Blue, Striped, and Black Marlin are caught every month of the year. Costa Rica marlin fishing is typically exceptional in June, July and August. It then slows a bit from October into early January when it picks up again.
Blue marlin range from 200-400lbs, black marlin range from 150-500lbs, and striped marlin (most common) range from 50-150lbs.
Did you know that Marlin and Sailfish are actually in the same family known as Billfish? The sub-species include Sailfish (Atlantic and Pacific), Black Marlin, Blue Marlin (Atlantic and Pacific), and Striped Marlin. Of the six major sub-species, four can be caught in Papagayo, Costa Rica.
Marlin are almost always targeted by trolling large artifical surface lures or rigged dead baits. The Blue Marlin is known as the toughest fighter and can grow to be well over 1,000lbs, but they all fight hard and put on a great show. The Blue Marlin was the fish featured in Ernest Hemingway’s The Old Man and the Sea.
Blue and Black Marlin are often confused with each other because the colors of individual fish vary greatly. The easiest way to tell them apart is to observe the pectoral fin. The Blue Marlin can actually retract that fin (there is also a visible pocket at the base of the fin), while that fin is always rigid on a Black Marlin.
Striped Marlin are typically smaller than Black or Blue Marlin, but are more common and always fight hard. They are known for their unforgettable series of jumps after they are hooked. They also fluorese (glow) when excited or hunting prey. Their favorite food is sardines and they can often be seen “tailing” just under the surface as they warm their bodies in the sun. They can often be seen “lit up” behind the boat as they chase the trolled lures.
You can learn more about Marlin on Wikipedia