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TECHNICAL NOTE NO. 45 - PREPARATION OF DRIED FISH SOLUBLES FROM CONCENTRATED PRESS LIQUORS ON A LABORATORY SCALE

Recent imports and subsequent use of dried fish solubles in this country have renewed interest in the possible domestic manufacture of this product. Earlier attempts by the U. S. Bureau of

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Commercial Fisheries to
produce dry solubles by
drum drying were not suc-
cessful because the final
product was hygroscopic.
Subsequently, it was

thought that a suitable prod-
uct might be obtained by the
use of organic solvents.
Accordingly, two prelim-
inary laboratory-scale
tests were carried out on
concentrated ocean perch
press liquor containing
50-percent solids.

The first method involved distillation with ethylene dichloride. Approximately two volumes of boiling ethylene dichloride were added to the press liquor and the two components were mixed together. This mixture was then added to approximately twice its volume of boiling solvent (ethylene dichloride) in a distilling flask. Distillation was carried out under reduced pressure, provided by an aspirator pump, until the distillate was clear. The solids were separated from the ethylene dichloride remaining in the flask by filtration on a Buchner funnel, washed with fresh solvent, and then placed under vacuum at 90° C. (194° F.) to remove final traces of solvent. The total solvent used in the entire procedure was about five times the volume of the concentrated liquor.

FIG. 1 PRODUCING DRY MENHADEN SOLUBLES ON PILOT PLANT DRUM
DRIER.

The second method of preparing the dried solubles was a cold extraction with mixed solvents. Approximately two volumes of methanol-acetone (1:1) were added to the press liquor in a Waring blendor, and then mixed for two minutes. The solvent was removed by filtration on a Buchner funnel, and the filter cake was remixed for 30 seconds with approximately two volumes of methanol-acetone (0.5:1). The solids were filtered off and remixed a third time for ten seconds with approximately one volume of acetone. The mixture was filtered and the filter cake was washed with approximately one volume of methanol. Solvent traces were removed under vacuum at 90 C. (194 F.) The total solvent used in the entire procedure was about six times the volume of the press liquor.

A proximate analysis of a sample prepared by each method is shown in table 1.

The dry solids were readily ground in a mortar to powders which differ in physical properties in that the distillation-dried material is somewhat lighter in color

Table 1 - Proximate Composition of Dried Ocean Perch Solubles Prepared by Ethylene Dichloride Distillation and by Methanol-Acetone Extraction

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the extracted material. and stronger in odor than When exposed to the air the powders do not readily absorb moisture and remain free flowing.

These procedures are tentative and additional trials by industry, either in the laboratory or on a pilot-plant scale,

would probably indicate that smaller volumes of solvent can be used, particularly in the extraction method where it may also be found that different ratios of methanol to acetone are more efficient, or even that a single solvent can be used. These considerations would have an important bearing upon the economics of the process.

Because of the preliminary nature of this work no effort was made to determine the effect of solvent treatments on the nutritive values of the dried solubles.

--BY GEORGE MANGAN AND JOSEPH H. CARVER, CHEMISTS,
MAYNARD A. STEINBERG, BIOCHEMIST,

EAST BOSTON (MASS. FISHERY TECHNOLOGICAL LABORATORY,
DONALD SNYDER, BIOCHEMIST,

COLLEGE PARK (MD.) FISHERY TECHNOLOGICAL LABORATORY,
BUREAU OF COMMERCIAL FISHERIES

ONE SKIPJACK TUNA TAGGED TWICE AND CAUGHT THREE TIMES

A skipjack tuna (a ku) with an insatiable taste for feather lures has set some sort of record in local piscatorial circles by getting himself on the hook three times within 16 days, the last time for good. According to the Director of the Pacific Oceanic Fishery Investigations of the U. S. Bureau of Commercial Fisheries, the small 6-pound tuna was first caught on November 20 by a fisherman on the Bureau's research vessel John R. Manning off the island of Lanai. A plastic dart tag was jabbed into the back of the tuna just below his second dorsal fin and he was tossed back into the ocean "in the hope that subsequent recaptures (for which the chances are currently running about 8 in 100) may shed light on the little understood movements of this commercially-valuable species in Hawaiian waters."

Only three days later, in the same area off Lanai, the same tuna was again caught by the John R. Manning. The sea-going scientists, busy tagging tuna, were a bit surprised to find one of their subjects already outfitted with one plastic streamer, but they quickly attached a second tag and again tossed the fish back into the sea.

and When the commercial sampan Dolphin fished off Lanai on December 6, chicken feather jigs were once again on the menu, the twice-tagged tuna was again caught for the last time.

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NATIVE FISHERMEN LEARNING LONG-LINE TUNA FISHING TECHNIQUE: The native Americar Samoans are learning the long-line method of tuna fishing, which the Japanese have successfully developed. A former naval 50foot tender has been made available for the project, and the Samoan fishermen have demonstrated their ability to catch big fish on a limited commercial scale. The only limit now seems to be imposed by their boats and fishing gear, and it has been rumored that the idle M/V Samoa may be leased by the Government of American Samoa for use as a fishing vessel.

The Samoan crew fishes off Tutuila, in sight of land, and disposes of its catch by selling tuna to the local cannery, and other types of fish are sold in Pago Pago direct to the local population for 10 cents a pound.

The Governor of American Samoa takes a close personal interest in the possibility of developing commercial fishing as a major Samoan industry. He has arranged permission to appoint each year a candidate from American Samoa to the U. S. Maritime Academy in New York on a full scholarship basis with all traveling and tuition expenses paid. This program should provide qualified Samoan masters of future fishing vessels.

