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Chapter 14: Climate change impacts, vulnerabilities and adaptations: Western and Central Pacific Ocean marine fisheries
... Tuna harvest is the largest commercial fishery in Tonga and is estimated at 2000 metric tons per year [19]. Given Tonga's geographical location within the WCPO, which accounts for the largest portion of the world's tuna catch, the country's tuna fisheries face the challenge of climatic variabilities such as global warming [20,21] and the El Nino Southern Oscillation (ENSO) [22,23], which threaten global fisheries production and impact the distribution and abundance of tuna [5,24]. These events have negative impacts which include increasing regional temperatures, changing weather pa erns, rising sea levels, ocean acidification, changing nutrient loads in ocean circulations, increasing stratification of the water column, and changing precipitation pa erns [21,25]. ...
... Changes in ocean currents and nutrient distribution can cause variations in the abundance and distribution of phytoplankton and zooplankton, which serve as vital prey for tuna [29]. These disruptions in the food chain can result in Given Tonga's geographical location within the WCPO, which accounts for the largest portion of the world's tuna catch, the country's tuna fisheries face the challenge of climatic variabilities such as global warming [20,21] and the El Nino Southern Oscillation (ENSO) [22,23], which threaten global fisheries production and impact the distribution and abundance of tuna [5,24]. These events have negative impacts which include increasing regional temperatures, changing weather patterns, rising sea levels, ocean acidification, changing nutrient loads in ocean circulations, increasing stratification of the water column, and changing precipitation patterns [21,25]. ...
The potential impacts of climate change on the distribution of tuna in Pacific Island countries’ exclusive economic zones have yet to be investigated rigorously and so their persistence and abundance in these areas remain uncertain. Here, we estimate optimal fisheries areas for four tuna species: albacore (Thunnus alalunga), bigeye (Thunnus obesus), skipjack (Katsuwonus pelamis), and yellowfin (Thunnus albacares). We consider different climate change scenarios, RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5, within a set of tuna catch records in the exclusive economic zone of Tonga. Using environmental and CPUE datasets, species distribution modelling estimated and predicted these fisheries areas in the current and future climatic scenarios. Our projections indicate an expansion in area and a shift of productive areas to the southern part of this exclusive economic zone of Tonga. This is an indication that future climatic scenarios might be suitable for the species under study; however, changes in trophic layers, ocean currents, and ocean chemistry might alter this finding. The information provided here will be relevant in planning future national actions towards the proper management of these species.
... Climatic variabilities such as global warming [20,21] and the El Nino Southern Oscillation (ENSO) [22,23] threaten the global fisheries production [5,24]. These events have negative impacts which include increasing regional temperature, changing weather patterns, rising sea levels, ocean acidification, changing nutrient loads in ocean circulations, increasing stratification of the water column and changing of precipitation patterns [21,25]. ...
The potential impacts of climate change on the distribution of tuna in Pacific Island Countries’ Exclusive Economic Zones have yet to be investigated rigorously, and so their persistence and abundance in these areas remain uncertain. Here, we estimate optimal fisheries areas for four tuna species; Albacore (Thunnus alalunga), Bigeye (Thunnus obesus), Skipjack (Katsuwonus pelamis), and Yellowfin (Thunnus albacares). We consider different climate change scenarios, RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5, within a set of tuna catch records in the Exclusive Economic Zone of Tonga. Using environmental and CPUE datasets, species distribution modelling estimated and predicted these fisheries areas in the current and future climatic scenarios. Our projections indicate an expansion in area and a shift of productive areas to the southern part of this Exclusive Economic Zone of Tonga. This is an indication that future climatic scenarios might be suitable for the species under study however, changes in trophic layers, ocean currents and ocean chemistry might alter this finding. Information provided here will be relevant in planning future national actions towards proper management of these species.
... When possible, inclusion of gear loss causes including identification, quantification and monitoring can further assist in evaluations of ALDFG scope and impacts. Finally, with changes to the state of global fisheries, including impacts from global climate change [34][35][36], changes in fish stocks and fisheries effort [1,34], impacts from illegal, unreported and unregulated fishing (IUU) [38,39] and an increasing shift to aquaculture as a global protein source [1,40], fisheries management that is responsive, flexible and adapts to change will be critical to ensure long-term sustainability. ...
Abandoned, lost or otherwise discarded fishing gear (ALDFG) represents a major sea-based source of marine debris globally, with far-reaching socioeconomic and environmental impacts. Estimates of the amount of ALDFG entering the ocean have implications for managers and policy makers as they work to tailor solutions at scale. While scientists have worked since the 1970s to develop quantitatively rigorous estimates for ALDFG, the estimate that 640,000 tonnes of ALDFG enters the ocean annually has been repeatedly and erroneously cited for over a decade. We trace the history of this misinformation and discuss the implications of the perpetuation of this estimate. We also discuss major challenges around the creation of statistically robust global ALDFG estimates, and present opportunities to refine and improve estimates of lost fishing gear.
