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water is then circulated to freeze the fish. In addition, more water is sprayed on the pipes where the ice has been built up, and as this cold water drips on the fish it also chills the fish. The addition of catches on top of alreadyfrozen fish seems to have no effect, the frozen fish being sufficiently cold so that they are not thawed. In fact, the ice that has been built up on them is helpful in cooling the brine water which is being circulated to freeze the new catch.

Benefits to be anticipated with the new freezing system:

(1) Efficiency will be increased in loading and unloading because the fish can be brought aboard and stowed below in about half the time required on a standard coil vessel. This is an extremely valuable factor when the fish are schooling as at that time every hour gained can be worth days and even weeks of searching. In this new method, the fish are brailed directly from the water into the hold through the hatch or the manholes, instead of being first brailed on the deck and stowed below later, as is the custom in the vessels equipped with standard coil systems.

(2) The quality of the fish will be better because it will be in the hold and under refrigeration in about half the time previously taken. When one considers that on the fishing grounds the water temperature is often as high as 85 90 F., with an air temperature of from 100 to 120° F., speed in getting the fish under refrigeration as rapidly as possible is vital.

(3) The back-breaking work of going below and icing fish, which is necessary in vessels equipped with standard coils, is virtually eliminated. Now only 1 or 2 men go below when the fish are being brailed into the hatch, and these men simply steer the fish so that they lay fore and aft. The Jo Ann's hold is divided into three compartments extending fore and aft for the full length of the storage space. These three compartments keep the fish from rolling about in the hold and damaging themselves or possibly piling up on one side of the vessel and causing a list. The compartments also aid in unloading, as one compartment can be completely unloaded to the bottom of the compartment, and then it is much easier to unload the other two on either side. Formerly, when the fish were brailed on deck, it was necessary for at least 8 men to go below, break loose the ice that was carried by the vessel, and then have the fish passed down to them through manholes or the main hatch. The fish were then stowed in bins which were made of removable planks. Generally a layer of fish was stowed, and a layer of ice shoveled on top of them. This process continued until that bin was filled, and proceeded from bin to bin until the vessel was fully loaded. Due to the cramped quarters in which the men worked, and the large quantities of ice which were carried, there was much shifting of ice from bin to bin and a great deal of manual labor. All of this work has been eliminated and the physical efficiency of the crew is not taxed as heavily, with the result that the crew will be able to concentrate their physical activity on capturing fish when they are running. In the past after a heavy set crews would be exhausted and would have to rest rather than fish available schools. There is also the possibility that 1 or

2 men can be eliminated from the crew. This would result in an increase of earnings for the remaining crew members, and would amount to from $75 to $100 a crew member per trip for each man less.

Since installing this new system, the Jo Ann made three trips in the early part of 1957 with the following results:

Trip 1: The length of the trip was 65 days. The trip was made during the early part of the year when fishing was spotty. The vessel came in with a short load, 79,070 pounds of yellowfin tuna, 8,405 pounds of skipjack. Rejects amounted to 775 pounds of raw skipjack, 980 pounds of raw yellowfin, and 1,890 pounds of cooked skipjack. The catch was small and rejects were a little higher than the purse-seine average, but the crew felt that this was due mostly to mishandling on their part because of unfamiliarity with the new system. The equipment was not considered fully tested, but from the experience gained some modifications were made before the second trip.

Trip 2: The length of the trip was 24 days. Fishing was conducted off Cabo San Lucas, the tip of Lower California, and vicinity. The vessel came in with a load of 120,560 pounds of yellowfin tuna and 56,145 pounds of skipjack. Rejects amounted to 180 pounds of raw yellowfin, 1,440 pounds of cooked yellowfin, and 2,880 pounds of cooked skipjack. The average rejects were 2.4 percent as compared to the purse-seine average of about 2.5 percent. The crew felt that most of the rejects were due to their receiving 20 tons of fish from another vessel which had the fish in 80 F. water for over 15 hours.

