Abstract
South Pacific albacore (Thunnus alalunga) is a highly migratory tuna species widely distributed throughout 0°–50°S in the South Pacific Ocean. Climate-driven changes in the oceanographic condition largely influence the albacore distribution, relative abundance, and the consequent availability by the longline fisheries. In this study, we examined the habitat preference and spatial distribution of south Pacific albacore using a generalized additive model fitted to the longline fisheries data from the Western and Central Pacific Fisheries Commission (WCPFC) and Inter-American Tropical Tuna Commission (IATTC). Future projections of albacore distributions (2020, 2050, and 2080) were predicted by using an ensemble modeling approach produced from various atmosphere-ocean general circulation models and anthropogenic emission scenarios (i.e., RCP 4.5 and RCP 8.5) to reduce the uncertainty in the projected changes. The dissolved oxygen concentration at 100 meters (DO100) and sea surface temperature (SST) were found to have the most substantial effects on the potential albacore distribution that the albacore preferred in the habitat with DO100 of 0.2–0.25 mmol L–1 and SST of 13–22°C. This study suggested that the northern boundary of albacore preferred habitat is expected to shift southward by about 5° latitudes, and the relative abundance is expected to gradually increase in the area south of 30°S from 2020 to 2080 for both RCP scenarios, especially with a higher degree of change for the RCP 8.5. Moreover, the albacore relative abundance is projected to decrease in the most exclusive economic zones (EEZs) of countries and territories in the South Pacific Ocean by 2080. These findings could lend important implications on the availability of tuna resources to the fisheries and subsequent evaluation of tuna conservation and management under climate change.
Highlights
Albacore tuna (Thunnus alalunga) is an important upper tropic-level oceanic predator distributed globally between approximately 50◦N and 45◦S, with relatively lower abundance in equatorial areas
Following the emerging objective of using CPUE is an important proxy for the economic viability of the south Pacific albacore fisheries (Pilling et al, 2016; Western and Central Pacific Fisheries Commission (WCPFC), 2018), we evaluate the future change in albacore relative abundance within the exclusive economic zones (EEZs) of the countries and territories in the South Pacific Ocean
We developed an ensemble forecast framework to evaluate the projected future potential distribution of south Pacific albacore under the scenarios of intermediate and high degrees of ocean warming (RCP 4.5 and Representative Concentration Pathways (RCP) 8.5)
Summary
Albacore tuna (Thunnus alalunga) is an important upper tropic-level oceanic predator distributed globally between approximately 50◦N and 45◦S, with relatively lower abundance in equatorial areas. One of the largest fisheries for albacore is in the South Pacific Ocean where annual harvest contributed about 60% of the catch in the Pacific. In the South Pacific Ocean, most of the albacore was catched by longline fisheries (>90%), the distant water longline fishing vessels from Taiwan, China, and the domestic longline fleets of various Pacific Island countries and territories (PICTs) (Brouwer et al, 2018), that total catch has fluctuated around 80,000 tons in recent 10 years. The troll fishery mainly captures juvenile albacores in New Zealand’s coastal waters and the central Pacific Ocean since the mid-1980s with the amount of total catch fluctuated around 2,000 tons. Salinity and chlorophyll-a (CHL) concentration were suggested to be related to the albacore abundance and distribution through affecting the availability of their prey (Xu et al, 2013; Novianto and Susilo, 2016)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
