* ICLARM is now known as WorldFish Center

Naga - The *ICLARM Quarterly
Vol. 22, No. 4 (October - December 1999)

Fishbyte (Fisheries Section of NTAFP)

The von Bertalanffy Growth Curve: When a Good Fit is not Good Enough
P.C. Craig

The 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.

P.C. Craig is a Fish Biologist. Box 532, Klamath, California 95548 USA.

An Overview of Goby-Fry Fisheries
K.N.I. Bell

A number 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.

K.N.I. Bell is at the J.L.B. Smith Institute Ichthyology, Private Bag 1015, Grahamstown, 6140 South Africa, and Rhodes University. Email:

Length-Weight Relationships of Freshwater Fishes in Greece
P.K. Kleanthidis, A.I. Sinis and K.I. Stergiouor

Length-weight 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.

P.K. 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, Hellas.

Length-Weight Relationships of Tuna Baitfish from the Lakshadweep Islands, India
A.K.V. Nasser

The 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.

A.K.V. Nasser is from the Minicoy Research Centre of Central Marine Fisheries Research Institute, Minicoy, Lakshadweep 682 559.

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