Members of one South Dakota family are speaking out against wildlife officials, as the state’s Department of Game, Fish and Parks has voided a 70-year-old catfish record held by their late patriarch.

On May 18, 1949, Ray Groves caught a 55-pound fish in the James River, the Argus Leader reports, hailed at the time – and for the next seven decades – as the largest channel catfish ever nabbed in the Mount Rushmore State.

Groves’ descendants were shocked to learn on Friday that the standing, which had been South Dakota’s oldest state fish record to date, would be nixed. Reps for department announced that they believe the angler had, in fact, caught a blue catfish.

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An illustration of a channel catfish (otherwise known as the ictalurus punctatus). (Encyclopaedia Britannica/UIG via Getty)

The news followed an “informal poll” from State Fisheries Program Administrator, Geno Adams, who sent a photo of Groves with his prize catch to experts in fish identification and South Dakota State University fisheries professors, the Associated Press reports. Unanimously, the specialists agreed the creature was a blue catfish.

For context, differences between the channel catfish and blue catfish can be subtle; a primary variance being whether a fin on the underside of the catfish is flat or curved.

Now, Groves’ relatives are blasting the department for the way they handled both the investigation and the decree.

The fisherman’s great-grandson, James Labesky, told the Leader that his mother and his grandfather had shared stories about Groves' fishing exploits, but he had never heard about the record being disputed.

"Seems like they're just looking at a picture of it and showing it to some fish specialists," Labesky said.

"The South Dakota Game, Fish and Parks is taking away my great grandfather’s state record away because they don’t think by looking at a picture it is a channel catfish ... I would think he would know the difference!" he also wrote on Facebook.

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Groves’ granddaughter Geri Rasmussen, too, lamented that the outdoor resource and recreation agency announced the news so publically – through a news article – without contacting the family first.

"They could have let us know," Rasmussen told the Leader. "I just think it was handled very poorly. He was always so proud of how many hours he spent pulling all those fish in."

Adams, meanwhile, said that he understands why Groves’ family may be frustrated, but that officials intend to stick to the edict.

"We don't look at this lightly. We understand this is a big deal to a large amount of people,” State Fisheries Program Administrator Geno Adams said of the news. (South Dakota Game, Fish and Parks)

"There's just a lot of information that doesn't line up to make that a channel catfish," Adams said. "And in the last few years it just became overwhelming."

"We don't look at this lightly. We understand this is a big deal to a large amount of people,” he added.

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As noted by the Leader, records for channel catfish in neighboring states are much lower than Groves’ catch, such as Iowa (38 pounds, two ounces), Nebraska (41 pounds, eight ounces) and North Dakota (41 pounds, one ounce).

Moving forward, reps for the state Game, Fish and Parks department have dubbed the quest for a new channel catfish record "Catrush 2019." They expect the mark to be broken several times over the next few weeks.

The Associated Press contributed to this report.