Trip 3: This was practically a record trip. The vessel fished on the West Coast of Lower California and returned with a full load in 8 days. Due to unloading difficulties, the vessel waited 20 days before unloading. The vessel landed 124,075 pounds of yellowfin and 72,815 pounds of skipjack with only 2,875 pounds of raw skipjack rejected. There were no cooked rejects and the raw rejects were caused, according to the crew, to smashed fish due to large catches which prevented good sorting. This trip served as a severe test of the new system of refrigeration, and in the opinion of observers proves that the system is a success.

The principle of this type of refrigeration is not completely new, but the method is probably unique. At any rate it is the first time it has been adapted to a purse-seine vessel fishing tuna. It is also the first time that a converted coil system has been used to refrigerate fish under such warm water and air temperatures. Vessel owners and fishermen are enthused and predict a great future for the system, and as of April 1958 two other purse seiners installed similar systems and one seiner installed it partially.

--BY A. D. SOKOLICH, MARKET NEWS REPORTER

D. MONTGOMERY, FISHERY MARKETING SPECIALIST
BRANCH OF MARKET NEWS

DIVISION OF INDUSTRIAL RESEARCH AND SERVICES
BUREAU OF COMMERCIAL FISHERIES
SAN PEDRO, CALIF.

YELLOWFIN, SKIPJACK, AND BIG-EYED TUNA FISHERIES TRENDS: Trends in the domestic yellowfin, skipjack, and big-eyed tuna fisheries is the subject of a report submitted to the President and the Congress on May 22 by the Secretary of the Interior Fred A. Seaton.

The report was made under provisions of the Fish and Wildlife Act of 1956. Section 9(b) of that Act authorizes the Secretary of the Interior, upon specific request, to determine whether or not there has been an adverse trend in a domestic fishery, and whether or not there has been an increase in imports of a directly competitive product.

The tuna industry, the report points out, is composed of many segments--large canners, small canners, importers, fishermen, and operators of such large vessels

the clearness of the water at this time of the year. Unfortunately, the weather was bad and artificial lights were necessary to see the fish with the television camera.

The television camera was fastened in the cod end of the net so that the behavior of the captured fish could be observed. In two of the experiments, holes (9 and 22 inches) were left in the ends of the nets so that the fish could escape. Surprisingly, none of the fish caught made any serious attempt to leave through these back doors. In all likelihood, this was due to the effect of the artificial light used. The fish caught included dogfish, blackback and yellowtail flounders, cod, small haddock, and herring. It was observed that the behavior of the fish was affected by the turbidity caused by the net itself, especially when towed at slow speeds.

HIGH-SPEED PLANKTON SAMPLER AND MULTIPLANE KITE OTTER TESTED (M/V Albatross III Cruise 110): This cruise (completed May 8, 1958) of the U.S. Bureau of Commercial Fisheries vessel Albatross III was made principally to calibrate equipment to be used with the Miller hi-speed plankton sampler. A new type of depressor, the multiplane kite otter, was used. Using 4-inch wire and this depressor, the wire curve was computed for speeds of 5, 7, and 10 knots, at depths of 50, 75, and 150 meters. The Miller sampler was tested at the same time.

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A search for fish eggs and larvae was made with a one-meter net. A concentration of eggs and/or larvae of haddock, cod, cusk, plaice, and rockling was found on the southeast part of Georges Bank.

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VERTICAL DISTRIBUTION OF FISH EGGS AND LARVAE STUDIED OFF GEORGES BANK (M/V Albatross III Cruise 111): Horizontal high-speed plankton tows were made at 2-hour intervals for a period of 48 hours in the South Channel and in the southeast part and southwest part of Georges Bank during this cruise of the U. S. Bureau of Commercial Fisheries research vessel Albatross III (completed May 28, 1958). The depths sampled ranged from zero to 75 meters. In addition 96 bathythermograph lowerings were made and 450 drift bottles released.

