Changes in fish consumption patterns: can they tell us anything about fish stocks?

 

    Fisheries data are of paramount importance if we want to know more about rivers and oceans. With this information, it is possible to monitor and manage the populations of fish and invertebrates inhabiting these waters, plan sustainable fisheries exploitation policies and maintain environmental balance, while also guaranteeing human nutrition and preserving the aquatic fauna.

    Something apparently so simple, such as fisheries statistics, however, are increasingly rare in Brazil and other developing countries. This is why scholars studying the environment need to make use, with increasing frequency, of alternative methods to obtain data that can fill some of these knowledge gaps.

    This is how this study was born. Comparing information collected in studies that followed fish intake by families in fishing villages in the South and Southeast regions of Brazil since the 1980s, we identified an ever-lower consumption of predatory fish and invertebrates, while the presence of smaller-bodied species increased on the plates of these families. We also investigated temporal changes in species richness, diversity and composition, size and trophic levels of fish, consumption of species threatened with extinction and the functional diversity of these species, that is, species with different preferential behavior and habitat.

    Our findings are worrisome because they confirm the trends observed around the world for fishing data. Such trends show that over the decades there has been a decrease in the trophic level of catches. The trophic level represents the number of steps in a food chain, in which the top predators occupy the highest levels. Herbivorous fish, for example, have lower values and omnivores have intermediate values. Humans tend to consume fish of high trophic level, such as groupers and meccas. However, these are less abundant than those of lower trophic levels, such as sardines. These species of higher trophic levels have a greater propensity to be exposed to fishing above the population's renewal capacity, leading to a decrease in their frequency in the nets and in the dishes. Thus, they are more quickly subject to over-exploitation and this is detected by a general drop in the trophic level around the world. Apparently, we may be seeing the same trend in the diet.

 

 

    Another relevant change concerns endangered species. According to our study, their consumption has always been low, but most of these species have changed over time, suggesting that many, especially rays and sharks, may have become rare on the plates. We were not able to conclude whether people stopped consuming these species from before because they decided to do so on their own, which is unlikely, or whether these former species became increasingly rare and were replaced by other threatened species in the diet.

That is why it is necessary to interpret these data with caution. It is not possible to say that these species are becoming extinct by only looking at what is happening with the diet, in the same way that it is not possible to ensure that the lower consumption of predators or the smaller size of the fish is because the larger ones are rarer. There are associated cultural factors that we have not been able to isolate. People may be selling the largest fishes or they simply stopped consuming some species now that access to the market is easier. However, these negative trends confirm those observed in the world and turn on a yellow, almost red light.

 

Next steps

    In addition to the environmental aspects, many other fields can be explored in the future based on the information raised in this study. The database we put together is quite large and may allow other questions to be answered, including those of a nutritional nature. We have information, for example, about the other food items that people have been consuming in fishing villages for decades. We can investigate whether there has been a replacement of fish for other proteins of animal origin and assess the nutritional and financial value of this replacement, which could identify aspects related to the health of these communities,  and their food security and sovereignty.

    So, there is a huge potential to obtain even more comprehensive data. If we improve our collections of household information, such as those made by the Brazilian Institute of Geography and Statistics (IBGE) and similar ones elsewhere, by better detailing the species of fish consumed, we may have an additional source of indirect information on fish stocks, but this time on national scales.

 

The paper can be found here:

Lopes et al. 2021. What fisher diets reveal about fish stocks. Ambio:

https://link.springer.com/article/10.1007/s13280-021-01506-0

 

Article originally written by Marcos Neves Jr. (in Portuguese)

https://www.ufrn.br/imprensa/materias-especiais/45788/mudanca-no-consumo-de-peixes

Adapted by Priscila Lopes

 

Gone with the flow: Belo Monte dam plays with Amazonian socioecological systems

 

While COVID-19 is taking a very high toll on Brazilian indigenous people, especially by reaping the elderly, who are the main holders of forest knowledge (1), the moment is being used to bend the rules and to force environmental deregulation (2). In 2016, Belo Monte, the third largest hydroelectric dam in the world, started operating partially despite its expected socioecological impacts over a 100 km stretch known as “Volta Grande do Xingu” (3). Full dam operation was due to begin in early 2020 and, along with it, a 6-year highly contested hydrograph test period that would alternate between a harsh and a harsher flood control annually (4).

