Preservation of marine biodiversity deserves serious consideration as almost 65% of the earth's organisms (excluding insects) are marine. There is little knowledge at present on the status of marine biodiversity. However, the seas are an important source of protein for human consumption and genetic diversity is a key factor in ecosystem functioning, stability and resilience. Overfishing and destructive practices may have unalterable impact on marine biodiversity. This paper discusses measures that can be adopted to protect the most productive areas of the marine ecosystem.
Malaysia is one of the world's most biologically diverse countries, ranking twelfth worldwide. Most documented works on biodiversity are studies on taxonomy and species abundance. The genetic diversity of marine species and species indicators used for estimating ecosystem health are poorly understood. There is little documentation on the changes in species composition and abundance over time in the varous ecosystems.
An overview of the fisheries of St. Lucia using currently available information is presented. The fisheries are entirely artisanal, characterized by relatively simple and inexpensive gears and boats. The 2,100 fishers (who land roughly 750 t per year of fish) appear socially and economically marginalized and beset by low occupational mobility. The status of the major species groups they exploit are briefly discussed, and initial indications of overfishing are noted. Consideration on both resource and resource-user situations in management of the island's fisheries is emphasized.
Small pelagic fish landings in the Philippines presently amount to about 500,000 t/yr. Catches are dominated principally by roundscads (Decapterus spp.), sardines (Sardinella spp.), anchovies (Stolephorus spp.) and mackerels (Rastrelliger spp.). In the commercial fishery virtually the entire catch is taken by purse seiners, basnigs, trawlers, ring netters and muro-ami. The annual commercial catch of small pelagic fishes has remained static since 1971. Nominal fishing effort (i.e., in terms of the numbers of principal commercial fishing vessels) has continued to increase, however.
Compensatory mechanisms of the Peruvian hake population (Merluccius gayi peruanus) in response to heavy exploitation and changes in species interaction are discussed. Changes in the rate of cannibalism, diet composition, maximization of fecundity and behavioral adaptation are noted.
Overfishing threatens to extinguish local fisheries for valuable tropical sea cucumbers by reducing population densities to the point where reproductive success trails behind natural mortality (known as depensation or the ‘Allee effect’). Once this happens, conventional management measures alone, such as closed seasons/areas, size limits and gear restrictions, will usually fail to repair the damage. A different suite of active management interventions must be considered to restore the spawning biomass of severely over-exploited populations.
A brief review of marine fishery development in Southeast Asia is given, with emphasis on the phase of rapid growth of catches that prevailed in the 1960s-1970s, and on the high expectations this phase generated, especially in the six countries that make up the Association of Southeast Asian Nations (ASEAN).
This paper estimates maximum sustainable yield and maximum economic yield from Schaefer and Fox surplus production bioeconomic models to find evidence of biological and economic overfishing, and their consequences in Gulf of Thailand demersal fisheries. The paper examines alternative policy instruments to reduce overfishing. The discussion emphasizes strengthening fishery management for implementing limited access, and a combination of co-management, and decentralization of fisheries management.
This contribution briefly reviews the various forms of overfishing, with emphasis on their implications for tropical coastal fisheries, e.g. the coral reef fisheries of the South Pacific. Addressed are : growth overfishing and its relationship to the study of growth and mortality of fish, and of gear characteristics; recruitment overfishing and its links with parental biomasses, as well as "biological" and ecosystem ovefishing.
Many exploited stocks of aquatic organisms are limited by the supply of juveniles and many also suffer from recruitment overfishing. Consequently, there is much interest in stock-enhancement programs, which are aimed at improving harvests by increasing recruitment to levels approaching the carrying capacity of the habitat. Most stock-enhancement programs involve the release of juveniles reared in hatcheries or the collection, rearing, and transplantation of wild juveniles. Optimized release strategies and increased fitness for life in the wild are required.