- The *ICLARM Quarterly
22, No. 4 (October - December 1999)
(Fisheries Section of NTAFP)
von Bertalanffy Growth Curve: When a Good Fit
is not Good Enough
von Bertalanffy growth function (VBGF) is used
for length based analyses of growth and mortality
patterns for management of fisheries. However,
certain fish have growth patterns that the VBGF
may not be able to describe adequately, e.g.,
the Acanthurus lineatus in Samoa. In such cases
a two-phase VBGF may be a useful approach.
Craig is a Fish Biologist. Box 532, Klamath, California
Overview of Goby-Fry Fisheries
of diadromous gobies, notably Sicydium spp.
and Sicyopterus spp., support fisheries
based on return migrations of postlarvae (fry)
to rivers. Most species are tropical, although
close relatives occur in Japan. The life-history
of this group has often been incorrectly described
as catadromous (spawning in the sea or estuary),
whereas anadromous (spawning in rivers) would
be more accurate. Among species, postlarvae range
in length from 12 to 30 mm. Postlarvae have often
been mistakenly described as new species because
adult characters are absent. Most fisheries are
in areas of volcanic habitat with high rainfall,
torrential streams and high rates of disturbance.
Even though some fisheries have been large, almost
no historical information on yields exists and,
at present, catch data are not regularly collected
anywhere. This is a major obstacle in monitoring
these fisheries, assessing reports of declining
yields and relating them to trends in other variables.
Bell is at the J.L.B. Smith Institute Ichthyology,
Private Bag 1015, Grahamstown, 6140 South Africa,
and Rhodes University. Email: email@example.com
Relationships of Freshwater Fishes in Greece
Kleanthidis, A.I. Sinis and K.I. Stergiouor
relationships were calculated for nine fish species
from Lake Volvi (Macedonia, Hellas), caught with
gillnets of five different mesh sizes between
October 1995 and October 1996. In addition, length-weight
relationships for 24 Greek freshwater fish species
and one hybrid were also obtained from the literature.
The values of the exponent of the length-weight
relationships for all fish species examined ranged
between 2.14 and 3.70 (mean = 3.12; SE = 0.032),
and the median value was 3.19.
Kleanthidis, A.I. Sinis and K.I. Stergiou are
from the Laboratory of Ichthyology, Department
of Zoology, P.O. Box 134, Faculty of Sciences,
Aristotle University of Thessaloniki, 54006, Thessaloniki,
Relationships of Tuna Baitfish from the Lakshadweep
parameters a and b of the length-weight relationship
of the form W=aLb were computed for 11 species
of baitfish from the pole-and-line fishery at
Minicoy and Spratelloides delicatulus from
the fishery at Agatti, Bangaram and Perumal Par.
Nasser is from the Minicoy Research Centre of
Central Marine Fisheries Research Institute, Minicoy,
Lakshadweep 682 559.