Climate change (CC) is accelerating and is already affecting marine ecosystems and their services. Coupled climate models and ocean observations indicate that the world's oceans are warming, resulting in changes in oceanic stratification, circulation patterns, sea ice and light supply to the surface ocean. While biological responses to these effects are visible, there is an increasing demand for information on the expected global impact of CC on the productivity of marine ecosystems. We know that primary production is likely to increase globally, and that ocean warming and changes in currents will continue causing distributional and phenological changes in plankton and fish populations. However, our understanding of how these processes translate into fish production scenarios, and our estimation of the risks and vulnerabilities of these for human societies, is constrained by: a) Difficulties of downscaling GCMs to the scales of biological relevance, b) Lack of ecosystem models capable of capturing biological processes at the right scale, c) Uncertainties over future global aquatic net primary production, and the transfer of this through the food web,, d) Inadequate methodology to estimate human vulnerabilities, and, e) The multiple additional stressors affecting fish populations, including country-specific exploitation patterns and policies. In this proposal we propose to investigate how CC scenarios would affect the potential production for global fisheries resources in the future, compared with past and present scenarios, and estimate the added vulnerability of these changes to human societies at national and global scale. The work will rely on state-of-the-art modelling approaches. We will use the QUEST ES Model coupled with physical forcing scenarios based on GCOMS, a model that couples the shelf seas ecosystems to the global ocean, to quantify physical forcing. POLGCOMS, a three-dimensional coastal-ocean regional ecosystem model will be used to estimate ecosystem dynamics up to plankton levels in selected Large Marine Ecosystems (LME). The following scenarios will be considered: pre-industrial (1800), present (2005), and future (2050 and 2100). We will then develop applications to estimate potential fish production changes based on three approaches: statistical relationships between primary production and fish abundance or/and catch, metabolic scaling theory combined with primary production estimates and metabolic scaling combined with ecosystem-specific predator-prey ratios. We will also investigate the consequences of climate-driven changes on the global markets of fishmeal for aquaculture and animal feeds through an integrated bio-economic model of the global fishery system. Specific supply-demand scenarios will be considered, based on climate forcing and global market trends, with particular emphasis on the ecological and economic viability of fishmeal replacement in the Scottish aquaculture industry (as a case study). Finally, we propose to investigate the risks and vulnerability of the impacts of CC on fish-producing countries. This analysis will be conducted in the context of an assessment of climate-driven change in fisheries productivity at national level (by disaggregating LME-information) and globally. The information will be based on both the ecosystem-estimated potential fish productivity in the scenarios described above and on fishmeal market scenarios. Such vulnerability scenarios will build on existing Theme 3 QUEST funded proposals by adding six further developments of the vulnerability assessment framework. Overall the project will provide us with a better understanding of the changes in potential marine ecosystem production from pre-industrial to future times, and the consequences of such changes for the vulnerability of human societies.

Malaysia

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Most of the world's fisheries are over-exploited and it seems inevitable that fish-farming will largely replace fishing, just as livestock arming has replaced hunting as the main source of food from land animals. Unfortunately, many farmed fish, such as salmon, are themselves predators and need to be fed on fish meal. Tilapia are tropical freshwater fish that can be grown largely on vegetable matter and agricultural waste and so promise much for future sustainable production. Global tilapia production grew 280 percent over the 10 years to 2012, with a harvest of ~4.5 million tonnes, more than 5 times greater than the entire UK fishery and aquaculture industry. Tilapia is now a $7.6 billion dollar industry. Most tilapia production is based on a handful of strains, but there are more than 50 wild species throughout Africa which could harbour valuable genes for growth, disease resistance, temperature & salt tolerance etc. Many tilapia will hybridize readily, so that the natural genetic traits could easily be bred into farmed strains without the need for GM technology. However, this feature also renders them vulnerable to genetic swamping by stocking with alien farmed strains into natural water bodies, a practice now widespread in Africa. At present, little is known of the status of wild tilapia strains, and international agencies seem to be largely unaware that widespread stocking is in progress, and there is little appreciation of its possible consequences. We propose to survey the natural tilapia diversity of Tanzania, a particular hotspot for wild tilapia strains. We will assess the effects of stocking at the molecular genetic level through sequencing the genomes of native and stocked forms. We will locate pure stocks of native forms and make recommendations for their conservation in-situ and ex-situ (e.g. in pond culture or sperm banks). We will estimate the growth rates of pure and hybrid forms in their natural habitats using scale rings and relate these to particular genetic traits, making predictions of the likely genetic consequences of stocking. We will also investigate the ecological niches of pure and hybrid strains from stable isotope ratios. It is possible that genetic material from native strains is actually helping hybrid forms to establish themselves, or indeed that the stocked forms may be failing to get established, perhaps in some habitats, if not supplemented by regular stocking programmes. We will develop quick molecular diagnostic tests of hybridization for the benefit of fishery managers in other locations, and use these to calibrate simple visual methods to identify hybrids in the field. The genome sequence information of all of these tilapia strains will be deposited in online public databases, where it will provide a major resource for future studies in tilapia strain development and conservation. We will also advise the government of Tanzanian and international agencies such as WorldFish about remaining pure populations of native strains to prioritise their conservation. This be backed up by depositing tissue/sperm samples for long-term deep-freeze storage, so that these unique and endangered genetic resources might be available to breeders seeking to improve tilapia strains in the future.