Larval haddock, cod, and flounder were fairly abundant and in general appeared to be concentrated at the 10-meter level in water deeper than 60 fathoms and at the 20-30 meter level in water of less than 60 fathoms.

North Pacific Exploratory Fishery Program

COMMERCIAL SHRIMP CATCHES OFF COAST OF WASHINGTON (M/V John N. Cobb Cruise 37): Additional shrimp fishery grounds with good commercial fishing possibilities were found off the coast

of the State of Washington by the U. S. Bureau of Commercial Fisheries exploratory fishing vessel John N. Cobb during a four-week cruise that ended on May 23, 1958. The grounds discovered by the vessel were in areas unexploited by commercial shrimp fishermen.

Best catches of "cocktail" size pink shrimp were made in the area between Destruction Island and Quillayute (see chart) at depths from 60-68 fathoms. Depths between 64 and 67 fathoms produced consistent catches at a rate of 400 to 1,500 pounds per hour. The discovery of this ground extends the present area of commercial fishing about 18 miles further to the north.

Six drags made about 20 miles west of Cape Flattery, Wash., at depths from 68 to 107 fathoms caught shrimp at a rate of 290 to 630 pounds per hour, and averaged close to 300 pounds per hour. Pink shrimp caught in this area were larger and averaged about 85 to the pound (heads on), however, a considerable amount of incidental fish were mixed with the shrimp. Incidental fish catches consisted of Pacific ocean perch, Dover sole, smelt, turbot, black cod, and other flatfish.

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LEGEND:

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- Shrimp trawl drag.

- Snagged shrimp
trawl drag.

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420 lbs. per hr.

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COLLA RIVER

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CAPE FALCON

A number of drags were made in deep water at depths from 100-200 fathoms in an attempt to locate the larger side-stripe shrimp. No commercial quantities of the species were located, although one 30-minute drag made northwest o Swiftsure Lightship yielded a catch of 30 pounds. These shrimp averaged about 35 to the pound heads on).

M/V JOHN N. COBB CRUISE 37 (APRIL-MAY 1958).

A total of 66 drags was made during the cruise at depths ranging from 49 to 203 fathoms. The area of operations included the offshore waters between Cape Falcon, Ore., to the Swiftsure Lightship, northwest of Cape Flattery. All drags, each of 30 minutes duration, were made with a 43-foot Gulf-of-Mexico flat-type shrimp trawl.

This cruise by the Bureau's exploratory fishing vessel was the second in a series of shrimp surveys being conducted in the North Pacific during 1958. The first exploration revealed good commercial beds of "cocktail" size pink shrimp off the northwest Oregon coast. Further explorations this year will be undertaken along the central and southern coasts of Oregon and in the Kodiak -Cook Inlet area of Alaska. These surveys are being made in cooperation with the fisheries agencies of Washington, Oregon, and Alaska.

Throughout the cruise records were maintained on bottom water temperatures, bottom type, organisms encountered, etc., which may be helpful in defining the typical environmental conditions prevailing in areas where concentrations of shrimp are located. Samples of shrimp were also taken for laboratory study.

Oysters

HEAVY SPRING RAINS THREATEN VIRGINIA INDUSTRY: Effects of heavy rains and excessive runoff this spring may be felt by Virginia's oyster industry for some years to come, biologists at the Virginia Fisheries Laboratory stated on May 8, 1958.

Excessive rainfall in the James River watershed already has pushed large amounts of fresh water over the oyster bars in the seed area. This stretch of river, from Hog Island to the bridge at Newport News, provides most of the seed oysters for Virginia's multimillion dollar oyster industry.

Although the Virginia oyster thrives in a mixture of ocean and river water, it cannot tolerate fresh waters very long. When waters become too fresh, oysters close up and wait for more favorable conditions. But there is a limit to the time they can remain closed, and this time shortens as water temperature rises. For over two weeks many oysters on beds in the upper half of the seed area have been denied a taste of salt water. Some oysters have died already and runoff from recent heavy rains has not yet reached the seed

area.

