Vulnerability of overexploited fish stocks & the overcapacity in fisheries management in the context of future climate variability
Currently, the global opinion of oceanic resources is based on utilitarian views, believing fish stocks to be inexhaustible and ‘renewable’ (Clover 2006). This can be highlighted through the overconsumption and widespread reliance on fish as a major source of protein in the diets of developing and developed nations alike (Allison et al. 2009, FAO 2014). Today, global fisheries management has aimed to regulate exploitation rates of targeted species by implementing total allowable catches (TACs), exclusive economic zones (EEZs), marine protected areas (MPAs) and individual transferable quotas (ITQs). However, the industry still experiences major challenges, including illegal, unreported and unregulated (IUU) fishing, overexploitation and overcapacity (FAO 2014).
The following report aims to investigate whether the overexploitation of marine fisheries will increase the vulnerability of fish stocks in a changing climate. The present study will focus on marine capture fisheries to elucidate issues within the longevity of global resource management. The history of fisheries management will be examined as well as past and current measures and the impacts of climate change to the sustainability of the industry. Australia has been utilised as a case study to contrast local responses to this global problem, with recommendations suggested based on the findings of the present report. Limitations to the following report include broad recommendations, as there are currently many unknowns and gaps within data of fisheries management.
Background
Fish, a natural food source rich in fatty acids, vitamins and minerals (Johnson & Welch 2010), contributes upwards of 50% of the dietary animal protein intake per capita in some of the world’s poorest regions (Ye et al. 2013). Since the early 1960’s pressure has been mounting on global catches due to population growth with average yearly fish consumption increasing from 9.9kg to 19.2kg in 2012 (FAO 2014). In the Western world, this has meant rising strain on grocery stores and restaurants alike to have a continuous fresh supply of seafood, creating further intensifying fishing effort and therefore depleting global fish stocks (Blackford 2009).
Industrial fishing began at the turn of the twentieth century in British waters with early management regulating catches via the implementation of time limits and seasonal restrictions (Blackford 2009). When the fishing industry adopted technologies established in World War II in the 1950’s such as radar and sonar to match the demand for fish, the United Nations responded through regulation of EEZs, TAC’s for each species and Individual Transferable Quotas (ITQs) for commercial fishing (Blackford 2009).
In the 1990’s fisheries again increased technological efficiencies by adopting remote sensing and global positioning systems to increase the breadth of exploration to the high seas, further strengthening fishing effort (Nellemann, Hain & Alder 2008). Improvements in technology coupled with longline catching, increase in ship size and improvements to freezing and refrigeration, ships had the ability to stay at sea for months on end (Blackford 2009), processing fish directly on board during fishing seasons (Nellemann, Hain & Alder 2008; FAO 2014). Whilst such advancements have certainly contributed to fishing effort ever increasing since the 1960’s, government subsidies also play an important role in enticing employees into the market, creating overcapacity (Nellemann, Hain & Alder 2008,9). To avoid low catches per fisher, fisheries turned to illegal fishing (IUU), misreporting true catches, as local penalties, globally, have been insufficient in deterring illegal activities (Clover 2006; Beddington, Agnew & Clark 2007).
Ye et al. (2013) demonstrated the global economic worth of fisheries has declined from $46 billion in 1989 to $5 billion in 2004 due to overcapacity in fishing fleets which in turn drives overexploitation in target species. Whilst global marine catches have decreased from a peak 86.3million tonnes in 1996 to 79.7 million tonnes in 2012 (FAO 2014), the number of fishers has more than doubled from 12 million in 1970 to 34 million in 2008 and the number of vessels has increased nine-fold over the same time period (Ye et al. 2013).
UNEP highlights that nearly 80% of the world’s fisheries species are considered at or close to harvest capacity (Nellemann, Hain & Alder 2008). Overexploitation or high capacity fishing over the past decade has led to other stressors such as habitat loss, invasive species and pollution (Johnson & Welch 2010; IPCCb 2013), as well as continual depletion of target stocks (Nellemann, Hain & Alder 2008,2) and loss of biodiversity (Nanola, Alino & Carpenter 2011) through bycatch mortality (Johnson & Welch 2010). The overexploitation of fish can lead to a reduction in age, size, genetic diversity and reproductive success (Johnson & Welch 2010; Nanola, Alino & Carpenter 2011; FAO 2014), forcing populations to be more dependent on annual recruitment, reducing their ability to counter environmental fluctuations (IPCCb 2013). Conversely, however, research shows that stocks that have been moderately fished demonstrate improvements in their resilience and rebuild time (Neubauer et al. 2013).
Exposure to climate variability when stocks are recovering can result in sustained change across many levels of marine food web interactions. (Harsem & Hoel 2013) This can result in a decrease in primary productivity (Salinger & Hobday 2013; Hollowed et al. 2013) and top predator and prey species interactions being catastrophically affected (Harsem & Hoel 2013; Salinger et al. 2013), potentially generating dominance switching and ecosystem reorganisation (Hollowed et al. 2013). Furthermore, Hollowed and colleagues (2013) believes that adaptation to climate change may improve through generations of targeted marine life that display a history absent of overexploitation.
