INTER-AMERICAN TROPICAL TUNA COMMISSION 93RD MEETING San Diego, California 24 and 27-30 August 2018 DOCUMENT IATTC-93-01 TUNAS, BILLFISHES AND OTHER PELAGIC SPECIES IN THE EASTERN PACIFIC OCEAN IN 2017 A. The fishery for tunas and billfishes in the eastern Pacific Ocean ....................................................... 3 B. Yellowfin tuna ................................................................................................................................... 54 C. Skipjack tuna ..................................................................................................................................... 63 D. Bigeye tuna........................................................................................................................................ 65 E. Pacific bluefin tuna ........................................................................................................................... 68 F. Albacore tuna .................................................................................................................................... 72 G. Swordfish .......................................................................................................................................... 78 H. Blue marlin ........................................................................................................................................ 80 I. Striped marlin .................................................................................................................................... 81 J. Sailfish .............................................................................................................................................. 83 K. Silky shark ......................................................................................................................................... 86 L. Ecosystem considerations ................................................................................................................. 88 INTRODUCTION This report provides a summary of the fishery for tunas in the eastern Pacific Ocean (EPO), summary assessments of the major stocks of tunas and billfishes that are exploited in the fishery, updated stock status indicators for silky sharks, and an evaluation of the pelagic ecosystem in the EPO, in 2017. The report is based on data available to the IATTC staff in March 2018. As a result, some of the data tables for 2017 are incomplete, and all data for 2016 and 2017 should be considered preliminary. All weights of catches and discards are in metric tons (t). In the tables, 0 means no effort, or a catch of less than 0.5 t; - means no data collected; * means data missing or not available. The following acronyms are used: Species: SKX Unidentified elasmobranchs ALB Albacore tuna (Thunnus alalunga) SSP Shortbill spearfish (Tetrapturus BET Bigeye tuna (Thunnus obesus) angustirostris) BIL Unidentified istiophorid billfishes SWO Swordfish (Xiphias gladius) BKJ Black skipjack (Euthynnus lineatus) TUN Unidentified tunas BLM Black marlin (Makaira indica) YFT Yellowfin tuna (Thunnus albacares) BUM Blue marlin (Makaira nigricans) Fishing gears: BZX Bonito (Sarda spp.) FPN Trap CGX Carangids (Carangidae) GN Gillnet DOX Dorado (Coryphaena spp.) HAR Harpoon MLS Striped marlin (Kajikia audax) LL Longline PBF Pacific bluefin tuna (Thunnus orientalis) LP Pole and line SFA Indo-Pacific sailfish (Istiophorus LTL Troll platypterus) LX Hook and line SKJ Skipjack tuna (Katsuwonus pelamis) IATTC-93-01 - Tunas, billfishes and other pelagic species in the EPO 2017 1 OTR Other1 CYM Cayman Islands NK Unknown NZL New Zealand PS Purse seine RUS Russia RG Recreational VCT St. Vincent and the Grenadines TX Trawl UNK Unknown Ocean areas: Stock assessment: EPO Eastern Pacific Ocean B Biomass WCPO Western and Central Pacific C Catch Ocean CPUE Catch per unit of effort Set types: F Rate of fishing mortality DEL Dolphin MSY Maximum sustainable yield NOA Unassociated school S Index of spawning biomass OBJ Floating object SBR Spawning biomass ratio LOG: Flotsam SSB Spawning stock biomass FAD: Fish-aggregating device Flags: IATTC Members & cooperating non-Members BLZ Belize BOL Bolivia CAN Canada CHN China COL Colombia CRI Costa Rica ECU Ecuador EU European Union EU (CYP) Cyprus EU (ESP) Spain EU (PRT) Portugal FRA France GTM Guatemala HND Honduras IDN Indonesia JPN Japan KIR Kiribati KOR Republic of Korea LBR Liberia MEX Mexico NIC Nicaragua PAN Panama PER Peru SLV El Salvador TWN Chinese Taipei USA United States of America VEN Venezuela VUT Vanuatu Other flags CHL Chile COK Cook Islands 1 Used to group known gear types IATTC-93-01 - Tunas, billfishes and other pelagic species in the EPO 2017 2 A. THE FISHERY FOR TUNAS AND BILLFISHES IN THE EASTERN PACIFIC OCEAN 1. Catches and landings of tunas, billfishes, and associated species ....................................................... 3 1.1. Catches by species ............................................................................................................................... 4 1.2. Distributions of the catches of tunas ................................................................................................... 7 1.3. Size compositions of the catches of tunas ........................................................................................... 7 1.4. Catches of tunas and bonitos, by flag and gear ................................................................................... 9 2. Fishing effort ....................................................................................................................................... 9 2.1. Purse seine ........................................................................................................................................... 9 2.2. Longline ............................................................................................................................................ 10 3. The fleets ........................................................................................................................................... 10 3.1. Purse-seine and pole-and-line fleets .................................................................................................. 10 3.2. Other fleets of the EPO ..................................................................................................................... 11 This document summarizes the fisheries for species covered by the IATTC Convention (“tunas and tuna- like species and other species of fish taken by vessels fishing for tunas and tuna-like species”) in the eastern Pacific Ocean (EPO). The most important of these are the scombrids (Family Scombridae), which include tunas, bonitos, seerfishes, and mackerels. The principal species of tunas caught are yellowfin, skipjack, bigeye, and albacore, with lesser catches of Pacific bluefin, black skipjack, and frigate and bullet tunas; other scombrids, such as bonitos and wahoo, are also caught. This document also covers other species caught by tuna-fishing vessels in the EPO: billfishes (swordfish, marlins, shortbill spearfish, and sailfish) carangids (yellowtail, rainbow runner, and jack mackerel), dorado, elasmobranchs (sharks, rays, and skates), and other fishes. Most of the catches are made by the purse-seine and longline fleets; the pole-and-line fleet and various artisanal and recreational fisheries account for a small percentage of the total catches. Detailed data are available for the purse-seine and pole-and-line fisheries; the data for the longline, artisanal, and recreational fisheries are incomplete. The IATTC Regional Vessel Register contains details of vessels authorized to fish for tunas in the EPO. The IATTC has detailed records of most of the purse-seine and pole-and-line vessels that fish for yellowfin, skipjack, bigeye, and/or Pacific bluefin tuna in the EPO. The Register is incomplete for small vessels. It contains records for most large (overall length >24 m) longline vessels that fish in the EPO and in other areas. The data in this report are derived from various sources, including vessel logbooks, observer data, unloading records provided by canners and other processors, export and import records, reports from governments and other entities, and estimates derived from the species and size composition sampling program. 1. CATCHES AND LANDINGS OF TUNAS, BILLFISHES, AND ASSOCIATED SPECIES Estimating the total catch of a species of fish is difficult, for various reasons. Some fish are discarded at sea, and the data for some gear types are incomplete. Data for fish discarded at sea by purse-seine vessels with carrying capacities greater than 363 metric tons (t) have been collected by observers since 1993, which allows for better estimation of the total amounts of fish caught by the purse-seine fleet. Estimates of the total amount of the catch that is landed (hereafter referred to as the “retained catch”) are based principally on data from unloadings. Beginning with Fishery Status Report 3, which reports on the fishery in 2004, the unloading data for purse-seine and pole-and-line vessels have been adjusted, based on the species composition estimates for yellowfin, skipjack, and bigeye tunas. The current species composition sampling program, described in Section 1.3.1, began in 2000, so the catch data for 2000-2017 are adjusted, based on estimates by flag for each year. The catch data for the previous years were adjusted by applying the average ratio by species from the 2000-2004 estimates, by flag, and summing