'What is already happening'

• There is evidence that location where high catches of cod, haddock, plaice and sole occur, as reported by UK commercial fishing vessels, seems to have shifted over the past 80-90 years. Climate change may be a factor but fishing and habitat modification have also had an important effect.
• Shifting distributions of fish, partly as a result of climate change are having an impact on the effectiveness of some fishery closure areas and on the apportionment of fishery resources between neighbouring countries (e.g. mackerel in the north-east Atlantic).
• New fisheries have developed for a number of warmer-water species including seabass, red mullet, anchovy and squid. The stock biomass of seabass in the Western Channel has quadrupled since 1985 from 500t, to over 2000t in 2004/5.

 'What could happen in the future'.

• As a result of climate change, the UK as a whole is expected to benefit from slightly (i.e. +1-2% compared to present) higher fishery yields by 2050, although regions such as the Irish Sea and English Channel may see a reduction.
• Models suggest that cod stocks in the Celtic and Irish Seas may to disappear completely by 2100, while those in the North Sea are expected to decline. Climate change has been 'eroding' the maximum sustainable yield of cod in the North Sea by around 32,000t per decade.
• Very little work has been carried out on the social and economic implications of climate change for the UK fishing industry, however calculations suggest that consequences will be significant only for fishery-dependent communities in the North of Scotland and in the southwest England.
• Ocean acidification may pose a significant threat to the UK shellfish industry, but more research is required.

What is already happening: Medium

In general there is probably more information available about fish and changes in the fishing industry than any other maritime sector or commodity. However there has been a surprising lack of studies which have attempted to communicate how changes in fish production or distribution might manifest themselves as impacts upon commercial fishing yields, profits or implications for society generally. Despite the large amount of data available, there is little consensus regarding whether or not climate change is having an impact on fisheries. Indeed recent crises in the European fishing industry have attracted considerable public interest and prompted a number of independent enquiries into the causes of the problems (Anon., 2004; RSE, 2004). While these enquiries have concluded that fishing is the main factor causing the decline of whitefish stocks such as cod and plaice, there remains a popular perception that environmental factors, such as climate change, are the main cause (see Fishing News, March 12th 2004; and Schiermeier, 2004).

Scientists currently disagree on the causes of an apparent northwards shift in fish distribution in the North Sea, and there are many competing but not mutually exclusive hypotheses to explain this phenomenon (see Rijnsdorp et al. 2009). However the most frequently voiced are: (1) warming causes species to expand northward, (2) fishing pressure has been consistently higher in the south compared to northern North Sea, causing higher mortality in the south and hence, an apparent overall distribution shift. It is possible that climate change is already having an effect, but this may be acting in combination with other important drivers, e.g. intensive fishing pressure and habitat degradation. Further work is needed to try to disentangle the various effects.

What could happen: Low

With regard to understanding what might happen in the future, there are even fewer studies available (particularly at the UK level) and consequently there is even less consensus among researchers and policy makers concerning necessary adaptation strategies and policies. Again, there have been several studies which have attempted to predict future fish distribution, fishery yield or spawning stock biomass of particular species, but this has rarely (if ever) been translated into consequences for fisheries and/or society. The knowledge-base is particularly uncertain with regard to the possible future implications of ocean acidification. It should be noted that there are now more studies than were available at the time of the 2007/8 MCCIP assessment (see Brander 2009), however the vast majority of these are review and/or 'scoping' studies, with very little quantitative assessment or predictive modelling. Consequently the level of confidence has not changed from that stated in the 2007-2008 Annual Report Card.

The top priority knowledge gaps that need to be addressed in the short term to provide better advice to be given to policy makers are:

1. An assessment of the social and economic implications of climate change on fishing fleets and dependent economies in the UK. So far there have been very few studies (if any) which have quantified implications specifically for the UK fisheries sector, even though this task is becoming increasingly urgent. The fishing industry itself has repeatedly questioned scientists about the challenges they are likely to face in the future, and in addition, the UK Climate Change Act (which became law on 26 November 2008) requires that a national adaptation programme be put in place and reviewed every five years which includes a thorough assessment to identify the most pressing climate change risks.
2. Improved understanding of the possible implications and level of threat posed by ocean acidification, particularly with reference to the UK shellfish industry.
3. Better wind and storm projections for the future, and improved understanding of how any changes in these variables might impact maritime safety, and/or access to fishery resources.

