Oysters.us - Remote Setting 1

Remote Setting (Part 1)
John W. McCabe

The term remote setting describes the act of procurement of competent bivalve larvae, especially oyster larvae, and inducing their metamorphosis elsewhere.

Typically, a shellfish hatchery will raise bivalve larvae all the way up to the eyed pediveliger stage (footed larvae with "eye spots"). Such larvae are deemed ready to attach temselves to some surface (i.e. deemed competent or ready to set). Hatcheries will then sell some or all of such larvae to shellfish growers who make necessary preparations at their facilities to then take the larvae to the next developmental stage. It's a win-win situation. The shellfish hatchery is relieved of any further growing expense and risk. In turn, shellfish grower are able to buy immense numbers of larvae at a modest price.

The larvae of several commercially important bivalve species lend themselves to remote setting, most notably oyster larvae and, to a much lesser extent, clam larvae. What follows is a description of remote setting with Pacific (or Japanese) oyster larvae (Crassostrea gigas). Remote setting of larvae of other bivalve species can be (in most cases is) more demanding.

Although remote setting has been essential in sustaining very high oyster production levels of Pacific oysters on the U.S. and Canadian West Coast for decades, the outcome of a remote setting effort by a grower is never predictable. Even the most experienced grower faces uncertainties. As such, remote setting adds to the fact that nothing is, or ever has been, easy in the oyster business.

Since it all starts at a shellfish hatchery, let's go there first.

Welcome to "Whoville"
A shellfish hatchery is a surreal place. Quadrillions of marine organisms live here together, silently, in a space that typically measures less than a soccer field. Most are invisible. Many millions of microalgae can fit in a thimble and several million shellfish larva can easily be carried in the palm of one's hand. Somehow, Dr. Seuss' Whoville comes to my mind.
The low, monotonous whir of pumps harmonizes well with the hum of lighting ballasts. Many water receptacles of varying shape and size chime in discreetly with burbling sounds. The air tastes moist and fresh and the temperature is comfortable. There are no seasons here. Everything looks tidy and clean. To the casual visitor, this world seems intriguing and somewhat surreal. Closer study, however, exposes brutal realities. If someone turns off the electrical supply, all of this "marine Whoville" will very soon cease to exist. The threat of death by starvation, disease, water quality issues (e.g. acidification, pollution) or equipment malfunction is omnipresent - 24/7.

Surprisingly few humans operate this place. In a pinch, as few as two or three competent people could work hard to keep this huge menagerie of fragile plants and animals alive.

The underlying principle of a commercial shellfish hatchery is simple: grow enough microalgae to feed enough bivalve larvae that will turn into enough seed that will satisfy the requirements of enough shellfish growers to generate enough hatchery income to justify its existence. Clearly, the problem-word in that absurdly long sentence is "enough". For example, what quantities of what species of microalgae (aka phytoplankton) at what stage of development are enough to make 1 billion oyster larvae in an early stage of development happy? Some hatcheries grow more than 20 different microalgae species to make sure that every bivalve species raised is assured its special daily "phyto-cocktail". What if thousands of liters of one microalgae species culture suddenly "crash"? A "crash" describes sudden death of microalgae cultures due to one or more reasons. It can happen overnight (as I have learned the hard way with my small algal cultures at home). A hatchery is usually prepared for such crashes by growing enough microalge to offset such a loss. I could easily list twenty more risks in a hatchery operation, some far greater than "phyto crashes". However, this would lead us too far away from the topic of remote setting. For now, suffice it to say that operating a shellfish hatchery can be an exceedingly expensive and risky business.

Inset image: Microalgae (or phytoplankton) growing containers (so called reactors). The green algae in the foreground is unknown to this writer (most algae species in shellfish hatcheries are green). The golden-brown algae in the background is likely a dense batch of the species Isochrysis galbana, certainly a shellfish hatchery favorite. Click image to enlarge.