Looking beyond the Samoan group, the Governor sees the possibility of Fijians, Tongans, and other South Pacific Islanders joining in a large scale commercial-fishing operation, reaping direct benefit from the valuable fish which abound in their waters.

A substantial amount of fish is being caught by Japanese fishermen in South Pacific waters for sale to the American Samoa cannery operated on a lease basis by a large United States west coast canner. The Governor feels that the Samoan people should have an opportunity to share in this growing industry.

The fishing industry has been a great boon to American Samoa. The Pago Pago cannery employs between 350 and 400 local people in the processing and packing of the tuna which 30 to 40 Japanese fishing vessels deliver to the cannery regularly.

The cannery's payroll is estimated to contribute a quarter of a million dollars annually to American Samoa's national income. More than any other factor, the cannery operation gives back to American Samoa the prosperity it lost when the U.S. Navy closed down its base in Pago Pago in 1950 (Samoa Bulletin, March 28, 1958).

Byproducts Production for U. S. & Alaska in 1957

The United States and Alaska production of fish meal and scrap amounted to over 262,000 tons during 1957--a decline of 33,000 tons or 11 percent as compared with 1956. The production during JuneAugust made up nearly 50 percent of the year's total.

Imports of fish meal during 1957 amounted to 81.2 thousand tons as compared with 91.4 thousand tons imported during 1956.

Production of fish oil dur

Thousand Tons

300

250

200

United States Production and Imports of Fish Meal, 1936-1957

FISH
MEAL

150

LEGEND:

DOMESTIC PRODUCTION
IMPORTS

100

50

ing 1957 totaled 20.1 million gallons, compared with 26.8 million gallons during 1956. A drop in the production of oil

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from menhaden--down 6.6 million gallons--was largely responsible for the over

all reduction in oil.

The yield of fish solubles during 1957 amounted to 187.8 million pounds. This represented a decline of 10.3 million pounds as compared with 1956. During 1957, the production of homogenized-condensed fish amounted to 56.8 million pounds--a drop of 2.8 million pounds as compared with the previous year.

Domestic Production, Imports, and Exports of Fish Oil, 1936-1957

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AERIAL TECHNIQUES BEING DEVELOPED TO CENSUS COMMERCIAL AND SPORT FISHING (Airplane Spotting Flight 58-1): To establish procedures for applying aerial techniques to census both commercial and sport fishing operations was the purpose of this airplane flight by the California Department of Fish and Game's Cessna 3632C. Since the results were encouraging, future aerial scouting routines will be devised. Considerable information was obtained on the possibilities of counting units of crab gear in the water and in making instantaneous counts of sport fishermen, both clam diggers and hook-and-line fishermen.

The inshore area between Yankee Point, Monterey County, and Bodega Bay, including San Francisco, Drakes, and Tomales Bays was surveyed by air to: (1) Establish procedures for applying aerial techniques to censusing the crab fleet, crab gear in operation, and sport clamming activity. (2) Tally the number of hook-and-line fishermen utilizing the beaches, piers, jetties, and rocky areas. (Dingell-Johnson Federal Aid Project F-12-R). (3) Scout for pelagic fish schools.

Weather conditions were excellent on March 2, with very clear skies and calm water prevailing over the entire area. On the 3rd rain showers prevented scouting until 10 a.m. but thereafter weather conditions were comparable to those on the previous day.

Crab Fishing Census: The crabbing area from Half Moon Bay to Bodega Bay was flown to determine the techniques of aerial censusing applicable to counting crab gear and crab boats as well as delineating the area of crab fishing activity.

The buoys of crab traps were visible at altitudes up to 2,000 feet. However, accuracy in survey observing would be best at 800 to 1,000 feet. Pictures were taken over the buoys at several altitudes from 800 to 2,000 feet. Infrared and Kodachrome film was used to determine which film would most clearly show the buoys on the surface of the ocean.

Twenty-one strings of traps consisting of 24 to 45 units were observed. These traps were set over sandy bottoms from Half Moon Bay to Bodega Bay

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AERIAL FISH SPOTTING UTILIZED BY SOME CALIFORNIA VESSELS: Some California vessels regularly and others erratically utilize planes to aid them in spotting fish. All of the plane spotters operate as independent contractors and they are hired by the vessels. There is no cannery, market, or any other commercial processing plant that hires plane spotters. This is probably due to the fact that in California there are only a few vessels that are owned and totally-controlled by canners. Practically all of the vessels operate individually and have contracts with canners for their fish catches.

Most of the spotters, at the present time, sell their services to the individual fishing vessel owners and their crews. The agreement for payment between the vessel owners and crews and the plane spotters provides for two different arrangements, depending upon which the parties prefer. One arrangement is that the plane spotter receives 7 percent of the gross proceeds of the catches the vessel makes as a direct result of the spotter setting them on the fish. The other arrangement is that the vessel pays the fish spotters 5 percent of the gross proceeds of all the fish the

vessel catches, whether or not the plane spotter is responsible for the catch.

The number of spotters varies greatly. It depends upon the season, availability of fish, and skill. At the present time, however, there are 8 pilots or spotters operating out of San Pedro. Although during the height of the sardine season there will be as many as 15, only a very small percentage of these pilots spot for fish on a full-time basis. Most of them have other jobs and drop in and out of plane spotting, depending upon whether they can make any money or not.

The equipment most of them use consists of a small light plane, such as a Piper or a Cessna, which is equipped with a two-way radio. None of the planes presently operating are float planes. Although float planes have been used in the past, they are considered impractical due to the extra maintenance costs. Two amphibious planes were also used in the past, one a "Widgen" and the other a "See-Bee." Both these planes proved to be expensive to operate and maintain and dropped out.

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