A popular bat-retrieving dog who worked for a New Jersey minor league baseball team has died.

The Trenton Thunder announced Monday that Derby died Saturday. They say the 9-year-old golden retriever had cancer.

"Derby was one of the biggest parts of our identity in the nine years of his life, and it breaks my heart to share this news with our fans ahead of our 25th season," general manager Jeff Hurley said in a statement.

Derby had trained with his father, Chase, before first taking the field in 2010. Chase died of cancer in 2013. Both dogs were featured in the ESPN show "E-60."

Derby delighted both fans and players alike with his routines. He also brought bottled water to umpires on hot days. The team favorite later became close with Hall of Famer and New York Yankees adviser Reggie Jackson.

Derby's son, Rookie, began bat duty in 2016.

The team will feature a special tribute video to Derby on Jan. 26, on what would have been Derby's 10th birthday.