Shellfish hatcheries for American oysters (aka Eastern oysters; C. virginica) date back to fledgling beginnings in the 1920s.




Inset image: A news blurb touting The Pedigreed Oyster in the Reading Eagle, March 18, 1927 (found in Google News Archive).

Pioneering work in successfully completing oyster development from a larval to early post-larval state in volume in a closed, controlled environment on a small scale can principally be attributed to W. F. Wells (1920) and H. F. Prytherch (1924, 1937). They built on and completed the remarkable research of W. K. Brooks (1891) and others. Large scale, reliable hatchery production of larval to post-larval oysters (C. virginica) was not perfected until the 1960s. Although Paul S. Galtsoff and Victor Loosanoofare usually associated with this success, there were numerous other naturalists that greatly contributed as well. In the 1970s, shellfish hatcheries rapidly expanded from the U.S. East Coast to also include the North-American West Coast. Since then, many more shellfish hatcheries have been built worldwide. In 1979, a detailed account of the history of shellfish hatcheries titled Oyster Seed Hatcheries on the U.S. West Coast: An Overview was furnished by J. W. Clark and R. D. Langmo.

Some large shellfish growers operate their own hatcheries to insure their stocking needs and sell surplus seed to other, typically smaller shellfish growers. Various universities also maintain sophisticated hatchery operations. Although such hatcheries usually focus on research and training, some are capable of producing commercial quantities of seed.
Most growers either can't afford or don't care for the risks involved in running a hatchery. However, a great number of North American oyster growers, most notably on the U.S. and Canadian West Coast, and also some clam growers, dare to short-circuit the typical hatchery grow-out from sensitive bivalve larvae to seed. They buy a hatchery's larvae in vast quantities and do the rest themselves. In fact, U.S. West Coast demand for oyster larvae has, for decades, been so great, that it can be feasible to specialize a shellfish hatchery operation on oyster larvae. The oldest and most famous hatchery of this type in the world is the Whiskey Creek Shellfish Hatchery in Tillamook, Oregon, USA. (view a short YouTube film by clicking HERE).

Spawning at the hatchery
As noted above, this example of remote setting focuses on Pacific (or Japanese) oysters (C. gigas). Most shellfish hatcheries keep so called brood-stock on hand. The term describes a relatively small number of mature bivalves that have been selected as likely to produce offspring with characteristics that
are desirable in the shellfish industry. The most obvious such desires are rapid growth, good meat weight, sound shells and a hardy constitution. It has long been known that among bivalves, all things being equal, a few develop better (from a subjective, commercial perspective) than others. Those few individual bivalves are candidates for hatchery brood-stock. Selective breeding of Pacific and Eastern oysters has been diligently studied and applied for decades. In terms of the Pacific oyster, the biggest name in brood-stock research on the North American West Coast (and quite possibly the world) is the Hatfield Marine Science Center, Oregon State University in Newport, Oregon, USA.
Unlike spawning in a natural setting, a hatchery does not depend on environmentally favorable circumstances. Instead, it creates such necessary circumstances whenever needed. Their brood-stock spawns when directed to do so by the hatchery operators. There are several ways to "convince" bivalves that the time for spawning has come (e.g. sudden water temperature increase, artificially introducing gametes into the water).
As described earlier in this report (see Four-Groups), the probable outcome of an oyster-spawning event is fertilized eggs and subsequent oyster larvae - ideally, many millions of them. In hatcheries, these oyster larvae can take two routes. Some will stay in the hatchery and will be reared further into seed. Others will be sold, as mature larvae, directly to growers.




Inset image (click to enlarge): Oyster larvae rearing basins. The contents look like huge batches of some brown bouillon soup. Each basin contains several million larvae. Very close inspection with the naked eye faintly reveals some movement.