In the upper reaches of the seed area, in places like Deepwater Shoal, some oysters are killed by fresh water almost every year. But this year some deaths have occurred already on nearly every important bar in the river. State biologists fear that, unless dry weather arrives immediately, a

catastrophe may occur. Even if the situation becomes no worse than it is at present, they expect a shortage of seed oysters next fall.

Another important oyster area that can be affected is the Rappahannock River. Conditions there are not yet as serious as in the James, and if a dry spell develops, the industry may escape damage. Laboratory biologists are keeping a close watch on conditions in the Rappahannock.

Oystermen in Maryland also are concerned about possible effects of fresh water. The Susquehanna River is dumping unusually large amounts of fresh water into the upper bay. Recent surveys have shown that some of the tributary rivers are saltier than the Bay, a very unusual situation. If this condition persists for any considerable time, the rivers could quickly become fresh for their entire lengths.

Like many clouds, this one has a silver lining. Fresh water also kills barnacles, mussels, and other organisms that foul oyster shells and interfere with setting and growth. No less important is the effect on oyster drills or screwborers, a serious oyster enemy that cannot tolerate fresh water as well as the oyster can. Removal of fouling, pests, and enemies can improve conditions for oyster setting and growth. Freshets, though they may cause serious temporary damage, often are followed by unusually good sets and by greatly improved oyster harvests for a few years. This has been the experience in the Rappahannock River during the past oyster season, following the disastrous mortalities of 1955.

Pacific Oceanic Fishery Investigations

CHARTS OF MONTHLY MEAN TEMPERATURES FOR NORTH PACIFIC SURFACE WATERS: A program of preparing and issuing charts which show the monthly mean temperatures for the surface waters of the North Pacific and the anomalies from the mean for the mid-ten-day period of each month was initiated by the U. S Bureau of Commercial Fisheries Pacific Oceanic Fishery Investigations (POFI) in Honolulu. The anomaly charts revealed that the surface temperatures during 1957 were consistently warmer than normal over vast areas of the eastern North Pacific, a report on POFI activities for the first quarter of 1958 reveals.

Beginning with January 1958, sea surface temperature charts of the northeastern Pacific were issued for the mid-ten days of each month for both 1957 and 1958. In addition, anomaly charts for the particular month for both years from the 30-year mean and of 1958 from 1957 were prepared. These charts showed that during the 1957 Jaguary-March period, the coastal waters between 35 N. and 45 N. were colder than normal and the offshore waters were generally warmer (to 6° F.) than normal. During the first quarter in 1958, somewhat the opposite situation existed--the entire coastal area was warmer than normal while the offshore areas showed a progressively increasing amount of colder than normal areas.

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ing each subsequent cruise, was begun in November 1957. Results from two such surveys and part of a third, which was under way in the first quarter of 1958, indicate that surface tuna schools are about three times more available in offshore waters during the Marquesan summer.

To date, stomachs from 243 skipjack caught in Marquesan waters have been examined. This study of the food habits of the Marquesan skipjack showed a preponderance of fish in their diet. Fish comprised 65 percent of the food items, crustaceans 30 percent, and the molluscs 5 percent. Of the food fishes, 22 families have been identified, and of the latter, 16 are primarily families of reefinhabiting forms. Of the crustaceans, the stomatopods were the most numerous. Thus the production of reef fauna appears to play an important role in the diet of the Marquesan skipjack.

