North Pacific Gyre | Images of Old Hawaiʻi

Historically the world was thought of having 4 oceans the Pacific, Atlantic, Indian and Arctic. Today we have five oceans (adding the Southern (around Antarctica)) covering over 71 percent of the earth’s surface and over 97 percent of the earth’s water. (National Geographic)

The term ‘Seven Seas’ has referred to bodies of water along trade routes, regional bodies of water, or exotic and far-away bodies of water.

In Greek literature (which is where the phrase entered Western literature), the Seven Seas were the Aegean, Adriatic, Mediterranean, Black, Red and Caspian seas, with the Persian Gulf thrown in as a “sea.”

In Medieval European literature, the phrase referred to the North Sea, Baltic, Atlantic, Mediterranean, Black, Red and Arabian seas.

As trade picked up across the Atlantic, the concept of the Seven Seas changed again. Mariners then referred to the Seven Seas as the Arctic, the Atlantic, the Indian, the Pacific, the Mediterranean, the Caribbean and the Gulf of Mexico.

Not many people use this phrase today, but you could say that the modern Seven Seas include the Arctic, North Atlantic, South Atlantic, North Pacific, South Pacific, Indian and Southern Oceans. (NOAA)

Oceans have currents, the continuous, predictable, directional movement of seawater driven by gravity, wind and water density. Ocean water moves in two directions: horizontally and vertically. Horizontal movements are referred to as currents, while vertical changes are called upwellings or downwellings. (National Geographic)

Ocean currents exist both on and below the surface. Some currents are local to specific areas, while others are global. And they move a lot of water. The largest current in the world, the Antarctic Circumpolar Current, is estimated to be 100 times larger than all the water flowing in all the world’s rivers.

A characteristic surface speed is about 2 to 20 inches per second. Currents generally diminish in intensity with increasing depth.

Vertical movements exhibit much lower speeds, amounting to only a few meters per month. As seawater is nearly incompressible, vertical movements are associated with regions of convergence and divergence in the horizontal flow patterns. (Britannica)

All of this moving water helps more stationary species get the food and nutrients they need. Instead of going looking for food, these creatures wait for the currents to bring a fresh supply to them.

Currents also play a major role in reproduction. The currents spread larvae and other reproductive cells. Without currents many of the ocean’s ecosystems would collapse. (Ocean Blue Project)

Ocean surface currents tend to form ring-like circulation systems called gyres. A gyre is a circular ocean current formed by a combination of the prevailing winds, the rotation of the Earth, and landmasses.

Continents interfere with the movement of both surface winds and currents. Gyres form in both the northern and southern hemispheres.

Gyres in the Northern Hemisphere travel in clockwise directions while gyres in the Southern Hemisphere travel in counter-clockwise directions. It takes about 54 months for water to travel the circuit of the North Pacific gyre, while only 14 months in the North Atlantic gyre.

In the Northern Hemisphere near the equator, trade winds drive currents westward, forming a North Equatorial Current (NE), which moves at about 1 m/sec. At the western boundary of an ocean basin, the water turns and flows towards the North Pole, forming the western-ocean boundary currents.

Western boundary currents are very strong. Two examples are the Gulf Stream (GS) that runs in the Atlantic ocean basin and the Kuroshio Current in the Pacific ocean basin.

They are narrower, but deeper and swifter, than the other currents in the gyre. For example, speeds of 2 m/sec have been measured in the Gulf Stream. These currents, as deep as 1 km, generally remain in deeper water beyond the continental shelf. Western-ocean boundary currents carry warm water from the equator north.

The broad, gentle pitch of the continental shelf gives way to the relatively steep continental slope. The more gradual transition to the abyssal plain is a sediment-filled region called the continental rise. The continental shelf, slope, and rise are collectively called the continental margin. (Britannica)

Eventually, the western boundary currents fall under the influence of the westerly winds and begin flowing to the east, forming the North Atlantic Current (NA) and North Pacific Current (NP).

When they approach the eastern-ocean boundaries of continents, they turn and flow south, forming the eastern-ocean boundary currents. Eastern-ocean boundary currents are shallower and slower than western-ocean boundary currents.

Current flow over the continental shelves (the edge of a continent that lies under the ocean), close to shore, carrying colder waters from the north to the south. Two examples are the California Current (Cal) in the Pacific Ocean basin and the Canary Current (Can) in the Atlantic Ocean basin.

