What's joining, what's leaving Pennsylvania's endangered and threatened species lists?

A species of crayfish has been proposed to be added to Pennsylvania’s list of endangered species and two fish are planned to be removed from that list because they are no longer found in the state.

The Pennsylvania Fish and Boat Commission will consider adding the digger crayfish, which has a limited range in northwestern Pennsylvania, and removing the black bullhead and threespine stickleback at its Oct. 23-24 quarterly meeting.

In addition, the longsolid mussel, which has been designated as federally threatened throughout its range, will be considered for the commonwealth’s list of threatened species.

Two other aquatic species are expected to be removed from the candidate list for those classifications. The numbers of least brook lamprey and brook stickleback fish now exceed threatened and endangered listing criteria and the agency’s staff consider them to be secure.

Christopher Urban, chief of the Natural Diversity Section and nongame, threatened and endangered species coordinator, spoke to the agency’s Habitat and Environmental Committee Oct. 4 about the proposed changes.

“It’s a long process, it typically takes about a year,” he said about adding or removing a species to the threatened and endangered list.

In addition to the Fish and Boat Commission’s review, each proposal is reviewed by the Pennsylvania Biological Survey, a nonprofit that includes scientists, academics, biological conservation professional and species specialists. “Their role is important. It’s a peer review role and it brings expert testimony our listing packages,” Urban said.

There’s a public comment period and a second vote by the Fish and Boat Commission’s board of commissioners before the change is implemented.

Since 2003, the agency has added 22 species to the threatened and endangered list and has delisted 21 species.

More: Three agencies partner to raise, stock freshwater mussels in Pennsylvania

Digger crayfish

Digger crayfish, creaserinus fodiens, has populations in states including Ohio but has a limited range in northwestern Pennsylvania.

The burrowing crayfish was first found in Crawford County in 2014 and since has been located in a total of nine places in Crawford and Erie counties. The agency’s staff recommends adding it to Pennsylvania’s list of endangered species.

Rare find: Fewer than 1,000 Digger Crayfish believed to be living in Pennsylvania

Black bullhead

“We haven’t seen this critter around in a long time,” Urban said. Pennsylvania is on the eastern fringe of the black bullhead’s range.

The fish, with the Latin name Ameriuruus melas, grows to only about 9 inches and lives in turbid waters and rivers. Historically they were found in western Pennsylvania including the Lake Erie basin and south to Westmoreland County. “Since 2000, we have not found them,” Urban said. They are considered as extirpated from Pennsylvania.

Threespine stickleback

Threespine stickleback, Gasterosteus aculaeatus, grows to 3 inches long and lives in shallow vegetated areas of tidal pools, creeks, marshes and estuaries. It has populations along the east and west coasts of the United States. In Pennsylvania, it was confined to the Delaware River and a few tributaries and has not been found in the state since 1997. “Because it’s not here, we don’t believe it warrants endangered species protection and are proposing to remove it from our endangered species list,” Urban said.

Longsolid mussel

The longsolid, Fusconaia subrotunda, is a freshwater mussel that is known to be found in Alabama, Kentucky, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia and West Virginia. In Pennsylvania, it’s been found in the Shenango River, Allegheny River, French Creek and Muddy Creek. In March, the longsolid was designated as a federally threatened species throughout its range, and the Fish and Boat Commission’s staff believes it should be added to the commonwealth’s list of threatened species.

Least brook lamprey

Least brook lamprey, lampetra aepyptera, are non-parasitic lampreys that grow to 6 inches in length. They have been found in 20 locations in northwestern and southeastern Pennsylvania. “It is expanding its range,” Urban said. The lamprey has been on the candidate species list since 1999 and the population is now considered by the agency as being secure. The agency recommends that it be removed from the candidate species list.

Brook stickleback

Brook stickleback, Culaea inconstans, is a small fish that grows to 2½ inches long and lives in cool, calm waters of lakes, ponds, sluggish stream, wetlands and bogs. It’s been on the candidate species list since 1999. It’s now found in more than 20 locations in Pennsylvania in the Ohio and Atlantic drainage basins with no known decline and is being considered as having a secure populations. “It’s expanding its range, it’s doing fairly well,” Urban said.

BJ Small, Fish and Boat commissioner from the Sixth District in Mechanicsburg, said there is a need for ongoing monitoring of the various species.

“It’s clear to remember that just because a species is being delisted or removed from the lists, it’s not always good news. It very well could be that they are not here any more. Where it is good news is being delisted because they are recovering, obviously there is data that proves and shows that.”

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“They play a part in the ecosystem. And some things we don’t even know about these species and the roles they play,” Urban said.

The Fish and Boat Commission reports 29 fish, five reptile, five amphibian, and ten freshwater mussel species are now listed as state endangered or close to extinction. Nine species are classified as threatened (likely to become endangered), and another four are candidates to reach endangered or threatened status in the future.

Brian Whipkey is the outdoors columnist for USA TODAY Network sites in Pennsylvania. Contact him at bwhipkey@gannett.com and sign up for our weekly Go Outdoors PA newsletter email on this website's homepage under your login name. Follow him on Facebook @whipkeyoutdoors, and Instagram at whipkeyoutdoors.

This article originally appeared on The Daily American: PA could add, remove some creatures from endanagered, threatened lists