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September 2002

Article

 


Harvesting nature's bounty wisely

Focus Interactive, University of Natal

'Serial overfishing' depletes species

The sea provides a huge slice of the world's protein intake. It offers jobs
to at least 200 million people worldwide. Its rich biodiversity, potential
for new natural products and recreational value has no parallel. But using
the sea's natural resources sustainably is becoming increasingly difficult,
says RUDI VAN DER ELST, of University of Natal affiliate the Oceanographic
Research Institute (ORI).

GLOBAL trends in fisheries paint a sombre picture. The world's total marine
fish catch has peaked at about 95 million tons per annum while industrial
fleets of the world are operating at an annual loss of some US$ 54 billion.
Nine of the world's 16 major fishing zones have been declared 'overfished'
by the FAO and of the 200 most valued species, some 60% are now being fished at, or beyond, levels of sustainability.

A further disturbing trend is the progressive change in species composition
of world fish landings. In the 1950s, the bulk of the global catch was made
up of some 50 species of fish. Progressively this expanded, with more
species being added as historically important species became depleted - a
process referred to as 'serial overfishing'. Now, more than 600 species
constitute the world's catch - and so the number of potential new species
will eventually run out and only depleted species will remain. Recent
estimates suggest that up to 27 million tons of wasted by-catch is dumped at sea each year, mostly in association with trawl fisheries. Prospects for
future sustainable fishery development do not appear promising.
South Africa has not been immune to these disturbing trends. In 1964, only
17 species of marine fish were reported in national landings: today there
are at least 51 species involved. By-catch is also a local problem - for
every ton of prawns caught, four tons of marine life is dumped overboard.

'Glimmers of hope'

The status of endemic fishes is particularly serious, as in the case of the
seabreams, a predominantly South African endemic fish family. Species such
as the seventyfour, red steenbras and musselcracker have been so severely
depleted that they represent no more than 5% of their original abundance in linefish catches. A more quantitative assessment, based on the species'
regenerative capacity, has revealed that 18 of 23 top linefish species are
below the 25% threshold level of spawner biomass, the threshold below which they lose their regenerative capacity. Invertebrate resources have also not escaped the attention of over-zealous harvesters. While mussels, oysters and crayfish are sustainably managed in KZN, other species along the South African coastline are in a perilous state, such as the Cape rock lobster and the abalone.

Despite these gloomy global trends, there are glimmers of hope. The Indian
Ocean appears to have escaped the major global fisheries collapses and has
capacity for growth and development. In South Africa new fisheries and
conservation policies have been promulgated that have sustainability as a
core concept.

For the past 45 years ORI and the South African Association for Marine
Biological Research (SAAMBR) have been contributing to the scientific basis
underpinning the sustainable development of some of the region's resources.

Many of the programmes are partnerships with other institutions, as well as
under the auspices of the South African Network for Coastal and Oceanic
Research (SANCOR). Research has increasingly been on quantitative investigations, such as developing operational management procedures (OMPs), where not only the regenerative capacity of a particular resource is investigated and modelled, but its response to various management regimes and socio-economic demands is also predicted.

It is not only consumable resources that need sustaining - some of KZN's
reefs are experiencing enormous diver pressure. An ORI programme, in
collaboration with UND's Marine Geoscience Unit, has mapped the most
vulnerable zones for conservation and the management of diver carrying
capacity.

ORI staff and students collaborate with colleagues in virtually all East
African countries from Eritrea and Somalia southward. Much of this is
focused on the assessment of fisheries in a project led by ORI on behalf of
the World Conservation Union (IUCN). Some 80 different fishery types have
now been identified, mostly artisanal, with many providing essential
socio-economic and food security benefits.

Centre of Excellence

However, most remain unstudied and few are managed for sustainability.
ORI has for years invested in data acquisition and, with Marine and Coastal
Management, Ezemvelo KwaZulu-Natal Wildlife and the KZN Coastal Management Unit, has developed a number of long-term resource databases. Some have been in operation for decades and are now extremely valuable in detecting gross environmental and fishery-induced trends. When it is recognised that some fish species attain ages of 40 years and more, the value of these archived fishery data becomes apparent.

At least 60 postgraduate degrees have been awarded to ORI staff,
contributing to the development of a KZN Centre of Excellence in marine
science. Recently, ORI assisted in the assessment of the status of South
African marine species to update the IUCN Red Data lists and also as a
source document for WSSD. Some startling facts emerged - the level of
endemism in the South African marine fauna is exceptionally high: 13% for
fishes and 36% for invertebrates. Yet, despite the decline in so many
species, no marine fish has ever gone extinct as a result of human impact.
In 1977 only four species of South African marine fish were red-listed. The
2002 list identifies 33 marine species that justify inclusion.


Clearly, great challenges remain to be confronted. One of these is the
long-term viability of ORI as a centre of marine science in KZN. This will
be achieved through the development of the new Ushaka Island Complex on
Durban's new waterfront. This eight-hectare Marine Park, which will rival
the best in the world, will not only display the rich biodiversity of the
Indian Ocean but will also sustain activities of marine education and
science in the region. ORI will be housed in a new institutional complex,
thus continuing to generate not only scientific information but also
creating marine science training and career opportunities in KZN.


More Information:

Read more about ORI at www.ori.org.za and examine the Red Data List at
www.redlist.org and see the WSSD website at www.joburgsummit2002.com
Visit the South African Network for Coastal and Oceanic Research at
 www.botany.uwc.ac.za/sancor/ and
www.panda.co.za  for information about current species status.

 




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