Decline in sea otter (Enhydra lutris) populations along the Alaska Peninsula, 1986–2001

During the 1990s, sea otter (Enhydra lutris) counts in the Aleutian archipelago decreased by 70% throughout the archipelago between 1992 and 2000. Recent aerial surveys in the Aleutians did not identify the eastward extent of the decline; therefore we conducted an aerial survey along the Alaska Peninsula for comparison with baseline information. Since 1986, abundance estimates in offshore habitat have declined by 27– 49% and 93 –94% in northern and southern Alaska Peninsula study areas, respectively. During this same time period, sea otter density has declined by 63% along the island coastlines within the south Alaska Peninsula study area. Between 1989 and 2001, sea otter density along the southern coastline of the Alaska Peninsula declined by 35% to the west of Castle Cape but density increased by 4% to the east, which may indicate an eastward extent of the decline. In all study areas, sea otters were primarily concentrated in bays and lagoon, whereas historically, large rafts of otters had been distributed offshore. The population declines observed along the Alaska Peninsula occurred at roughly the same time as declines in the Aleutian islands to the east and the Kodiak archipelago to the west. Since the mid-1980s, the sea otter population throughout southwest Alaska has declined overall by an estimated 56–68%, and the decline may be one of the most significant sea otter conservation issues in our time

Phocine Distemper Virus in Northern Sea Otters in the Pacific Ocean, Alaska, USA

Phocine distemper virus (PDV) has caused 2 epidemics in harbor seals in the Atlantic Ocean but had never been identified in any Pacific Ocean species. We found that northern sea otters in Alaska are infected with PDV, which has created a disease threat to several sympatric and decreasing Pacific marine mammals

Phocine distemper virus in northern sea otters in the Pacific Ocean, Alaska, USA.

Phocine distemper virus (PDV) has caused 2 epidemics in harbor seals in the Atlantic Ocean but had never been identified in any Pacific Ocean species. We found that northern sea otters in Alaska are infected with PDV, which has created a disease threat to several sympatric and decreasing Pacific marine mammals

Sensitivity of tetrodotoxin and saxitoxin to changing ocean conditions

This dataset, consisting of 3 separate files, provides the basis for our manuscript entitled "Saxitoxin and tetrodotoxin bioavailability increases in future oceans". Each file contains the data for one figure. For detailed calculation methods please refer to the method and supplementary information sections of the associated manuscript. Fig1_STX_and_TTX_pH-availability contains abundance data of saxitoxin (STX) and tetrodotoxin (TTX) protonation states across the pH range from 6 to 10 at 3 different temperatures. It is calculated based on published pKa data using the Henderson-Hasselbalch equation. Temperature is taken into account employing a pKa-influencing factor of -0.2/+10C. Fig2_Dinos_HAEDAT_STX_concatenated contains all the information required for plotting the pH and temperature dependent global toxicity map. It combines georeferenced records for localities with STX-related HABs (extracted from the Harmful Algal Information System metadatabase - HAEDAT) and the distribution of two dinoflagellate genera, which are known to produce STX, Gymnodinium and Alexandrium (extracted from the NOAA COPEPOD database). For each location we also extracted current and future pH and sea surface temperature from the Global marine environment dataset (GMED)/ IPCC (WCRP CMIP3) multi-model database. We calculated the abundance of the toxic STX form based on the pH and temperature for each of the respective locations in current and future conditions. Fig3_STXinClamTissue contains the compiled total STX content in clam tissue data from the PSP Program website of the Quagan Tayagungin Tribe for the time frame between June 2012 and July 2018 for each month at Spit Beach, Sand Point (Alaska). Based on this data we further calculated the current and future toxic proportion of this total STX content for the location's specific current and future temperature and pH data

Bartonella spp. Exposure in Northern and Southern Sea Otters in Alaska and California

Since 2002, an increased number of northern sea otters (Enhydra lutris kenyoni) from southcentral Alaska have been reported to be dying due to endocarditis and/or septicemia with infection by Streptococcus infantarius subsp. coli. Bartonella spp. DNA was also detected in northern sea otters as part of mortality investigations during this unusual mortality event (UME) in Kachemak Bay, Alaska. To evaluate the extent of exposure to Bartonella spp. in sea otters, sera collected from necropsied and live-captured northern sea otters, as well as necropsied southern sea otters (Enhydra lutris nereis) unaffected by the UME, were analyzed using an immunofluorescent antibody assay. Antibodies against Bartonella spp. were detected in sera from 50% of necropsied and 34% of presumed healthy, live-captured northern sea otters and in 16% of necropsied southern sea otters. The majority of sea otters with reactive sera were seropositive for B. washoensis, with antibody titers ranging from 1:64 to 1:256. Bartonella spp. antibodies were especially common in adult northern sea otters, both free-living (49%) and necropsied (62%). Adult stranded northern sea otters that died from infectious causes, such as opportunistic bacterial infections, were 27 times more likely to be Bartonella seropositive than adult stranded northern sea otters that died from noninfectious causes (p<0.001; 95% confidence interval 2.62-269.4). Because Bartonella spp. antibodies were detected in necropsied northern sea otters from southcentral (44%) and southwestern (86%) stocks of Alaska, as well as in necropsied southern sea otters (16%) in southcentral California, we concluded that Bartonella spp. exposure is widely distributed among sea otter populations in the Eastern Pacific, providing context for investigating future disease outbreaks and monitoring of Bartonella infections for sea otter management and conservation