Namibian fish affected by climate change

by Mar 22, 2012Climate Change, Conservation Threats

WINDHOEK – Preliminary evaluations indicate that climate variability has an effect on the distribution of marine species because of the changes in temperature.

A group of marine scientists from Namibia, South Africa and Angola are meeting outside Windhoek to identify and quantify trends in climate variability in the Benguela Current, which is shared by the three countries.

According to Professor Harald Loeng, Head of Research under the Climate Fish Programme in Norway, the purpose of the workshop is to summarise scientific knowledge that was gathered since the early 1980s for publication.

Available data has in most cases only been used by southern countries for quota purposes and have not been publicised.

Loeng said all marine areas could be impacted by climate variability.

He said the salinity of the ocean water, the frequency of upwelling, temperature and currents can be affected, which in turn have an effect on the ecosystem.

“What we are trying to do is to identify the consequences of climate change and climate variability,” Loeng said.

It is expected that at least 20 scientific papers will be published in October 2012, following the workshop.

A Namibian scientist in the Ministry of Fisheries and Marine Resources, Paul Kainge, said the effects of climate variability on marine organisms in Namibian waters are under review.

“Although we have collected enough data, we don’t have conclusive evidence as yet, only by the end of year,” Kainge added.

According to him, the temperature has effects on the distribution of marine resources, especially in the upper continental shelf.

He explained that when the southern Benguela Current mixes with the Central Benguela, some species that prefer colder conditions move away to other areas and this affects the distribution of these species.

The redistribution of species simply means that fish species that are normally found in a certain region or area move away to another area, temporary or permanently, because of changes in water temperatures.

Angolan Oceanographer and Researcher Pedro Tchipalanga said they can observe a lot of problems in their waters as fish populations had declined in Angola since the 1990s.

“As a result, the price of fish is going up and people are complaining,” Tchipalanga said.

He could, however, not say with certainty whether the decline in fish is the result of over-fishing or due to climate variability.

“But the fact is, fish are declining. Some are moving away horizontally and others vertically,” the Angolan oceanographer said.

According to Tchipalanga, an example of the impact of temperature changes was observed during the 1995 “Benguela Nino” when pilchards from Angola moved to Namibian waters.

On 3 March 1995, the “Benguela Nino” reached its peak in the waters off Southern Africa.

“Benguela Nino” is Africa’s equivalent of the El Nino generally associated with South America’s Pacific waters.

On that day, a major temperature increase brought on by the Benguela Nino in the waters off Angola caused pilchards to escape in large numbers towards Namibia where the water kept its usual cool temperature.

South African Marine Scientist from the Ocean 2 Coasts under the Department of Environmental Affairs, Steve Kirkman, said there had been “quite” big changes in the state of their marine resources.

“I am not sure the role of climate variability on some of those changes, as it is not easy to disentangle the effects of climate change/variability,” Kirkman admitted.

Some of the changes that he pointed out in South African waters are the movement of pelagic fish, such as sardines, in an easterly direction from the West Coast.

Seabirds such as the Cape Garnet and penguins had been affected, as their numbers have declined over years.

The birds are either moving away or declining in the specific areas where they used to live because their prey (fish) has moved away.

The changes also have an economic impact on industries as vessels have to cover longer distances to reach the fish that redistributed itself to other areas.

According to Kirkman, there had even been some movement of fishing infrastructure because of the changes, although they are not permanent.

“The changing in resource distribution is back and forth,” said the South African scientists.