The number of families arrested at the Southwest border rose dramatically between October and November of this year, according to new data that has immigration experts wondering if previous levels of illegal immigration are destined to return.

Numbers released by U.S. Customs and Border Protection on Friday show immigration officials apprehended just over 7,000 family units — consisting of at least one adult and one child — at the border last month, compared to 4,839 in October. That 45 percent increase accompanied a 26 percent surge in child migrant apprehensions, from 3,168 to 4,000 over the same one-month span.

The substantial uptick in apprehensions of both unaccompanied children and families has baffled some immigration experts. But others view it as a symptom of Obama-era catch-and-release policies, which remain in place as President Trump is set to begin his second year in office.

“These numbers are supposed to go down as the winter starts and you’re supposed to see a spike in the spring months,” said Leon Fresco, an immigration attorney with Holland and Knight.

Fresco, who led the Justice Department’s Office of Immigration Litigation during the Obama administration, suggested there may have been a “pent up demand to come to the U.S. that was not being met because people were very worried about what would happen to them if they came.”

“Now they realize that they will be treated the same as if they came last year, and they’re starting to enter illegally,” he explained.

Fresco and others told the Washington Examiner that one of the biggest issues Trump faces as he continues to shoot for fewer border crossings is the administration’s inability to end “court-imposed catch-and-release” practices, in which non-criminal illegal immigrants are turned loose until they are expected to appear in court – sometimes months or years later.

At a Senate Judiciary Committee hearing in October, Attorney General Jeff Sessions told lawmakers that Trump has sought to change the practice but may need Congress to intervene. A 2015 settlement agreement by a federal judge in California, which barred law enforcement officials from detaining illegal immigrant children and families, has made it particularly difficult for the White House to enact change.

“The Trump administration has restored tough enforcement and consequences for regular adult illegal immigrants but for these specific cases, in which young people and families are arriving, they have not found their way around the court restrictions,” said Jessica Vaughn, director of policies studies at the Center for Immigration Reform, a conservative think tank based in Washington., D.C.

When human smugglers in Central America receive word that many illegal immigrants are still being released by border patrol officials, “they will take full advantage of that,” Vaughn told the Washington Examiner.

“People thought, ‘Well, Trump is going to do something different.’ But now that they’re realizing the outcomes are the same, they’re coming back over,” said Fresco, who predicts the level of illegal immigration “isn’t going to get worse, it’s just going to return to normal.”

CBP chief Ronald Vitiello told reporters earlier this month that rising apprehension rates for child migrants and families are partially due to the exploitation of “legal and policy loopholes” by transnational criminal organizations. He did not specifically reference catch-and-release policies.

Declining to elaborate on Vitiello’s remarks, a separate CBP official said “folks [at the agency] are looking into it.”

Ira Mehlman, a spokesman for the Federation for American Immigration Reform, was reluctant to attribute the soaring number of apprehensions to the survival of catch-and-release policies.

“You’d probably have to ask Customs and Border Protection why they’re seeing this difference. What we have heard is that catch-and-release is returning, or it never really went away, but I’m not sure why that would explain this,” Mehlman told the Washington Examiner.

Compared to the same period of time in recent years, the 45 percent increase in family unit apprehensions is staggering. Apprehensions of illegal immigrant families figure grew by 7.4 percentage points between Oct. and November of 2015, and by 18 percentage points during the same months a year later.

The same goes for arrests of unaccompanied illegal minors, which increased 13 percent between Oct.-Nov. of 2015, and 9.5 percent the following fall.

Tyler Houlton, a spokesman for the Department of Homeland Security, told the Washington Examiner that "cherry picking data to compare the highest month of border apprehensions during the Trump administration to the lowest during Obama's does not show the full picture."

"Under President Trump, illegal immigration has declined dramatically over the last year," Houlton said in a statement. "The administration is working tirelessly to secure the border, enhance interior enforcement and establish a merit-based immigration system."

To combat the flow of child migrants and families from Central America, Vaughn said the Trump administration needs Congress to act.

“The best solution would be for Congress to provide authority to Immigrations and Custom Enforcement that would overrule these judges,” Vaughn said, referring to a decision by the Ninth Circuit Court of Appeals in July that upheld the 2015 ruling on catch-and-release policies.

Vaughn continued, “Congress can pass a law overriding that settlement agreement and those judge’s interpretation of it, and the Trump administration believes that is the answer to this problem.”

“The problem with that,” Fresco explained when asked about a potential legislative solution, “is no Democrats are going to vote for something like that right now.”