| Bigeye
Tuna |
|
(click me) |
|
Family: |
Scombridae (Mackerels and Tunas) |
Genus and Species: |
Thunnus obesus |
Description: |
The body of the bigeye tuna is cigar-shaped
(tapered at both ends). The head is pointed and the eye is relatively large.
The color is dark metallic brownish blue to dark yellow on the back becoming
gray or whitish below. There often is a bluish stripe on the side. In most
individuals, the length of the pectoral fins should enable one to identify
the species properly. Both bigeye and yellowfin tuna look similar, but bigeye
tuna have pectoral fins which extend well past their anal fin, while yellowfin
tuna have much shorter pectoral fins. Tuna which cannot be distinguished
by external characteristics can be positively identified by liver
characteristics. Bigeye tuna livers are striated (covered with blood vessels)
along the trailing edges, while yellowfin tuna livers are smooth. Small bigeye
tuna also may be distinguished from albacore by the characteristics of the
liver. The liver is heavily striated in the albacore while the bigeye tuna
liver is only striated along the trailing edges. |
Range: |
Bigeye tuna occur worldwide in warmer seas.
In the eastern Pacific these tuna range from Peru to Iron Springs, Washington.
They are occasional visitors to California, entering our fishing grounds
in June and remaining until November. These fish prefer temperate water in
excess of 70° F, but significant catches have occurred in water as cool
as 65° F. |
Natural History: |
The diet of bigeye tuna includes fishes,
squid, and crustaceans. Like most other tunas, they feed on what is most
abundant in the area. Bigeye tuna do not spawn in waters off California,
but spawn further south in the Pacific. Bigeye tuna are approximately 3 years
old at first spawning. In the equatorial regions of the Pacific, the peak
spawning is between April and September. A bigeye tuna weighing 159 pounds
will produce an estimated 3.3 million eggs per year. The young are fast growing
and weigh about 45 pounds when they first mature. They live 7 or 8 years. |
Fishing Information: |
Bigeye tuna generally are not accessible
to recreational anglers because they travel far below the surface during
the day. Only rarely are they seen on the surface, and then, only momentarily
while feeding. This makes the fish hard to locate since they leave no telltale
surface signs nor can they be easily located by trolling. Most bigeye tuna
are taken incidental to albacore or marlin fishing. The best way to fish
for them is to troll marlin lures in an area where the fish are known to
occur. Most bigeye tuna taken in southern California weigh 50 to 100 pounds,
with an occasional 150 to 200 pounder landed. |
Other Common Names: |
gorilla, tuna, patudo. |
Largest Recorded: |
80 inches; 435 pounds; 215 pounds (California). |
Habitat: |
Pelagic Environment |
|
