Salmonellainfection in grey seals (Halichoerus grypus), a marine mammal sentinel species: pathogenicity and molecular typing ofSalmonellastrains compared with human and livestock isolates

The population of grey seals Halichoerus grypus in Canadian waters is currently used as a commercial source of meat for human consumption. As with domestic livestock, it is important to understand the occurrence in these seals of infectious agents that may be of public health significance and thus ensure appropriate measures are in place to avoid zoonotic transmission. This study examined the prevalence of antibodies against Brucella spp., Erysipelothrix rhusiopathiae, 6 serovars of Leptospira interrogans, and Toxoplasma gondii in 59 grey seals and determined by polymerase chain reaction (PCR) the presence of these potentially zoonotic agents in specific organs and tissues of seropositive animals. The presence of encysted Trichinella spp. larvae was also investigated by digestion of tongue, diaphragm and other muscle samples, but none were detected. Seroprevalence against Brucella spp. and E. rhusiopathiae was low (5 and 3%, respectively). All 59 seals tested had antibodies against L. interrogans, but no carrier of this bacterium was detected by PCR. Seroprevalence against T. gondii was 53%, and DNA of this protozoan was detected by PCR in 11/30 (37%) seropositive animals. Standard sanitary measures mandatory for commercialization of meat products for human consumption should greatly reduce the potential for exposure to these infectious agents. However, special consideration should be given to freezing seal meat for at least 3 d to ensure destruction of tissue cysts of T. gondii.

Download Full-text

Simulations to evaluate management trade-offs among marine mammal consumption needs, commercial fishing fleets and finfish biomass

Marine Ecology Progress Series ◽

10.3354/meps11129 ◽

2015 ◽

Vol 523 ◽

pp. 215-232 ◽

Cited By ~ 5

Author(s):

L Smith ◽

R Gamble ◽

S Gaichas ◽

J Link

Keyword(s):

Marine Mammal ◽

Commercial Fishing ◽

Trade Offs ◽

Fishing Fleets

Download Full-text

Utilizing next-generation sequencing to identify prey DNA in western North Atlantic grey seal Halichoerus grypus diet

Marine Ecology Progress Series ◽

10.3354/meps13520 ◽

2020 ◽

Vol 655 ◽

pp. 227-240

Author(s):

KR Flanders ◽

ZH Olson ◽

KA Ono

Keyword(s):

Next Generation Sequencing ◽

Feeding Habits ◽

Atlantic Menhaden ◽

Halichoerus Grypus ◽

Frequency Of Occurrence ◽

Grey Seal ◽

Next Generation ◽

Significant Difference ◽

Generation Sequencing ◽

Seal Diet

Increasing grey seal Halichoerus grypus abundance in coastal New England is leading to social, political, economic, and ecological controversies. Central to these issues is the foraging ecology and diet composition of the seals. We studied grey seal feeding habits through next-generation sequencing of prey DNA using 16S amplicons from seal scat (n = 74) collected from a breeding colony on Monomoy Island in Massachusetts, USA, and report frequency of occurrence and relative read abundance. We also assigned seal sex to scat samples using a revised PCR assay. In contrast to current understanding of grey seal diet from hard parts and fatty acid analysis, we found no significant difference between male and female diet measured by alpha and beta diversity. Overall, we detected 24 prey groups, 18 of which resolved to species. Sand lance Ammodytes spp. were the most frequently consumed prey group, with a frequency of occurrence (FO) of 97.3%, consistent with previous studies, but Atlantic menhaden Brevoortia tyrannus, the second most frequently consumed species (FO = 60.8%), has not previously been documented in US grey seal diet. Our results suggest that a metabarcoding approach to seal food habits can yield important new ecological insights, but that traditional hard parts analysis does not underestimate consumption of Atlantic cod Gadus morhua (FO = 6.7%, Gadidae spp.) and salmon Salmo salar (FO = 0%), 2 particularly valuable species of concern.

Download Full-text