Black Marlin Vs. Blue Marlin

If you’re a fisherman, marine biologist, or simply an enthusiast interested in marlin species, this guide is for you.

We’ll dive deep into the differences between the Black Marlin and Blue Marlin, covering everything from their physical characteristics to their preferred habitats.

By the end of this guide, you’ll be able to easily identify each species, even if you’re a novice to marlin.

Physical Characteristics

Understanding the physical differences between the Black Marlin and Blue Marlin is key to identifying them. Here are the main distinguishing features:

• Speed: Blue Marlin are faster swimmers than Black Marlin. This trait often makes Blue Marlin more challenging to catch.
• Head and Bill: Black Marlin have thicker heads and shorter bills, often downturned slightly. In contrast, Blue Marlin have a thinner bill and a more streamlined appearance.
• Dorsal Fin: The dorsal fin of a Blue Marlin is taller than that of a Black Marlin.
• Pectoral Fins: The pectoral fins of a Black Marlin are rigid and do not fold flush against its body. On the other hand, the pectoral fins of a Blue Marlin fold easily against the fish’s sides.

Additional characteristics

Above were some of the more obvious differences between a Black Marlin and a Blue Marlin; however, there are a few more subtle differences that are worth mentioning:

• Coloration: Black Marlin are predominantly very dark blue above the lateral line, quickly fading to hues of green or gold, then to shades of silver or white below. They can display faint blue vertical stripes. Blue Marlin, on the other hand, are often vividly blue with shades of purple, frequently with iridescent blue vertical stripes running the length of the body.
• Branchiostegals: These refer to the bony elements in the umbrella-like membrane on a marlin’s throat below the gill plates or operculum. A Black Marlin’s branchiostegals are much longer and reach farther back to the rear edge of the operculum than a Blue Marlin’s. This gives the appearance of a bigger head and, in addition to the thicker shoulders, makes a Black Marlin look like it’s got way more weight forward than aft.
• Second Dorsal and Anal Fins: These can be definitive but are really only helpful if the fish is lying quietly on its side next to the boat or hanging at the dock. If the origin or start of the second dorsal occurs at a point before where the second anal fin occurs, you have a Black Marlin. If you see the exact opposite, then it’s a Blue Marlin.

Habitats of Black Marlin and Blue Marlin

The habitats of Black Marlin and Blue Marlin are largely influenced by their preferences for different water depths and conditions.

Black Marlin Habitats

Black Marlin are typically found closer to the surface, at around 50 fathoms or less. This preference for shallower waters often leads them to areas with abundant food sources and warmer temperatures.

Black Marlin are known to frequent areas of broken ground, rock piles surrounded by flats, and coral reef systems that hold varieties of baitfish. These environments can be target-rich for Black Marlin, especially when bait is present in large quantities.

One notable habitat for Black Marlin is the Zane Grey Reef just outside Pinas Bay, Panama. This area holds bait in large quantities and is a small rock pile coming up from about 300 feet with a few small satellite peaks looming in the flats that surround it.

When conditions are right, Black Marlin will pile up in this tight area and tear through schools of bait.

Blue Marlin Habitats

On the other hand, Blue Marlin prefer deeper waters, at around 100 fathoms or more. This preference for deeper waters is often linked to their faster swimming speeds and their ability to dive deep to hunt for food.

Blue Marlin are often found in open oceans, far from land. They are highly migratory and can travel long distances in search of food and for spawning. Their habitat is generally offshore in waters over 100 meters deep, and they are known to dive to depths of up to 800 meters.

In summary, while both species can be found in similar geographical locations, their preferences for different water depths and conditions lead them to occupy different habitats within those areas. Understanding these habitat preferences can be crucial for successful marlin fishing.

Identification Guide for Beginners

For those new to marlin fishing, here’s a beginners guide to identifying Black Marlin and Blue Marlin:

1. Look at the speed: If the fish is swimming exceptionally fast, it’s likely a Blue Marlin.
2. Examine the head and bill: A thicker head and shorter bill indicate a Black Marlin, while a thinner bill and more streamlined appearance suggest a Blue Marlin.
3. Check the dorsal fin: A taller dorsal fin points to a Blue Marlin, while a shorter one suggests a Black Marlin.
4. Observe the pectoral fins: If the pectoral fins are rigid and do not fold flush against the body, you’re looking at a Black Marlin. If they fold easily against the fish’s sides, it’s a Blue Marlin. (This is my go-to method)

Remember, practice makes perfect. The more you observe these species, the better you’ll become at distinguishing between them.

FAQ

Conclusion

Understanding the differences between Black Marlin and Blue Marlin is not only fascinating but also crucial for successful fishing. Whether you’re a seasoned fisherman or a novice, this guide should help you identify these majestic creatures with ease. Happy fishing!