However, a strong El-Niño in 2015-2016 significantly reduced the river flow to levels that, although above those of the alternate hydrograph, prevented the natural forest flooding. This natural experiment compromised ecological processes, including the reproduction and growth of fish and turtles, and impacted the Indigenous peoples who depend on the natural environment (4). In April 2020, after strong and continuous pressure from the civil society, the Brazilian Environmental Agency (IBAMA) demanded the adoption of a less severe transition hydrograph for the year. This decision was not initially questioned by Belo Monte operating company, possibly because the Covid-19 pandemic first resulted in a significant drop in industrial activities, and therefore, in the energy demand. As demand for energy resumes, a dangerous strategy seems to have been set in motion to avoid fines and still achieve the required average flow. For example, the required flow for July is 1300 m³/s), which one supposes would be more or less the daily flow every day of the month. However, the operating company adopted another strategy: it strongly reduced the flow during the first 20 days of July to an average of 1022 m³/s, which compromised navigation, fishing and regular river-related activities. In the last days of the month, the company greatly increased the flow to a daily average of 1517 m³/s. By doing that, the company probably maximized its energy production and decreased its chance of being fined, with no concern whatsoever for the socioecological consequences of playing with the flow.

Locals leaving the area afraid of further unexpected floods (last week of July, 2020)

Sudden increases in flow were made without due notice to communities, who still lack alarm systems. The Indigenous peoples reported losses of boats, engines and ornamental fishponds, which represent, for many, all of their assets. At a time of extreme vulnerability, Amazonia and its people are paying the highest price for a policy that promotes impunity (5), with consequences yet to be seen. This example also raises the question: will this be the “new normal” to Amazonia’s environmental policies?

 

By Priscila Lopes, Cristiane C. Carneiro & Juarez C. B. Pezzuti

 

 

1.         L. Ferrante, P. M. Fearnside, Protect Indigenous peoples from COVID-19. Science. 368, 251–251 (2020).

2.         A. Press, Brazil: blow to Bolsonaro as judge orders release of expletive-ridden video. The Guardian (2020), (available at https://www.theguardian.com/world/2020/may/22/bolsonaro-brazil-cabinet-video-court-judge).

3.         D. B. Fitzgerald, M. H. Sabaj Perez, L. M. Sousa, A. P. Gonçalves, L. Rapp Py-Daniel, N. K. Lujan, J. Zuanon, K. O. Winemiller, J. G. Lundberg, Diversity and community structure of rapids-dwelling fishes of the Xingu River: Implications for conservation amid large-scale hydroelectric development. Biol. Conserv. 222, 104–112 (2018).

4.         J. Zuanon, A. Sawakuchi, M. Camargo, I. Wahnfried, L. Sousa, A. Akama, J. Muriel-Cunha, C. Ribas, F. D’Horta, T. Pereira, P. Lopes, T. Mantovanelli, T. S. Lima, B. Garzón, C. Carneiro, C. P. Reis, G. Rocha, A. L. Santos, E. M. D. Paula, M. Pennino, J. Pezzuti, Condições para a manutenção da dinâmica sazonal de inundação, a conservação do ecossistema aquático e manutenção dos modos de vida dos povos da volta grande do Xingu. Pap. NAEA. 28 (2020), doi:10.18542/papersnaea.v28i2.8106.

5.         H. Escobar, Illegal deforestation in Brazil soars amid climate of impunity. Sci. AAAS (2020) (available at https://www.sciencemag.org/news/2020/08/illegal-deforestation-brazil-soars-amid-climate-impunity).

SERI: A new approach to measure resilience of small-scale fishers

Do you know what social-ecological resilience means?  Well, it can be a little bit tricky to understand but I will try to explain it to you. Resilience is defined as the ability of a system to cope with disturbances while maintaining its functions. For instance, the ecological resilience of coral reefs has declined because of overfishing, rising temperatures, and other factors, which has led to radical regime shifts that make them more vulnerable to natural disasters. In the social context, resilience is the capacity of human communities to absorb changes and adversities while maintaining their livelihoods. For example, fishing communities may maintain their social resilience despite transformative changes, e.g., technological or cultural, that involve regime shifts, such as a shift from a fishing economy to a tourism-based economy, if such transformations maintain or improve their livelihoods. So, when social systems are nested in ecological systems through mutual feedbacks, i.e., fisheries system, the term social-ecological resilience  (SER) is adopted.

But can we measure fishers' resilience? Yes, we can do it. A new research just published in Ecology & Society proposed a new index to measure social-ecological resilience of small-scale fishers. The SERI – Social-Ecological Resilience Index – is a practical tool based on an integrative ecosystem approach and it can be of great value to marine conservation planning.

The new approach consider the social-ecological system as a whole, that is, human and environmental systems must be considered in unison, as an integrated system. The authors believe that altering the relationship between fishers and fisheries resources could influence fisher resilience, which is likely to depend on how management strategies are delivered and perceived, how environmental changes are felt, and on the intensity of resource dependency (Fig. 1). 

Figure 1: A conceptual framework for assessing the social-ecological resilience (SER) of small-scale fishers as a function of policy, environmental, and socioeconomic changes in the system. SRi = Social Resilience at the individual level; SRc = Social Resilience at the community level; ER = Ecological Resilience. Adapted from Marshall et al. 2009.

