Evolutionary characterization of a highly repetitive sequence identified from the false killer whale (Pseudorca crassidens)

The false killer whale, Pseudorca crassidens, exhibits one of the widest and most continuous distributions among cetaceans. However, basic information about its biology is poorly known due to the low frequency of sightings and its offshore habits. Moreover, most of the knowledge on this species has been obtained from stranded animals. On 3 March 2012, in the proximity of a colony of South American sea lions (Otaria flavescens) located at Caleta de los Loros, Río Negro Province, Argentina (40o59’S, 64o14’W), a cetacean skull was found in the intertidal zone. The specimen was later identified as P. crassidens. The present note reports a new record of false killer whale in the continental shelf waters of Argentina and provides new data on the distribution and skull morphometrics of the species.

Download Full-text

The abundance of false killer whale, Pseudorca crassidens (Artiodactyla: Delphinidae) in coastal waters of Golfo Dulce and Osa Peninsula, Costa Rica

Revista de Biología Tropical ◽

10.15517/rbt.v68i2.37196 ◽

2020 ◽

Vol 68 (2) ◽

Author(s):

Erika Sánchez Robledo ◽

Lenin Enrique Oviedo Correa ◽

David Herra-Miranda ◽

Juan Diego Pacheco-Polanco ◽

Sierra Goodman ◽

...

Keyword(s):

Costa Rica ◽

Population Size ◽

Killer Whale ◽

Small Population ◽

Killer Whales ◽

Apparent Survival ◽

Osa Peninsula ◽

Small Population Size ◽

False Killer Whale ◽

Pseudorca Crassidens

Introduction: False killer whale (Pseudorca crassidens) is a tropical and subtropical social species that live in groups with individuals of mixed ages and sex classes. False killer whales have been documented since the late 1990s in Southwestern Costa Rica. Objective: To estimate the abundance of false killer whales in Osa Peninsula waters. Methods: Cetacean surveys off the Osa Peninsula Waters (OPW), Costa Rica, yielded opportunistic encounters with false killer whales in Drake Bay and Caño Island (2001-2015) and observations during formal surveys in Golfo Dulce (2005-2015). Photo-identification data was analyzed using capture-mark-recapture models in the study area, through an open population (POPAN) framework, considering the effect of time on the parameters apparent survival and capture probability, producing an abundance estimate for a superpopulation in the entire study area. Results: False killer whale abundance in OPW is characterized by a small population size of no more than 100 individuals, complemented by a very low probability of encounter and a contrasting high apparent survival. Conclusions: This population estimate should be taken as conservative, however, the small population size of less than 100 individuals should be considered vulnerable, in contrast to the increasing anthropogenic impacts in the coastal seascape. We argue the potential occurrence of population units along the coastal seascape of the Pacific littoral and oceanic island-associated units at Isla del Coco.

Download Full-text