The catfish resources

widely distributed in the tropical Indo-Pacific and they constitute a regular, sometimes dominant, component of the demersal fish landhigs along the Indian Coast. Species of the genus Tachysurus contribute nearly 99% of the catfish catch, particularly T. thalassinus. T. tenuispinis, T. serratus and T. dussumieri. Osteogeneiosus militaris also forms a fishery along the northwest coast

Acoustic surveys and abundance estimation of catfish

Many fisheries research and development projects include the evaluation of size and potential yield of the fish resources as an essential part of their objectives. While exploratory surveys depending on fishing trials alone are very time-consuming and expensive, and at best can only provide information about the distribution and abundance of the fish which are vulnerable to the type of fishing gear and method of fishing applied, the modern calibrated, highly sensitive acoustic instruments provide the under-water vision required to enumerate correctly and even to size the fish present in practically the entire water column

Taxonomic considerations and general distribution of commercially important catfishes

The taxonomy of our commercially important marine catfishes is still in a state of uncertainty. The nomenclature has suffered a lot of changes brought about by various taxonomists. When some authors have used the genus name Tachysurus, and hence the family name Tachysuridae, others preferred the name Anus and the family name Ariidae. Valenciennes (1840), Bleeker(1847), Gunther (1864), Day (1878), Weber and Beaufort (1913), Herre (1953), Jordan (1963), Fischer and Whithead (1974) and Fischer and Bianchi (1984) all have used the name >4r/us Val. 1840, whereas Fowler (1941), Chandy (1953), Munro (1955), Tilak (1965), Jayaram and Dhanze (1978 a, 1978 b) and Menon (1979) replaced the name Ar/us Val. 1840 by Tachysurus Lacepede 1803

Thyrsoidea macrura (Bleeker), the longest giant Moray eel from the Indian waters

A specimen of the giant moray eel, Thyrsoidea macrura, measuring 3080 mm in length (after preservation), obtained from Karwar is described. This appears to be the longest specimen of the species on record

Population dynamics of Tachysurus dussumieri in North Kerala

The paper presents the results of the study on age and growth of Tacltysurus dussumiert from North Kerala Coast with particular emphasis oa population dynamics. The recruitment pattern, stock position, mortality and yield per recruit studies indicated that the resource is at present under heavy fishing pressure. The influence of climatological, hydrological and water movements were understood and their elfect was found from the fact that the fishery was laainly concentrated along the shallow coastal wate rs upto a depth of 70 m. The impact of mechanisation on the fishery causing heavy damage to the brooders with eggs/embryo, was critically analysed and suggestions and measures enumerated. It is suggested that the situation can be overcome by reducing fishing pressure or by extending the area of operation to midshelf as well as intensifying the hooks and line efforts along the existing fishing limits

Development and sequential ossification in the marine catfish, Tachysurus thalassinus Ruppell

The development of Tachysurus thalassinus is described based on experimental rearing of embryos, from early embryonic stage to complete absorption of yolk sac. The time taken for development from egg to complete absorption of yolk is thirty five days. The progressive ossification of embryonic/larval skeleton is studied with the help of alizarin -red S stained, embryonic skeleton at various stages of development. The prominent characters of the species are laid down early in the larval stages and maintained throughout the life

Hooks and line fishery in North Kerala with particular reference to catfish resources

The paper deals with the hooks and line fishery along North Kerala during 1979-1985. Marine cat-fishes were traditionally harvested from this area by non-mechanised gears, such as hooks and line, drift net and boat-seines till early sixties. The operations by hooks and line yielded a steady catch. The catfishes alone contributed about 90% in the hooks and line landings. The dominant species in the landings were Tachysurus tenuispinis, T. dussumieri and T. thalassinus from the depth ranges of 40-70 m and T. serratus from 10-30 m. T. tenuispinis is vulnerable to the gear at the age of 3 years and above and T. dussumieri, T. thalassinus and T. serratus at the ages 4, 2 and 6 years and above respectively. Introduction of trawlers and purse seiners initially contributed to a sudden hike in its production. But exploitation of juveniles and eggs/embryos carrying male brooders on large-scale, ultimately resulted in low recruitment. As brooders are not susceptible to fishery by hooks and line, it is suggested to intensify the catfish fishing by this gear

A review of the taxonomic position of Tachysurus serratus (Day) and Tachysurvs thalassinus (Roppell)

The systematic position of T. serratus and T. thalassinus is established by a study of the morphometric, meristic, osteological and other characters of fishes of varying sizes belonging to both sexes

An instance of abnormally ripe ovaries in the Indian Mackerel, Rastrelliger kanagurta (Cuvier)

A case of abnormally ripe ovaries, the first of its kind, is reported wherein an additional lobe in stage VI was found along with the normal pair of ovaries in stage IV. The estimated number of ripe and maturing ova in this abnormal sac was 18,600 each

Echo Location of Fish

One of the most significant developments in recent times in the sphere of fishing has been the introduction and use of acoustics in fishing operations. From merely finding the depth of fishing grounds with echo sounders, sophisticated acoustic instruments now aid in the location of fish schools, their identification as well as quantification