The variables used to compose the SERI are assigned to the individual, community, and ecosystem levels of the fisheries system, because fisher resilience is influenced by fishers themselves, fisheries resources, and aspects related to resource dependency at the community level (Fig.2). 

Figure 2: Proposed components (three circles forming SERI), indicators (represented by icons), and subindicators (variables in the rectangles) to measure the SERI of small-scale fishers, where SERI = (SRi + SRc + ER)/3. SRi = Social Resilience at the individual level; SRc = Social Resilience at the community level; ER = Ecological Resilience.

The SERI was applied to fishers living in three marine protected areas located in the northeastern coast of Brazil: Extractive Reserve Batoque, Extractive Reserve Prainha do Canto Verde, and State Sustainable Development Reserve Ponta do Tubarão (Fig. 3). The results show that the social resilience at both individual and community levels and the ecological resilience are important to fisher SER. Given the high contribution of the biological sensitivity indicator to form SERI, together with the lower ecological resilience values found in the three reserves, working toward the protection, restoration, and maintenance of biodiversity may enhance SER in these marine reserves. Individual and community resilience, especially through capacity building and leadership, should also be promoted. In addition, some fisher socioeconomic aspects are crucial to defining individual resilienceamong small-scale fishers in the considered areas. For example, older fishers, fishers who depend solely on fishing, and fishers who had higher-mean CPUEs were found to be less resilient.

Figure 3: Study area located on the Brazilian northeastern coast, highlighting the reserves located in the states of Rio Grande do Norte and Ceará. Pictures on the left, from top to bottom: the fisher association in RESEX Batoque, rafts (the main fishing craft in RESEX Canto Verde), and the estuary in RDSE Ponta do Tubarão.  

The findings of this study may provide a key to understanding the most important aspects of SER in coastal areas. By knowing the aspects that affect fisher coping strategies in response to changes to their social-ecological system, we can devise smarter management approaches that inform where conservation strategies and policy decisions are likely to be most effective. 

Besides being a feasible tool and to broaden the resilience discussion, this new index is a useful framework that can assist governments and environmental organizations to better understand SER among fishing communities. How resilient are the coastal fishing communities in your country? If you are interested in applying this index to your country, you can find all the necessary information and source data used to calculate the SERI in the supplementary materials of the research.



Silva, M. R. O., M. G. Pennino, and P. F. M. Lopes. 2020. A social-ecological approach to estimate fisher resilience: a case study from Brazil. Ecology and Society 25(1):23. 
https://doi.org/10.5751/ES-11361-250123

Some species play a key cultural role in our lives – could that be used to protect nature and benefit local people?

This text was originally published in the People and Nature blog.

Protecting nature is a challenge we have been failing to tackle. The longer we take, the harder finding solutions becomes, given the growing demand for natural resources by an ever-increasing human population.

Fishers waiting for an arapaima (Arapaima sp.) to come up to the surface to harpoon it, during an arapaima co-management harvest season in the Amanã Sustainable Development Reserve, Amazonas, Brazil. Photo credit: Carolina Freitas)

Human activities have triggered the extinction or sharp decline of numerous species in the last centuries, and the artificial imbalance of many, if not most ecosystems worldwide. Over the last decades, parks and reserves have been showcased and implemented as one of the main solutions to protect wildlife and ecosystems. However, these initiatives often fail to reconcile environmental goals with the social rights of local peoples with a long history of living in close dependence on nature. In many cases and contrarily to expectations, market insertion has not necessarily undermined the connection, respect and customary rules local people adopt towards nature, but the collapse of some species might have such negative impact. Preventing species collapse and promoting ecosystem protection needs us to include aspects we may have overlooked. Ecologists have long used keystone species as the basis for conservation plans and decision making, but what about species that play a key role in human culture? Could conservation efforts be focused on these culturally important species (CIS) as a way of protecting both nature and traditional ways of life? In this perspective article, we use data from the literature and explore the outcomes of two management schemes, both encompassing multiple independent initiatives, to show that the cultural importance of some species should be regarded as a highly relevant aspect of conservation strategies in places where natural resource use is critical to local livelihoods.

Local fishers interacting with aquatic resources in the Juruá River basin, Amazonas, Brazil. Left: Man carrying an arapaima (Arapaima sp.) individual (Photo: Helder Espírito-Santo). Right: Man carrying a yellow-spotted river turtle (Podocnemis unifilis) (Photo: Carolina Freitas)

We argue that management initiatives focusing on the recovery of CIS will likely stimulate the interests of local people, their engagement and compliance, as well as local surveillance against infractions. Local and continuous enforcement is potentially more effective than official institutional mechanisms, which are typically funding and staff-deficient and only sporadically deployed, especially in developing countries. CIS-management can achieve a wide range of positive ecological, social, cultural and economic outcomes and be an effective tool to reconcile biodiversity conservation with local people quality of life.