When it is time to fill an order from a shellfish grower, the hatchery operators filter batches of fully developed ("footed" and "eyed") oyster larvae from the water in their rearing basins. There are various ways to strain and count all these larvae. Even coffee filters have been used at times in the straining process of bivalve larvae. The larvae can then be centered on a small, porous fabric square that sometimes looks as if cut from an ordinary white bed sheet. The sides of the fabric square are then turned up, bunched at the top and banded, thus rendering a larvae package in the shape of a little ball. Such a ball with two million oyster larvae measures about the size of a golf ball. Once this procedure is done, time is of the essence. The larvae, now out of water, must stay moist and cool. Depending on the grower's order, one or several of these balls may have to be shipped promptly at the same time. In a small, Styrofoam lined box, the larvae balls are then bedded on all sides in moist paper towels or newspaper, along with one or more small cooling packs. A reliable overnight courier company then transports the larvae to the oyster grower.

Arrival of Larvae at a Grower
The inset image shows an example of the aforementioned shipping box of larvae. In this case, it came from the Whiskey Creek Shellfish Hatchery in the State of Oregon and was delivered promptly by a Federal Express man at 1200 hours Pacific Standard Time at the famed Olympia Oyster Company in the State of Washington.
It has been properly labeled on the lid of the Styrofoam box liner with the buyer's name and the quantity of "18 x 10, diploids, 3 - 6's". The first part of the label's lower text, highlighted with a red square in the inset image, indicates the total amount of larvae in this shipment. The timely Federal Express man can now easily trump any braggartry among his colleagues by validly claiming to have, single-handedly, transported eighteen million live oysters.

Dips and Trips
Next on the labeling, the term diploids is used. Diploid means, simply put, that these oyster larvae have, like humans, two sets of chromosomes. From the practical standpoint of a grower, the diploid post-larval oysters (i.e. after metamorphosis) are likely to grow at about the same rate that wild oysters would and, when reaching maturity, would be able to reproduce. In moderate climates with a fairly warm summer and fall, the oysters, when preparing to spawn, would often have a "milky" consistency and later, after spawning, their meat could seem sunken-in (a temporary condition called spawned out). Although such meat conditions are irrelevant to cooked oysters, many half-shell oyster lovers do not much care for "milky" or "spawned out" oysters.

Had the label read triploid instead of diploid, the larvae would have had, simply put, three sets of chromosomes instead of two. From the practical standpoint of a grower, the triploid oysters would grow at a considerably faster rate and 99% (or more) of them would never reproduce. Instead of preparing to spawn and turning milky, these oysters would just go right on feeding without investing resources into the production of gametes. Hence, triploids are unlikely to ever appear "milky" or "spawned out".

Today, at least half of the C. gigas larvae produced by shellfish hatcheries worldwide are triploid. The reader might wonder why any grower would buy diploid larvae and seed when triploids appear to be so commercially advantageous. There are a number of reasons that could prompt a grower to choose triploid oyster larvae or seed over diploid. Some growers appreciate the potentially substantial natural sets the diploids can produce in addition to the seed growing and remote setting a grower employs. After all, it is a well known fact that, for millennia, the extraordinary fecundity of oysters has been their recipe for survival. One grower advised that juvenile triploids simply did not survive on his tideland while diploids did. The principal of a large U.S. West Coast shellfish growing company recently informed me of excessively high mortality levels among his three to four year old C. gigas triploids. Many growers in France have blamed triploid oysters as the underlying reason for the recent outbreak of a devastating, herpes-like disease among one to two year old Pacific oysters in recent years. Some buyers who are firm adherents of the tenets of organically grown food simply don't want triploid oysters. They don't believe that mass production of triploid larvae and seed is natural - and they are correct. When, not if, oysters achieve a formal organic qualification, I feel certain that triploid oysters will not be acceptable - no more than oysters raised on tideland that has been sprayed with pesticides (a long-standing practice of big oyster growers on Willapa Bay in Washington State to kill indigenous mud shrimp).