Hypoxia (low oxygen) is starting to become an issue of major concern for waters around the UK (Weston et al. 2008). However, little is understood with regard to the possible impact of low oxygen zones on fish and fisheries. In the central North Sea an area known as the 'Oyster Grounds' (part of the Dogger Bank) has witnessed decreasing oxygen levels in recent years (see Weston et al. 2008) and hypoxia has also been reported for coastal waters around the German Bight. Continued monitoring of this ecologically important region is essential if the causes and consequences of these potentially damaging low oxygen levels are to be fully understood. Low oxygen is predicted to occur more regularly in the future as a result of climate change. Waters will be warmer by 2-3ºC and therefore contain less dissolved oxygen by 0.4 mg l^-1; the period of stratification will last for longer, and summer storms that normally dissipate areas of hypoxia will likely decrease in the future. In the Kattegat, the Baltic Sea, and the Gulf of St. Lawrence, cod completely avoid low oxygen waters (Chabot and Claireaux 2008). Furthermore, in the Baltic Sea cod eggs do not survive low oxygen conditions, and years with extensive hypoxia have been related to very poor stock recruitment for this species (Köster et al., 2001).

So far, a surprisingly small amount of research has been directed towards understanding the future implications of climate change for fishing fleets, fishermen, coastal economies and society and this is certainly the case within the United Kingdom. There are a number of studies that investigate the vulnerability and adaptive capacity of the fisheries sector and dependent communities to climate change at a global scale (Allison et al. 2009; McClanahan et al. 2008). However, until recently there has been little directed analysis at the local scale of how climate variability and change is affecting the lives and livelihoods of those involved in the UK fishing and fish processing sectors.

A recent review paper by Badjeck et al. (2010) attempted identify the main pathways through which climate variability and change are impacting, or are likely to impact upon fishing-dependent communities in the future. The authors of this study point out that most research so far has looked at climate-driven changes in ocean productivity and its impact on fish distribution and have not considered indirect effects, such as the fact that extreme weather events may disrupt fishing operations and/or land-based infrastructure. Storms and severe weather events (which are anticipated to become more commonplace around the UK) can destroy landing sites, boats and fishing gear (Westlund et al. 2007). For instance, during Hurricane Gilbert in 1988, Jamaican fisherfolk lost 90% of their fish traps resulting in a huge loss of revenue and high cost of repairs, as well as resulting in the inability to resume fishing activities promptly after the disturbance (Aiken et al. 1992). Additionally, loss of revenues can be the result of closures or reduction of fisheries activities during weather anomalies, for example because of food safety concerns. In the UK, flash-floods are often accompanied by the release of untreated sewage from 'combined sewer overflows' (CSOs), and this can have serious consequences for shellfisheries or aquaculture facilities further downstream. Shellfisheries are monitored (for example by Cefas and Marine Scotland) to determine whether or not there are any signs of serious algal toxins, pathogenic bacteria or contaminants, and they are closed immediately if statutory levels have been exceeded. Peperzak (2003) attempted to evaluate whether harmful algal blooms are likely to occur more or less often over the next 100 years in the North Sea as a result of climate change, and concluded that we should expect more blooms, and hence fishery closures, largely as a consequence of an increase in extreme precipitation events (intense rainfall).

Fisheries managers and fisherfolk have historically had to adapt to the vagaries of weather and climate. Uncertainty is inherent in fisheries management, so there is an expectation of change and a stock of knowledge and experience of coping with it and adapting to it (Miller et al 1992). Badjeck et al. (2010) have argued that diversification is a primary means by which individuals can reduce risk and cope with future uncertainty. There is some evidence that the inability of fishing households to adapt to environmental change is not only linked to the level of poverty (or ability to raise capital), but also to the "specialization trap" where fisherfolk overly rely on one species or activity.

In the UK, fisheries contribute less than 0.05% to national GDP, however there are some regions where fisheries provide the mainstay of employment and are vitally important to the local economy. While fishermen account for a small percentage of the national workforce (0.2% in Scotland and 0.1% in England and Wales), national fishery statistics suggest that dependency is as high as 24% in the Western Isles, and 20% in Fraserburgh (NE Scotland), Brixham and Newlyn (SW England). Around 20% of UK fishermen are located in the south west of England and 13% in Aberdeenshire (see Anon. 2004), consequently, declines (or increases) in revenue as a result of climate change would be anticipated to affect these areas disproportionably more than any others. The fishing industry is also a significant component of Scotland's rural economy, for example in the North East and West Highland, Orkney and Shetland the value of landings accounts for approximately 6% of the area's GDP.

