Study links at-risk orcas’ failed pregnancies to scarce food
SEATTLE – Endangered killer whales attending Washington state inner waters have pregnancy problems because they can not find enough fish to eat, according to new research.
The researchers analyzed the hormones in feces collected at sea and found that more than two-thirds of the killer pregnancies failed over a seven-year period. They joined these problems to nutritional stress caused by a small amount salmon Chinook, the preferred whale system.
“A lot of whale design, but when nutrition is poor, we do not experience these pregnancies,” said Sam Wasser, lead author of the article and professor of biology at the University of Washington.
Southern resident breeders along the west coast of the United States have fought since they were listed as endangered species in 2005. They represent only 78, below a decade of the decade. Whales face threats of lack of food, pollution and ship.
The new study, which will be published on Thursday in the journal PLoS ONE focuses on providing food as a major stressor among which consumption of fish to whales. Unlike other killer whales they eat marine mammals, orcas that spend the summer in Puget Sound mainly feed on salmon, especially Chinook.
Many species of Chinook salmon along the west coast are classified as threatened or endangered because of a number of factors, including loss of habitat for urban development, dams, fishing, pollution and competition from fish Not native.
The toxins that accumulate in the fat of the whales that are released when the animals are weakened and metabolized this fat plays a role in the problems of pregnancy.
“Food is the driver. But what we still can not say is how it is affected by its interaction with toxins,” Wasser said, adding that there were not enough samples to tell how much toxins are influential.
The use of trained dogs to sniff poop whale, a team of scientists collected about 350 stool samples from 79 single whales in the inland waters of British Columbia and Washington State between 2008 and 2014.
In the laboratory, the hormones progesterone and testosterone were analyzed and evaluated whether orca was pregnant and at what time. They also used DNA to determine the whale’s identity, gender, and family line. The pregnancy is considered satisfactory if the female whale was later seen with the calf.
Their analysis showed 35 orcas pregnancies between 2008 and 2014. The eleven calves were seen with their mothers when the births were successful. Puget Sound killer whales can be individually identified and tracked intensely, so researchers know when the offspring are born in one of the three orcas families, known as the J, K, and L pod.
The study found 24 failed pregnancies. No calves were observed in these cases, indicating that whales have lost babies or calves died soon after birth. These women showed signs of nutritional stress – more than those who delivered correctly.
The researchers also recorded the number of vessels in the area collecting whale droppings. We studied two hormones that play an important role in physiological stress and were able to differentiate stress from poor diet and stress from boat traffic.
The team compared hormonal data to the abundance of two Chinook salmon records in the Pacific Northwest.
Data over time suggests that orcas have experienced periodic nutritional stress, partly caused by the change of time and soundness of courses salmon in the Columbia and Fraser rivers, according to the study.
The study said that improving these Chinook salmon migrations could help save the orcas in Puget Sound.