... This study has taken a notably distanced approach to what is obviously a situation with very real livelihood impacts for those who depend on these fisheries. The work of (Bell et al. 2018(Bell et al. , 2009(Bell et al. , 2012 has addressed this issue in the context of the specific Western and Central Pacific fishery examined in this study. It is of note that the small island developing states that comprise the majority of landmass in this region are already highly reliant on foreign aid. ...
Ocean temperatures are increasing. Little work has been done to examine the effects that these changes will have on fishery production. The study at hand seeks to incorporate the influence of climate change into an established static bioeconomic fishery model. Stock biomass is approximated to be a function of sea surface temperature. Following a feasible generalized least squares regression using data from the Western and Central Pacific, the interaction between fishery effort and temperature is found to be statistically significant. From this model, various functional forms relating effort, catch, profit, and temperature are specified. In particular, a function that returns an effort requirement given a target catch level and temperature forecast is generated.The importance of these tools for fishery management is explored through application to Western and Central Pacific tuna fisheries. Recommendations for extensions into future research are made and the foundation for a model of efficient effort allocation across time and the entirety of a management area, given changing temperatures, is specified. The study has succeeded in establishing the statistically significant role that temperature plays in the fishery production function.
... Many studies reported in the Special Issue have focused on coral reefs and seagrass communities reflecting the higher risks in coastal areas supporting these important habitats. More recently, interest in deep sea areas has increased, due to the deployment of Fish Aggregation Devices (FADs), which have expanded range of traditionally coastal local fishermen (Bell et al., 2018a;Leroy et al., 2013), deep sea mining (Roche and Bice, 2013;Sharma, 2015) and the potential pollution related impacts from legacy shipwrecks (Carter et al., 2021). ...
Marine ecosystems across the world's largest ocean – the Pacific Ocean – are being increasingly affected by stressors such as pollution, overfishing, ocean acidification, coastal development and warming events coupled with rising sea levels and increasing frequency of extreme weather. These anthropogenic-driven stressors, which operate cumulatively at varying spatial and temporal scales, are leading to ongoing and pervasive degradation of many marine ecosystems in the Pacific Island region. The effects of global warming and ocean acidification threaten much of the region and impact on the socio-cultural, environmental, economic and human health components of many Pacific Island nations. Simultaneously, resilience to climate change is being reduced as systems are overburdened by other stressors, such as marine and land-based pollution and unsustainable fishing. Consequently, it is important to understand the vulnerability of this region to future environmental scenarios and determine to what extent management actions can help protect, and rebuild ecosystem resilience and maintain ecosystem service provision.
This Special Issue of papers explores many of these pressures through case studies across the Pacific Island region, and the impacts of individual and cumulative pressures on the condition, resilience and survival of ecosystems and the communities that depend on them. The papers represent original work from across the tropical Pacific oceanscape, an area that includes 22 Pacific Island countries and territories plus Hawaii and the Philippines. The 39 papers within provide insights on anthropogenic pressures and habitat responses at local, national, and regional scales. The themes range from coastal water quality and human health, assessment of status and trends for marine habitats (e.g. seagrass and coral reefs), and the interaction of local pressures (pollution, overfishing) with increasing temperatures and climate variability. Studies within the Special Issue highlight how local actions, monitoring, tourism values, management, policy and incentives can encourage adaptation to anthropogenic impacts. Conclusions identify possible solutions to support sustainable and harmonious environment and social systems in the unique Pacific Island oceanscape.
Changes in climate factors affect the distribution of various tuna species differently due to their unique physiological adaptations and preferred habitats. As the resulting spatial distributions of tunas alter in response to climate change and climate variability, the distribution of fishing effort will, in turn, be affected. This study uses a quantitative model to estimate the impacts of SST and ENSO events on trip distance of the Hawaii deep-set longline fleet between 1991 and 2020. The results show that the higher the SST of the fishing grounds of the Hawaii longline fleet, the longer trip distance; whereas ENSO events could result in shorter trip distance, possibly due to changes in catch rates of different tuna species through spatial redistribution during El Niño and La Niña events.
