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Table I--Analytical Data on Sharks and Livers--San Marcos Island, Mexico, September-October 1942 S HA R K
L I V E R
Per gran Per pound No. Local
of oil of liver Inches Percent U.S.P. Millions of
U.S.P. Units 20 Sardinero Eulamia ae thalorus
72 3,500 1.14 21
4,400 1.56 22
66 16,300. 4.9 Average for livers
72 8,070 33 Gambuso
70-1/8 68 17,500 5.4 2 Injerto
74 67,000 22.6 M 682
75 58,000 4
M 69-1/8 76
85,000 29.4 12
32 48,000 7.0 16
27.0 M 622
73 52,000 17.3 F 575
20,700 7.3 M 654
29,500 10,0 M 68
53,000 19.5 M 681
87,000 31.3 M 652
76 51,000 м 68
81 80,000 29.5 32
74 81,000 27.2 34
78 69,000 24.5 35
51 96,000 22.3 36
21,000 7.6 Average for livers ...
72 61,000 20.0 6 Pilota Eulemia galapagensis
32 7,700 1.12 M 62
54 94,000 23.1 8
44 106,000 21.2 ୨
M 54-5/8 55 73,000
18.3 Average for livers ...
46 70,000 14.7 10 Puro
F 48-5/8 69 26,000 11
72 28,000 9.2 26
46-1/8 79 19,300
6.9 Average for livers
8.0 23 Puro
51,000 1 Cornuda Sphyrna diplana
49-3/8 54 52,000 12.8 5
74 27,100 9.1 13
66 46,000 14
45-7/8 59 20,500 15
53 145,000 35.0 18
12,500 3.5 25
м 67-5/8 66 63,000 18.9 Average for livers
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. I value was con
a verted to vitamin A by using a factor of 732.
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 souplin, 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.
and coarsely and evenly serrate (i.e., scalloped or saw-
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 zyop
There is a conspicuous groove at the angle of the mouth,
PURO (Scoliodon longurio).
ir present, is not so extensive or conspicuous as shown
in Figure 2, see Section 4. (4) If: The middle of the base of the first dorsal fin is nearer
the ventral fins than to the pectoral fins, the fish is
a GREAT BLLE SHARK (Prionace glauca).
nearer the base of the pectoral fins than to the base of
(5) If: The second dorsal fin is very much smaller than the first,
being less than half its area, see Section 6.
the fish is Aprionodon fronto.
tip of the snout to the mouth is scarcely more than half
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
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 il : 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) It: The front of the second dorsal fin is
opposite or behind the middle of the
But if: The front of the second dorsal fin
Is in advance of the middle of the anal
fin, see Section 9.
shoulder-like basal extensions, as shown
But if: The teeth of the upper jaw are with
out extensions to their basal portions,
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.
(11) IP: Some of the fins
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.
eye to the hind border of the other, passes
upper jaw, see Section 3.
CORNUDA or MARTILLO (Sphyrna diplana), see Figure 6.
that part of the fin is lifted upward, it reaches only about as high as the
The fore margin of the head is deeply rounded, as in Figure 9, and the distance 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 101!, and
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.
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 Manpower 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, klarine, 0-88.21).--Has complete
SHIP CAPTAIN (Alaster II, 0-88.02).--This title covers persons licensed by
I hope this action of the Committee may be helpful to the industry.