Modal and empirical lengths at sexual maturity for six deep-sea species in Ecuadorian oceanic waters

The objective of the present work was to establish modal lengths, empirical lengths at sexual maturity, and proportions of mature individuals of six deep-sea species from the bycatch of the experimental fishery for Patagonian toothfish (Dissostichus eleginoides). Fishing was conducted in Ecuadorian oceanic waters by only one vessel, between 2017 and 2021. Modal lengths were identified using frequency distributions. The length at sexual maturity (Lm) was estimated using the empirical equation: Ln Lm = -0.1189 + 0.9157 * Ln (Lmax). Modal lengths presented a little annual increment in Antimora rostrata and Coryphaenoides armatus while the values decreased for Centroscymnus owstonii, C. delsolari, and Hydrolagus melanophasma. Interannual lengths were similar for Etmopterus granulosus. Modal lengths were higher than the sexual maturity length for H. melanophasma, C. delsolari, C. owstonii and A. rostrata. Furthermore, Coryphaenoides armatus showed a similar value and E. granulosus a lower modal length. Empirical length at sexual maturity was between 56.35 and 66.26 cm TL for all species except for H. melanophasma, which was 100.53 cm TL. Antimora rostrata and C. armatus presented an increment of mature individuals while the annual percentage decreased for H. melanophasma, C. owstonii, and C. delsolari. Etmopterus granulosus showed a lower proportion of mature individuals. El objetivo del presente trabajo fue establecer tallas modales, tallas empíricas de madurez sexual y proporciones de individuos maduros de seis especies de aguas profundas provenientes de la captura incidental de la pesquería experimental de merluza negra (Dissostichus eleginoides). La pesca fue realizada en aguas oceánicas ecuatorianas por un solo barco entre 2017 y 2021. Las tallas modales se identificaron mediante distribuciones de frecuencia. La talla de madurez sexual (Lm) se estimó mediante la ecuación empírica Ln Lm = -0,1189 + 0,9157 * Ln (Lmax). Las tallas modales presentaron un pequeño incremento anual en Antimora rostrata y Coryphaenoides armatus, mientras que los valores disminuyeron para Centroscymnus owstonii, C. delsolari e Hydrolagus melanophasma. Las tallas interanuales fueron similares para Etmopterus granulosus. Las tallas modales fueron mayores que las tallas de madurez sexual para H. melanophasma, C. delsolari, C. owstonii y A. rostrata. Coryphaenoides armatus mostró un valor similar y E. granulosus una talla modal menor. La talla empírica de madurez sexual estuvo entre 56