Small Bigeye and Yellowfin

Though small bigeye and yellowfin are easy to confuse, they are important to identify! In some oceans, one of these stocks may be experiencing overfishing while the other is healthy—and without accurate catch data, scientists cannot produce effective stock assessments and managers cannot make informed decisions about conservation measures. In the majority of cases, the observer is the most skilled and best-positioned person on the vessel to carry out a realistic estimate of the bigeye and yellowfin brought on board.

Though large adult bigeye and yellowfin are characterized by dissimilar body and fin shapes, these differences are less noticeable when they are young. However, the small tunas do have somewhat different markings and—to a lesser extent—colors. The following photo gallery will illustrate the typical characteristics of small bigeye and yellowfin, and provide some side-by-side comparisons.