Sharks are as fascinating as they are endangered, and scientists have been sounding the alarm on the rate at which shark populations are declining.
Sixteen out of 31 oceanic shark species are now critically endangered or endangered, a study published in the journal Nature found earlier this year. The number of oceanic sharks and rays in the world has declined by 71% from 1970 to 2018, the researchers observed.
Now, scientists have been able to use artificial insemination to bring 97 baby sharks to life, a new study published in Scientific Reports revealed, in what a release describes as the “largest-ever effort to artificially inseminate sharks.”
Artificial insemination of sharks could foster healthier populations in aquariums by encouraging genetic diversity, removing the need to transport sharks between institutions for mating purposes, according to the researchers. Moving sharks from one place to another is a costly process that is also stressful for the animals.
The study was led by scientists from the South-East Zoo Alliance for Reproduction & Conservation, a nonprofit based in Florida, in collaboration with the Aquarium of the Pacific in California, Ripley’s Aquarium of the Smokies in Tennessee, The Florida Aquarium, Adventure Aquarium in New Jersey, and the Field Museum in Chicago.
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Scientists collected semen from 19 male whitespotted bamboo sharks and used it to inseminate 20 females. The study took four years to complete, according to lead author Jennifer Wyffels, who conducted research for the study with the South-East Zoo Alliance for Reproduction & Conservation and is now a postdoctoral researcher at the University of Delaware.
Whitespotted bamboo sharks, or Chiloscyllium plagiosum, a species from the Indo-Pacific Ocean considered “near threatened” by the International Union for Conservation of Nature, were an ideal candidate for this research, Wyffels explained via email.
Reaching a maximum length of about 3 feet (1 meter), “they are a smaller shark species and easier to handle for reproductive procedures compared to 6- to 8-foot (1.8- to 2.4-meter) sand tiger sharks,” Wyffels explained.
“Many aquariums have bamboo sharks and that was important so that we could exchange semen between institutions,” she added.
The fact that whitespotted bamboo sharks lay eggs was also key.
“It is much easier to monitor eggs for embryo development than it is to examine a pregnant female shark,” Wyffels said.
Two to three females were inseminated at a time, Wyffels explained, but they each had to be monitored for about six weeks prior to confirm they were laying eggs, and that those eggs weren’t being fertilized with sperm stored in the body from previous mating encounters — an ability of many shark species.
“Females that store sperm are no longer dependent on repeated mating with males to fertilize their eggs throughout the laying season and can instead focus their energy and efforts on other activities such as feeding,” Wyffels said.
Each trial required nearly nine months to complete before a new one could start, according to Wyffels.