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Table I--Analytical Data on Sharks and Livers--San Marcos Island, Mexico, September-October 1942
S HA R K

I I V E R
Na me

Vitamin A
Sample

Per gran Per pound No. Local

Scientific
Sex Length Oil

of oil of liver Inches Percent U.S.P. | Millions of

Units U.S.P. Units 20 Sardinero

Eulamia ae thalorus

F 27.

72 3,500 1.14 21

M 467

4,400 1.56 22

F 434

66 16,300. 4.9 Average for livers

72 8,070 33 Gambuso

Eulamia azureus

M 70-1/8 68 17,500 5.4 2 Injerto

Eulamia lamiella

F
64

74
67,000

22.6 3

M 682
75 58,000

19.8 4

M 69-1/8 76

85,000 29.4 12

M 38-3/8

32 48,000 7.0 M 70%

76
78,000

27.0 19

M 622

73 52,000 17.3 24

F 57

20,700 7.3 27

M 654

29,500 10,0 28

M 68

53,000 19.5 29

M 681

87,000 31.3 30

M 651
76 51,000

17.6 31

м 68

81 80,000 29.5 32

M 59
74 81,000

27.2 34

F

78 69,000 24.5 35

51 96,000 22.3 36

M 59

80

21,000 7.6. Average for livers

72 61,000 20.0 6 Pilota Eulamia galapagensis F 55-7/8

32 7,700 1.12 M 62

54 94,000 23.1 8.

M
63

44 106,000 21,2 9

M
54-5/8 55 73,000

18.3 Average for livers ...

46 70,000 14.7 10 Puro

Eulamia velox
F 48-5/8 69

26,000 11

F

454 72 28,000 9.2 26

46-1/8 79 19,300

6.9 Average for livers ...

73 24,400 8.0 23 Puro Scoliodon longurio

35

68

51,000 1 Cornuda Sphyrna diplana

49-3/8 54 52,000 12.8 5

F 621

74 27,100 9.1 13

F 71
66 46,000

13.8 14

F
45-7/8

59 20,500 15

F 641

74 47,000 15.8 17

F 66

53 145,000 35.0 18

F 391

62

12,500 3.5 25

M 67-5/8 66 63,000 18.9 Average for livers

63

52,000 14.9 Sex not recorded. NOTE:

Percent oil was de termined by the Stansby cold shaking method, vitamin A by the Carr-Price, antimony-trichloride method at a wavelength of 620 mmu., and a bandwidth of 15 mmu. E value was converted to vitamin A by using a factor of 732.

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Virtually all the sharks taken commercially on the west coast of Mexico belong to two families, those related to the soupfin (Galeorhinidae), of which there are twelve species, and the hammerheads (Sphyrnidae), of which there are five species.

Although only seven species were identified at San Marcos, the remainder of the west coast members of these two families were examined at Stanford University Natural History Museum, and were made the basis of the following simplified keys for identification. Provided a given shark belongs to one of these two families--this may be ascertained by reading the description at the head of each key--it may be identified by reading Item 1 of the appropria te key, and following the directions given thenceforth.

A KEY TO THE SHARKS OF THE WEST COAST OF MEXICO FAMILIALY RELATED TO THE PACIFIC SOUPFIN (GALEORHINIDAE)

The fishes of this family have spindle-shaped bodies, which are not flattened, nor expanded laterally. They are not hammer-headed, have no spines in the dorsal fins or keels at the base of the tail; and their tails are of normal length, being much shorter than the rest of the body. They have five gill openings on each side of the body; have two dorsal fins, an anal fin, a pair of pectoral fins and a pair of pelvic fins. The first dorsal fin is situated in front of the pelvic fins; and the teeth are conspicuous, more or less triangular or knife-like, not plate-like or pavement-like. Although these sharks bear a family relationship, there is a wide range of value in the Vitamin A potency of their livers. Some, like the soupfin, are exceedingly potent in this respect; others, like the tiger shark, almost worthless.

(1) If: Spiracles (a pore situated behind the eye) are present,

see Section 2.
But if: Spiracles are absent, see Section 3.
(2) IP: The teeth of both jaws are deeply notched on one side,

and coarsely and evenly serrate (i.e., scalloped or saw-
toothed), as shown in Figure 1, the fish is a TIGER SHARK
or TINTORERO (Galeocerdo arcticus).

But if: The teeth are not as in Figure 1, those on the side

Figure 1 of the jaw being rather minutely notched on the outer edge below the point, and the lower part of the notch is divided into two to five points, the fish is a SOUPFIN SHARK (Galeorhinus zyopterus).

