Monthly Archives: June 2015

Australian darters hunt by stalking and stabbing

Published June 29, 2015 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2015 Susan Scott
darter

Australian darters are also known as snakebirds, anhingas and water turkeys. ©2015 Susan Scott

Burnett River, Australia » It’s all well and good to have a sailboat in Australia and talk about sailing the Great Barrier Reef. It’s another thing to actually do it.

As with most outdoor adventures, weather is everything. Like our own northeast tradewinds, the southeast tradewinds here can blow your socks off, which is currently the case. A voyage to the closest atoll, Lady Musgrave, in this weather would feel like a trip from Oahu to Kauai in gusty trades and high seas. Not fun. We’re waiting.

But no worries. Our sailboat, Honu, is at the mouth of the Burnett River, a nutrient-rich body of water where fresh and salt water meet. The conditions outside the estuary might be frightful, but in here it’s calm and there’s enough wildlife to keep me entertained for weeks. Besides white pelicans, blue soldier crabs, pink parrots and frisky dolphins, we’re surrounded by snakes.

Well, they look like snakes at first glance. In fact, they’re birds known as snakebirds or Australian darters. On the southeast coast of the U.S., people call them anhingas.

Darters paddle their bodies smoothly underwater between the rows of boats in the marina, holding their narrow heads and S-shaped necks above the surface looking for all the world like fast snakes. In a flash the “snake” disappears, leaving only the V of its wake.

The birds aren’t chasing prey. When they’re on the move they’re stalking it, and when they dive, they’re stabbing it.

Because darters’ feathers aren’t waterproof, they get soaked and heavy, handy for sinking beneath the surface. The bird propels its body with its feet, slipping silently and smoothly along, head up, until it spots something to eat. The darters’ favorite is fish, but they also eat invertebrates and river turtles.

The bird impales its food with a sharp, daggerlike beak. This is possible because the darter has a hingelike mechanism in its long neck that enables the bird to snap neck, head and pointy bill forward as if throwing a spear.

Darters can stay underwater for only a minute or so, so it’s worth waiting around to see their next trick. With a toss of the head, the bird throws its catch in the air and swallows it head-first in one gulp.

After dinner the darter jumps to a safe place, in this case a pier, and, like its cormorant cousins, hangs its wings out to dry.

I was surprised to see that darter bodies are plump, because in the water they look sleek as snakes.

If I get tired of estuary animals, I can always walk to the beach park and watch kangaroos. I may not be on the GBR, but I’m inside it, and that’s just as good.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2015 Susan Scott

 

Saving Great Barrier Reef has been an uphill battle

Published June 22, 2015 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2015 Susan Scott

Bundaberg, Australia » My co-captain, Craig, and I flew Down Under last weekend to collect our 37-foot ketch, Honu, which we stored here in October. We have a month to explore some of the 900 islands and 3,000 coral banks that make up the Great Barrier Reef Marine Park.

To fully appreciate this 1,200-mile-long marvel of nature, I did some research on the history of the reef as a national park.

Because the GBR is so famous, most people assume it has long been protected from commercial fishing. Not so. When the Australian government created the Great Barrier Reef Marine Park in 1975, only 4 percent was off-limits to anglers, leaving most of the reefs, islands and inside waters open to commercial fishing. This included everything from hand-collecting aquarium fish to trawlers dragging nets across the ocean floor.

UNESCO named the GBR a World Heritage Site in 1981, but that didn’t give it more protection. By the end of the 20th century, overfishing, toxic discharges from nickel and coal mines, agricultural runoff and ship harbor dredging caused failing fisheries and gasping corals. The celebrated reef was in trouble.

Australian lawmakers rose to the challenge — and it was a challenge because fishing interests strongly opposed the creation of no-catch zones. Eventually, in 2004, the legislature increased the protected area of the park from 4 percent to 33 percent and created long-term conservation plans.

One-third of the GBR roped off (figuratively) for the recovery of fish stocks, corals and other invertebrates was, at 134,000 square miles, the largest protected ocean area in the world.

A year later, it became second largest. The first, at 139,000 square miles, is our own Northwest Hawaiian Islands, designated in 2006 the Papahanaumokuakea National Marine Monument.

The protected part of the GBR isn’t one solid piece, but consists of separate zones based on ecosystems. Color-coded maps, widely available, show users what kind of fishing and collecting is allowed in each area.

Judges are serious about these rules. One commercial angler caught fishing in a restricted “green” zone received a fine of AU$40,000, or $31,000.

Like all large wilderness areas in the world, controlling human activity on the GBR is a continual uphill battle for Australian lawmakers and managers. Environmental organizations and people with tourism concerns pull one way; big business and fishing industries pull the other. And even when compromises are struck, there are cheaters.