                                                                                            By Carolina Freitas & Priscila Lopes

Freitas et al. 2019. Co‐management of culturally important species: A tool to promote biodiversity conservation and human well‐being. People and Nature:https://doi.org/10.1002/pan3.10064

Assessing drivers of tropical and subtropical marine fish collapses of Brazilian Exclusive Economic Zone

A key step in facing a crisis is to identify the most vulnerable targets. The current biodiversity crisis is threatening all the world's ecosystems, causing the sixth mass extinction on Earth. The marine ecosystem is no different, over 60% of fish stocks are already threatened due to overfishing, climate change, pollution and habitat destruction. In the terrestrial environment, it seems clear that larger organisms are the most threatened because they are easier and more valuable targets and because of characteristics of their life history, such as the fact that they usually have slower growth and produce less offspring, among others. When considering fish, understanding their most vulnerable traits is not so obvious. Smaller species at low trophic levels are also fishing targets and are apparently more sensitive to climate variability. Larger carnivores are more valuable targets, and their response to environmental changes is slower, which may be an advantage after all. Using a catch-based analysis, we identified the exploitation status of 132 commercially valuable fish species in Brazil using four categories: Collapsed stock (when current catch is less than 10% of historical maximum catch), Overexploited, Fully Exploited and Development.

 

Figure 1: Graphical abstract of the study.

 

Based on this exploitation status, we identified which combination of characteristics and external factors (climate and fisheries) makes species more vulnerable to stock collapse. The biological characteristics tested were maximum body size, trophic level, preferable habitat (reef, demersal or pelagic) and resilience. As external factors, we tested sea surface temperature, sea surface salinity, type of fishing (industrial versus small scale) and price. We found that the two most important factors affecting vulnerability to species collapse were the response of species to sea temperature and species size. Smaller species negatively affected by higher temperatures are the most threatened. We suggest that overexploitation of species with vulnerable biological characteristics affects the way species respond to climate variability, making them more sensitive to warmer temperaturas.

 

Check out the entire paper here:

 

Verba, J. T., Pennino, M. G., Coll, M., & Lopes, P. F. (2019). Assessing drivers of tropical and subtropical marine fish collapses of Brazilian Exclusive Economic Zone. Science of The Total Environment, 134940.

 

By Julia Tovar Verba

Drivers of abundance and biomass of Brazilian parrotfish

During the past weeks Natalia Roos, member of the FEME, published her first PhD chapter in the MEPS 40th Anniversary volume.

 

Here below a little summary. If you want to check the entire paper checks here:

https://www.int-res.com/abstracts/meps/v623/p117-130/.

 

 

 

 

The large Brazilian coast encompasses most of the reef environments in the southwestern Atlantic, which are characterized by unique reef formations and high rates of endemism. Parrotfishes (Labridae: Scarinae) are among the most ubiquitous and dominant reef fish worldwide, and in Brazil the group is composed by 60% of endemic species (i.e. six species). It is known that parrotfishes may affect the physical structure and composition of benthic communities through the grazing and bioerosion. Despite their ecological importance, parrotfishes have been intensively target in many regions worldwide. In Brazil four endemic species are now threatened at some level due overfishing, including the largest Brazilian parrotfish Scarus trispinosus, which may reach up to 90 cm of total length. Signs of depletion of these species bolster our need to understand their patterns of abundance and biomass, habitat preferences and assemblage structure across different reef types inform conservation and management. We assessed abundance and size class distributions of six parrotfishes in northeastern Brazil and identified habitat preferences based on reef attributes. Species distributions were variable and related to their respective feeding modes and reef types. Such heterogeneity in habitat use is suggestive of functional complementarity rather than functional redundancy among Brazilian parrotfish assemblages. Moreover, outer-shelf reefs sustained larger individuals for most of the species, whereas inner-shelf reefs supported higher abundances of small individuals. Despite being nurseries or developing areas, shallow inshore reefs sustain intense artisanal fishing activities targeting parrotfishes. The ongoing fishing pressure in nursery habitats may be causing significant declines in adult numbers in deeper outer shelf reefs that are yet to be quantified. Such information may have important implications for management and conservation in the face of increasing fishing pressure on parrotfish. Moreover, conservation of Brazilian endemic parrotfishes requires protecting reefs with diverse attributes in order to conserve functional diversity.

 

Who are the losers in the messy and unsustainable fisheries management in Brazil?

This is not a difficult question to answer: everyone in the social-ecological system will lose!! From the artisanal fishers to the Brazilian president and from the bottom to the top of the marine food web. In one of our latest posts, we learned that from the current government we should only expect unsustainable measures instead of measures that could benefit both fisheries and biodiversity conservation. In the foreseeable future, we can expect higher exploitation rates instead of control and protection of vulnerable stocks. As a consequence, fisheries could collapse affecting millions that depend directly or indirectly on this activity.

