The complex roles of markets on coral reefs

“Like the chameleon, one eye on the future, one eye on the past”
Malagasy proverb

Two weeks ago, the UN GBO-5 (Global Biodiversity Outlook) reports that we are falling short on all global biodiversity targets (read more here or read the report in full here). The aforementioned quote always reminds me to keep in mind that our past actions are intricately linked to the future. As humans and the primary driver of biodiversity loss, we are responsible to choose THE future we want by acting NOW. 

How does accessibility from human societies affect natural resources? This seemingly simple question has fueled a large body of research and that’s where my research lies. 

Ecosystem accessibility is the main driver of their conditions, with the most accessible ecosystems being most at risk of resource depletion. People’s socioeconomic conditions can change as they get further from urban centers and can profoundly influence people’s relationship with the environment. However, the mechanisms through which increasing accessibility from human societies affects natural resources are still unclear.

I thus decided to spend several months in northwest Madagascar to (i) unravel the respective influences of the local fish market and coastal communities on reef fish biomass and (ii) investigate how communities’ socioeconomic and resource use characteristics change with increasing proximity to markets.

Our analysis reveals interesting nonlinear patterns between accessibility and fish biomass. We found that fish biomass increases as reefs are further away from the market in both reef categories, i.e., fishing permitted and fishing prohibited, but that this effect levels off at about six hours from markets (b). Alternatively, we found that reefs where fishing is permitted remained relatively depleted when they were < 1.5 hours from the nearest community, but biomass began to increase after 1.5 hours (a). Once again, market integration is a major driver of fish biomass however, the mechanisms associated with this market effect remain poorly understood.

Modeled relationships
between fish biomass and travel time from the nearest
community (a) and travel time from the nearest market (b) for reefs where fishing
is permitted (orange) or fishing is prohibited (green).

We also highlight that the ways coastal communities use marine resources changes predictably with market proximity. More precisely, communities further away from markets had fewer material assets, higher fish consumption (scale effect); more spear and line fishing and less gill net fishing (technique effect); and increasing management. All communities were highly dependent on fishing livelihoods. 

Why are these findings important?

Market proximity influenced the fishing techniques used by coastal households:
New or altered technologies are more likely to occur near markets and are driven by resource demand (consumers). Thus, future changes in wealth related to market access may affect fishing techniques being used by fishers independently of gear restrictions. However, there is large amount of variation in how fishing gears differentially target the proportion, number, and characteristics of fish species. For example, gill nets capture a significant proportion of key herbivores such as grazers and scrapers/excavators that have been identified as critical to the resilience of coral reefs but nets can also be particularly successful on degraded reefs that are dominated by herbivores.

An understanding of the gear selectivity in northwest Madagascar would allow for effective gear-based strategies that can act as complementary strategies to existing restrictions.

Market proximity can also affect communities through the scale effect, and more specifically through both demand and displacement aspects:
We found that all of the study communities sold a high proportion of their catches, often directly to markets or to middlemen. In many coral reef fisheries, middlemen are essential intermediaries, collecting sea products directly from fishers and providing new trade opportunities and links to markets and contributing to fishing income generation in remote communities. However, most fishers lack information about market prices thus middlemen may drive fish prices down when competition is high prompting households to fish more to ensure stable incomes. Although locally managed marine areas that preferentially provide access to local users, can control harvesting pressure from “outsiders,” this does not prevent right holders from increasing fishing pressure to unsustainable levels if fish demand rises and prices drop for example. 

Fish market – Ambilobe, Madagascar.
Photo: E. Maire

Furthermore, although home ranges of fishing vessels can be used to measure the ability of fishermen to travel further away to catch more fish, all fishing vessels in our study were unmotorized. Most fishing communities in Madagascar commonly use small dugout canoes for one to four persons that are unsafe for high sea fishing, de facto restricting fishing trips’ duration and geographical influence on surrounding reefs.

However, increased market demand and relatively higher economic development close to markets might lead fishers to access more powerful and larger boats to expand their fishing grounds to more remote areas to maintain catch. Such changes could exacerbate the effect of markets and call for greater consideration of technology introductions and improvements as a consequence of economic development.

Our study emphasizes the need to better quantify links between markets and fishing communities through household-level surveys to implement market-based actions that could help to regulate the effect of markets on both fish stocks and fishing communities.

Read the paper in full here

Related work: In previous studies conducted at larger scale, we have highlighted that market proximity is a major driver of reef fish biomass (national and global studies).

‘Humanity at a crossroads’
More broadly speaking, behind the market demand there are consumers in Madagascar or elsewhere. As individuals and consumers we all have responsibilities to limit our impact on natural resources and our contribution to climate change. Like the chameleon, we must keep one eye on the past and remember the cumulative impact of our actions but we also need to shape the world of tomorrow. Everyone needs to act to tackle the climate emergency. Governments, industries, and us! Interesting reading on that topic here.

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