Friend Feature: Northern lampfish, Stenobrachius leucopsarus

Northern lampfish Stenobrachius leucopsarus found by Samish Tribe Natural Resources staff during a nearshore fish survey in Fidalgo Bay. This deep water fish died of unknown causes before it was caught in their survey net. But how did it end up in a shallow bay? Image by Samish Tribe DNR

The Samish Tribe’s Natural Resources team regularly spreads a net in the nearshore waters of Fidalgo Bay. The net is called a beach seine and is used to catch fish gently and keep them safe so they can be released after counting and measuring. In this way, they can track how many species of fish and how many of each species are there over time. The net usually comes up with the usual suspects: staghorn sculpin, sharpnose sculpin, shiner perch, sometimes a surf smelt, English sole, or a snake prickleback.

Mystery fish

Recently, they caught a fish no one on their team had seen before. It was a dark fish, smaller than your pinky finger, with enormous eyes, a rounded head, big, Pacman-style mouth, and mysterious, silvery gold pits along the whole length of the lower part of its body on both sides.

Two of the seine team had a guess about its ID. Expert ichthyologists (fish scientists) at NOAA Fisheries, where they sent photos of the already-dead fish for identification confirmed it: Northern lampfish Stenobrachius leucopsarus. This was a member of the lanternfish family - a deep sea, light-emitting lanternfish!

Deep, dark, and cold? The perfect habitat

Northern lampfish have light-emitting pits along the whole length of the lower part of their bodies. These phoptophores generate light energy through chemical reactions similar to those in glow sticks and bracelets or fireflies.

Though Northern lampfish are common in the northern North Pacific Ocean, there is a good reason this team had not seen one before. They live at up to 1,000 meters (about 3,300 feet) deep during daylight hours, swimming around, munching on small fish or tiny crustaceans, like euphausids and copepods.

At night, some Northern lampfish swim in great numbers upward to about 50 meters (160 feet) below the surface under the cover of darkness, while others stay down in the mesopelagic depths (200-1000 meters) all the time. Who else is making that nightly migration? Their prey! Nothing like hunger to inspire a trip. Who isn’t making that trip? Many of their predators; more migration motivation. More on those below.

What’s a photophore for?

Like the other 200 species of lanternfishes, Northern lampfish have tiny light-emitting organs on their bodies, and larger, fast-flashing ones on their tails (stern chasers). These little pits are called photophores. You may have heard these cool light tricks called bioluminescence (light from living organisms).

Many deep sea wildlife use bioluminescence. Some for avoiding predators (squid), some for attracting prey (anglerfish), some for alarms (plankton), and some even for distraction, like leaving a spare, glowing arm on a passing fish for a predator to follow while the true prey makes a getaway (sea cucumbers and brittle stars). Can you find the Northern lampfish in the photo? Key below. Photos by Steven H.D. Haddock, 2010, Bioluminescence in the Sea

Bioluminescence can come from various sources. For lanternfish, there is a protein in the photophores called luciferase which glows in the dark when activated by a chemical reaction It is similar to the glow sticks and bracelets you might have worn for special events.

Love lights

Each species of lanternfish has a special pattern of photophores, helping males and females to find their appropriate Valentines in the dark. When they do, males fertilize groups of eggs that females deposit right into the water column. And that’s it for parenting. The little ones are on their own from there. Larvae hatch out with just a few photophores, which increase in number with growth. Adults reach about 13 cm (5 inches). Okay, so a little bigger than your pinky finger.

Light snacks

Scientists speculate that their light shows might trigger the bioluminescence in their plankton prey to kick on, making for an easy-to-see snack. You may think that their flashy behavior is not such a bright idea for avoiding predators. It actually helps. Lanternfish photophores point downward and to the sides, providing counterillumination camo. Bigger fish and mammals, looking upward for snack-shaped shadows against the light above just see light. Predators above them see their dark dorsal surface (back) against the dark depths. Brilliant!

Key to Gallery of Marine Bioluminescent Organisms

(a) Bioluminescent bacteria (b) radiolarians (c) hydromedusa (d ) red-tipped tentacles and white stinging cells from a siphonophore (e) pelagic polychaete worm ( f ) larva of the acorn worm (l) luminescent frenzy from a comb jelly; (m) krill Thysanoessa sp.; (n) live photo of anglerfish Chaenophryne longiceps; (o) ostracod Conchoecia sp. that uses coelenterazine instead of typical ostracod luciferin; ( p) hatchetfish with an overlay of ventral photophores shown by their blue fluorescence; (q) large copepod Gaussia princeps; (r) myctophid lampfish with species-specific pattern of photophores, and white “sternchaser” organ; (s) Tactostoma sp., in white light, and (t) under fluorescent illumination, showing the red and green photophores. All images show animals illuminated by a white-light strobe except a, k, and l, which record bioluminescent light, and g, p, and t, which use fluorescence illumination to reveal photophore patterns. (Photos: Steven H. D. Haddock, 2010).