After overexploitation has been recorded, most catch reductions are introduced too late (Johnson & Welch 2010; Nellemann, Hain & Alder 2008) with the delay prolonging the recovery time and only intensifying pressures of rebuild (Neubauer et al. 2013). Additionally, Ye et al. (2013) and DAFF (2013) revealed that recovery of depleted stocks may take decades to recover in climate variability, even after fishing effort has been removed, compromising their ability to be resilient in times of distress (Johnson & Welch 2010). Recent recovery of globally exploited fish stocks has been slow, with only 1% successfully rebuilt in the last 15 years and the majority still below target biomass levels (Neubauer et al. 2013; Nellemann, Hain & Alder 2008).
In 2002, the World Summit on Sustainable Development (WSSD) set targets for fisheries to maintain and restore the maximum sustainable yield (MSY) of stocks by 2015 (Ye et al. 2013; Neubauer et al. 2013). In 2008, whilst Ye and colleagues (2013) found 68% of global fisheries were still at or above MSY, the Marine Stewardship Council (MSC) successfully certified over 135 fisheries as globally sustainable (Smith, Smith & Webb 2012; Blackford 2009). Successful fisheries management is based on a balance between biological, economic, social and political objectives (Beddington, Agnew & Clark 2007; Allison et al. 2009). Unfortunately the management of global fish stocks and allowable catches is based on single-species’ models from over 50 years ago, which doesn’t account for either inter-species relationships, climate change variables or a balance between economic, social, political and biological factors (Beddington, Agnew & Clark 2007).
IPCCa (2013) believes with high confidence that destructive overfishing will amplify and enhance the vulnerability and sensitivity of natural systems to any additional disturbances as a result of climate change. Research indicates global warming will have direct ecological impacts to fish populations such as increased stratification (leading to lower nutrient availability, reduced oxygen levels, and oceanic acidification (Salinger & Hobday 2013; Hollowed et al. 2013), sea level rise, changing ocean currents (Hollowed et al. 2013), increase sea surface temperature (Allison et al. 2009) and change in salinity (Salinger et al. 2013). Such variability in habitat will consequently lead to changes in productivity, population dynamics of species (Salinger et al. 2013) and the availability of sustainable harvests (Hollowed et al. 2013). Exposure to increasing global ocean temperatures and lowering PH levels may potentially affect the physiology, distribution, and life cycle (Adebo & Ayelari 2011; Johnson & Welch 2010) as well as forming issues with the reproductive performance of marine fish (Johnson & Welch 2010). Furthermore, IPCCb (2013) conditions with medium confidence that future catch size will have to be altered due to warming effects of climate change modifying the body size of fish species.
Australia has been recognised globally as implementing strong ecosystem-based management, employing the Commonwealth Fisheries Harvest Strategy to enforce biomass/catch limits, bycatch policies (Smith, Smith & Webb, 2012; Australian Fisheries Management Authority 2013), and apply stock rebuilding strategies to proactively recover overfished stocks and ensure long term sustainability and productivity (DAFF 2013). Valued at just 1.4billion, (Johnson & Welch 2010) Australia has attempted to improve the economic return by decreasing fishing effort and avoiding overcapacity (Australian Fisheries Management Authority 2013), effectively reducing the amount of overexploited fisheries from 24 in 2005 to 18 in 2008 (Ye et al. 2013), with 53% currently considered as sustainably managed by the MSC (Smith, Smith & Webb, 2012). However, the Australian Fisheries Management Authority (2013) indicates climate change modeling has not been incorporated in the current management policies and procedures, despite research indicating that predicted increases in ocean temperatures are likely to cause a 35% reduction in economic value of Australian fisheries by 2070.
Discussion
Advanced management systems utilised in countries such as Australia have effectively prevented stock depletion through input measures, such as limiting vessel numbers and restricting fishing seasons, more rapidly than in countries with simple output measures or TACs (Caddy 1998; Beddington, Agnew & Clark 2007). TAC-regulated fisheries have been driven through competition for government incentives, and have subsequently led to overcapacity, resulting in lower catches per fishing effort and reduced economic outcomes for employees (Beddington, Agnew & Clark 2007). ITQs have proven to be a more successful alternative strategy to eliminate high competition and to effectively support conservation measures. However, misreporting and illegal fishing still occurs as only wealthier nations can afford to implement policing of such behaviours (Beddington, Agnew & Clark 2007; FAO 2014). Originally set up to reduce the effects of trawling on seafloor structures (Johnson & Welch 2010; Nellemann, Hain & Alder 2008), only ecosystem-based management approaches have successfully targeted the reduction of bycatch through MPAs (Beddington, Agnew & Clark 2007).
