Big Eye Tuna

About the same range as the Yellowfin - from a few pounds to more than 300, but most taken off Florida have run 50-100 pounds. World record 435 pounds;

Family	Scombridae
Description	Mackerels, tunas, bonitos
Environment	Brackish & Marine
Etymology	Latin, scomber = mackerel.
Genus	15
No. of Species	54
Order	Perciformes
Class	Actinopterygii
Reproductive Guild	Nonguarders
Distribution	Tropical and subtropical seas. Body elongate and fusiform, moderately compressed in some genera. Snout pointed, premaxilla beaklike, free from nasal bones which are separated by the ethmoid bone; mouth large; teeth in jaws strong, moderate, or weak; no true canines; palate and tongue may bear teeth. The 2 dorsal fins separate and depressible into grooves with 5-12 finlets behind second dorsal and anal fins; first dorsal fin with 9-27 rays, origin well behind the head. Pectoral fins high on body. Pelvic fins moderate or small with 6 fin rays, placed below the pectoral fins. Caudal fin deeply forked with supporting caudal rays completely covering hypural plate. At least 2 small keels on each side of caudal fin base, a larger keel in between on caudal peduncle in more advanced species. Lateral line simple. Vertebrae 31-66. Body covered with small to moderate scales or a scaly corselet developed (area behind head and around pectoral fins covered with large thick scales) and rest of body naked or covered with tiny scales. Gill membranes not united to isthmus. Thunnus and close relatives with a specialized vascular system for heat exchange; the evolution of this and related adaptations for endothermy are discussed in Block et al. 1993 (Ref. 11221). Primarily swift, epipelagic predators; some species occur in coastal waters, others far from shore. Mackerels (Scomber and Rastrelliger) filter plankton with their long gill rakers. Spanish mackerels, bonitos and tunas feed on larger prey, including small fishes, crustaceans and squids. The main predators of smaller scombrids are other predacious fishes, particularly large tunas and billfises. Dioecious and most display little or no sexual dimorphism in structure or color pattern. Females of many species attain larger sizes than maels. Batch spawning of most species takes place in tropical and subtropical waters, frequently inshore. Eggs are pelagic and hatch into planktonic larvae. Among the most important of commercial and sport fishes. [Thunninae=ISSCAAP 36; Scombrinae=ISSCAAP 37]. Also Ref. 50681. According to the recent phylogenies (Ref. 58009), two subfamilies can be recognized: - Gasterochismatinae with one species Gasterochisma melampus. - Scombrinae: divided currently in four tribes (Ref. 58010), only Scombrini are supported by molecular data; more research is needed for Scomberomorini, Sardini, and Thunnini.

Thon Obese (French), Gorssaugenthun (German), Tonno Obeso (Italian), Patudo (Spanish), Mebachi (Japanese)

The open sea. As the bigeye proves, it stays deep most of the time and so may not be as rare as as the low number of angling encounters would indicate. Occur in areas where water temperatures range from 13°-29°C, but the optimum is between 17° and 22°C. Variation in occurrence is closely related to seasonal and climatic changes in surface temperature and thermocline. Juveniles and small adults school at the surface in mono-species groups or mixed with other tunas, may be associated with floating objects. Adults stay in deeper waters. Eggs and larvae are pelagic. Feed on a wide variety of fishes, cephalopods and crustaceans during the day and at night

Confusingly similar in looks to the Yellowfin TunaÐeven down to the yellow inlets edged in black. The gold stripe common to the Yellowfin is usually absent, but may be dimly present. The eye is indeed larger, but this might not be readily apparent without a side-by-side comparison. A scientist might have to examine the liver to be perfectly sure of identification with some specimens, but anglers seldom have to worry, simply because the Bigeye is a rare catch, whereas the Yellowfin is common in many areas. Dorsal spines (total): 13 - 14; Dorsal soft rays (total): 14-15; Anal spines: 0; Anal soft rays: 14; Vertebrae: 39. A large species, deepest near the middle of the first dorsal fin base. Lower sides and belly whitish; a lateral iridescent blue band runs along the sides in live specimens. The first dorsal fin is deep yellow, the second dorsal and anal fins are light yellow, the finlets are bright yellow edged with black.

Are multiple spawners that may spawn every 1 or 2 days over several months. They spawn over periods of the full moon. Spawn throughout the year in tropical waters

Summary of Distribution: Atlantic, Indian and Pacific: in tropical and subtropical waters. Absent in the Mediterranean. Highly migratory species
Note: Distribution range colors indicate degree of suitability of habitat which can be interpreted as probabilities of occurrence (fishbase.org)

	Pelagic Longline This fishery uses a longline to catch a variety of pelagic fish on the high seas such as tuna and swordfish. A deep-set longline is used to primarily target tuna and a shallow-set longline is used to target swordfish or mixed species including bigeye, Albacore and yellowfin tuna. Baited hooks are attached to a line that floats in the ocean using buoys and flagpoles.

Not targeted but sometimes hits trolled lures or shows up in a chumline; see Yellowfin Tuna.