Almost one-third of global fisheries stocks are now overexploited or collapsed (FAO 2016), which is not different in Brazil. The last Brazilian Red List of Threatened Species was published in 2014 (Decree nº 445) and included 475 species of fish and marine invertebrates threatened with extinction (MMA 2104). Instead of being received as a warning sign that we should step on the break and adopt mitigating or precautionary measures, the Red List was met with strong opposition by the industrial fishery sector and even by some artisanal fishers. Those against the list argued about the economic effects this list would have on fishery-dependent people. Did they use any data to back up their claims? No. But I decided to check if fishers had any basis to oppose the list and what they would gain or lose if instead of fishing stocks uncontrollably, we decided to manage them (Silva 2018). 

I investigated how many threatened fish species may disappear from the Brazilian coast in the following decades, and I checked if the fishers’ economic gains would improve or not if stocks were rebuilt. For that, I evaluated the status of specific fish stocks in the Brazilian coastline and explored different management scenarios to provide an overview of the major trends besetting fishers’ economic gains in the medium and long-term. I identified the main endangered fishes targeted by all coastal states and predicted the biomass and maximum sustainable yield for these species. I also created three management scenarios based on the reduction of fishing pressure, and calculated fishers’ revenue in these scenarios: scenario 1 (Current level – historical catch), scenario 2 (20% catch reduction due to management), and scenario 3 (50% catch reduction due to management).

Among the most abundant landed species, ten species were selected for the analyses: Alopias superciliosus (Bigeye thresher), Epinephelus morio (Red grouper), Hyporthodus niveatus (Snowy grouper), Kajikia albida (White marlin), Lopholatilus villarii (Tilefish), Lutjanus purpureus (Red snapper), Mycteroperca bonaci (Black grouper), Mycteroperca interstitialis (Yellowmouth grouper), Mustelus schmitti (Narrownose smooth-hound) and Sparisoma axillare (Yellowtail parrotfish). Artisanal fisheries target four of these selected species: L. purpureus, M. bonaci, M. interstitialis, and S. axillare. Industrial fisheries also catch L. purpureus and M. bonaci, in addition to catching H. niveatus, K. albida, A. superciliosus, M. schmitti, the E. morio, and L. villarii.

Four of these species actually seem to present increasing biomass: E. morio, L. purpureus, L. villari and M. schmitti. In contrast, six species are in risk of collapse (A. superciliosus, H. niveatus, K. albida, M. bonaci, M. interstitialis and S. axillare), and for two of them, the management scenarios we tested did not seem enough to bring them back (A. superciliosus and M. interstitialis) (Hellooooo!!!! These species need urgent help!!!). Here, I am presenting only the historical catch and predictions of these two most worrying fish stocks (Figure 1). 

Figure 1: Situation of the Brazilian fish stocks analyzed, highlighting the two most worrying declining fish stocks. The graphs show the historical catch (Historical) and predicted biomass (historical and 2100 prediction – Predictions) for Alopias superciliosus and Mycteroperca bonaci fish stocks. 

After we evaluated the effect of management on declining species, we found that fishers’ revenues should increase in the shortterm for A. superciliosus and M. interstitialis, but once these species collapse, theirrevenue will of course drop to zero.On the other hand, even though H. niveatus and M. bonaci showed highermarket prices than the first two ones, their revenues are expected to decrease in allscenarios because their catches are already decreasing.However, for K. albida and S. axillare, fishers’ revenues can be maintained andeven increased in the long-term if managers implement one of the management scenarios. 

Failing to manage these species will keep fishers’ profit for a few years, but once theendangered species collapse all of their profits will drop to zero in a few years or decades, depending on the species.For these species, the future benefits that fish stocks can provide willdepend largely on how well they are rebuilt and managed. However, fishstocks can be rebuilt if Brazil takes the responsibility of assuring that fishers and fishes willnot be losers. Short-term pain is necessary for a long-term gain and it is up to the country to make sure that the pain is not felt the strongest by the poorest and most vulnerable fishing groups.

Summing up, I am saying that the fish stocks in Brazil present declining biomass pattern, reinforcing the need to implement urgent conservation strategies. Management actions that forces catch to decrease could be crucial to support the rebuild of these fish stocks and to maintain fishers’ livelihoods in Brazil in the long term. 

Although there is an effort to protect fisheries in Brazil with the Decree nº 445, it is not done seriously by the government. Brazil's Red List has been facing a political battle to define management measures, worsening an already serious problem and ignoring the consequences for the environment and society. The recent update about this novel, it is the request for temporary suspension of the decree by the current Minister for the Environment. To keep things not so good, the Brazilian government is  firing people for doing their jobs. 

An employee from IBAMA (Brazilian Institute of Environment and Renewable Natural Resources) lost his position at the environmental agency because he arrested the president of Brazil for fishing in an ecological preserve where fishing is an environmental crime. 

