Dorado: The glutton of the ocean

Written by:
Hans Kruit, 8 November 2013

Dolphinfish (mahi mahi) are highly migratory and found worldwide in tropical and warm temperate seas, inhabiting the surface waters.

Mahi are the rabbits of the ocean and grow incredibly fast. They may turn out to be the fastest-growing wild fish known to man. In captivity, these fish have been shown to grow 1.3 to 2.7 inches a week, up to four feet and 40 pounds in a year.

In the wild, at five months, they can reach 5-6 pounds and are mature. Mahi are sexually productive at an early age. All mahi can reproduce by three to five months of age or 22 inches in length.

At one year, most exceed 20 pounds. Three-year-olds usually exceed 30 pounds. Few fish live beyond the fourth year.

Once the fish reach maturity, they spawn every four to six weeks and broadcast about 400,000 eggs.

The eggs, which are about the size of the head of a pin, hatch in about 60 hours. The little fish start growing immediately at a rate of one to one-and-a-half inches a month. This fast growth rate keeps them eating constantly, and they are very aggressive biters most of the time.

Mahi are opportunistic feeders, foraging in the entire water column. They eat everything from paper nautilus to their number one dietary preference, flying fish (malolo).

They also feed both at night and during the day. Mahi consume, on average, 5.6 percent of their body weight daily. Small fish were the most voracious, eating up to 19.8 percent of their weight, while the stomach content of large bulls often contained as much as 10 percent of the fish's body weight.

Eighty-seven percent of all mahi die during their first year. The 10 percent that make it to the second year can reach 40-50 pounds. The remaining 3 percent comprise the rare population of 60- to 70-pounders. Scientists say that few, if any, mahi make it past five years. The all-tackle world record 87-pounder, caught in the Pacific, was probably four years old.

source: Lahaina News