(3) If: There is a conspicuous groove at the angle of the mouth,

beginning on the lower jaw, and extending forward around
the angle of the mouth, paralleling the upper jaw for one
fourth to one third the distance from the angle to the
front of the mouth, as shown in Figure 2, the fish is a

PURO (Scoliodon longurio).
But if: No groove is present at the angle of the mouth, or

ir present, is not so extensive or conspicuous as shown

in Figure 2, see Section 4. (4) IP: The middle of the base of the first dorsal fin is nearer

the ventral fins than to the pectoral fins, the fish is Figure 2.

a GREAT BLLE SHARK (Prionace glauca).
But if: The middle of the base of the first dorsal fin is

nearer the base of the pectoral fins then to the base of

the ventrals, see Section 5.
(5) If: The second dorsal fin is very much smaller than the first,

being less than half its area, see Section 6.
But if: The second dorsal fin is almost as large as the first,

the fish is Aprionodon fronto.
(6) If: The snout is bluntly rounded, and the distance from the

tip of the snout to the mouth is scarcely more than half
the distance between the angles of the mouth, as shown

Figure 3
in Figure 3, the fish is a GAMBUSO (Eulamia azureus).
But if: The snout is not as shown in Figure 3, but is more or less acu tely pointed,

and the distance between the tip of the snout and the mouth is almost or quite as great as the distance between the angles of the mouth, or greater, see Sec

tion 7. (7) IP: The head is very narrow, so that the distance between the nostrils is hardly

more than the length of a nostril, the fish is a PURO (Eulania velox). But if : The head is not so narrow, and the distance between the nostrils is sev

eral times the length of a nostril, see Section 8.

(8) If: The front of the second dorsal fin is

opposite or behind the middle of the

anal fin, the fish is Eulamia cerdale. But if: The front of the second dorsal fin

Is in advance of the middle of the anal

fin, see Section 9.
(9) If: The teeth of the upper jaw have broad,

shoulder-like basal extensions, as shown
in Figure: 4, the fish is a SARDINERO
(Eulamia aethalorus).

But if: The teeth of the upper jaw are with

out extensions to their basal portions,

see Section 10. (10) If: The teeth of the upper jaw are deeply

Figure 4 notched in a sharp angle, on the outer edge, and rather coarsely serrate toward the basal portion, as in Figure 5a, see Section 11.

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(11) IP: Some of the fins
are tipped with

Figure 5b
white, the fish

is Eulamia platyrhynchus. But if: None of the fins are tipped with white, the fish

is a PILOTA (Eulamia galapagensis).

A KEY TO THE HAMMERHEAD SHARKS OF THE WEST COAST OF MEXICO

These sharks are distinguished from all others by the peculiar shape of the head, which is expanded at the sides to become mallet-shaped or shovel-shaped. Five kinds of hammerheads have been described, as follows:

(1) If: A line drawn from the hind border of one eye

to the hind border of the other passes through

the mouth (i.e., both jaws), see Section 2.
But if: A line drawn from the hind border of one

eye to the hind border of the other, passes
in front of the mouth, or merely crosses the
upper jaw, see Section 3.

(2) It: The hind border of the second dorsal fin is so prolonged that when that part of the fin

Figure 6
is lifted upward, it reaches about twice as
high as the fore border of the fin; and if
the distance along the hind margin of the lateral expansion of the head is at
least equal to the distance between the angles of the mouth, the fish is the

CORNUDA or MARTILLO (Sphyrna diplana), see Figure 6.
But if: The hind border of the second dorsal fin is not so prolonged, so that when

that part of the fin is lifted upward, it reaches only about as high as the

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(4) If: The fore margin of the head is deeply rounded, as in Figure 9, and the dis

tance from the nostril to eye is greater than the diameter of the eye, the fish is Sphyrna corona.

But if: The fore margin of the head is only

slightly curved, as in Figure 1017, and
the distance from nostril to eye is not
greater than the diameter of the eye, the
fish is Sphyrna tudes.

Piguro 10

0-0-0

1 Figures 7 to 10 taken from "Three New Sharks of the Genus Sphyrna from the Pacific Coast of Tropical

America," by Stewart Springer, Stanford Ichthyological Bulletin, vol. 1, No. 5, pp. 161-169. By permission of Mr. Springer and the Stanford Natural History Museum.

FISHING BOAT ENGINEER CLASSED AS CRITICAL OCCUPATION

The following letter was sent to the Deputy Coordinator of Fisheries on May 2, to announce the addition of engineer of fishing vessels of 20 tons or over to the War Manpower Commission's list of essential activities.

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This is in further reference to your letter of March 24 submitting occupations in the fisheries industry for addition to the List of Critical Occupations,

The War Hanpower Commission's Interdepartmental Committee on Essential Activities, in addition to those jobs such as Refrigerating Engineer and certain supervisory jobs dependent upon local determination which are already on the List, has decided after very careful consideration to add to the List of Critical Occupations the Engineer, Chief, Ship for commercial fishing vessels of twenty tons and over and Ship Captain for commercial fishing vessels of twenty tons and over

The existing defintions will be expanded to read:

ENGINEER, CHIEF, SHIP (Engineer, Chief, Marine, 0-88,21).--Hes complete
charge of all engines, boilers, electrical equipment, refrigerating
equipment, sanitary equipment, all deck mạchinery, and steam connections
aboard ship; keeps log of performance of equipment on voyage; requisitions
supplies and repairs; oversees fueling of ship; takes inventories of all
stores and materials; supervises other repairing equipment, (In addition to
the "Engineer, Chief, Ship described in the foregoing, this title includes
the Engineer, Chief, commercial fishing vessel of 20 tons or over.)

SHIP CAPTAIN (Alaster II, 0-88.02).--This title covers persons licensed by
the Government to have complete charge of and responsibility for any vessel
or watercraft requiring licensed officers. (In addition to the "Ship
Captain" described in the foregoing, this title includes the Ship Captain,
commercial fishing vessel of 20 tons or over whether licensed or not.)

I hope this action of the Committee may be helpful to the industry.

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