Well, there is something wrong in this, we are going against what has been done around the world to protect marine biodiversity. We need governments to wake up and take responsibility for the devastating impact of overfishing, instead of presidents who really do not care about environmental issues. The future of all components of the fishing industry chain can be gloomier than ever if the government (and society) close their eyes for what has been happening. Let’s move because we all can be losers!!!

                                                                              By Monalisa Silva

 

 

Cited references:

 

FAO. 2016. The state of world fisheries and aquaculture. FAO, Rome.

 

MMA, Ministério do Meio Ambiente, Brazil. 2014. Portarias Nos. 443, 444, 445, de 17de Dezembro de 2014. Diário of União Seção 1, 245:110 (18 December2014).

 

SILVA, M. R. O. 2018. Coastal social-ecological systems: an integrative analysis to fishery conservation in Brazil. Tese (Doutorado) – Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, p. 126. 

Following the Fish: The Role of Subsistence in a Fish-based Value Chain

This week we are re-posting a post of the  University of British Columbia about a recent published article of our FEME members Ana Helena Bevilacqua and Adriana R. Carvalho, with Ronaldo Angelini, Jeroen Steenbeek and Villy Christensen. Check it out!!!

Bahia Formosa, RN State, Brasil. Photocredit: MGrazia Pennino.

Small-scale fisheries are important for livelihood in communities, providing jobs and food security to local inhabitants, but their contributions are poorly documented. A new study looks at how modelling can track the benefits provided by a fishery by following the people and activities involved in fish production.

The study measured the contributions of a small-scale fishery in the Baía Formosa area of the Rio Grande do Norte State, Brazil, to its local inhabitants. The researchers tracked the benefits that were created by the fishery, and what role it played for income generation and food security at the local level.

“We need to understand the importance of fisheries for communities, supporting food security and employment, and that doesn’t stop when the fish are landed at a port. We need to follow the fish from sea to plate,” said Dr. Villy Christensen, one of the study’s authors, professor at the Institute for the Oceans and Fisheries and principal investigator in the Global Ocean Modelling unit. Along with professor emeritus Carl Walters and other fisheries scientists, Christensen helped develop the value chain methodology along with the modelling software used in the study, Ecopath with Ecosim (EwE).

To do this, the researchers followed the journey of a fish through its fish value chain using the EwE modelling software. Following the fish value chain involves tracking the activities, processes, and people involved in turning the raw fish caught by a fisher into the final fish product purchased by a consumer. The researchers then examined the benefits created by different levels of the value chain, including what kinds of jobs were created by the fishery, whether the fish caught were mostly eaten by local people or tourists, and other information relevant to understanding the role of the fishery in the community.

The researchers found that the small-scale fishery played a crucial role for the local inhabitants, providing a means for subsistence, food security and employment opportunities.

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The researchers found that the small-scale fishery played a crucial role for the local inhabitants, providing a means for subsistence, food security and employment opportunities.

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Most fish caught by the fishery were sold at the local marketplace or eaten by the fishers themselves rather than purchased by tourists, which establishes the local importance of the fishery as a means for subsistence and food security. In fact, nearly all of the catches – 94 per cent – were consumed by locals and fishers’ households, contributing to a substantial flow of 18.7 million USD per year into the local economy. Since most fishers were also eating their own catch, they also avoided the cost of buying other sources of protein, which produced average subsistence earnings that put them above the poverty line threshold for fishers.

In addition to its contributions to income, the researchers found that fishery also created employment opportunities beyond the fishers themselves. For every fisher there were two people working on land, mostly in restaurants and street markets, where one third of the employees were women. Restaurants also played a large role in the local economy, as they generated 35 per cent of the jobs and 23 per cent of the revenue from only 5 per cent of fish production.

Since the fishery plays such an integral role in the lives of Rio Grande do Norte fishers and local inhabitants, changes to the fish value chain can affect the community’s well-being, and increase its vulnerability and susceptibility to poverty.

In order to predict how conservation policies might affect fishery-dependent communities, the researchers argued that policy-makers and managers must first understand the contributions of fisheries and different aspects of the fish value chain. That way, they say, policies that benefit both people and the environment can be effectively put in place.

The study “Following the Fish: The Role of Subsistence in a Fish-based Value Chain” was published in the journal Ecological Economics.

What else biodiversity changes could reveal about the effects of marine fisheries?

Biodiversity is essential for the adequate provision of various ecosystem services which we depend substantially upon for, among others, the development of fisheries, extractivism and agriculture. Our connection with nature in general and with biodiversity specifically is as old as our prehistoric hunter-gatherer origins, as humans have always observed and tried to understand the rhythm of nature in our quest for benefits that improve our welfare. There is nothing intrinsically wrong or very different from the behavior of so many other species in doing this. Our problems only began to emerge when profit and unnecessary consumption needs associated with population growth got into the equation and unbalanced the game between humans and the rest of nature.

