Enhancing fish stocks with wave-powered artificial upwelling

Ocean fisheries are declining worldwide due to overexploitation. Productivity could be enhanced and the problem alleviated by pumping nutrient-rich deep ocean water (DOW) to the surface to feed phytoplankton, the bottom end of a marine food chain, mimicking natural upwelling which sustains the most productive ocean fishing grounds in the world. Various pump types and power sources have been proposed for this purpose. The present article proposes a simple wave-powered pump to demonstrate the concept cost-effectively at prototype scale. Possible solutions to the problems of dilution and plunging of dense, nutrient-rich DOW are discussed. Two further possible benefits of this proposal are discussed: by extracting wave energy, relatively calm fishing grounds may be created close to markets, and by pumping up very large quantities of cold DOW, the surface temperature could be lowered enough to reduce coral bleaching on parts of the Great Barrier Reef.     

Assessment of MSC-certified fish stocks in the Northeast Atlantic

This study examines the status and exploitation level of 31 northern European stocks targeted by fisheries certified by the Marine Stewardship Council (MSC) as being sustainable and well managed. In the first year of certification, 11 stocks (52% of stocks with available data) were exploited above the maximum sustainable level and four stocks (16% of stocks with available data) were outside of safe biological limits. MSC states that it certifies sub-standard stocks because they will improve once they are in their program. However, after a duration of certification of one to ten years (average four years), no significant changes in fishing pressure or stock size were detected. In the last certified year with available data, seven stocks (44% of stocks with available data) were subject to overfishing and five stocks (21% of stocks with available data) were outside of safe biological limits. Certification should guarantee that fishing quotas are set correctly and are enforced. However, in 11 stocks quotas were set 20–60% above the level that fishers were taking, whereas in three stocks landings exceeded quotas by 30–50%. The study concludes that MSC should change its rules such that overfishing or unsafe stock sizes lead to immediate suspension of certification and that no certification is issued in the first place for a stock that is already in such a situation.     

Towards a market-oriented management model for straddling fish stocks

Management of straddling fish stocks has been noted for its political complexity. Negotiations frequently falter as each party seeks to focus upon their own individual and shorter-term goals than the collective interest of the sector. Entrenched positions are often only deepened as new entrants participate to establish their own claims to any emergent share of resource. Unsurprisingly, deadlocks are common and typically compromises are reached only after the real period of biological then economic crisis has passed. Examples to illustrate this tendency can be found in most of the world's oceans and is writ large within the current impasse over blue whiting (Micromesistius poutassou) in the North Atlantic. The development of this fishery is discussed and it is shown that despite the scope to add value to the resource base through a pattern of exploitation focussed more upon human consumption than fish meal and oil, there seems little incentive to extricate participants from the cycle of demise that has engulfed negotiations so far.     

Concern for Southern Ocean fish stocks and bird populations

The paper highlights the challenges faced by parties to the Commission for the Conservation of Southern Bluefin Tuna (SBT). The parent stock of SBT is at historically very low levels and the probability of stock recovery under present catch quota levels is also low. Seabird kill associated with longlining for SBT is now a major concern and several species of endangered Albatross could be heading for extinction unless improved methods of bird exclusion are widely adopted in the SBT longline fishery. Australia in particular has much to lose if these trends are not reversed.     

Impacts of climate change on commercial fish stocks in Norwegian waters

The Norwegian fishing areas extend over various marine ecosystems that will respond differently to climate change. In the North Sea the productivity of the boreal fish species are likely to decrease under global warming and new warm-water species are expected to become more abundant. In the arctic marine ecosystem of the Barents Sea the fish productivity is expected to increase and their distributions expand northward and eastward under global warming increasing the importance of the Russian as well as the Norwegian sectors of the Barents. In the past, decadal-scale climate variations have been shown to strongly influence productivity and distributions of fish stocks. The importance of such shorter-term variations are expected to continue also under global warming. Under global warming the optimum temperature for fish farming along the Norwegian coast will be displaced northwards from the northern part of West Norway towards the Helgeland coast.     

