Vaihola, Siosaia and Kininmonth, Stuart (2023) Ecosystem Management Policy Implications Based on Tonga Main Tuna Species Catch Data 2002–2018. Diversity, 15 (10). pp. 1-19. ISSN 1424-2848
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Abstract
Despite the crucial role played by international and regional tuna fisheries in facilitating the successful implementation of the ecosystem approach to fisheries management, there exist
disparities in viewpoints among these stakeholders, resulting in gaps between regional fisheries
management and local communities. Nevertheless, the Tongan government, under the Ministry
of Fisheries, is dedicated to the efficient management of its tuna resources, aiming to establish it as the
preferred and optimal approach for ensuring the long-term sustainability of its tuna fisheries and
the ecosystem services they provide to the community. Recognizing that an appropriate legal, policy
and institutional framework is in place for sustainable management of tuna, the first part of this
paper presents a review of current Tonga fisheries laws and policies for its tuna fisheries. This review
reflects the implementation of an information-based management framework, namely the Tonga
National Tuna Fishery Management and Development Plan. The tuna fisheries in Tonga mainly catch
albacore (Thunnus alalunga), bigeye (Thunnus obesus), skipjack (Katsuwonus pelamis), and yellowfin
(Thunnus albacares) tuna. These tuna species are caught within Tonga’s exclusive economic zones and
play a crucial role in the country’s economy; hence, it is crucial to examine the spatio-temporal distributions of their catch in relation to their environmental conditions. In pursuit of this goal, the tasks
of mapping (i) the spatio-temporal distribution of catch landed at ports and (ii) the spatio-temporal
of environmental conditions were performed. The study utilizes longline catch per unit effort data
spanning from 2002 to 2018 for albacore, bigeye, skipjack, and yellowfin tuna. It also incorporates data
on environmental conditions, including sea surface temperature, sea surface chlorophyll, sea surface
current, and sea surface salinity. Additionally, the El Nino Southern Oscillation Index is mapped
in relation to catch data to examine the potential effects of climate change on the tuna catch. Results
show that bigeye, skipjack, and yellowfin CPUE show a central–northernmost distribution and are
primarily caught between latitudes 14◦ S–22◦ S, while albacore, shows a central–southern distribution.
The highest CPUE for all species are in latitudes 15.5◦ S–22.5◦ S and longitudes 172.5◦ W–176.5◦ W.
The data indicate that sea surface current velocities range from −0.03 to 0.04 ms−1
, sea surface salinity
ranges from 34.8 to 35.6 PSU, sea surface chlorophyll concentration varies from 0.03 to 0.1 mg m−3
,
and sea surface temperature fluctuates seasonally, ranging from 18 ◦C to 30 ◦C. Mapping also reveals
that times of reduced catches in Tonga coincide with periods of moderate to strong El Nino events
from 2002 to 2018
| Item Type: | Journal Article |
|---|---|
| Uncontrolled Keywords: | economically important species; exclusive economic zone; fisheries research; national obligations; tuna fishery management |
| Subjects: | G Geography. Anthropology. Recreation > GC Oceanography G Geography. Anthropology. Recreation > GE Environmental Sciences |
| Divisions: | School of Agriculture, Geography, Environment, Ocean and Natural Sciences (SAGEONS) |
| Depositing User: | Nirma Narayan |
| Date Deposited: | 21 Mar 2024 03:54 |
| Last Modified: | 21 Mar 2024 03:54 |
| URI: | https://repository.usp.ac.fj/id/eprint/14542 |
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