At some point, we began to indulge excessively in nature provisions, as if they were permanent, secure, and unchanging, until one day, belatedly, we realized that something was not going well between us and the relationships we have with ecosystems. Such relationships are supposed to be as harmonious as possible, but there is unequivocal evidence that this has not been the case for a while. Whole populations of species are disappearing because of the constant disturbances we cause on them. There are countless fish species that have a smaller body size today than they had in the past, because we prefer to catch and eat the larger ones (which are also the most fertile individuals). These non-isolated facts are signs that we have been weakening the vital functions that nature provides us and we do that by affecting the biological interactions that keep them operating. 

A universal premise assumed by the typology of the tree of life is here generically summarized as "only from life can more life emerge". This could even be considered the first general law of biology, since all micro and macroscopic life forms depend on their precursors, to subsidize the rates of diversification in a region. This is how speciation happens. There are striking differences between the "types of life" (i.e., animal, plant...) that inhabit the planet, including the various types of attributes we use to differentiate and recognize them, which are products of selective forces that operate in the systems that harbor them. In these environments, innumerable natural factors constantly act to determine how much life can exist for short or long periods across geographical scales. 

In all terrestrial and aquatic biomes, thousands of life forms have diversified to form the exuberant biodiversity that pulsates everywhere, although at first this was done so that they could "adapt", colonizing territories and establishing their niches. Accidentally, they have made available all the resources that we benefit from today, from the air that is breathed into matter that decomposes. On the other hand, all human acts that disturb or alter biodiversity, produce countless consequences that affect the organization of many communities and the functioning of vast ecosystems, especially in the tropical region. 

This is worrying because as species signal the devastating effects of impacts, we remain unaware of how the pathways of biodiversity change, especially those caused by selective fishing pressures, resulting in the depletion of fish stocks, for example. Thus, the interactions between the factors (human-fishing-biodiversity) are relevant to be scientifically understood, since their relations can affect species that directly or indirectly promote the desired goals of fishing sustainability. It is essential to elucidate how these relationships take place over time and space, in order to identify which aspects of biodiversity respond more directly or strongly to the effects of fishing, and which remain indifferent or neutral to it in some hotspot, if any at all, given the current levels of depletion and of global changes. 

It is reasonable to assume that fishing acts differently on diverse parameters of diversity, including other dimensions beyond species level, such as evolutionary legacy, nest variability, and morphological heterogeneities, which, when dissociated, represent what we call, respectively, phylogenetic and functional diversity. These exercise complementary roles and, when observed together, are considered essential variables to estimate and understand the main aspects related to biodiversity (Schmeller et al., 2018), and can overcome preconceived ideas about the consequences of fishing-mediated declines on us and on ecosystems. 

Mechanistically, it is possible to classify the correlation of fishing with biodiversity as an essential connection, which the stronger and more positively imbricated, the more it favors us. Otherwise, these forces inevitably annihilate or seriously compromise each other, depending on how intense and stable the associations between them are. The performance of this union is presented in two main ways. One route ensures that nature replaces stocks free of charge, through the natural regulation of biomass, diversity and co-occurrence of all fish species in addition to those of fishing interest. The species we catch and consume may be more or less similar to each other, such as mullet, sea bass and marlin, because of their position in phylogenetic trees. Such positions inform us how long ago individuals have differed from each other and therefore, on how much evolutionary history we are currently putting pressure on. In this way, each species participates as a small part of the big machinery known as biodiversity. And in each place of such machinery, various forces of nature synchronize in the same way to form communities, assemblies or multi-specific aggregates of fish targeted by fisheries.

Local gains from fishing tend to directly reflect the conservation status of a region's biodiversity, since local natural processes ultimately determine the diversity of individuals that may be caught. By maximizing the development of attributes that ensure the survival and plasticity of responses to dominant conditions (ie, fitness = individuals most suited to the highest reproductive yields), organisms end up developing in parallel, and especially to human eyes, valuable attributes such as size. But to the extent that we "preferentially" fish these attributes (eg, heavier and larger fish), there is a negative repercussion on the evolutionary aspects of the groups that are exploited by the activity. Over time, fish diversity and quantity decrease, and both fishing and wild communities are hampered by processes triggered by loss of composition and reduction of biotic heterogeneity in stocks. On its turn, this increases pressure on certain groups.

The process described above, of the influence of fishing on biodiversity, is the second route, which is not generally positive, since it leads biodiversity to respond to the stressful removal of species with the best commercial attributes. Not coincidentally, these species tend to be ecologically peculiar and quite difficult to be replenished or compensated for. In part this is because the more peculiar the evolutionary position of a species in relation to the abundance of close relatives that occur in a certain place (ie, more or less branches), the more vulnerable they are to overfishing, and they leave us without potential substitutes.

