Keen observers might have noticed a message President Obama was sending in the fish he served at his dinner with 20 women senators Tuesday: Alaskan halibut.

Why the choice, aside from the fact that the firm, white fish is both sustainable and tasty? Because it's what Sen. Lisa Murkowski (R-Alaska) planned to serve that night before the meal got moved to the White House.

The menu offering represented "a thank you gesture to Senator Murkowski," according to her spokesman Matthew Felling, since Murkowski allowed the venue for dinner to be changed with just a day's notice.

While Alaska's senior senator offered to provide the halibut herself, White House protocol doesn't allow for outside food to be taken in with such little warning. So instead, the White House kitchen procured its own.

Halibut has emerged as one of the little-noticed themes in Obama's dinners with Republican and Democratic senators: it was one of the menu choices last week at the Jefferson Hotel when the president dined with a dozen Democrats. (Sen. Sheldon Whitehouse (D-R.I.) said he ordered it that evening "just for the halibut." Ba-dum-bum-swish!)

The original Alaskan halibut, one can only assume, is still sitting in Murkowski's freezer. Luckily for everyone involved, there's enough halibut in the sea for several politicians to buy it at once.