Abstract
Due in part to population declines, climate change and industrial development there is increasing concern for the conservation and management of the five stocks of beluga (Delphinapterus leucas) within Alaskan waters. The population trends vary greatly for the different management stocks with the Bristol Bay stock currently increasing an estimated 4.8 % annually. Therefore, there is an interest in performing health assessments and establishing baseline values for several immune parameters in the apparently healthy and growing population of Bristol Bay that can also serve as a comparison for stocks with declining populations, such as Cook Inlet. To this end, blood samples were collected from a total of 27 belugas in 2008 (n=18) and 2012 (n=9). Samples were collected in collaboration with other research efforts [NMFS Marine Mammal Research Permit Nos. 782-1719 (2008) and 14245 (2012)] and in cooperation with the Bristol Bay Native Association, Bristol Bay Marine Mammal Council, and the Alaska Beluga Whale Committee. Blood samples were used for complete blood cell counts including total and differential white blood cell counts and for the isolation of peripheral blood mononuclear cells (PBMC). Archived PBMC were used for assessing the adaptive immune system, as measured by lymphocyte proliferation assay and immunophenotyping subpopulations of lymphocytes. Belugas sampled averaged (± SD) a total white blood cell count of 18,807 ± 4805 with differential counts as follows: neutrophils 6293 ± 2085; monocytes 1109 ± 820; lymphocytes 6416 ± 2514; and eosinophils 4230 ± 1918. Monoclonal antibodies specific for cell surface proteins on lymphocyte were used to identify lymphocyte subsets. As previously reported in belugas, the majority of the lymphocytes were MCH class II+ (92.9 ± 3.4 %; 5924 ± 2233). The remaining subtypes of lymphocytes identified were T cells (62.0 ± 14.7%; 2778 ± 1142), T helper cells (33.7 ± 6.8%; 2157 ± 1033) and B cells (11.8 ± 6.5%; 1301 ± 1289). The present study will provide information on the health and immune function of the Bristol Bay beluga population which is relevant for the management of that stock and which may serve as a comparison for other free-ranging beluga populations.
* Presenting author
^ Deceased