Managing Sustainable Fish Stock
Dr Alan F Koropitan citing reports Cheung and his colleagues in the journal Global Change Biology, increasing to 720 ppm CO could affect 20 percent decline in fishery stocks Indonesia in 2100.
Decline in our fish stocks in 2100 was not just the domain of the increase in CO in the air up to 720 ppm with a scenario like the current emission level.
It should be emphasized, CO is only one of anthropogenic material, either in air or in the waters, which may play a role essential for living things. The presence of CO in the waters become important to work in phytoplankton primary production process so that the trophic level can work well.
In the context of primary production processes, the need for significant CO as the feed material for the first trophic level. While the fish resources are in the middle and trophic level above. Empirical facts show, the decline in fish stocks that occur as a function of growth, recruitment, natural mortality, and arrests, as well as the influence of anthropogenic CO one.
Biological indicators of ecological
Decline in fish stocks can be evaluated from some biological-ecological indicators, such as biomass and fish size. Coastal & Marine Resources Research in 2009 in Aru and Banda Sea Waters shows, the size of swordfish caught in generally the same as those caught Lease, which is sized from 48 to 54.15 cm (Syahailatua, et al. 1993).
Fish catch reached 87 cm in size mackerel, skipjack reached 50.84 cm. Opportunities of potential catches of large tuna which is still fairly high in the waters. The tuna has reached maximum size and grow in these waters have not reached the maximum catch, and there are still chances of arrest.
According to the World Food and Agriculture Organization (FAO), for groups of reef fish which decreased the average size of catch 50 cm, the current dominant captured the size of 46 cm. This occurs because of the high intensity of fishing in waters off eastern Indonesia. Compare with research Faunce et al (2002).
Catches of red snapper in the Gulf of Biscay between 25-30 cm, lower than that caught in the waters of Maluku. From the decline in catch size is evident that the biological ability to grow to the size of the fish catch has been limited by the increasing intensity of fishing.
Besides the ability to grow, other factors that affect fish stocks are ruaya characteristics of fish (migratory species). In real terms of biomass production declined not tuna fisheries, but in terms of size has indeed been a decline. These conditions provide evidence that the high intensity of fishing has led to decline in the size of tuna fishing.
As the fish migrate in broad geographically, tuna will always move at any time. Indonesia's marine waters is not a permanent place of tuna fish world.
Analysis of The Society of Tuna Fisheries Investigation (Sadhori, 1985) in Indonesia to mention, when the Indian Ocean tuna catch was not focused in one location only and always occurs monthly change in the migration of tuna.
Note that researchers expressed surprise Dr. Anthony Lewis in the National Tuna Congress (National Congress of the tuna) in General Santos City, Philippines, 2009. Mentioned that the migration of tuna world was empty in the waters of North Maluku. Of course this provides opportunities for the increased production of Indonesian tuna.
Catch the intensity of
Empirical fact that productivity catching tuna in the Indian Ocean at 281.2 kg / day decreased to 177 kg / settings (Astuin, 2001). Improved fleet reaches 66 percent, while the ratio of the productivity decline of tuna is only about 54 percent.
That is, increasing the fleet is much higher than the decline in catches of tuna or a 47 percent drop in monthly production. BRKP research results in 2007 showed, there have been changes as a consequence of shrinkage pelagic fish stock (biomass) and the increase in purse seine fishing effort semiindustri uncontrollable.
Pelagic fish production decline expected due to alteration of species and competition of food and space to fish habitat. Fishing pressure is not balanced with the power to recover these stocks. The number of active vessels and diminishing number of trips, but the number of operational days at sea increases.
Based on statistical data of 2007-2008, marine capture fisheries production increased by 2.71 percent from 4.73 million tons in 2007 increased to 4.86 million tons in 2008.
The number of fishing vessels of all sizes in 2007 were 590 314, while in 2008 increased to 590 380, or 0.01 percent. In 2007, the number of fishermen fishing in the sea 2.75 million and 2.77 million by 2008, an increase of 0.8 percent.
Sustainable management
To protect fish stocks decline in catch, as feared, Dr. Allan, at least there should be immediate action plan which sought, namely the handling of Illegal Fishing and Moratorium and the rationalization of fishing activity.
Combating illegal fishing is absolutely necessary to provide more space for our fishermen to be able to utilize optimum territorial waters.
While the moratorium precedence to protect ecosystems were under pressure by restricting destructive fishing gear or a balance between carrying capacity of the biomass and fishing intensity that should be given (rationalization).
The next action plan is to revitalize the area along coastal region which is still potential for aquaculture development. An important part that can not be separated is to rehabilitate coastal ecosystems such as mangroves and coral reefs. Mangrove and coral reef ecosystems are either going to be able to increase fish biomass (carrying capacity).
Thus, it is clear that the decline in stocks not only because of the influence of anthropogenic load (increased CO), but also because of other environmental components.
For that, a mindset that needs to be developed in the study of decline in stocks is a logical framework that is holistic by integrating information on biology, fish ecology, the pressure of human activity, and niche resources (as a medium of live fish).
Lecturer YONVITNER Laboratory Fishery Resources Management Faculty of Fisheries and Marine Science IPB
source: http://cetak.kompas.com/read/xml/2010/03/08/02542218/Mengelola.Stok.Ikan.Berkelanjutan
