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.
Try bucktail or marabou jigs on these spring-run fish. White, yellow, chartreuse and pink are good colors; the proper sizes can range from 1/8 to 1/2 ounce, depending on the current and depth. Both plain jigs and those adorned with either a soft-plastic tail or a pork-rind strip are deadly.