11. Tuna conservation

In general, "conservation" is the struggle for long-term sustainability. Two broad generalizations can be made about tuna conservation: (1) conservation needs tend to vary inversely with species fecundity, and need increase with average size and the money paid for individual fish, and (2) conservation needs are most serious in the Atlantic, followed by the Pacific and then Indian oceans, in direct relation to the history and intensity of industrial-scale exploitation in each ocean. The Atlantic foreshadows what might be expected in other oceans if the Atlantic's lessons go unheeded. Half the world's tuna are taken from the central and western Pacific, where no fully implemented international management regime yet exists for waters of the high seas. In terms of economic or political importance, the major tunas are the skipjack, yellowfin, bigeye, albacore, and northern and southern bluefins. Skipjack account for roughly half the annual world catch of these six tunas. Overexploitation of skipjack seems to have been reached in specific areas of the Atlantic. Exploitation of Pacific skipjack stocks appears low to moderate. Yellowfin landings appear close to the maximum sustainable yield (MSY) level in the Atlantic, where fishing effort and mortality may be in excess of levels associated with MSY. Pacific yellowfin exploitation rates are considered moderate. In the eastern Pacific, recent assessments suggest that increased effort directed at juvenile tunas is probably reducing economic yield and sustainability for bigeye and yellowfin. Indian Ocean yellowfin catches are increasing. Albacore are overfished in the North Atlantic, and South Atlantic albacore are considered fully exploited. Albacore exploitation in the central and western Pacific is relatively low and sustainable. Atlantic and Pacific bigeye tuna populations have declined rapidly. Bluefin tunas are everywhere depleted, and their recovery has not been allowed anywhere. The case of the bluefin shows that when an animal is worth enormous money, politics will go to great lengths to disfigure science.