Sri Lanka is an island country with a land area of 65 610 km2. With the declaration of the exclusive economic zone (EEZ) in 1976, the country gained sovereign rights over an ocean area of 536 000 km2 and EEZ extending from 24 to 200 nm. The continental shelf is about 26 000 km2 with an average width of around 22 km, and the coastline is 1 100 km long. The total annual fish production of Sri Lanka was 25 000 t in 1952 and 269 850 t in 1998. Major fish species caught in Sri Lankan waters are skipjack, blood fish, yellow fin tuna, mullet, shark, trevally, Spanish mackerel, prawns, lobsters.
Scomberomorus guttatus known as Indo-Pacific king mackerel, is one of the commonly appearing Perciforms in the coastal waters of Bangladesh. There are commercial fisheries, although large volumes are captured mainly by artisan fishermen. It is one of the principal species in the drift gill net fishery of Bangladesh, but the catch is not identified separately. In the coastal waters of Bangladesh, the fishing pressure is increasing due to increase in the number of artisan fishing crafts.
The growth of Indian mackeral Rastrelliger kanagurta in the Visayas Sea, central Philippines, is estimated, based on length-frequency data from 1983 to 1987 and the Compleat ELEFAN program. Results are TL8 = 38 cm and K = 0.8 year -1. These estimates are tentative and other vital statistics could not be estimated due to the absence of small fish in the available catch samples.
This contribution presents von Bertalanffy growth parameter estimates for species/stocks of jack mackerels of the genus Trachurus from around the world, and compares them with growth parameters for T. symmetricus murphyi caught off central-Chile (33 super(o)S-39 super(o)S). It is found that Trachurus stocks inhabiting upwelling areas such as the Humboldt and Benguela current systems grow better than their ecological equivalents in temperate waters, such as the North Sea.
Analysis of RAPD loci in Indian mackerel (Rastrelliger kanagurta), as generated by the arbitrary primer OPA 07 (GAAACGGGTG), revealed a maximum within-region genetic variability for samples from the east coast of India. Dendograms did not show clear centre-specific clusters. Restricted intermixing among the individuals between the east and west coasts in suggested.
The 1987-1995 length composition of quarterly catches of Scomberomorus commerson (Lacepede 1800) was analyzed to determine various biological reference points for management purposes. These include: fishing mortality producing maximum yield-per-recruit in weight (F sub(max)), fishing mortality producing 50% relative mean mature biomass (F sub(50)), and fishing mortality producing recruits that would exactly replace their parent stock (F sub(rep)). F sub(max) provided misleading suggestions to increase fishing mortality on the stock which is currently at a low level.
A new method for estimating the maximum girth of roundfish is proposed as illustrated; this is based on an elliptic approximation of the cross sections of the fish body. Results derived from a small sample horse mackerel, Trachurus trachurus, suggest that maximum girth estimates based on the elliptic model are more precise than the values estimated by applying a conventional method.
The seasonally oscillating growth parameters and length-weight relationships for Scomber japonicus caught in the Gulf of Guayaquil, Ecuador, were determined based on length-frequency data from 1989 to 1996, using the FiSAT software package of Gayanilo et al. (1996). Estimates of growth parameters are in general agreement with previous studies on the same species. Results also imply that the growth of Scomber japonicus slows down during the cold season by approximately 50% with respect to the average growth.