The intensity of the fishing-biodiversity (positive or negative) relationship is dynamic and may suffer significant imbalances over time. Such imbalances can act as good indicators of the biodiversity status directly as a consequence of fishing. A contrast between functional vs. phylogenetic compositions can inform how much a coastal environment is susceptible to decline or loss of biodiversity. It is through this lens way that we intend to look at the health of the biodiversity of marine fish stocks in Brazil. We believe that assessing the relationships of fishing activity with descriptors of spatial and temporal coastal diversity may bring up important information. We believe that fishing is not likely to always work on the same types of attributes (e.g. habitat preference, reproductive or trophic guild) with the same artificial selective intensity. This could lead to interesting differences between the sets of species handled by fishing, whose causes and consequences may lead us to predict the main types of transformations that may occur due to the patterns of changes in the general and essential descriptors of biodiversity.

A lot of people believe that fish is all the same, a mistake not taken easily by the ichthyologists! However, it is important to note that the more similar the target species are, in terms of basic attributes such as food habits (which reflects on the taste of the fish) and body size, the more dangerous the effects of long-term fishing on them. This is so because fishing tends to focus on certain patterns that are difficult to find (fishers, depending on consumer demand, always want larger fish with specific tastes, but only a few species have all the desired characteristics). Therefore, finding out which combinations of traits best express the ways in which fishing acts on biodiversity is paramount in identifying changes in fish composition patterns that may be signaling the health of the ecosystems in which they operate. 

We have been developing a conceptual model to show the correlations we expect to observe between fishing and biodiversity. We expect biomass removed by fishing to affect positively or negatively the variability in the clades or traits of fished subsets.

In this sense, we believe that the measures of richness, divergence and phylogenetic (Tucker 2017) or functional integrity (Hatfield et al. 2018) represent some of the most important ways to evaluate how, when and how much biodiversity variability is related to fishing as a source of chronic disturbances (e.g., Teichert et al. 2018). These indicators should allow us to identify where the greatest and worst effects of fishing are, and to predict which routes are responsible for their magnitude in each place or time period (e.g., Worm et al. 2006).



These inferences will allow us to find out if there are plausible reasons to worry about the differences between the levels of diversity associated with fishing yields along the coastal gradients of Brazil, and whether significant losses can be detected within one or more facets of biodiversity (ie, taxonomic, functional or phylogenetic). In what direction and at what pace is all of this developing? What are the deficits we are generating for future communities? And, what can we do about it, other than standing and watching? 

All of this is important not only to identify the way the coastal fishery has affected biodiversity, but also to inform and invite the consumer society to consider: "if we fished less, how many different fish communities there would be in the seas?" The answer to this can be both disastrous and spectacular (e.g., Duffy et al. 2016), depending on the quality of the legacy we choose to leave in the oceans. In addition, it represents a fundamental issue relevant to the life quality of the species that support our survival. It is our way of seeing and living with the other species that determines the quality of our own life history. Since the moment we were born until well after we die, nature acts upon us, in such a way that to harass it, to attack it or to despise it are acts of carelessness and disrespect that hurt our very existence. In the ship of life, we are navigating along with all other evolutionary branches. Fortunately or not, it is only us who enjoy the privilege of having the helm to choose the destiny of all, with the caution and parsimony that should precede the forecasts that are based on the accumulation of observations. Welcome aboard the Anthropocene!

By Priscilla Ramos Cruz and Priscila F. M. Lopes

References

• Duffy, J. E., Lefcheck, J. S., Stuart-Smith, R. D., Navarrete, S. A., & Edgar, G. J. (2016). Biodiversity enhances reef fish biomass and resistance to climate change. Proceedings of the National Academy of Sciences, 113(22): 6230-6235.
• Hatfield, J. H., Harrison, M. L., & Banks-Leite, C. (2018). Functional diversity metrics: How they are affected by landscape change and how they represent ecosystem functioning in the tropics. Current Landscape Ecology Reports, 3:35–42.
• Schmeller, DS, Weatherdon, LV, Loyau, A., Bondeau, A., Brotons, L., Brummitt, N., ... & Mihoub, JB (2018). A suite of essential biodiversity variables for detecting critical biodiversity change. Biological Reviews, 93(1): 55-71.
• Teichert, N., Lepage, M., & Lobry, J. (2018). Beyond classic ecological assessment: The use of functional indices to indicate fish assemblages sensitivity to human disturbance in estuaries. Science of The Total Environment, 639: 465-475.
• Tucker, CM, Cadotte, MW, Carvalho, SB, Davies, TJ, Ferrier, S., Fritz, SA, & Pavoine, S. (2017). A guide to phylogenetic metrics for conservation, community ecology and macroecology. Biological Reviews, 92(2): 698-715.
• Worm, B., Barbier, E. B., Beaumont, N., Duffy, J. E., Folke, C., Halpern, B. S., ... & Sala, E. (2006). Impacts of biodiversity loss on ocean ecosystem services. science, 314(5800): 787-790.