Survey for Placental Disease and Reproductive Pathogens in the Endangered Hawaiian Monk Seal

March 30, 2018

The lack of reproductive pathogens identified in the sampled population indicates that factors other than reproductive pathology, such as resource limitation or other external stressors, may drive the observed variability in monk seal reproductive rates.

There is considerable temporal and spatial variability in the reproductive rates of Hawaiian monk seals (Neomonachus schauinslandi). Poor reproductive performance limits the recovery of this endangered species; however, causal factors are not fully understood. There is serologic evidence that highly migratory species are exposed to pathogens that can impact reproductive success, but the prevalence of placental infections in HMS has not been evaluated. Placental tissues (n=50), including tissues from 25 percent of known HMS births, were opportunistically collected in 2011 from six Northwestern Hawaiian Islands and three main Hawaiian Islands. Reproductive histories of the sampled females were representative of the breeding population, as determined through comparisons in age of primiparity and mature reproductive rate. Placental tissues were examined histologically and screened by PCR for Coxiella burnetii, Brucella spp., Chlamydia spp., Leptospira spp., herpesviruses, and Toxoplasma gondii. There was no histologic evidence of placental pathology, and molecular analyses were negative. These negative results can be used to estimate pathogen prevalence in the nonsampled population. For an approximate population size of 1,300 HMS, we can estimate with 99 percent confidence that the prevalence of each pathogen tested is 9 percent or less. This is low relative to other pinnipeds and indicates that factors other than reproductive pathology, such as resource limitation, may drive variability in HMS reproductive rates. Further investigation into the cumulative impacts of resource limitation and other stressors on HMS reproduction is warranted.

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Barbieri M, Duncan C, Harting AL, Pabilonia KL, Johanos TC, Goldstein T, Robinson SJ, Littnan CL. Survey for Placental Disease and Reproductive Pathogens in the Endangered Hawaiian Monk Seal (Neomonachus schauinslandi). (Published in the Journal of Wildlife Diseases). 

Last updated by Pacific Islands Fisheries Science Center on 02/26/2019

Hawaiian Monk Seal