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

S

Name

Scientific

L I VE E R

Vitamin A
Per gram Per pound

NOTE: Percent oil was determined 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.

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 appropriate key, and following the directions given thenceforth.

A KEY TO THE SHARKS OF THE WEST COAST OF MEXICO FAMILIALY RELATED TO THE PACIFIC SOUFFIN (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) If:

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:

(3) If:

Figure 1

The teeth are not as in Figure 1, those on the side 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).

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
if 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 BLUE SHARK (Prionace glauca).

But if:

The middle of the base of the first dorsal fin is nearer the base of the pectoral fins than 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 in Figure 3, the fish is a GAMBUSO (Eulamia azureus). But if:

(7) If:

Figure 2

Figure 3

The snout is not as shown in Figure 3, but is more or less acutely 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 Section 7.

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 (Eulamia velox).

But if:

The head is not so narrow, and the distance between the nostrils is several times the length of a nostril, see Section 8.

(10) If:

The teeth of the upper jaw are without extensions to their basal portions, see Section 10.

Figure 4

The teeth of the upper jaw are deeply
notched in a sharp angle, on the outer
edge, and rather coarsely serrate toward the basal portion, as in Figure 5a,
see Section 11.

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.

Figure 6

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

(4) If:

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.

and

But if: The fore margin of the head is only
slightly curved, as in Figure 101,
the distance from nostril to eye is not
greater than the diameter of the eye, the
fish is Sphyrna tudes.

0-0-0

Figure 10

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, Marine, 0-88.21).--Has complete
charge of all engines, boilers, electrical equipment, refrigerating
equipment, sanitary equipment, all deck machinery, 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 (Master 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.

Sincerely yours,

Geen Sereng

Collis Stocking, Chairman
Essential Activities Committee