On The Trails: Gunnels and others

A crescent gunnel emerges from its hiding place. (Photo by Bob Armstrong)

By Mary F. Willson

Gunnels are small intertidal fish, very slender, bearing a long dorsal fin. They are unusually slimy; that mucus coat protects them from dehydration when the tide goes out. They can breathe air through the skin for hours.

They eat a variety of small invertebrates and fish eggs. These fish actually copulate, unlike most fishes; the sperm enter the female, but the eggs are not fertilized until they are laid. Females lay dozens to hundreds of eggs, in clusters hidden under rocks, in empty mollusk shells, or in seaweed. Egg clusters are guarded by one parent or both, depending on the species. The eggs incubate for a couple months, hatching into planktonic larvae that swim around for a couple more months.  There are said to be about 19 species of gunnel in the world; there are two in Alaska: the crescent gunnel and the penpoint gunnel. 

Gunnels commonly hide under rocks, in dense algae, or eel grass. They can come in different colors, depending on the species: reddish, green, tan. In some cases the color apparently depends on the larval habitat, but they reportedly do not change once the color is set (except some species for breeding). They are said to live usually in places that match their colors. Despite the hiding and the color matching, they have many predators, including seals, otters and mink, fish such as salmon and halibut, and birds of many kinds, including cormorants, guillemots, gulls, and others. 

These videos show how two avian predators handle gunnels that they want to eat. Take a few minutes to have a look; for the heron, something a bit subtle happens partly through the sequence (https://youtu.be/5C3mpCCdTac; https://youtu.be/v7nTgwkXXdo). As you will see, gunnels don’t seem to be easy prey to handle. Both of these avian predators have to work at it, although they do it in different ways.

Here at home, July 9 was moderately eventful. A late brood of mallards visited the pond: seven large but still fuzzy ducklings and their mama. For the first time in several years, I saw a black bear strolling through the front yard, snatching mouthfuls of horsetail on the way. The fur on its back was very disordered and misarranged, as if it had vigorously scratched its back on a tree trunk. And then, several sharp taps announced the arrival of a male hairy woodpecker, accompanied by a big, well-grown juvenile. The male took a bite of suet and they both left. I hadn’t seen this woodpecker for about three weeks, although before that, I’d seen him almost every day.  Even if I missed a day or two, it was clear that his visits during that time were few. Was he busy raising chicks?? But it takes longer than three weeks to raise nestlings and juveniles. So was he a part-time father?

The next day, I walked with a friend at Sandy Beach. The highlights were the songs of Swainson’s thrushes and wrens, and watching a sapsucker tap repeatedly on the metal cap of a tall wooden post. That cap not only protected the post from rain, it served another purpose too.

In early July, I walked the dike trail on two days, looking for bees. I saw none on beach pea or lupine. However, in the white clover, which is extremely abundant out there, I saw one bee on the first walk and two bees on the second one. That suggests that our bees may be in trouble. However, I have sporadic reports of many bees in certain, limited spots, such as a stand of that invasive orange hawkweed. More intense study is needed!

Thanks to Bob Armstrong for the videos (and for sharing his good photos and observations on other occasions)!

• Mary F. Willson is a retired professor of ecology. "On The Trails" appears periodically in the Juneau Independent. For a complete archive of Mary Willson’s “On the Trails” essays, go to https://onthetrailsjuneau.wordpress.com.