Balanced harvest or unforeseen chaos?
Due to the extreme fishing pressures and over-harvesting experienced by fish stocks around the word, a new method to sustainably harvest fish has been proposed; balanced harvesting. Balanced harvesting has been put forward as a way to supply the worlds growing food demand while still protecting the oceans. However there has been much debate as to whether or not this will really work and several recent high-profile studies (including in Science, Proceedings of the National Academy of Sciences and Fish and Fisheries) have weighed in on this subject. The way balanced harvesting works is that rather than focusing on a small number of species and protecting certain size-groups, fishing pressure is spread evenly across the ecosystem.
Meaning every species and every size within a species is harvested in proportion to its natural productivity.
Balanced harvest is probably not technologically possible, because few fisheries are able to target individual species selectively. Methods that are used in most cases to catch fish by industries is likely to get a wide variety of organisms and not just individual species targeted. Another problem with balanced harvest would be micromanaging species’ relative harvest rates, this would be next to impossible. Balanced harvesting would likely be very expensive, especially on the management side as it would require modern scientific monitoring of every species in the ecosystem. Currently only most commercially valuable species and a few by-catch species are being monitored. Monitoring every species in the ecosystem would require research surveys or on-board observers, for example. Modern fisheries management for a single species can already cost as much as 25% of the gross value of the catch. Fisheries will expend significant effort catching sizes and species of fish that have no commercial demand.
Balance harvesting might have a negative effect on the fishers as there are
concerns that they won’t receive as much money per kilogram of catch as they would under the traditional fishing practices. This is because under balanced harvesting a large proportion of the catch will be made up of small fish and small fish are worth less. There is also doubt about the feasibility and practicality of unselective fishing over all size classes as small fish are notoriously hard to catch. Society might also not react well to large quantities of small fish being used for fertilizer as these fish are too small for human consumption. For a fishing method proposed to supply the worlds growing food demand while still protecting the oceans this seems like a lot of waste. Recreational anglers have also expressed concern that increased fishing for small fish will reduce the food available for large trophy fish, thus communication with recreational and sports fishers will be an important component of balanced harvesting.
Balanced harvest would mean a decrease in the size of fish that is harvested, this is most likely going to decrease the market value of the fish. Balanced harvest also includes harvesting across all species, this might be a waste because not all fish are palatable or simply preferred by most consumers. The consumer that would benefit would be the aquaculture industry due to decreased fishmeal prices. Balanced harvest looks at “conservation” and not the economic and social component of a fishery.
There are serious marketing concerns regarding the public resistance to diversifying catch. Expending significant effort catching sizes and species of fish that people may not want to buy or eat, is a huge concern associated with balanced harvest. How do we encourage diet change? Diet is often integrated into culture and changing it would not be easy. There is general pubic unease because of the shifts in policy, which would now conflict with previous advice to avoid immature fish and spawning fish. This creates a period of confused answers to consumer questions and past public education to favour more selective fishing methods.
The human population is increasing, but the amount of food available for consumption is not. Can we acquire ‘extra’ food in the form of protein from our oceans? Some may argue that this is the answer to our problem, and even though the cost of balanced harvest is high, it will be worth the cost as we will be catering to essential human needs. The question then arises…. Are we actually catering to essential human needs? It has been projected that between now and 2050, the increase in food demand will not be from new mouths to feed, but from people eating more protein. Will this be worth the extra cost, now that we will be catering to the richer countries where people can afford to consume more?
Another aspect to keep in mind is that balanced harvest may produce more food, but this will be in the form of new types of fish that will be introduced to consumers. Will this meet consumer tastes? Or will it go to waste because it does not?
The non-selective catches of fish at different life stages is a cause for concern, because not all fish species mature or become fecund at the same size. The increased catch of small fish for some species may mean an extinction due to fecundity at a small size and inability to contribute to the next generation. When small fish are removed from a system, prey is removed for the large fish and this would decrease the large fish population size. The small fish are also prey for other organisms and this means that these organisms would lose their food source.
In practice, one of the challenges faced by fisheries is to find a coherent suite of policies and management measures that jointly, effectively, and efficiently fit balanced harvest. On the management side, it would require modern scientific monitoring of every species in the ecosystem; currently only the most commercially valuable species and a few by-catch species are monitored, via research surveys or on-board observers, for example. There will be challenges associated with assessing and, if adopted, managing such a massive change in approach. Such a huge change in approach could lead to institutional resistance and confusion among interest groups. Major implications for the choices of strategies and tactics for managing human uses of ecosystems. Nevertheless, the Commission, in their evaluation of evidence and information to help develop their thinking about technical measures, should seek out differing opinions between proponents of Balanced Harvesting and doubters, but will also have thought about how to distinguish between valid arguments and concerns, and attitudes that are possibly unnecessarily inflexible or dogmatic. Early research on balanced harvest focused essentially on its bio-ecological and modelling aspects, with little on policy, economic, and operational implications. The lack of evidence might make management and policy makers a little uncertain, and unwillingness to abandon traditional management policies .
The science behind balanced harvest is more complicated as it looks further down the food web and at ecosystem based interactions. Fisheries do not only target fin fish, they also target species that are part of the benthic food chain. Balanced harvest needs to take into account how much of these benthic populations are being removed, so as to not disrupt the proper functioning of the system. For example, if filter feeders are removed from the system, this can cause nutrient build up which can inevitably lead to the ecosystem crashing. Humans are not the only consumers of fish, predators of the sea also consume fish that we consume, this needs to be considered so that we do not remove important prey species.
The main aim of balanced harvesting is to maintain a biomass pyramid of the same shape as the natural pyramid. However, we must remember that over years of fishing and over exploitation of our fish resources, that we have already altered this pyramid. Therefore, it may not be clear how much smaller the fish component of this pyramid would be.
There are currently policies and conservation which aim to rebuild marine mammal populations, actions such as these all affect the biomass pyramid. The ocean and all her creatures are incredibly interconnect from unicellular plankton to seabirds, all all these complex interactions taken into consideration with balanced harvest? Changing the amount of small fish in an ecosystem can have ramifications that would undo our good intentions. If balanced harvest require harvesting all species, in all size classes, this begs the question; how far down would we need to go down in the food web? Is it even practical to harvest single-celled organisms? but if we don't, what are the consequence and would we be truly balanced? This concept is primarily a management, a fishing capability and market conundrum. Research can provide insight into necessity and consequence, but we can't make any certain statements until such research is complete.
There are biological risks of not being ‘purist’ about unselectivity, for instance increasing fishing on (impractically) small individuals.For example what are the risks that species which were not targeted would increase in abundance to permanently occupy the roles of those that were targeted. Is it safe not to target gobies?? Do pipefish take over if sandeels are harvested? Do lesser spotted dogfish (or crustaceans) take over when there are no more gadoids? Will we be unintentionally designing a new alternative ‘stable state’. How much do you actively need to catch all species selectively in order to avoid such consequences?
More demand-side solutions needed. Target the AMOUNTS of meat and fish demanded rather than ways to produce more meat and fish.
Why not work on giving people in rich countries incentive simply to eat less meat and fish? Recent research suggests significant benefits for both the environment and human health. This would probably help the economy too, considering the enormous economic burden of over-consumption-related ailments. Alternatively, a country could include food-related carbon emissions in carbon taxes as meat and fish have high carbon costs, carbon taxes creates incentives to eat less meat and fish. Carbon taxing fish and meat may also help to avoid exacerbating food insecurity for the poor. New Zealand did it! And it works for them so it's not impossible - only balanced harvest is impossible.