Bending the Curve of Global Freshwater Biodiversity Loss

By Abigail Lynch

Even though freshwater covers less than 1% of the earth’s surface, it holds more described fish species than all the world’s oceans. In fact, freshwaters are home to 10% of all species. Yet, when people think of freshwater, biodiversity is not often the first thing that comes to mind. Likely, at least in part, as a consequence of this inattention, global freshwater biodiversity has reached crisis levels of decline. As merely one example, populations of freshwater megafauna (reaching over 60lbs), such as sturgeon, have crashed by 88% in the last half century.

Proportions of freshwater taxa threatened with extinction. Source: IUCN (2019). Figure source: Tickner et al. (2020)

For those of us in the field of freshwater fisheries, this plight is not news. But, we’ve bemoaned this crisis for long enough without much effect. A new initiative led by David Tickner (WWF) has developed an Emergency Recovery Plan aimed at changing this trajectory – bending (like Beckham!) towards a goal of reversing the rapid worldwide decline in freshwater biodiversity – changing the story from one of collapse to one of recovery. While this situation is undoubtedly dire, the Emergency Recovery Plan is inherently optimistic. Freshwater biodiversity loss is by no means a lost cause. The Plan is a strategic approach to deliver solutions at the scale necessary to reverse this immense collapse. It is structured around six priority actions (listed below with some fisheries-specific context):

  • Accelerate implementation of environmental flows

Environmental flows are required hydrological regimes necessary to maintain freshwater ecosystems. Water resource management can optimize allocation as well as design and operate water infrastructure to meet the ecological and human needs from systems. For some fisheries, this may be as simple as allowing sufficient flow to support habitat downstream of a hydropower facility.

  • Improve water quality to sustain aquatic life

As clean water is essential for humans, it is also for aquatic life. Minimizing runoff of excessive nutrient loads and pollutants can have a significant impact on aquatic habitat. A secondary benefit is fewer consumption advisories for fisheries due to cleaner water.

  • Protect and restore critical habitats

Protection measures are more common strategies in terrestrial and even marine environments than they are in freshwater. Perhaps because “no man ever steps in the same river twice,” place-based strategies have often eluded freshwaters. Nonetheless, protection and restoration efforts can have a significant impact on freshwater biodiversity recovery and resilient fisheries.

  • Manage exploitation of freshwater species and riverine aggregates

Policy frameworks and enforcement for freshwater fisheries on a global scale are often woefully inadequate. Consequently, making sustainable management difficult. However, the 2016 Rome Declaration on Responsible Inland Fisheries helps outline steps to make freshwater fisheries sustainable, including improved biological assessments and science-based management.

  • Prevent and control nonnative species invasions in freshwater habitats

Invasive species have significant economic as well as ecological impacts on freshwater fisheries. The simplest solution is to prevent introductions altogether through vigilant monitoring of major introduction pathways, such as ballast water and live animal trade. For species that are established, rapid efforts to control are often the only means to eradicate before costly control measures are the only means to keep invasions at bay.

  • Safeguard and restore freshwater connectivity

Freshwater ecosystems are often defined by connectivity; up- and downstream, in-channel and across floodplains. Fisheries productivity often depends upon it. Fragmented habitat often has direct consequences on fish populations, particularly for migratory species. In places with defunct structures, removing barriers have immense ecological benefit and no social consequences. In places with emerging infrastructure, strategic environmental assessment can minimize environmental and social risks.

The six priority areas of the Emergency Recovery Plan will help provide clean, naturally flowing waters which benefit freshwater biodiversity and people. Photo credit: WWF.

These six priority action areas of the Emergency Recovery Plan highlight rapid measures to implement globally to let rivers flow more naturally, protect and restore critical habitats, and curtail pollution. Most of these efforts are external to the fisheries community, but there are a number of areas where fisheries management can engage, such as the control of invasive aquatic species, ending overfishing, and restoring aquatic connectivity.

This plan provides a way forward. It moves beyond just documenting decline and bemoaning its loss. That is exciting and inspiring for those of us in the field of freshwater fisheries and for the world writ large with a means to ensure the valuable services these ecosystems provide!

For more, please view the full paper here.

Freshwater fauna, big and small, can benefit from the Emergency Recovery Plan. Photo credit: WWF.

Tickner, D., J. Opperman, R. Abell, M. Acreman, A. Arthington, S. E. Bunn, S. J. Cooke, W. Darwall, G. Edwards, I. Harrison, K. Hughes, T. Jones, D. Leclère, A. J. Lynch, P. Leonard, M. McClain, P. McIntyre, D. Muruven, J. D. Olden, S. Ormerod, J. Robinson, R. Tharme, M. Thieme, K. Tockner, M. Wright, L. Young. 2020. Bending the Curve of Freshwater Biodiversity Loss – An Emergency Recovery Plan.  Bioscience. biaa002.

One Comment Add yours

  1. Robert A Athearn says:

    Work to restore beavers to their original range.

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