Abstract
ABSTRACT The reproductive biology of thresher shark species of the Ecuadorian Pacific was analysed based on 1236 specimens of Alopias pelagicus (711 females and 525 males) and 354 of A. superciliosus (164 females and 190 males) landed in “Playita Mía”, from January to December of 2019. The length of A. pelagicus females ranged between 67.2 and 184 cm PCL (precaudal length) and the males between 69.0 and 178.4 cm PCL, A. superciliosus registered a minimum and maximum size of 76.0 and 202.2 cm PCL for females and 94.0 and 204.8 cm PCL for males. The most frequently captured size class for A. pelagicus was 147.2−157.2 cm PCL and for A. superciliosus was 156.0-166.0 cm PCL. The sex ratio (F:M) for A. pelagicus and A. superciliosus was 1.35F:1M and 0.86F:1M respectively. For A. pelagicus males the inflection point of the clasper length adjustment, was 134.2 cm PCL and size at first sexual maturity (L 50 ) was estimated at 136.0 cm PCL. For A. superciliosus males the inflection point of the clasper length adjustment, was 136.8 cm PCL, and the first sexual maturity (L 50 ) was estimated at 138.7 cm PCL.
Highlights
The Pacific sharpnose shark Rhizoprionodon longurio (Jordan and Gilbert 1882) is a small shark that inhabits coastal waters of the eastern Pacific Ocean, from southern California to Peru (Compagno 1984)
During the period 2005–2009, a total of 590 individuals of R. longurio were examined from December to May in fishing camps on the coast of Sinaloa and Sonora, Mexico
In the fishery targeting R. longurio, the fishing gear remained in the water for an average of 12 h
Summary
The Pacific sharpnose shark Rhizoprionodon longurio (Jordan and Gilbert 1882) (family Carcharhinidae) is a small shark that inhabits coastal waters of the eastern Pacific Ocean, from southern California to Peru (Compagno 1984). It is found on muddy bottoms and its diet consists of demersal species (Márquez-Farías et al 2005). Rhizoprionodon longurio migrates seasonally, reaching the northernmost part of the Gulf of California This seasonal mobility and the distinct population size and sex structure of this species make it difficult to understand its life cycle.
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