Published\t\t\t\t<\/p>\n
\t\t\t\t\tAug 17, 2026 12:17 PM EDT<\/p>\n
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This back to school season, U.S. Fish and Wildlife Service (FWS) biologists are testing out a backpack of their own. But this one doesn\u2019t carry notebooks and pens. It tracks crayfish movements and survival.\u00a0<\/p>\n
The trial is part of the FWS\u2019 efforts to boost the populations of the Big Sandy crayfish (Cambarus callainus), a freshwater crustacean that lives in the rivers and streams of Appalachia. Since 2016, these four-inch long creatures have been considered a federally threatened species as water pollution and habitat loss have shrunk their range.\u00a0<\/p>\n
That\u2019s why the White Sulphur Springs National Fish Hatchery in West Virginia is trying to propagate this rare species with the help of the West Virginia Ecological Services Field Office. The hatchery raises crayfish for one or two months, putting about a year\u2019s growth into them in that time. Then, they\u2019re released into their habitat in the fall.\u00a0<\/p>\n
\u201cAt that point, we need to be able to track them,\u201d Andrew Phipps, a fish biologist at the hatchery, tells Popular Science. \u201cWe need to build on that, to go back to the creek, and say, hey, these little guys lived, or they didn\u2019t live.\u201d\u00a0<\/p>\n
Right now, Phipps and his colleagues use visible implant elastomer (VIE) tagging to mark the fish. They inject a colored tag under the crayfish\u2019 pleon (a fancy way to say its tail region), which lets them know that a specimen is from the hatchery. \u201cBut it doesn\u2019t give us an individual ID,\u201d Phipps explains.\u00a0<\/p>\n
Phipps and his colleagues typically release nearly 300 animals with these tags, which also makes tracking them down a painstaking process. They have to go out in the crayfish habitats\u00a0 and keep sampling until they find one, a difficult task given that the crayfish are small and the river is not.\u00a0<\/p>\n
So, FWS biologists are developing a new tagging protocol for their Big Sandy crayfish. Other options, like the VI Alpha tag, allow researchers to individually identify specimens, but the crayfish would have to be a lot bigger. \u201cIf you put it in and they\u2019re too small, it\u2019ll kill them,\u201d Phipps says.\u00a0<\/p>\n
Holding the crayfish over winter for them to reach the right size for the tag, however, is too much of a risk. \u201cWe\u2019re looking for a happy medium,\u201d Phipps explains\u2014something safe for 25 millimeter crayfish.\u00a0<\/p>\n
That\u2019s where the \u201cbackpacks\u201d come in. They encase a Passive Integrated Transponder (PIT) tag, a tiny, batter-free microchip with a unique code that\u2019s activated when scanned, since injecting it into the tiny crayfish would be too dangerous. And the key to attaching the tag onto the crayfish?<\/p>\n
\u201cWe basically superglue that thing on there,\u201d Phipps says.\u00a0<\/p>\n
First, regular superglue attaches the tag on the back of the crayfish. This glue is then covered in another type of more flexible superglue, and finally, the team squirts baking soda water on it to help the backpack system set more quickly.<\/p>\n
The tagging system was first trialled in a common surrogate crayfish species, Faxonius sanbornii, to make sure it was safe. \u201cWe didn\u2019t want to do a test on a listed species,\u201d Phipps notes.\u00a0<\/p>\n