HAWAIIAN SKIPJACK STUDIES: Skipjack tagged in Hawaiian waters during the summer and fall of 1957 continued to be recaptured and returned to the POFI laboratory at Honolulu, although the rate of recovery was considerably below that reported for the previous quarter (213 recoveries). A total of 46 tagged fish was recovered bringing the over-all recovery rate to 9.1 percent. Recoveries were made in the areas in which the fish had been released as well as in other areas of the fishery, with certain exceptions. The recoveries do indicate, however, that a large portion of the fish tagged last season are resident in Hawaiian waters and that a group of fish tagged at any one location may disperse throughout the body of fish contributing to the Hawaiian fishery. An important exception to these statements are fish tagged near Kauai. Very few of these fish have been recovered, and only one to the east of the tagging area.

Catches of skipjack during January by the Hawaiian fleet were high, in fact landings during the month were higher than for any previous January. During February and March, landings dropped to more normal low levels.

The collection of temperature records and salinity samples from shore based-monitoring stations continued. As compared with the same period in 1957, temperatures at Koko Head, Oahu, were about the same. Salinities, on the other hand, were noticeably higher than in 1957, reaching the highest level since observations were started in November 1955. This is a continuation of the high level which started during the last quarter of 1957.

ALBACORE TUNA PROGRAM: Work under the albacore tuna project during the first quarter of 1958 was confined to laboratory analysis of the data presently at hand. Biological work included the beginning of the analysis of data pertaining to the general population of fish north and northeast of the Hawaiian Island chain, and the herbivore-predator relation in the plankton for the central North Pacific. Oceanographic work consisted of a continuation of the analysis of the chemical and physical data from the central North Pacific and the preparation of the current series and historical series (1957) of sea surface temperature charts from ship's weather reports for the middle 10 days of each month.

Data on the ecology of the albacore tuna to date reveal the general distribution of the albacore and its movements as shown by tagging, temperature, and productivity. The hypothesis relative to the migration suggested by the data is that there are three groups of fish with the one containing the smallest size fish performing a complex migration to the west coast and then back to the Japanese winter fishery. It also appears that this migration is acted upon independently by the environments of the eastern and western North Pacific.

Northeastern Pacific albacore survey data were examined in regard to the distribution of the three major size-frequency curves of albacore. The small fish were taken in the warmer portion of the temperature range occupied by the albacore. The number of these "roncommercial" small fish that appear in the catches of the northern United States west coast is determined by the temperature of the tongue of warm water which progresses northeastward into the area during spring and late summer. When the temperature of the tongue reaches or exceeds 620 F. large numbers of small-size albacore may be expected to appear off Oregon and Washington.

The recovery of only one tagged albacore was reported during the first quarter of this year. It was recovered on November 17, 1957, by a Japanese long-liner at 38°08' N., 174°53' E. exactly one year after its release from the POFI research vessel Charles H. Gilbert at 36°44' N., 127°37' W. During this period it had gained approximately 15 pounds.

It appears that the albacore are found in those regions where the herbivore-predator ratio is around 20 to 1 and that they are not found in the regions of ratio maxima. This replaces the more narrow belief that the albacore are associated with the Calanus population although it appears that Calanus is the most common and abundant herbi

vore.

TILAPIA STUDIES: The efficiency of the Hawaiian skipjack fishery is affected, in part, by an inadequate supply of natural bait. The species of natural bait presently available have a low survival potential in the baitwells. POFI is presently working towards a possible alleviation of these problems by studies of the potentialities of tilapia as a substitute bait. In the tanks at the Honolulu laboratory, young tilapia are being produced primarily for the purpose of physiological and ecological studies. The production in these tanks dropped considerably during the first quarter of 1958 (winter months) with monthly totals of 35, 3,181, and 7,952 fish. We continue to be plagued with mortality from a sporozoan parasite. Potassium permanganate, copper sulphate, and pyridylmercuric acetate were used as germicides on the living fish, with the latter being considered as most effective. Formalin sterilization of the tanks proved to be an effective measure.

Another and more ambitious study of tilapia, particularly the economics of commercial production of bait-size tilapia and the use on commercial vessels, is a cooperative program managed and operated by POFI on the island of Maui. During

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