When delving into the debates and disputes currently raging around protection of the GBR, or nearly any environmental issue, it’s easy to get caught up in the negative and believe that all is lost.

I choose to focus on all that’s left. I’m about to sail into a park that hosts thousands of fish and invertebrate species as well as being breeding grounds for seabirds, sea turtles and whales. Coral reefs, sea snakes, dugongs, mangrove forests and fantastic life forms I don’t even know (yet) thrive here.

I appreciate what people are doing to keep the Great Barrier Reef great. It is, after all, still very well-named.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2015 Susan Scott

 

Man and fish die in fight between apex predators

Published June 15, 2015 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2015 Susan Scott

A swordfish recently killed angler and charter boat captain Randy Llanes in the Big Island’s Hono­ko­hau Harbor. After the fish entered the anchorage — an unusual occurrence because swordfish live far offshore, Randy jumped into the water and speared it. The fish got tangled in an anchor line and in its death throes stabbed Randy in the chest.

Being at the top of the food chain, billfish have few predators — only orcas, sharks and humans.

Marlin, spearfish, sailfish and swordfish are all members of the billfish family, 12 species that roam the deep oceans of the tropics and subtropics.

The distinctive top bill of the fish is an extension of the upper jaw. In swordfish the jawbone is flat, sharp-edged and tapers to the tip, like a sword. At about a third the length of the fish, the swordfish bill is the longest among billfish.

Swordfish grow to 15 feet, but even when small, such as the 6-foot-long Hono­ko­hau swordfish, their bills are formidable weapons.

Years ago I found a swordfish bill in an otherwise empty rental unit. The former tenants must have considered the 34-inch-long bill trash because they left it lying on the lanai with a dead potted plant. If that flowerpot had been filled with gold, though, I wouldn’t have been more thrilled. I hung the remarkable bill on my bedroom wall.

swordfish

Besides its remarkable bill, the swordfish is also exceptional for having warm eyes. Special eye muscles act like tiny space heaters warming the fish’s tennis ball-size eyes and brain from 50 to 59 degrees Fahrenheit.

Swordfish spend their days hunting about a quarter-mile deep in 37-degree water. Because warm eyes capture light better than cold eyes, the heating helps the fish find and catch prey in its chilly, dark habitat.

As fish eaters, all 12 species of billfish slash their bills back and forth with tremendous strength and speed to stun and injure their prey. Once again, swordfish are exceptional because in addition to slashing, they sometimes stab a large fish that happens by.

The swordfish’s broad bill (the fish are also called broadbills in some countries) is truly swordlike, the edges sharp enough for the fish to withdraw it from a predator’s or prey’s flesh.

No one knows why a swordfish was in Hono­ko­hau Harbor, but whatever caused the powerful young fish to swim past an experienced spear-fisherman, it was an ill-fated moment. Two apex predators with comparable weapons came face to face, and both lost their lives.

Those of us who routinely enter the ocean do it for various reasons, but we all have one thing in common: We understand the risks and go anyway.

I didn’t know Randy, but as a lifelong fisherman and deep-sea charter boat skipper, he realized the danger of spearing a swordfish. Friends and family say Randy died doing what he loved.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2015 Susan Scott

 

If fish’s spikes don’t get you, it’s razor-sharp teeth might

Published June 8, 2015 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2015 Susan Scott

Porcupinefish — related to puffer fish — improve on the defensive adapta-tion of inflation with pop-out spikes. These were found on Leeward Oahu’s Maili Beach. Courtesy Kimberly Coffee-Isaak

Porcupinefish — related to puffer fish — improve on the defensive adaptation of inflation with pop-out spikes. These were found on Leeward Oahu’s Maili Beach. Courtesy Kimberly Coffee-Isaak

A photo arrived in my inbox recently with a note from Kane­ohe reader Richard, whose friend Kimberley found an object on Wai­anae’s Maili Beach that baffled them both. Richard wondered whether I knew what it was.

Courtesy Kimberly Coffee-Isaak

Courtesy Kimberly Coffee-Isaak


Courtesy Kimberly Coffee-Isaak

I did, but not from my Hawaii experiences. While exploring the Sea of Cortez (Gulf of Cali­for­nia), I found the white spikes so common on Baja’s desert beaches that I often wore shoes to protect my feet. The little spears were in all stages of decay, from newly dead to Kimberley’s wad of spines held together only by dried skin. They were porcupinefish.

