STEM Logo

Dive Dry with Dr. Bill

#436: Down on the Farm... Down Under

Many scientists believe that fish "stocks" throughout the world are dwindling fast as a result of over fishing. Funny, the only fish "stocks" I have first hand knowledge of were back in 6th grade when Mr. Becker had us students start a business called The Fish House to raise and sell tropical fish. In fact, that was the only company I've ever owned stock in. Back when I was young my grandfather, a survivor of the 1929 market crash, told me never to buy stocks. When he was in his late 80s or early 90s, I asked him how he was doing financially since he had retired decades before. He said "Great... all because of my utility stock dividends." I asked him why he told me never to buy stocks and he replied "I meant back then."

Hmmm. I guess my "senior citizenitis" caused me to digress a bit. I was actually referring to the populations of wild fish that are harvested in international waters where the principle of "the common" rules for the most part. In other words, it's pretty much a fiasco. Some nations greatly overfish certain species in these waters, resulting in declines of as much as 90% of the pre-exploitation levels. Those nations exhaust these resource for others, just as some cows exhausted the grass in "the common" of early American towns by taking more than their share. Good examples are the pre-WWII depletion of marine life in the Sea of Cortez by the Japanese, the intense harvesting of lucrative bluefin tuna globally, and the overfishing by foreign ships off the coast of Somalia that helped trigger anger by local fishermen that has now turned into rampant piracy.

In response to diminishing numbers of wild fish, many are putting their "stock" into aquaculture, or "fish farming." But raising fish like Atlantic salmon in large pens with very dense populations contained in relatively small areas is hardly free from ecological problems. Feeding these fish requires large amounts of food. Initially some foods were based on grains, but more and more aquaculture companies have looked towards wild fish such as anchovy, sardines and mackerel that can be harvested in large numbers... and ground up into fish "meal." This reduces food available for wild predator fish to use in their recovery.

If you were an ecology student of mine in the early 70s, you know that "We are what we eat... minus what we excrete." Even those who didn't attend my classes must realize that large numbers of fish fed large amounts of food in a relatively small area produce prodigious poop! Concentrated caca is not good for (wo)man or beast. It increases the likelihood of disease, artificially elevates levels of nutrients that can imbalance local ecosystems and is just plain gross! Recent studies by Stanford-based scientists indicate that these wastes do not disperse uniformly ("dilution is NOT the solution"). They may form high concentration plumes that can disperse and affect marine life for miles. Get my drift?

Highly concentrated populations also lead to rapid transmission of disease and parasites. Here on Catalina we learned this lesson during the late 90s when our endemic island fox population crashed. The population had been at very high density by the mid 90s. Then canine distemper struck, beginning near the East End and traveling toward the West. We were fortunate it did not penetrate past the Isthmus very much, leaving a much reduced population there to begin its recovery and the captive breeding program we initiated prior to my departure from the Conservancy. With farmed fish, a disease or parasite that affects the pens can easily be transmitted to any wild stocks in the waters outside. In addition, fish farms often use concentrated antibiotics to combat these diseases and they can have their own ecological impacts.

Given these ecological concerns about fish farming, are there ways we can address them and successfully raise food this way? I learned of some last year when I visited Mom in Sarasota and was given a tour of Mote Marine Lab's facilities and an update on their programs. Mote has long been a leader in a number of different areas of marine research including sharks, coral reef ecosystems, marine mammals and sea turtles to name a few. As a long time visitor to Sarasota, I was well aware of their research and educational programs which date back over 50 years. During this visit, one of the newer projects that really intrigued me was their Center for Aquacultural Research.

Declining wild fish stocks and increased demand for seafood make ecologically sensitive aquaculture a high priority for the future. Mote's Center is looking at ways to expand production without incurring the serious ecological side effects found in many current operations. As a nation, the U.S, imports 70% of the fish it consumes resulting in a trade deficit of about $8 billion, second only to the trade deficit caused by oil imports. Inland from Sarasota Bay, Mote operates a 200 acre facility that raises species including sturgeon, snook, red snapper, red drum, pompano and conch. No, you won't find those in the Casino Point dive park (at least I hope not). The scientific research associated with these projects is published in hopes of improving the practice of aquaculture through out the world. In addition, Mote provides native species for ecologically restoring affected wild habitats.

Mote is unique in that its facility uses a closed system to recirculate sea water after purifying it so there is no waste introduced into natural ecosystems or need for a continual supply of new sea water. This allows fish farms to be located inland where property may be more available and reasonable in price rather than along the immediate coast. Computers automate the process of feeding the fish, resulting in less waste of food. The water cleansing process involves settling ponds where solid wastes are broken down naturally. Marine and wetlands plants filter out the excess nutrients from fish food and fish waste, and the plants are used for ecological restoration as well. Mote uses no antibiotics in their operation which eliminates another concern.

Much as I enjoy "swimming with the fishes" (and not in the manner employed by members of another Chicago "family"), I must admit I enjoy eating some of them as well. I do so in moderation. There are some, like sharks, I won't touch. I made a pact with "the landlord" when I moved here... I won't eat sharks as long as they don't eat me. So far that has worked remarkably well. I haven't harvested anything from the sea in decades and only eat what others have legally taken. I am glad to know of operations like Mote that are helping to make aquaculture an ecologically, and financially, viable option to supply me with seafood in my "golden years."

© 2011 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

To return to the list of ALL of Dr. Bill's "Dive Dry" newspaper columns, click here.


Young "Dr. Billy" (on left) and The Fish House board of directors, farmed and wild salmon in Vons;
Mote Marine Lab entrance area and sturgeon raised in their aquaculture facility.

This document maintained by Dr. Bill Bushing.
Material and images © 2011 Star Thrower Educational Multimedia