Tennis Balls Instead of Golf Balls
A hatchery that sells oyster larvae can accommodate a grower that practices remote setting by packing and shipping various sizes of the aforementioned "larvae balls", usually in one million larvae increments. By doing so, the hatchery helps match a grower's remote setting tank size(s). In this example case, the label reads "3 - 6s", thus indicating that the shipping box holds three pouches (or "larvae balls") of six million oyster larvae each. A ball of six million oyster larvae measures about the size of a tennis ball. Subsequently, the hatchery had to utilize a piece of fabric measuring about 24 x 24 cm (~ 9.5 x 9.5 inches) for each ball. The Olympia Oyster Company operates three large remote setting tanks. Each tank requires six million larvae for remote setting.

William W. Budge
The methodology of shipping lots of little cloth pouches full of millions of oyster larvae from a hatchery to far-away oyster growers for remote setting is certainly a great invention, particularly if one considers that this invention revolutionized U. S. West Coast oyster cultivation back in the 1970s. I had often wondered who came up with it.

For online searches of U.S. American patents and trademarks, the United States Patent and Trademark Office (http://www.uspto.gov) provides several powerful search utilities. Most bountiful (and very fast) patent searches can also be conducted via http://www.google.com/patents. Thousands of oyster-related U. S. patents exist. The reading of just a small fraction can easily keep an oyster aficionado engaged for many hours on end. The mixture ranges from brilliant ideas to blatant opportunism, devoid of any ingenuity. Someone hoping to develop or further some new method or design that could actually be of great value to others might grow discouraged when trying to navigate this jungle of preexisting patent claims to avoid potential infringement. Oftentimes, talented attorneys have applied their formidable wordsmithing skills to the descriptive language of patents, thereby expanding the coverage of patent protection to the outermost limits of what might be called "interpretative clarity". For example, in an excellent report on cultchless oyster setting back in 1981, the researchers Herbert Hidu, Samuel R. Chapman and David Dean devoted an interesting paragraph to the discussion of the associated legal minefield. The paragraph ends as follows:

"[…] It is literally impossible to rear a cultchless seed oyster without infringing on someone's broadly stated patent. Unfortunately, the
remaining problems with rearing cultchless oysters appear
not to be biological, but legal."

It so happens that one of the patents on the production of cultchless oyster seed lamented in this paragraph, patent # 3,526,209, was granted to the person who also was granted the unrelated patent # 3,735,737: William W. Budge. This patent application was filed Sept. 14, 1970, with the title "Method and Package for Storing and Shipping Oyster Larvae". The patent describes almost precisely today's modus operandi of shipping hatchery larvae to oyster growers - and even includes a drawing of how to fold the square of cloth around a little pile of oyster larvae to produce the aforementioned "golf balls". On May 29, 1973, the patent was granted to William W. Budge from Hillsborough, California. The assignee was Pacific Mariculture, Inc. in Pescadero, California.

The results of my search of William W. Budge (commonly called Bill Budge) and Pacific Mariculture suggest that he was a brilliant and dedicated scientist who served as the president of said company. Back in the 1960s and 70s, Pacific Mariculture worked on the cutting edge of marine aquaculture, primarily in the area of abalone cultivation and secondarily in oyster cultivation. An online publication titled "ADVANCES IN THE REMOTE SETTING OF OYSTER LARVAE", prepared by Gordon and Bruce Jones, funded by the Aquaculture and Commercial Fisheries Branch of the British Columbia (BC) Ministry of Agriculture and Fisheries , furnishes some details of Budge's pioneering work in remote setting. In combination with his according U. S. patent # 3,735,737, I find it reasonable to honor William W. Budge as the "Father of Commercial Remote Setting of Oysters".

Part 1 Part 2
Top of Page

 

Footnotes located at the bottom of Part 2

Health advisory: There is a risk associated with consuming raw oysters or any raw animal protein. If you have chronic illness of the liver, stomach, or blood or have immune disorders, you are at greatest risk of illness from raw oysters and should eat oysters fully cooked. If you are unsure of your risk, you should consult your physician.



Advisements on any errors discovered are most welcome: Contact
© 2019 John W. McCabe