Harbor Porpoise (Phocoena phocoena) Abundance in Alaska: Bristol Bay to Southeast Alaska, 1991-1993

Between 1991 and 1993, Alaska harbor porpoise (Phocoena phocoena) abundance was investigated during aerial surveys throughout much of the coastal and offshore waters from Bristol Bay in the eastern Bering Sea to Dixon Entrance in Southeast Alaska. Line-transect methodology was used, and only those observations made during optimal conditions were analyzed. Survey data indicated densities of 4.48 groups/100 km2, or approximately 3,531 harbor porpoises (95% C.I. 2,206-5,651) in Bristol Bay and 0.54 groups/100 km2, or 136 harbor porpoises (95% C.I. 11-1,645) for Cook Inlet. Efforts off Kodiak Island resulted in densities of 1.85 groups/100 km2, or an abundance estimate of 740 (95% C.I. 259-2,115). Surveys off the south side of the Alaska Peninsula found densities of 2.03 groups/100 km2 and an abundance estimate of 551 (95% C.I. 423-719). Surveys of offshore waters from Prince William Sound to Dixon Entrance yielded densities of 4.02 groups/100 km’ and an abundance estimate of 3,982 (95% C.I. 2,567-6,177). Combining all years and areas yielded an uncorrected density estimate of 3.82 porpoises per 100 km2, resulting in an abundance estimate of 8,940 porpoises (CV = 13.8%) with a 95% confidence interval of 6,746-11,848. Using correction factors from other studies to adjust for animals missed by observers, the total number of Alaska harbor porpoises is probably three times this number.

Antibodies to Influenza and West Nile Viruses in Horses in Mexico

INFLUENZA A virus (IAV) (family Orthomyxoviridae) is a highly infectious respiratory pathogen of birds and mammals, including human beings and horses (Palese and Shaw 2007). The virus is classified into different subtypes based on the antigenic properties of the haemagglutinin (HA) and neuraminidase (NA) proteins. Sixteen HA subtypes (H1 to H16) and nine NA subtypes (N1 to N9) have been identified (Fouchier and others 2005). Two subtypes, H3N8 and H7N7, have been isolated from horses. The H7N7 subtype was first isolated from a horse in Czechoslovakia in 1956 (Prague/56) (Sovinova and others 1958), and the H3N8 subtype was first isolated from a horse in Miami, USA, in 1963 (Waddell and others 1963). The H7N7 subtype has not been isolated from horses for three decades and is presumed to be extinct (Webster 1993). The H3N8 subtype is currently a common cause of disease in horses worldwide. In horses, influenza is characterized by an abrupt onset of pyrexia, depression, coughing and nasal discharge, and is often complicated by secondary bacteria infections that can lead to pneumonia and death (Hannant and Mumford 1996). Although H3N8 is a major cause of morbidity in horses throughout the world, information on the seroprevalence of IAV in horses and other domestic animals in Mexico is limited.