Home & Garden Columns

Wild Neighbors: The Dog That Runs in the Rough Water

Joe Eaton
Friday May 07, 2010 - 11:38:00 AM
Oblivious Hawai'ian monk seal, Po'ipu Beach Park, Kaua'i.
Ron Sullivan
Oblivious Hawai'ian monk seal, Po'ipu Beach Park, Kaua'i.
Honu's day off: green turtle on the beach
Ron Sullivan
Honu's day off: green turtle on the beach

The trick to spotting a Hawai’ian monk seal, according to Kaua’i-based naturalist David Kuhn, is to look for the orange plastic cones delimiting its space on the beach.  

It works. That’s how we found one of the endangered seals plus a bonus green turtle at Poi’pu Beach Park on the South Shore one afternoon. We spotted the turtle first, hauled out at the edge of the water, its carapace about the size of one of the larger paella pans at the Spanish Table. It wasn’t there to lay eggs, as it turned out, although there are nesting beaches not far away. It just seems to like to hang out on that stretch of beach. The turtle was awake, but immobile. 

The seal, an adult female maybe seven feet in length, was a little farther along, on a kind of isthmus between the sandy beach and an outlying shelf of rock. The volunteer seal wrangler, a woman from Buffalo who wisely spends her winters on Kaua’i, told us that a half-dozen monk seals had come ashore that day. The previous day’s heavy rain had left nearshore waters too murky to hunt for fish, and the seals had opted for some down time. 

At any given time, she said, there are about 30 monk seals on and near the island. Some even give birth on Kaua’i; there was a heavily pregnant female at Hanapepe, further west along the coast. Most of the species’ population occurs in the Northwestern Hawai’ian Islands, though, on Midway and Laysan and more obscure specks of sand like Lisianski Island, French Frigate Shoals, and Pearl and Hermes Reef. The monk seal is one of Hawai’i’s two native mammals, the other being a subspecies of hoary bat; it was designated the official state mammal a couple of years ago, edging out the small Indian mongoose, the feral pig, and the poi dog. 

The seal was more restless than the turtle. Every now and then she would turn over, stretch her neck, or give herself a desultory scratch with one flipper. She seemed oblivious to the human gawkers, surrounding her at a distance that would have freaked out the most tolerant harbor seal. Her pelt was silver-gray, a little paler on the belly, and she had big brown eyes. The docent pointed out a couple of semi-circular scars on the seal’s skin: “Cookie-cutter shark.” These are small sharks that bite into a marine mammal or another fish and then twist, excising a plug of flesh. 

Seal taxonomists say that monk seals are the most primitive of living seals, having diverged from the mainstem of phocid evolution some 15 million years ago. They are thought to have originated in the ancient Atlantic, leaving descendant species in the Mediterranean (also endangered) and the Caribbean (extinct.) One population swam through the intercontinental gap where Panama would eventually be and colonized the atolls northwest of Kaua’i. Hawai’ian monk seals retained their cold-water ancestors’ insulating layer of blubber. To prevent overheating, hauled-out seals move as little as possible and slow down their respiration and heart rates. 

The first Hawai’ians, who didn’t know from seals, named the animal ‘ilio holoikauaua—“the dog that runs in the rough water.” Judging from the absence of monk seal remains in archeological sites, they seem to have left it alone. A Russian captain named Lisianski encountered the species in 1805. Subsequent Europeans slaughtered monk seals for their skins and blubber; they were also killed by feather hunters, guano collectors, and bored servicemen. Population counts in recent decades have never exceeded 1500, and have sometimes dipped as low as 500. NOAA Fisheries, the federal agency with jurisdiction over marine mammals, gives a current estimate of 1200 and falling. 

Like all species with small populations, Hawai’ian monk seals are vulnerable to random events, like an outbreak of ciguatera—algal toxins that concentrate in fish—on Laysan in 1978. Beach erosion in the northwestern islands has reduced their breeding habitat. And basic demographics are not on the seals’ side. Females don’t give birth until they’re six years old; only 60 or 70 percent produce pups in any given year. The sex ratio at some breeding sites is skewed toward males, who have an unfortunate tendency to mob females, sometimes with fatal results. Pups are especially prone to entanglement in lost or discarded fishing gear. 

The Poi’pu seal wrangler told us one factor driving the decline is a change in a predator’s strategy. At French Frigate Shoals, home to the largest subpopulation of monk seals, Galapagos sharks have learned to patrol the shore for pups entering the ocean. In the water, the pups are defenseless, and mortality rates have risen. Wildlife managers have responded by relocating pups and removing the sharks, although it would be difficult to eradicate them all.  

In an uncharacteristic moment, the Bush administration designated much of the northwestern chain as the Papahānaumokuākea Marine National Monument in 2006. That may at least give the seals some relief from the effects of commercial fishing. These engaging beasts could use a break.