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How do you convince people that a river they’ve known their whole lives is not the river it once was … or could be?

That turned out to be my challenge last week, when I traveled to Zambia in support of The Nature Conservancy’s new project to restore the Zambezi River. After several days of meetings with our partners — including WWF and universities and government agencies from Zambia, Zimbabwe and Mozambique — I finally got to spend some time on the river itself, in Lower Zambezi National Park.

This was my first experience in an African wilderness, and I was awestruck by the sheer abundance of hippos and crocs and the throngs of elephants, buffalo, antelope and baboons brought to the river’s edge by the blazing heat and parched hills that marked the end of Zambia’s long dry season. (Click here for a slideshow of the river, dam and wildlife.)

While the wildlife had left me with a childlike sense of wonder, it was our dinner companion that night who brought home for me the importance and challenge of this project.

We sat down to dinner amidst a throbbing insect soundtrack, a slow-burning fire glowing in the foreground with the Zambezi a sinuous darker void in the darkness beyond. Joining us was Kevin, a Zambian who manages the lodge where we were staying. Conversation turned to the health of the river and he told us the majority of his guests were anglers lured by the aptly named tiger fish, a fearsome predator with teeth right off the costume rack of a B-horror movie.

Kevin mentioned that fish numbers were down and had been going down for a while. This seemed a natural opening to talk about one of the specific objectives of our Zambezi project: working with dam managers to improve how they release water from the massive upstream Kariba Dam (called “environmental flow releases”), in part to promote the productivity of fish in this part of the river.

My Conservancy colleague suggested this: “You know,” he said, “some people think the fish decline is because the river no longer has high water during the rainy season because how the dam is operated.”

Kevin, nothing if not blunt, shook his head and said: “Nah, that’s crap. The real reason is that people in the villages take too many fish — they use nets with a small mesh that catch everything in the river, even the smallest fish. That’s why the fish numbers are going down. But what can you do? You can’t simply tell people not to fish -- they have nothing else. What will they do then, come and rob you at night?” He went on to relate his skepticism that the operation of Kariba Dam should, or even could, be altered; it just seemed risky to him.

In this one riposte, Kevin succinctly framed both the need and challenges for the Zambezi project.

First, although the river appears healthy — its water is clean and its banks are wild and rich in wildlife — appearances can be deceiving. The river is not healthy, or at least not the same healthy it once was. Kariba Dam — big enough to store every drop of water flowing in the river for two years — has tamed it, made it a different river. Before the dam, the river ran high during the rainy season and very low in the dry. Today, the big reservoir behind Kariba captures the floods and evens out the flows throughout the year.

Though we don’t have fisheries data from before Kariba, if the Zambezi is like most other big rivers, much of its fish abundance would have been produced in the floodplain grasslands and wetlands when they were inundated by high flows. Now the Zambezi mostly stays in its banks.

Second, the challenges for conservation and of people are intertwined. Overfishing is hurting the Zambezi and, ultimately, the people that depend upon it. The people who live here need some combination of better fisheries management, alternative sources of income and protein, and more fish in the river (one of the goals of the environmental-flows project). These livelihood challenges are inextricably linked with nature conservation and restoration.

Finally, even potential beneficiaries of changes can be skeptical of deviations from the status quo, because the risk of disruption looms larger than the as-yet-unproven possibility of benefits. Thus, the benefits must be clearly analyzed, demonstrated, and communicated.

Kevin’s conviction that overfishing, not flow regime, is the cause of fish decline is partly right — it is a problem for the river as it is today, this river. But this river is different from the river it once was. It’s not surprising that Kevin doesn’t suspect the flow regime; the current river is the only river he’s ever known. Kariba was built in 1955, and so the only people who can really remember how the river previously worked — let’s say those at least 12 years old then — are nearly 70 years old today. For everyone else, this river is the river. And this Zambezi is being overfished. But perhaps some aspects of the old Zambezi can be restored.

It’s clear we need good communication tools. If Kevin — who has much to gain from a new flow regime — was skeptical of changes to the river’s management, what would other people say?

Fortunately, we got some practice at that communication later in the conversation. Kevin mentioned that the anglers know they need to fish near the river’s edges, where it flows next to or through downed logs, grasses and other vegetation. “Not out in the middle of the river,” he said. “The water’s too fast and the fish don’t like it. The fish are along the edges.”

I explained that what we talked about before — environmental flows to restore the connection between river and floodplain — was really the same thing as creating lots and lots of such “edge” habitat. Rather than just being restricted to the sides of the river, the shallow, calm, and vegetated “edge” habitat would cover an extensive plain — the difference between grazing cows in a strip of grass along a highway versus a vast meadow.

Kevin nodded his head thoughtfully. I don’t know if he was convinced, but we’d found some common understanding and vocabulary of how the river worked.  We have much work ahead of us.

-- Text by Jeff Opperman, Cool Green Science Blog