New Zealand Journal of Marine and Freshwater Research abstracts
Short communication
Promising signs of regeneration of blue cod and oyster habitat changed by
dredging in Foveaux Strait, southern New Zealand
H. JOHN CRANFIELD1
GLEN CARBINES2
KEITH P. MICHAEL1
ALISTAIR DUNN1
DEAN R. STOTTER1
DARREN J. SMITH1
1National Institute of Water & Atmospheric
Research Ltd
P. O. Box 14 901, Kilbirnie
Wellington, New Zealand
email: j.cranfield@niwa.cri.nz
2National Institute of Water & Atmospheric
Research Ltd
P. O. Box 6414
Dunedin, New Zealand
Abstract Epifaunal reefs in Foveaux Strait are oyster
(
Ostrea chilensis Philippi, 1845) habitat. One hundred and thirty years
of oyster dredging has diminished the complexity and distribution of these
reefs. Commercial densities of blue cod (
Parapercis colias (Forster in
Bloch and Schneider, 1801)) were discovered on epifaunal reef habitat in 1989
and became the focus of a major blue cod fishery. We document habitat changes
that followed the closing of the oyster fishery in 1993 and interactions
between the blue cod and oyster fisheries after the oyster fishery was reopened
in 1996. Evidence from blue cod fishers and oyster surveys suggests that the
benthic habitat of some oyster beds regenerated in the absence of dredging and
that the relative density of blue cod, and then oysters, rebuilt to commercial
levels. Benthic habitat was modified once more when oyster dredging restarted
and the relative density of blue cod on oyster beds fell again. The
observations suggest that rotational fishing of oysters could mitigate the
effects of dredging on habitat and that marine protected areas could expedite
habitat recovery. Increasing habitat complexity and blue cod density on a reef
of oyster shells formed by an oyster fisher suggests that habitat enhancement
might remedy effects of dredging. The questions raised by the observations
could be answered by management experiments on the scale of the fisheries.
Keywords Parapercis colias; blue cod; Ostrea
chilensis; oysters; Foveaux Strait; fish habitat; epifaunal reefs; oyster
shell reefs; dredging; habitat degradation; rotational fishing; mitigation;
habitat enhancement; marine protected areas
New Zealand Journal of Marine and Freshwater Research, 2001, Vol. 35
M01016
Received 30 January 2001; accepted 19 July 2001
PDF file of entire paper: medium quality (975K); (scanned from paper original: notes about this process)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