Arnason (2007) attempted to estimate the economic impact of climate change on fisheries and on the national economies of Iceland and Greenland. The author assumed that fisheries yields would increase by around 20% for the most important fish stocks (in particular cod and Atlanto-Scandian herring) in Iceland and up to 200% in Greenland over the next 50 years (based on projections from ACIA 2005). The analysis then used econometric techniques based on economic growth theory to estimate the role of the future fisheries sector in the wider economy of each country. Somewhat surprisingly the dramatic increase in fisheries yields assumed for Iceland resulted in only miniscule increases in national GDP, despite the fishing industry currently accounting around 10% of GDP and 40% of export earnings. The accumulative impact of climatic warming on Icelandic GDP was only 4% by 2054, and given economic volatility and measurement errors, this level of economic growth is considered hardly detectable at the 95% significance level. Benefits for the national economy of Greenland were greater (a 40% increase in GDP by 2054) but this assumed an enormous increase the fish stock (by 200%) and it should be remembered that the fishing industry in Greenland is the main source of non-government employment and local economic activity (over 90% of all exports). In the UK a slight increase in fisheries yield is also anticipated in the future, by around 1-2% (see Cheung et al. 2009b). Such change might be insignificant when uncertainties of the prediction are considered. Also, given the very small contribution that fisheries make towards national GDP it seems highly unlikely (based on the work of Arnason 2007) that such changes in fisheries profitability will have significant consequences for the national economy, although there could be minor benefits for highly dependent regions such as the Highlands and Islands.

The ACACIA report written by Des Clers (University College, London) and Brander (ICES) in 2000 provided the European impact assessment for the IPCC Third Assessment (2001) and includes a short chapter on Fisheries. Some of the economic and social implications of climate change for fisheries are set out in chapter 9 of the ACACIA report (ACACIA, 2000) from which Table 1, showing supply side and demand side adaptations of fisheries to climate change impacts, is taken. Many of the same adaptation options were also recently highlighted by McIlgorm et al. (2010) who reviewed how fishery governance may need to change in the light of future climate change.

In December 2009, Sumaila and Cheung (writing in a report for the World Bank) attempted to establish the costs of adaptation to climate change in the fisheries sector worldwide. The analysis began by detailing the likely impact of climate change on the productivity of marine fisheries (more than 1,000 species) and, through that, on landed catch values and household incomes. Adaptation costs were then estimated, based on the costs of restoring these revenue indicators to levels that would have prevailed in the absence of climate change. The impact of climate change on marine fisheries was assumed to primarily occur through changes in primary productivity, shifts in species distribution and through acidification of the oceans. The authors considered three scenarios that reflect these impacts. Climate change was predicted to lead to losses in gross fisheries revenues world-wide of $10-31 billion by 2050.

Governments have implemented various measures to manage fisheries, both to conserve fish stocks and to help communities that depend on fishery resources adapt to changes caused by overfishing and other factors. Measures include buybacks, transferable quotas, and investments in alternative sources of employment and income. Adaptation to climate change is likely to involve an extension of such policies, with a focus on providing alternative sources of income in fishing communities to lessen the dependence on fishery resources. In Europe (including the UK) the estimated annual cost of adaptation was between 0.03 and 0.15 $ billion. As compared to 1.05 - 1.70 $ billion of anticipated annual adaptation costs in East Asia and Pacific.

Table 1. Adaptations of fisheries to climate change (from chapter 9 of ACACIA, 2000)

Allison et al. (2009) provided an assessment of the 'vulnerability' of 132 national economies to potential climate change impacts on their capture fisheries using an indicator-based approach. Vulnerability to climate change depends upon three key elements: exposure (E) to physical effects of climate change, the degree of intrinsic sensitivity of the natural resource system or dependence of the national economy upon social and economic returns from that sector (S), and the extent to which adaptive capacity (AC) enables these potential impacts to be offset. In a further development of this work, Cefas scientists (as part of the recently completed NERC 'Quest-GSI' project) used a number of different Global Climate Models (GCMs) that provided outputs of sea surface temperature and improved formulation of fisheries catches. In terms of vulnerability, the authors ranked the UK as 215^th out of 225, with good adaptive capacity and a relatively small anticipated impact. The Channel Islands were ranked 208 and the Isle of Man was ranked 218^th.

To date it would seem that there have been few studies which have specifically looked at the socio-economics of the UK fishing fleet in relation to climate change. However a number of ongoing studies may provide useful insight in the near future, notably the NERC-funded 'Quest-Fish' project which aims to elucidate how climate change will affect global fish production and which may provide projections for industrial fisheries (e.g. those for sandeels) around the UK, as well as the Scottish aquaculture industry (which is reliant on international supplies of fish-meal). In addition, the Defra-funded ACME ('Adapting to Climate Change in the Marine Environment') project will build on the work of Cheung et al. (2009a,b) to predict the future re-distribution of fish stocks around the UK and how the UK fishing fleet will respond to these changes using a variety of different modelling approaches, including the 'Random Utility Model' developed by Hutton et al. (2004). Finally, the NERC-Defra joint call for research proposals on ocean acidification (published in July 2009) asked for submissions focussed on "Improved understanding of the potential population, community and ecosystem impacts for all life stages of commercially important species". This work is urgently needed to allay fears and to provide better information to the UK shellfish industry in particular.

Pinnegar, J.K., Cheung, W. W. L. & Heath, M. (2010) Fisheries in MCCIP Annual Report Card 2010-11, MCCIP Science Review, 19pp. www.mccip.org.uk/arc