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An intense public debate has fuelled governmental bans on marine mammals held in zoological institutions. The debate rests on the assumption that survival in zoological institutions has been and remains lower than in the wild, albeit the scientific evidence in support of this notion is equivocal. Here, we used statistical methods previously applied to assess historical improvements in human lifespan and data on 8864 individuals of four marine mammal species (harbour seal, Phoca vitulina ; California sea lion, Zalophus californianus ; polar bear, Ursus maritimus ; common bottlenose dolphin, Tursiops truncatus ) held in zoos from 1829 to 2020. We found that life expectancy increased up to 3.40 times, and first-year mortality declined up to 31%, during the last century in zoos. Moreover, the life expectancy of animals in zoos is currently 1.65-3.55 times longer than their wild counterparts. Like humans, these improvements have occurred concurrently with advances in management practices, crucial for population welfare. Science-based decisions will help effective legislative changes and ensure better implementation of animal care.

Domoic acid (DA) is a naturally occurring marine neurotoxin produced by Pseudo-nitzschia diatoms. Adult California sea lions (Zalophus californianus) can experience multiple post-exposure syndromes, including acute toxicosis and chronic epilepsy. Additionally, a delayed-onset epileptic syndrome is proposed for California sea lions (CSL) exposed in utero. This brief report explores a case of a CSL developing adult-onset epilepsy with progressive hippocampal neuropathology. Initial brain magnetic resonance imaging (MRI) and hippocampal volumetric analyses relative to brain size were normal. Approximately 7 years later, MRI studies to evaluate a newly developed epileptic syndrome demonstrated unilateral hippocampal atrophy. While other causes of unilateral hippocampal atrophy cannot be completely excluded, this case may represent in vivo evidence of adult-onset epileptiform DA toxicosis in a CSL. By estimating in utero DA exposure time period, and extrapolating from studies conducted on laboratory species, this case provides circumstantial evidence for a neurodevelopmental explanation correlating in utero exposure to adult-onset disease. Evidence of delayed disease development secondary to gestational exposure to naturally occurring DA has broad implications for marine mammal medicine and public health., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier B.V.)

Fish lice, ectoparasites of the genus Argulus , are branchurian crustaceans that can significantly impact fish health by causing mechanical damage to cutaneous barriers and increasing susceptibility to other infections. While many treatments have been reported in teleosts and invertebrates, there are no published treatments for elasmobranchs. This study evaluated the safety and efficacy of a commercial formulation of milbemycin oxime and lufenuron in freshwater stingrays for treatment of Argulus spp. Seven juvenile Magdalena river stingrays ( Potamotrygon magdalenae ) and 10 juvenile smooth back river stingrays ( Potamotrygon orbignyi ) had severe infestations of Argulus spp. that were identified visually and microscopically. Animals were treated with milbemycin oxime and lufenuron (at 0.015 mg/L and 0.30 mg/L, respectively) in a 6-hr immersion once weekly for two treatments. They were visually examined for skin lesions as well as behavior and appetite daily by animal care staff. A subset of animals was euthanized and necropsied on days 8, 9, 43, and 78 after treatment initiation. There were no Argulus spp. detected at the time of the second treatment. Complete gross and histologic evaluations were completed for all animals. At all time points, no gross abnormalities were detected with the exception of thin body condition in some animals; no Argulus spp. were noted. Histologic lesions were all attributed to poor nutritional state at the time of acquisition. No histologic evidence of acute or chronic toxicosis was detected. The commercial formulation of milbemycin oxime and lufenuron, applied at the dose and for the exposure time used in this study, effectively eradicated Argulus spp. in a population of juvenile P. magdalenae and P. orbignyi , and did not cause mortality or clinical gross or histologic evidence of acute or chronic toxicity., (Copyright 2019 by American Association of Zoo Veterinarians.)