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Decline of whale shark deaths documented by citizen scientist network along the Venezuelan Caribbean coast

Published online by Cambridge University Press:  21 September 2020

Leonardo Sánchez
Affiliation:
Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela; and Centro para la Investigación de Tiburones de Venezuela, Caracas, Venezuela
Yurasi Briceño
Affiliation:
Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela; and Centro para la Investigación de Tiburones de Venezuela, Caracas, Venezuela
Rafael Tavares
Affiliation:
Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela; and Centro para la Investigación de Tiburones de Venezuela, Caracas, Venezuela
Dení Ramírez-Macías
Affiliation:
Tiburón Ballena México, Conexiones Terramar, La Paz, Baja California, México
Jon Paul Rodríguez
Affiliation:
Centro de Ecología, Instituto Venezolano de Investigaciones Científicas; IUCN Species Survival Commission, Gland, Switzerland; and Provita, Caracas, Venezuela E-mail [email protected]

Abstract

Type
Conservation News
Copyright
Copyright © Fauna & Flora International 2020

At the beginning of this century, observations of the Endangered whale shark Rhincodon typus in Venezuelan waters comprised 20 opportunistic records spanning the previous 51 years (Romero et al., 2000, Biodiversity 1, 11–15), suggesting they were present infrequently. A decade later, there were sightings year-round, distributed all along the coast. News of killings of whale sharks also became more frequent. In 2014, the Centro para la Investigación de Tiburones de Venezuela began to systematically document whale shark observations and engage fishers linked to shark encounters. They interviewed 222 people from 17 towns, spanning Maracaibo in the west to Margarita Island in the east. Reports included 142 sightings and 21 deaths of whale sharks during 2014–2017, the latter by entanglement in nets, harpooning or other capture methods. Although most encounters were opportunistic or incidental, they generally lead to the killing of sharks and the sale of their fins.

In 2016–2020 the organization visited the 17 coastal towns where reports were more frequent. Firstly, they contacted community leaders and fishers connected to shark kills, built personal relationships, developed trust, and explained the work of the organization. After one or two visits, workshops at schools, fisher cooperatives or local businesses expanded the visibility of and interest in the project. An invitation to share information on social media followed. Whale shark sightings now reach the organization within minutes. Fishers film untangling and releasing of sharks instead of killing them. Others film themselves swimming with whale sharks. Diving operators offer whale shark watching tours, increasing their value from a one-time sale of fins to repeat visits with tourists.

The clearest success indicator, however, is a sharp decline in shark killing. Prior to October 2017, interviews documented 21 shark kills. In contrast, during 2018–2020, after implementation of workshops, relationship building, and establishment of the social media network, no whale shark killings were reported. Although underreporting is possible, it seems likely that the news would reach the organization, in particular as news of captures of other shark species rapidly spread. The evidence collected through this citizen scientist network suggests that the whale sharks seen are mostly juveniles (with a mean length of c. 7 m), and appear in a number of localities along the Venezuelan coast. Reports have mentioned the presence of 1–10 sharks simultaneously and during several months. Additional field data would facilitate estimation of seasonality and abundance. Although past records suggest whale sharks were only present occasionally along the Venezuelan coast, they are now a common occurrence and perhaps are here to stay.