This isn't quite exact, but 1/4 cup of butter (so a half stick if you're in the US) is 57 grams according to the conversion chart from allrecipes below. So use just a slightly heavy 1/4 cup or 1/2 stick.
Yellowtail, including Yellowtail Jack (Seriol landei), are recognized by a yellow stripe across their body and their yellow tail. Range & Habitat: Yellowtail is caught year round, but more commonly during summer in the Pacific Coast and the Sea of Cortez. They are caught primarily with hook and line, and their average weight is 10 to 20 lbs.
Tackle and Techniques. You can't fish Yellowtail with one rod, On a slow bite most fisherman prefer to use small anchovies for bait, go as light as 12 to 15 pound line on a small conventional reel with a light rod as the fish can be fussy or line-shy.