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

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.

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Population size, survival and reproductive rates of northern Norwegian killer whales (Orcinus orca) in 1986–2003

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315413000933 ◽

2013 ◽

Vol 94 (6) ◽

pp. 1277-1291 ◽

Cited By ~ 24

Author(s):

Sanna Kuningas ◽

Tiu Similä ◽

Philip S. Hammond

Keyword(s):

Population Size ◽

Killer Whale ◽

Survival Rates ◽

Clupea Harengus ◽

Orcinus Orca ◽

Adult Males ◽

Killer Whales ◽

Apparent Survival ◽

Photo Identification ◽

Reproductive Rates

A long-term photo-identification study of killer whales (Orcinus orca) in northern Norway was initiated in 1986, when their prey the Norwegian spring-spawning herring (Clupea harengus) started to winter in a complex fjord system. The aim of this work was to estimate population size and apparent survival rates in this killer whale population using photo-identification and mark–recapture techniques with data collected during October–December 1986–2003. Total population size was estimated to be highest in 2003: 731 individuals (SE = 139, 95% CI = 505–1059) using a model taking heterogeneity of capture probabilities into account. Apparent survival of adult males and adult females was estimated using the Cormack–Jolly–Seber model as 0.971 (SE = 0.008) and 0.977 (SE = 0.009), respectively. Calving intervals ranged from 3 to 14 years (mean = 5.06, SE = 0.722). These are the first estimates of northern Norwegian killer whale population parameters, allowing their dynamics to be investigated and comparisons to be made with killer whale populations globally.

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False killer whale (Pseudorca crassidens) echolocation and acoustic disruption: implications for longline bycatch and depredation

Canadian Journal of Zoology ◽

10.1139/z09-061 ◽

2009 ◽

Vol 87 (8) ◽

pp. 726-733 ◽

Cited By ~ 16

Author(s):

T. A. Mooney ◽

A. F. Pacini ◽

P. E. Nachtigall

Keyword(s):

Killer Whale ◽

Killer Whales ◽

Noise Levels ◽

The North ◽

False Killer Whale ◽

Source Level ◽

Acoustic Device ◽

Pelagic Longline Fishery ◽

Pseudorca Crassidens ◽

The North Pacific

False killer whales ( Pseudorca crassidens (Owen, 1846)) depredate fish caught by the North Pacific pelagic longline fishery, resulting in loss of target species catch and the whales themselves becoming bycaught. This incidental take of false killer whales exceeds sustainable levels. In an effort to address a potential solution to reducing this depredation and bycatch, we tested an acoustic device designed to deter false killer whales from approaching longlines by reducing the whales’ echolocation performance capabilities. The device produced a series of complex, broadband signals (1–250 kHz) at high intensity levels (up to 182 dB). In the experiment, a trained false killer whale was asked to detect a target in the presence or absence of the acoustic device. Baseline performance capabilities were 95% correct responses. Initially, the device reduced the whale’s echolocation performance to chance levels. However, subsequent sessions demonstrated improvement in echolocation performance up to 85%. This improvement was likely a result of behaviorally adapting to the task and a decrease in the source level of the echolocation “disruptor”. The results underscore the challenges in using acoustic devices to reduce depredation and bycatch, and demonstrate the need for concern regarding anthropogenic noise levels and effects on odontocete echolocation capabilities.

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Eumops floridanus (Chiroptera: Molossidae)

Mammalian Species ◽

10.1093/mspecies/seab012 ◽

2021 ◽

Vol 53 (1009) ◽

pp. 125-133

Author(s):

Jessica M Vannatta ◽

Jeffery A Gore ◽

Verity L Mathis ◽

Brian D Carver

Keyword(s):

United States ◽

Population Size ◽

The United States ◽

Small Population ◽

Species Level ◽

Small Population Size ◽

Restricted Distribution ◽

Dead Trees ◽

Fish And Wildlife Service

Abstract Eumops floridanus (Allen, 1932) is a molossid commonly called the Florida bonneted bat or the Florida mastiff bat. Eumops floridanus is the largest species of bat in Florida and is one of 16 species in the genus Eumops. With one of the smallest distributions of any bat in the United States, it is endemic to southern peninsular Florida where it roosts in cavities of live and dead trees and man-made structures. Eumops floridanus was formerly classified as a subspecies of E. glaucinus but has been elevated to species level based on morphology. Due primarily to its restricted distribution, small population size, and the continued loss of habitat, E. floridanus is federally listed as “Endangered” (EN) by the United States Fish and Wildlife Service.

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