One major current, the equatorial Countercurrent (EC), appears to be an exception to the circulation pattern set up by the gyres. This countercurrent forms just north of the equator in the region between the north equatorial current and the south equatorial current and flows in the opposite direction. (Hawaii-edu)

I suspect many people would believe the occasional glass fishing float found on our shores is strictly a Japanese and Pacific Ocean phenomenon.

Actually, the first glass fishing floats probably came from Norway and were used in the Atlantic. From 1762 to 1880, a Norwegian glass company was in business and it is believed they were producing glass floats as early as the late-1700s.

The first time these “modern” glass fishing floats are mentioned is in the production registry for Hadelands Glassverk in 1841. The registry shows that this is a new type of production.

However, there might have been some other versions of glass floats in use before that time. In the early 19th-century, the Schimmelmanns Glassverk (1779–1832) produced dark brown and very thick, bottle glass floats.

Aasnaes Glasvaerk, in business from 1813 to 1883, produced 122,493 glass floats just in the year 1875. A glass float with Aasnaes’s mark on the seal button is a collector’s item.

Early evidence of glass floats being used by fishermen comes from Norway in 1844, where small egg-sized floats were used with fishing line and hooks. Around the same time, glass was also used to support fishing nets.

The Japanese started producing small glass floats in the early-1900s and the first Asian floats came ashore along the West Coast just before 1920.

These Japanese floats are part of early recycling efforts – initial Japanese floats were made from recycled sake bottles. Most floats are shades of green because that is the color of glass from these sake bottles (especially after long exposure to sunlight).

Other brilliant tones such as emerald green, cobalt blue, purple, yellow and orange were primarily made in the 1920s and 1930s. The most prized and rare color is a red or cranberry hue.

To accommodate different fishing styles and nets, the Japanese experimented with many different sizes and shapes of floats, ranging from 2 to 20 inches in diameter. Most were rough spheres, but some were cylindrical or “rolling pin” shaped.

Asahara Glass Company had several factories and made a variety of sizes. Asahara made baseball- to orange-size floats for tako jigs, salmon gillnetting and seine fishing; grapefruit-size floats for seine and long-line cod fishing; basketball-size for tuna operations, bottom trawls and crab trapping; and the small rolling pin floats were used for tako jigs and troll fishing.

The earliest floats, including most Japanese glass fishing floats, were hand made by a glassblower. Recycled glass, especially old sake bottles, was typically used and air bubbles in the glass are a result of the rapid recycling process.

After being blown, floats were removed from the blowpipe and sealed with a “button” of melted glass before being placed in a cooling oven. This sealing button is sometimes mistakenly identified as a pontil mark (scar where the punt was broken from a work of blown glass.) However, no pontil (or punty) was used in the process of blowing glass floats.

While floats were still hot and soft, marks were often embossed on or near the sealing button to identify the float for trademark. These marks sometimes included kanji symbols.

A later manufacturing method used wooden molds to speed up the float-making process. Glass floats were blown into a mold to more easily achieve a uniform size and shape.

Seams on the outside of floats are a result of this process. Sometimes knife markings where the wooden molds were carved are also visible on the surface of the glass.

By 1939, millions of Japanese glass floats were being used; although Japanese glass fishing floats are no longer being manufactured for fishing, there are thousands still floating in the Pacific Ocean.

By the 1940s, glass had replaced wood or cork throughout much of Europe, Russia, North America and Japan.

Today most of the glass floats remaining in the ocean are stuck in a circular pattern of ocean currents in the North Pacific Gyre.

Off the east coast of Taiwan, the Kuroshio Current starts as a northern branch of the western-flowing North Equatorial Current. It flows past Japan and meets the arctic waters of the Oyashio Current.

At this junction, the North Pacific Current (or Drift) is formed which travels east across the Pacific before slowing down in the Gulf of Alaska.

As it turns south, the California Current pushes the water into the North Equatorial Current once again, and the cycle continues.

Although the number of glass floats is decreasing steadily, many floats are still drifting on these ocean currents. Occasionally, storms or certain tidal conditions will break some floats from this circular pattern and bring them to ashore.

They most often end up on the beaches of Hawaiʻi, Alaska, Washington or Oregon in the United States, Taiwan or Canada.

Today, most of the remaining glass floats originated in Japan because it had a large deep sea fishing industry which made extensive use of the floats; some were made by Taiwan, Korea and China.

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