Potential use of dorsal fin spines of the roosterfish for age estimation

The roosterfish (Nematistius pectoralis Gill, 1862) is the only species in the genus Nematistius (family Nematistiidae). The most distinguishable external feature of this species is the presence of 7 elongated (comb-shaped) dorsal spines, which give rise to its common name (Rosenblatt and Bell 1976) and allow it to be easily identified from other species (Niem 1995). This species does not present sexual dimorphism. The roosterfish is distributed in the Pacific Ocean, from San Clemente in southern California to San Lorenzo Island in Peru, including the Gulf of California and the Galapagos Islands (Love et al. 2005). It is a coastal pelagic species that plays a dominant role as a nearshore predator in the waters of Mexico and Central America (Love et al. 2005, Sepulveda et al. 2015). It inhabits mainly coastal areas, with juveniles often found along the shoreline and larger individuals commonly distributed in areas close to reefs and subsurface features (Niem 1995, Sepulveda et al. 2015). Roosterfish can reach up to 191 cm in total length and weight over 50 kg (Robertson and Allen 2015). In terms of feeding habits, it is considered a specialist predator that commonly feeds at depths of 3 to 4 meters, mainly on coastal pelagic species such as mojarras (e.g., Eucinostomus gracilis and E. dowii) and anchovies (e.g., Anchoa ischana y A. spp.) (Rodríguez-Romero et al. 2009). In Mexico, the roosterfish is reserved for recreational fishing activities, with commercial protection offered within a coastal strip of 50 nautical miles from shore, and daily retention limits set at two organisms per day per fisher (NOM-017-PESC-1994, DOF 19951,