The IATTC, for purposes of catch and effort statistics, is concerned principally with the Antigua Convention Area, which is bounded by the coastline of North, Central, and South America, 50°N, 150°W, and 50°S. This area is also frequently and commonly referred to as the eastern Pacific Ocean (EPO).

The staff maintains detailed records of gear, flag, and fish-carrying capacity for most of the purse seine and pole-and-line vessels that fish for yellowfin (Thunnus albacares), skipjack (Katsuwonus pelamis), bigeye (T. obesus), or Pacific bluefin (T. orientalis) tuna in the EPO.  Detailed records are not maintained for most longline vessels, nor for sport-fishing vessels and small craft such as canoes and launches.  However, catch data for most of the longline vessels, and for U.S.-flag sport-fishing vessels and some other vessels, are obtained from various sources and entered into the IATTC’s data bases.

Estimates of the catches of tunas come from several sources, including logbooks kept by the fishermen, data recorded by observers, and unloading data provided by the canneries.  The word “catch” in these tables refers to the retained catches, unless otherwise noted.  The principal source of this information is unloading data.  Some of the tunas caught are, for various reasons, discarded at sea.  Data on fish discarded at sea by most vessels have been collected by observers since 1993.  Recreational catches landed in California are included in the landings.  In the case of bluefin, these landings have become an increasingly important component of the catch in recent year.