The spectre of uncertainty in management of exploited fish stocks: The illustrative case of Atlantic bluefin tuna

The recent overexploitation of East Atlantic and Mediterranean bluefin tuna stock has been well documented in the media where it has become the archetype of overfishing and general mis-management. Beyond the public debate, the crisis also highlighted how the interactions between science and management can change through time according to the awareness of the public opinion. To reflect these issues, the history of Atlantic bluefin tuna overfishing is first described. Then, the major uncertainties that undermine the current scientific advice are summarized and the importance of reducing their impacts by improving knowledge and developing robust scientific framework is considered. The study also discusses how uncertainty was used by different lobbies to discredit science-based management. The recent improvement in bluefin tuna stock status following the implementation of the rebuilding plan shows that, despite uncertainty in the scientific advice, the management of a heavily exploited fish stock can be positive when there is a political will. However, optimizing long-term yields of modern fisheries implies good science. The study concludes by advocating for the implementation of a scientific quota that should be part of the management framework to support the scientific advice.     

Moving beyond catch in allocation approaches for internationally shared fish stocks

Allocation schemes are one way to combat the tragedy of the commons, the situation whereby individual users of a shared resource put their own interests above the collective good. In the case of shared fisheries, developing equitable and transparent allocation schemes can help to ensure stable cooperative management agreements, which in turn will facilitate sustainable fisheries. Allocation schemes for shared fisheries resources, which have been in existence for decades, have recently been facilitated by Regional Fisheries Management Organizations (RFMOs). These schemes vary in the scale of interested parties, from simple two-country systems sharing Pacific salmon, to multi-country systems sharing Atlantic bluefin tuna. Most RFMOs tend to base allocation schemes on historical catch records, spatial stock abundance estimates, or a combination of these. Socio-economic factors do not appear to influence allocation to any major extent. Unfortunately, previous attempts at creating and enforcing allocation programs have not, by and large, been able to curb the serial depletion of fish stocks, particularly when the number of fishing countries is large. Several RFMOs are currently in the process of initiating or reformulating allocation programs. In this paper, current allocation approaches are reviewed and discussed in the context of their possible transference to new or evolving programs. Specifically, lessons from game theory are drawn on, and the potential for better incorporation of socio-economic circumstances in allocation decisions, which can incentivize improved compliance, is explored. The relevance of conclusions from the literature analyzing international water agreements is also discussed, and a combined socio-economic-ecological construct whereby allocation programs can be based on the sharing of benefits other than catch is proposed.     

Assessing and monitoring local and long-range-transported hydrocarbons as potential stressors to fish stocks

The Arctic is poorly described and understood compared to the North Sea and other boreal areas. We need to learn how knowledge obtained at boreal conditions may be applied at Arctic conditions. Increasing activity of the hydrocarbon industry may cause exposure stress from discharges. Within a joint industry research programme (Biosea) we studied how responses in fish from oil exposure may differ at North Sea boreal and Barents Sea Arctic conditions. Hydrocarbon uptake, metabolites, and enzymatic and genotoxic biomarker type of effect responses were measured in cod (Gadus morhua L.). Hydrocarbon metabolites remain longer in fish bile than original hydrocarbons, which are eliminated fast from tissues. The metabolites may be measured to background concentrations. They describe exposure and they constitute a link to other effects. Body burden, biliary polyaromatic hydrocarbon (PAH) metabolite concentration, and quantities of Cytochrome P-450 1A (CYP1A) and DNA adducts increased with oil in water concentration. The extent of biomarker expression was lower for some biomarkers and elimination was slower at the lowest temperature. The results show that several factors have to be accounted for if warm-water biomarker data are to be applied in cold water.     

Modelled effects of primary and secondary production enhancement by seamounts on local fish stocks

This paper addresses how large aggregations of fish found on many seamounts are sustained. We used a generic seamount ecosystem model from the Northeast Atlantic to examine the impact of a potential increase of local primary production on higher trophic levels, to quantify the immigration of allochthonous micronekton that would be required to maintain a “typical” seamount community, and to quantify if the necessary immigration ratios could be supported by local oceanographic conditions. Our simulation predictions indicate a lack of autochthonous resources in the system to support large amounts of seamount aggregating fish. In other words, autochthonous seamount production may be responsible for sustaining only a small amount of its total biomass. Additionally, our study supports the idea that enhancement of primary productivity also cannot sustain large aggregations of seamount fish. Our seamount model, which took into account high abundances of fish, marine mammals, seabirds and tuna, required a total immigration of allochthonous micronekton of 95.2 t km⁻² yr⁻¹ less than the potential available biomass after considering the immigration of prey based upon average current velocities and prey standing stocks in oceanic waters. Our model predicted that the horizontal flux of prey would be sufficient to sustain the rich communities living on seamounts.