino et al . , ; Márquez Farías & Lara Mendoza, ; Moura et al ., ), but was similar to sizes registered for this species from the same area by Di Giácomo and Perier ().…”

Reproductive biology of the eyespot skate Atlantoraja cyclophora (Elasmobranchii: Arhynchobatidae) an endemic species of the Southwestern Atlantic Ocean (34ºS - 42ºS)

“…This is consistent with the fact that the liver actively participates in the synthesis of yolk precursors (Koob, Callard, 1999;Prisco et al, 2002;Díaz-Andrade et al, 2009). Sexual dimorphism in maximum length and size at maturity has been observed in many chondrichthyans (Mabragaña et al, 2002;Ungaro, 2004;McFarlane, King, 2006;Ebert et al, 2008;Colonello et al, 2016;Chierichetti et al, 2017). Viviparous elasmobranchs females usually mature and grow to large size than male, showing a positive correlation between litter and size (Colonello et al, 2011).…”