Beddington (cited in Ye et al. 2013) believes that overexploitation has arrived due to open access or ‘tragedy of the commons’ (Caddy 1998) coupled with national government subsidies for fisheries. Incentives for fishing are currently encouraging overfishing and should be redirected towards funding for the regrowth of depleted stock levels (Ye et al. 2013; Clover 2006). UNEP recommends, “Governments need to respond with more urgency” in strategically and sustainably managing fisheries (Nellemann, Hain & Alder 2008). Globally, there is an apparent need to introduce additional MPAs to target conservation effort towards protecting biodiversity hotspots (Nellemann, Hain & Alder 2008; Clover 2006) and coastal habitats such as coral reefs for life stage development for migratory fish populations (Johnson & Welch 2010).
Both IPCCa (2013) and IPCCb (2013) alike state with high confidence that local measures or global reductions in fishing effort will not be sufficient in offsetting current damages to marine ecosystems. Current population forecasts suggest that only 6 of 22 Pacific Island nations will be able to meet the demand for fish in 2030, suggesting that current consumer and dietary behaviour will have to adjust unquestionably (Smith, Smith & Webb 2012; Clover 2006). In addition, the majority of population growth until 2050 is predicted to occur in nations that currently rely heavily on the protein source of fish (UN-DESA cited in Hollowed et al. 2013), again reiterating the importance of dietary changes to the elimination of pressure on the overexploitation of the fishing industry. Merino et al. (cited in Hollowed et al. 2013) demonstrated that even with improved management, if current consumption continues, collapse of fisheries management is inevitable.
(Ye et al. 2013) considers that fisheries will unfortunately soon be looking more towards high sea fishing due to shallow fishing grounds being depleted, running higher risks of overexploitation due to the life span, reproduction rates and low fecundity of deep sea fish (Nellemann, Hain & Alder 2008; Johnson & Welch 2010).
This study recommends along with Nellemann, Hain & Alder (2008), IPCCa (2013) and IPCCb (2013) alike that there is an inherent need for fisheries management to adopt sustainable ecosystem-based management techniques that remain flexible in the face of climate adversity and aim to reduce and rebuild overexploited stocks (Johnson & Welch, 2010; Harsem & Hoel 2013). Safe biological limits are currently modeled around outdated and narrow focused data that is only further disillusioning public perceptions on the state of the world’s fisheries (Beddington, Agnew & Clark 2007). It is subsequently recommended for fisheries scientists and climate change experts to collaborate in order to establish holistic models for sustainable catches.
IPCCb (2013), Johnson & Welch (2010), Nellemann, Hain & Alder (2008) and Harsem & Hoel (2013) unanimously agree that the weaknesses of overexploited fish stocks will be further exacerbated in future climate change conditions. There is an apparent need for a combined approach to fisheries management that incorporates best practice sustainable yields, increased focus on the reduction in illegal fishing through higher penalties, decrease in incentive based catches, restoration of depleted stocks through encouragement, as well as stricter harvest policies. Additionally, there is a need to address data-poor and undersampled fisheries so as to better capture a true understanding of global statistics and further predict changes in the marine environment. (Smith, Smith & Webb 2012; Hollowed et al. 2013)
Conclusion
The present study aimed to elucidate whether overcapacity and overexploitation in fisheries management would lead to increased sensitivity within fish stocks to climate change. Research demonstrated, in summary, there is high confidence that overfishing is enhancing the vulnerability of fish populations to climate disturbances, with current exploited stocks potentially collapsing due to prolonged recovery time in temperature uncertainty (IPCCb 2013; Johnson & Welch 2010; Hollowed et al. 2013). Fisheries have responded to current statistics by moving from depleted shallow fishing grounds to high seas in discovery of new target species to replace overexploited stocks. However, deep-sea fish present higher vulnerabilities to both climate change and overexploitation and such methods will only compound pressures on the sustainable longevity of fisheries (Ye et al. 2013).
Success has been found in the management of Australian fisheries, which has implemented ecosystem-based management, bycatch policies, harvest strategies and recovery methods for depleted target species on a national scale. Recommendations have revealed the need for progression away from output management strategies such as TAC’s and ITQ’s and toward input measure utilised by Australian fisheries management. These include the limiting of vessel numbers, ship size, restrictions on fishing seasons, implementation of MPAs and reduction of government funding.
Research has highlighted an inherent need to bridge gaps of incomplete data retrieval in order to build truer models to reveal optimum biological sustainable catches. The future and prosperity of natural resource management during climate uncertainty relies on collaboration with climate change experts in order to implement climate variables into such models (Salinger et al. 2013).
To avoid global collapse of fisheries in the somewhat near future, management must also adopt sustainable methods of adhering to MSYs, avoid fishing techniques such as longline fishing that produce bycatch mortality, penalise and police IUU fishing and promote MSC award status. However, this report has also revealed that this, in itself, will not be sufficient in the sustainability of fisheries. There is a major need to lower the pressure from consumer habits of developing nations globally, distributing protein sources evenly within diets.
Finally, fisheries must create maintain flexible management in order to be adaptable in future climate change. However, this can only be executed if a base understanding of current situations is acquired (Harsem & Hoel 2013; Salinger et al. 2013). Education for stakeholders to comprehend the implications of overfishing to the permanency of fisheries management will help in the sustainability of targeted species and the facilitation and recovery of depleted stocks (Beddington, Agnew & Clark 2007).
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