Porcupinefish and puffer fish are closely related but have one big difference. When threatened, both family members puff up with water in hopes of making their bodies too big for a predator to swallow. But the well-named porcupinefish have added security. Embedded in their skin are sharp, 1- to 2-inch-long spines.

porcupine fish

Porcupine fish. Courtesy David Schrichte.

Porcupinefish spines lie flat against the fish’s body. When the fish is threatened, though, it inflates its body with water and out pop the spikes.

One kind of porcupinefish is called a burr fish because its short spines permanently stand up, like rose thorns. Hawaii hosts one burr fish and two porcupinefish, which can be found throughout tropical waters.

Burr fish. Courtesy David Schrichte.

Burr fish. Courtesy David Schrichte.

The point of puffing up is to become a ball too big to get down the throat, and spikes on the ball are even more off-putting. But that doesn’t stop some fish from trying. People have found inflated porcupinefish stuck in the throats of dead marlins and tiger sharks.

Porcupinefish and puffer fish have another well-known defense. They carry bacteria that manufacture the nerve poison tetrodotoxin, which the fish store in their skin and organs.

puffer

Pufferfish. Courtesy David Schrichte

Puffer fish nerves aren’t susceptible to tetrodotoxin, nor are the nerves of their main predators, sharks and billfish. The poison works on other species, though. Tetrodotoxin sometimes kills people who eat the Japa­nese puffer fish dish called fugu.

If all else fails, porcupinefish bite with the efficiency of a guillotine using two razor blade-type teeth, one upper, one lower. Porcupinefish have bitten off the fingers of several Hawaii fishermen and divers who dared to come too close.

Porcupinefish balloon out by sucking water in, and they also blow it out. Their strong water jets uncover meals of snails, crabs and shrimp buried in the sand.

I can’t answer Kimberley’s question as to how it happened that this was all that was left of the fish on the beach. I’m just glad she spotted the long-dead puffer fish before stumbling foot-first onto its spines.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2015 Susan Scott

 

Size of tusks determines walruses’ pecking order

Published June 1, 2015 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2015 Susan Scott

Last week, I received an unsigned email from someone who’s been watching walruses via a live stream (at: 808ne.ws/1BAGACw) from Alaska’s Round Island.

“Some walruses poke others with their tusks, almost to the point of being pushy jerks,” he or she wrote. The writer wanted to know what was happening in that “great mound of walrus?” Is there a pecking order as to what part of the beach individuals lie on? And why do they mostly lie on their backs?

walrus

The entire Pacific walrus population (there’s an Atlantic one, too) winters in the Bering Sea on and around the pack ice. Mating takes place in the water in January and February, with males fighting one another for females.

When two males meet, they raise their heads from the water and turn sideways, showing their tusks. Often that’s all it takes, and the male with the smaller tusks backs down. If the rivals have tusks of equal size, the fight is on; sometimes males pierce each other with those strong, pointed weapons.

With skin an inch or more thick, however, punctures aren’t usually lethal.

walrus

Pups are born 15 months later in the spring. At that time, the sexes separate. Females with offspring migrate north to the Chukchi Sea, where they live on pack ice. Males head south to Bristol Bay, where, between foraging for clams, they haul out to rest on land, in some places by the thousands.

And that’s what we’re watching on the webcam. That great mound of walrus is a pile of bulls. You can tell they’re males from the bumps on the necks and shoulders called “bosses,” and the huge tusks. The largest are 3 feet long. Both sexes use their tusks to help pull their one-to-two ton bodies from the water onto ice floes, hence their nickname “tooth walkers.” The tusks are also handy for chopping holes in the ice to dive or breathe through, and as bayonets to fight off polar bears and orcas.

Walrus Cam - Round Island (968222)

Walruses are highly social animals that like to travel and rest in groups, but togetherness only goes so far. Females tusk-jab one other for better positions on ice floes and males tusk-fight other males for access to females.

I didn’t find anything in the walrus literature about why the males usually lie on their backs on the beach but it looks like a space issue. With those jutting tusks, it seems near-impossible for the animals to lie on their bellies, and there’s little room for sideways positions.

Nor did I find the answer to my question: If broken, do tusks grow back? The webcam shows individuals with broken and missing tusks.

The thousands of male walruses on Round Island beaches are there May through August. The biggest males with the largest tusks get the prime real estate at the top of the beach. But with coming and going for clam hunting, the guys in this crowd are constantly jostling, elbowing and poking one another to get back to the most favorable space.

The Alaska Department of Fish and Game lost their walrus webcam funding 10 years ago, but thanks to a charitable donation from Explore.org, there’s an excellent new system.

Only tune in, though, when you have time to spare. Walrus watching is addicting.

Walrus Cam - Round Island (968081)


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2015 Susan Scott