Characterization of the biological factors of the most common elasmobranch populations in Bahía Santa Elena

Abstract

The North Pacific of Costa Rica represents an important marine-coastal scientific information gap, where the lack of a focus on resilience of the populations subject to conservation results in a failure of the management system, the objective of this work was to determine the biological factors of the most common elasmobranchs in Bahía Santa Elena, the research covered a period from September 2015 to August  2016, for this, samples were taken once a month, and the diversity, relative abundance and distribution of the species were determined through an underwater census. A sample of 289 individuals was used. To identify biometric aspects together with reproductive biology, work was done in Estero Grande using a trammel. At the fish receiving stations in Cuajiniquil, the catch size structure was determined. Additionally, a survey was applied to 120 fishermen to know the social perception regarding the factors of sustainable development. Among the main results, it was obtained that the months with the highest rainfall are related to peaks of the diversity indices, with little spatial distribution. A seasonal replacement of species is presented, highlighting the arrival of Rhinoptera steindachneri, Mobula munkiana, during the rainy months and Mustelus henlei and Sphyrna lewini during the Trade Winds. The main spawning period for Myliobatiformes is near November, however Urotrygon nana presents a second spawning period in July. Biometrics indicates dominance of sizes outside of sexual maturity in sharks and mature in rays. Finally, bottom gillnet fishing activity was characterized by low economic performance, which affects the capture of S. lewini juveniles.