Bottom trawling on seamounts
Seamounts are well recognized as areas of high biological productivity
and have been the focus of commercial fishing for species that form large aggregations
The most fished species since 1979 has been orange roughy, which spawn and feed on
See more on deep-sea fisheries
Rough seas for orange roughy
Seamounts - discovery of a new ocean world
Other species fished on seamounts include oreo and cardinalfish, and to
a lesser extent alfonsino, bluenose, and rubyfish.
The catch of orange roughy from seamounts was 30 percent of the total
in 1985, and by 1995 had increased to 80 percent. It has since dropped to 60-70
There are 800 seamounts covering about 3 percent (121,500 square kilometres)
of the New Zealand EEZ. The area of seamounts is approximately 45 percent of the land
area of New Zealand.
NIWA study of deepwater fisheries and impact on seamount habitat .....
National Institute of Water & Atmospheric Research (NIWA) research
to measure the intensity of trawling, shows that heavy bottom trawl gear has a direct
physical impact on the seabed (Clark, O'Driscoll 2003).
Bottom trawling is known to have occurred on 248 seamounts, and about
100 are currently being fished.
The 23 most intensely fished seamounts were trawled 38,517 times from 1979
until 2000. The length of a trawl is normally 2 to 3km, so the total distance trawled
on these seamounts alone was about 100,000 km during the 20-year period.
The Crack seamount on the Chatham Rise had the highest catch during the
20 years leading up to 2000, with 48,442 tonnes of orange roughy. It was trawled
3,970 times during this period.
It is evident from NIWA camera stations on the Ritchie seamount off the
east coast of the North Island, that about half of the seamount area has been damaged.
The peak and upper slopes have suffered the main impact, with heavily marked gouges from
bobbins and trawl doors, while there are few marks on the flanks. The NIWA survey
showed very little micro-fauna.
The Ritchie seamount has been fished for orange roughy and cardinalfish
since 1986, with 1,244 bottom trawls during 14 years producing a catch of 5,556 tonnes.
Fishing industry claims .....
The Orange Roughy Management Company, claims the fishing industry's
footprint on the sea floor is less than 5 percent of the world's 75 percent of ocean, and
is adamant seamounts higher than 1,000 metres in the New Zealand EEZ are not fished, because
many are inaccessible or too steep or do not have the commercial fish.
For 25 years, the fishing industry has been able to exploit the seabed,
out of sight of public scrutiny. Now, with a greater awareness emerging, the industry is
playing down its activity and the destruction caused by bottom trawling.
There is an elementary need for the government to publicly report
the extent of trawled seafloor, just as the extent of pastoral, crop and
forested land, and other land uses are accounted for.
Entrusting the fishing industry with voluntary measures is not
effective protection .....
The government's willingness to entrust the fishing industry with voluntary measures
must be questioned, considering the Seafood Industry Council, an industry association,
says a ban would be devastating to a $1.2 billion industry of which $800 million comes
from exports of fish caught by trawling.
Voluntary measures are reliant on trust, but this is severely lacking
with an industry that has a history of deceiving the public. The Orange Roughy
Management Company has previously claimed that it was not fishing outside the New Zealand
EEZ, when in fact vessels associated with it were operating in the Tasman Sea and the
The Ministry of Fisheries reports that there are 20-30 New Zealand
flagged vessels currently involved in the practice in the high seas. New Zealand
is one of 11 countries that take 95 percent of the catch by bottom trawling on the high
While some may accept voluntary measures, there will always be those that do
not. Regulating offenders is one of the principal responsibilies of government.