Albacore Tuna, South Pacific, Troll, Pole and Line

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1 Albacore Tuna, South Pacific, Troll, Pole and Line Content last updated 8th Mar 2016 Stock: South Pacific Albacore Tuna, South Pacific, Troll, Pole and Line Management: Inter-American Tropical Tuna Commission and Western and Central Pacific Fisheries Commission Overview Albacore tuna are a high migratory species of tuna that is widely distributed in temperate and tropical waters worldwide. In the Pacific Ocean there are two managed populations of albacore tuna, North and South Pacific. Albacore appear to migrate north and south seasonally. Migrations south appear to occur during the summer months and migrations north during winter months. Juveniles tend to be captures in sub-tropical waters of the sub-tropical convergence zone (STCAZ). Adult albacore are caught by a number of longline fisheries operating throughout the south Pacific. Juvenile albacore are targeted by surface fisheries, troll pole in this region, which occur from December to April. Catches of albacore tuna in the South Pacific increased after 2000 to more than 60,000 t and continued to increase to over 80,000 t. The longline fishery, which has expanded in recent years due to the development of small scale fisheries in the Pacific Island Countries, catches the vast majority of albacore in the South Pacific. The troll fishery captures less than 10,000 t a year. Total catches in 2014 were 83,033 t, with 80,538 T being caught in longline fisheries and 2,247 t in troll and pole fisheries. Stock Status less risk more risk Albacore tuna in the South Pacific has been scored a low risk. The spawning potential is most likely above levels necessary to support the maximum sustainable yield (MSY). The limit reference point for South Pacific albacore is 20% of the spawning biomass with no fishing (20%SBF=0) and the current spawning biomass is estimated to be 40% of this value. Therefore the population is not overfished. Fishing mortality levels are lower than MSY (F=0.39) and therefore overfishing is not occurring. We have awarded a low and not very low concern because there are no target reference points in place. Management less risk more risk The management of South Pacific albacore has been scored a moderate risk. Albacore in the South Pacific are managed by the Inter-American Tropical Tuna Commission (Eastern Pacific Ocean) and Western and Central Pacific Fisheries Commission (Western and Central Pacific Ocean). There is a limit reference point for South Pacific albacore but no target reference point and no harvest control rules. Few management measures specific to this species have been adopted. However, populations appear to be healthy at this time. So we have awarded a moderate risk score. Bycatch less risk more risk The bycatch in the albacore tuna South Pacifc Ocean troll fishery has been scored a low risk. Bycatch and discards in troll and pole and line fisheries typically makes up a small proportion of the total catch (Kellher 2005). Baitfish are typically used in troll and pole fisheries. The ratio of tuna to baitfish is around 30:1 and in most cases baitfishing makes up a small proportion of the total fishing mortality for baitfish species (Gillet 2012). Habitat less risk more risk The seabed effects of the fishery are scored a very low risk. This is because trolling occurs at the surface and do not come in contact with bottom habitats. Outlook Current risk status Outlook Reason Stock Low Stable The biomass appears to be healthy and fishing mortality rates are currently sustainable. Management Moderate Stable Although few management measures are in place; the population appears to be healthy. Bycatch Low Stable Bycatch in this fishery is very low and impacts to the habitat are minimal. Habitat Very low Stable Troll/pole and line fisheries have minimal contact with bottom habitats. Type Current Risk Status Outlook Reason Stock

2 Management Bycatch Habitat

3 Stock Status Details less risk more risk Time-trends The biomass of South Pacific albacore has shown a fairly steady decline since peaks seen in During this overall decline peaks were observed in 1970 and The assessment model predicts the biomass spatially. Trends are fairly similar in most regions, expect for region 2 (east of NW Australia), which shows an increasing tend over time. Recruitment trends are similar to biomass trends in most regions. Catch per unit effort series also show a downward trend since The spawning stock biomass has been reduced to around 41% of unfished levels {Harley et al. 2015}. Fishing mortality rates on juvenile albacore have been increasing over time. A large jump in juvenile fishing mortality occurred just before Fishing mortality rates on adults increased through 2000 and has since increased considerably due to increased longline fishing pressure {Harley et al. 2015]. Stock structure and recruitment Albacore tuna in the South Pacific are considered a discrete stock based on fishery and tagging data {Harley et al. 2015}. Data gaps and research priorities The 2015 assessment identified several areas of uncertainty. These included 1) Japan not providing operational level data, 2) relative weights used to scale the catch per unit effort analysis, 3) weighting applied to the length frequency data, 4) uncertainty in growth of younger fish. It was suggested that additional biological studies on growth rates, natural mortality values, and aging and movement studies be conducted. In addition, operational data should continue to be analysed as should the weighting of the different data sources and recruitment distribution scenarios. Harley, S.J., Davies, N., Tremblay-Boyer, L, Hampton, J. and McKechnie, S Stock assessment for south Pacific albacore tuna. WCPFC-SC /SA-WP-06.