Our study explores variations in the risk of fishery-dependent coastal nations to ocean acidification, sea surface temperature change, sea level rise, and storms. Our findings reveal differences in risk based on geographical location and the development status of a country. Our findings indicate significant geographical differences for three of the four risk indicators including sea level rise, sea surface temperature changes, and storms. Strategies for reducing risk globally thus need to be adapted to regional differences in risks. We further detected multiple inter-regional differences, indicating that risk was not uniformly distributed within geographic regions suggesting that some regions could see an increase in conflicts over fish resources due to uneven impacts of climate change on fisheries. In addition, we found that a number of countries are at medium to very high risk to multiple climate-related impacts, indicating the need for strategies that increase adaptive capacity in general in these countries to cope with any kind of impact in addition to specific risk reduction strategies. We also found that overall small island developing states were most at risk. Yet, further analysis showed that grouping of countries in pre-defined groups fails to detect variations in risk among countries within these groups. More specific national indicators provide more nuanced insights into risk patterns.
We examined spatial and temporal variations in the demersal fish assemblage on the continental shelf of the central Great Australian Bight to understand how the assemblage is affected by both fishing and environmental gradients. Data from the Great Australian Bight Trawl Sector (1988–2018) and fishery-independent trawl surveys (2005–2009, 2011, 2015, 2018) were used for the analyses. The independent survey data were used to analyse trends in overall species composition and abundances, while the commercial fishery data were used to extend the time series for the key commercial species, Deepwater Flathead (Platycephalus conatus) and Bight Redfish (Centroberyx gerrardi). The demersal fish assemblage was dominated by four commercial species: Deepwater Flathead, Bight Redfish, Ocean Jacket (Nelusetta ayraud), and Latchet (Pterygotrigla polyommata); and one by-catch species: Wide Stingaree (Urolophus expansus). Assemblage composition varied between day/night and along an east-west gradient. Survey abundance and commercial catch-per-unit-effort of several species declined at the end of the time series. Survey abundance was low in 2011, 2015, and 2018 for Bight Redfish and in 2015 and 2018 for Deepwater Flathead. Assemblage composition and catch rates of some species recorded in 2011, 2015, and 2018 were distinct from previous years, but the differences appear to reflect the longer gaps between these surveys and the combined effects of historical fishing pressure and environmental variability. Recent downward trends in the abundance indices of target species, as well as long-term changes in the assemblage, demonstrate the need for continued fishery-independent monitoring. The relative importance of fishing pressure, environmental variability, and other human activities in driving these changes warrant further investigation.
Bstract
This paper explores how changes in sea surface temperature (SST) affect tuna catch in countries in the Eastern Pacific Ocean (EPO). We apply a production function approach to establish the relationship between SST and the catch of yellowfin (Thunnus albacares) and skipjack tuna (Katsuwonus pelamis) that use purse seines. We use data for 1° latitude/longitude grids within the exclusive economic zones of countries in the EPO. Catch of yellowfin and skipjack tuna increases with SST in all countries, with high values of catch recorded in the eastern coastal borders. The biggest increase in revenue from yellowfin and skipjack tuna as result on 1 °C increase in SST is for Mexico, while Kiribati had the smallest increase. However, if we adjust the increase in revenue by coastal population, the highest values are for Kiribati and French Polynesia. The higher tuna catch translates to higher government revenue from tuna fishing licenses, and more jobs for tuna fishers and those in the tuna processing industry in the state. However, the reduction on catch of other species may offset the positive effects on tuna catch, and may even result in a negative impact overall. We highlight the importance of conducting research on SST that is specific to species, gear, and location to fully account for the impact of ocean warming.
For Australian fisheries to remain productive and sustainable (environmentally and commercially), there is a need to incorporate climate change considerations into management and planning, and to implement planned climate adaptation options. Here, we determine the extent to which Australian state fisheries management documents consider issues relating to climate change, as well as how frequently climate change is considered a research funding priority within fisheries research in Australia. We conduct a content analysis of fisheries management documents investigating categories and themes relating to Australian state fisheries, climate, and environmental change. We also reviewed recent Research Priorities from the major fisheries research funding body for reference to climate change related themes, and the number of subsequently funded projects which considered climate change or related topics. Results show that commercial state fisheries management documents consider climate only to a limited degree in comparison to other topics, with less than one-quarter of all fisheries management documents having content relating to climate. However, we find that the south-east and south-west regions of the Australian coastline have the highest incorporation of “climate” and “environmental protection considerations” in their fisheries management documents, and that fisheries are more likely to have more “climate-related mentions” within their related management documents, if they (i) primarily target species with higher economic commercial catch values, (ii) commercial catch weights, or (iii) a greater number of commercial fish stocks existing. Only a small number of recently funded fisheries research projects considered climate change, representing only a small proportion of fisheries research investment. Given the extensive climate-driven impacts recently documented among key Australian fisheries species and associated ecosystems, we conclude that there is a clear need for fisheries management in Australia to consider longer-term climate adaptation strategies for Australian commercial state fisheries to remain sustainable into the future. We suggest that without additional climate-related fisheries research and funding, many Australian agencies and fisheries may not be prepared for the impacts and subsequent adaptation efforts required for sustainable fisheries under climate change.
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