Hakai Magazine

On South Africa’s west coast, harmful algal blooms suck the oxygen out of the water, driving crayfish to beach themselves en masse. Photo by Xinhua News Agency/Getty Images

A Mad Dash to Save Stranded Crayfish

When masses of crayfish end up on the beach after an algal bloom strips oxygen from the water, South African communities and authorities race to ship the valuable crustaceans back out to sea.

Authored by

by Chloe Williams

Article body copy

On a misty night this past February, 100 or so people gathered on the beach in Elands Bay, a small fishing town on South Africa’s west coast. Earlier in the week, the water had turned red, and the day before, the wind had shifted directions. Francina Noxolo Sokuyeka knew the warning signs well, and she and other Elands Bay residents were ready for what came next. As the tide receded, the first crayfish appeared. By morning, the beach was covered in crustaceans, many no bigger than a human hand. And with every tide, they just kept coming. The shellfish piled high in heaps that stretched at least five kilometers along the coast. By the end of the week, roughly 500 tonnes of crayfish had washed ashore.

The mass stranding would be a blow to a fishery on the brink of collapse—last year, fishers in the area were only allowed to catch a total of 700 tonnes of crayfish. But for Elands Bay residents, who live in a country with an unemployment rate of nearly 35 percent, the event had a different connotation. “It was happiness all over our faces,” Sokuyeka says. Many among the crowd took crayfish home. They also knew that the beaching would bring a work opportunity: in the coming days, they would be paid to rescue the stranded crustaceans.

Crayfish, also known as west coast rock lobster, support one of South Africa’s most valuable fisheries, especially on the country’s west coast. In recent decades, however, crayfish populations have crashed. In 2021, harvestable stocks were at just 1.5 percent of their pristine levels. Overharvesting and illegal fishing are largely to blame for the fishery’s collapse, but mass strandings like this one haven’t helped.

Known locally as crayfish walkouts, the strandings are driven by harmful algal blooms. These sudden proliferations of algae, sometimes referred to as red tides, are common along South Africa’s west coast, especially in late summer. When the algae die, they sink to the seafloor where they are decomposed by bacteria. The process uses up most of the oxygen in the water, causing crayfish and other marine life to flee toward the coast where breaking waves reoxygenate the water. The animals do not actually walk out of the ocean, but when the tide recedes, they get stuck on land. Trapped, the crayfish are vulnerable to sun exposure, desiccation, and trampling.

The phenomenon of walkouts has perfectly natural roots, says George Branch, professor emeritus of marine biology at the University of Cape Town in South Africa. But as crayfish populations have dwindled, he says, walkouts have become increasingly concerning. Some evidence suggests walkouts have increased. From the 1960s to 1980s, researchers recorded one or two walkouts per decade. In the 1990s, however, South Africa suffered a spate of crayfish mass strandings that killed more than 2,200 tonnes of crayfish—a 24-fold increase over previous decades. Since then, the threat has continued, with two particularly large strandings hitting the west coast in the past five years, says Grant Pitcher, a researcher who studies harmful algal blooms with South Africa’s Department of Forestry, Fisheries and the Environment (DFFE). Algal blooms also seem to be growing more common, according to Pitcher, although a lack of historical data makes drawing conclusions challenging.

Beached crayfish are not long for this world, but when they first arrive on shore, the animals are still alive. They may even survive a few hours out of water, Branch says. “They’re quite tough things.” So, ever since the 1990s, authorities have implemented a strategy to save what they can.

That means that now, when crayfish suddenly appear on a beach, the DFFE can activate the West Coast Rock Lobster Contingency Plan, spurring provincial and municipal authorities, the police service, the defense force, and local communities to transport live crayfish from the beach back out to sea.

Triggering the plan meant that the first morning after the walkout began in Elands Bay earlier this year, law enforcement officers arrived to patrol the beach and stop people from helping themselves to the bounty. (At least, any more than they already had.) Preventing this self-directed harvest is important, says Danie Van Zyl, a marine research technician with the DFFE who was involved in coordinating the response, because this opportunistic harvesting takes away from efforts to save the crayfish, and eating the crayfish, which have just been lying in the sun, could result in food poisoning.

With the area secured, about 100 locals, including Sokuyeka, were hired to sort the live crayfish from the dead. The first of these rescues were sent to local crayfish factories where the animals were temporarily stored in oxygenated tanks. Later, workers loaded crates full of live crayfish into trucks and drove them to a neighboring town where they were shipped out to sea aboard commercial fishing boats. A few kilometers off the coast, beyond the area affected by the algal bloom, the crayfish were dumped overboard.

The rescue operation went on for four days. Responders managed to return roughly 30 of the 500 tonnes of stranded crayfish to the ocean. The rest were buried on the beach.

“We lost quite a lot,” says Charles Malherbe, an environmental manager for the regional governmental district that includes Elands Bay, who assisted in the cleanup. In the past, smaller walkouts gave responders a chance to salvage a higher proportion of stranded crayfish. But this year, he says, there were just too many to deal with.

Because crayfish live along roughly 1,000 kilometers of South Africa’s coastline, the impact of the walkout on the wider population is limited, but it may have localized effects, Van Zyl says. Most of the beached crayfish were juveniles and females, which could diminish future stocks.

Still, saving 30 tonnes of crayfish is better than saving none. “Every [west coast rock] lobster rescued or saved makes a difference,” Malherbe says. Authorities are now revising the contingency plan to smooth out logistical kinks that caused delays during the recent rescue. Ideally, responders would be mobilized even faster, Van Zyl says.

It’s only a matter of time before another walkout occurs, and for residents, the phenomenon remains both a blessing and a curse. “In the years to come, there will be a problem,” Sokuyeka says. “There will be no crayfish in the sea.”

Article footer and bottom matter

Cite this Article:

Cite this Article: Chloe Williams “A Mad Dash to Save Stranded Crayfish,” Hakai Magazine, Jun 13, 2022, accessed July 19th, 2024, https://hakaimagazine.com/news/a-mad-dash-to-save-stranded-crayfish/.

Related Topics