4 Management Details less risk more risk Catch 2014 (t) Advised catch 2015 (t) Agreed TAC 2015 (t) Advised TAC 2016 (t) 83,033 t Stock harvest strategy Stock assessments of albacore tuna in the South Pacific are conducted on a regular schedule (since 1999) by the Secretariat to the Pacific Community. The last assessment was conducted in 2015 and covered the southern hemisphere section of the Western and Central Pacific Fisheries Commission. The Inter-American Tropical Tuna Commission, which manages tuna in the eastern Pacific Ocean, refers to this assessment for south Pacific albacore {IATTC 2015}. The 2015 assessment used the MULTIFAN-CL model. This model is a size and age specific and spatially structured model. The assessment included catch per unit effort series from a number of fisheries, along with information on size and biological data {Harley et al. 2015}. The Western and Central Pacific Fisheries Commission adopted a management measure in 2015, which revised and replaced a 2010 measure, which limits the number of vessels actively fishing for South Pacific albacore south of 20 degrees S. The number of vessels actively fishing cannot be increased above 2005 levels or historical levels from {WCPFC 2015}. The Inter-American Tropical Tuna Commission (IATTC) does not currently have any management measures in place for South Pacific albacore. Surveillance and enforcement The Western and Central Pacific Fisheries Commission (WCPFC) and the Inter-American Tropical Tuna Commission (IATTC) are in charge of albacore in the South Pacific. The WCPFC and IATTC have compliance monitoring systems in place to assess members compliance with management measures. In the western and central Pacific Ocean north of 20 degrees N, vessel monitoring systems (VMS) are required and in the eastern Pacific VMS systems are required on vessels larger than 24 m {WCPFC 2012a,b}{IATTC 2011}{IATTC 2004}. WCPFC Conservation and management measure for South Pacific albacore. Conservation and Management Measure WCPFC. 2012a. Conservation and management measure for compliance monitoring scheme. Conservation and Management Measure Commission Ninth Regular Session, Manila, Philippines, 2-6 December WCPFC. 2012b.. Commission vessel monitoring system. Conservation and Management Measure Commission Eighth Regular Session, Tumon, Guam, March IATTC Fishery Status Report No. 13. Inter-American Tropical Tuna Commission. IATTC Inter-American Tropical Tuna Commission (IATTC). 2011a. Resolution on the process for improved compliance of resolutions adopted by the Commission. Resolution C nd Meeting, La Jolla, CA, 4-8 July IATTC Inter-American Tropical Tuna Commission (IATTC) Resolution on the establishment of a vessel monitoring system (VMS). Resolution c-04-06, 72nd Reunion, Lima Peru. Harley, S.J., Davies, N., Tremblay-Boyer, L, Hampton, J. and McKechnie, S Stock assessment for south Pacific albacore tuna. WCPFC-SC /SA-WP-06.

5 Bycatch Details less risk more risk Gillett, R Report of the 2012 ISSF Workshop: the management of tuna bait fisheries: The results of a global study. ISSF Technical Report International Seafood Sustainability Foundation, Washington, D.C. Kelleher, K Discards in the world s marine fisheries an update. FAO Fisheries Technical paper 470.

6 Habitat Details less risk more risk Gear effects, targeting and behaviour n/a Habitat risks n/a Mitigation measures n/a All content 2018 Seafish. Origin Way, Europarc, Grimsby, DN37 9TZ. This page created on 12th September 2018 at 08:58pm.