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Consequences of biomanipulation for fish and fisheries









Lammens, E.H.R.R. Consequences of biomanipulation for fish and fisheries. FAO Fisheries Circular. No. 952. Rome, FAO. 2001. 23p.


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    The decrease in aquatic vegetation in Europe and its consequences for fish populations (1987) 1987
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    A diverse aquatic vegetation is essential to maintain a diverse fish fauna. The fish is an important part of a complex network of relations between nutrients, phytoplankton, epiphytes, herbivorous invertebrates, the aquatic vegetation and fish. In Northwest Europe and North America and probably in the rest of the industrialized world, the (submersed) aquatic vegetation (macrophytes) is rapidly disappearing from eutrophicated waters. The decrease is well documented. As a consequence of abun dant growth of epiphytes, which are better competitors for inorganic carbon and light in highly eutrophicated waters than submersed aquatic macrophytes are, the condition of the aquatic vegetation becomes worse. Shallow, eutrophic, relatively clear water that is rich in water plants, can change to phytoplankton dominated turbid water, within short time. This change may occur without a remarkable increase in the actual nutrient loading. Invertebrate grazers like snails, macrocrustaceans and cl adoceran zooplankters are able to protect aquatic macrophytes against the negative effects of this competition by removing epiphytes and phytoplanktonic algae. As a man predator on invertebrates, the fish indirectly influences the well-being of the aquatic vegetation. There is evidence that aquatic macrophytes are the source of biochemical compounds that negatively affect the growth of algae (allelopathy) and attract grazers. These processes are mainly found in model systems and under semi-na tural conditions. Their ecological significance still has to be tested in the field.A situation with turbid, phytoplankton dominated, water without aquatic vegetation can continue after removing nutrients from effluents because: (i) blue-green algae (phytoplankters) may excrete toxic substances, negatively affecting the growth of aquatic macrophytes; (ii) abundantly occurring young fish, but also invertebrate animals like mysids, prey on the bigger (phytoplankton grazing) cladocerans; (iii) acid rain, polluted bottom sediments and/or bird flocks contribute to the nutrient loading of a water body. Restoration techniques are: lowering the nutrient loading in combination with protection of the remaining stands of reed, replanting of aquatic plants, creation of artificial refugia for zooplankton and manipulation of young-of-the-year fish populations. Chemical and mechanical control of "nuisance" growth and heavy stocking with herbivorous fish including the common carp (Cyprinus carpi o) have to be omitted or executed very carefully to avoid phytoplankton-dominated turbid water. In small systems with "nuisance" growth, stocking (50-150 kg/ha, max. 250 kg/ha) with grass carp (Ctenopharyngodon idella) can improve the water quality.
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    Assessment of IUU activities on Lake Victoria 2012
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    Fishing all over the world is a major source of food for humanity and a provider of employment and economic benefits to those engaged in the activity. However, with increased knowledge and the dynamic development of fisheries, it should be known that world living aquatic resources, although renewable, are not infinite and need proper management, if their continued contribution to the nutritional, economic and social well-being of the growing world’s population is to be sustained. Lake Victoria i s Africa’s largest and most important inland water body with a total water surface area of 68,800km2. Lake Victoria contributes significantly through its fishery and generation of electricity to the economic benefits of not only the riparian states, Kenya, Tanzania and Uganda, but also to the neighboring countries and the world at large. Lake Victoria is arguably the most important single source of freshwater fish on the African continent, contributing significantly to national and regional econ omies and livelihoods of the regions inhabitants. Although not often associated with inland fisheries, Illegal, Unreported and Unregulated (IUU) fishing and the trade of illegal fish has threatened the biological, social, financial and cultural integrity of the lakes resources and those that depend on them. Given that Lake Victoria’s living resources are shared amongst the three riparian states, a regional fisheries body, the Lake Victoria Fisheries Organization (LVFO) was formed in 1994 though the technical assistance of the FAO to manage the fisheries resources in Lake Victoria as a single ecological entity. Within the LVFO mandate, the identified areas of IUU fishing are considered in the form of: Illegal or misuse of fishing gears; illegal fishing, fish landing, processing and trading; unregulated fishing number of boats, fishers and gears (capacity); unregulated, unreported or undocumented domestic and regional fish trade; fishing and landing undersize fish in undesignated landing sites; and fishing during closed seasons or in the closed breeding areas or critical habitats. The decline of Nile perch stocks suggest that fisheries management and compliance structures within the three riparian states and at LVFO at the moment are at various levels of disarray, hence allowing IUU fishing to continue thriving unabated. Since the introduction of Nile perch into Lake Victoria in the 1950’s it has been the focus of an intensifying commercial fishery. In 1980, a total of 4 439 to ns of Nile perch were harvested, a decade later over 338 115 tons of Nile perch were landed annually. From 2000 to 2010, and average of 253 404 tons of Nile perch are caught. Despite relatively consistent landings reported by the LVFO, total biomass of Nile perch decreased from 1.4 million tons (92% of total biomass in Lake Victoria) in 1999 to it lowest recorded estimate of 298 394 tons in 2008 (14.9% of total biomass in Lake Victoria). Currently, as of 2010, the Nile perch biomass was estimate d at 18% of total biomass in Lake Victoria, which equates to 367 800 tons. Although a slight increase in biomass between 2008 and 2010 was observed, Nile perch biological indicators suggest that the fish is in a critical survival state. The average size of Nile perch has decreased from 51.7 cm TL to 26.6 cm TL, according to hydro acoustic surveys suggesting that a significant portion of total Nile perch biomass is less than 50 cm TL (legal size for export). It was reported by the LVFO stock asse ssment team that in 2006 and 2008, less than 2% of the Nile perch biomass was in fact greater than 50 cm TL. The size at first maturity of male and female Nile perch is also decreasing, this common amongst fish populations that are stressed (or overexploited). Despite the biological indicators, which suggest legal size Nile perch are less than 2% of total Nile perch biomass, the average number of fishermen increased by 33% between 2000 and 2008. During the same period, Frame survey and MCS compl iance missions noted a marked increase in the number of illegal gears being deployed to target undersize Nile perch. The number of vessels increased by 37% and the use of outboard engines increased by approximately 50%. It has been reported that motorized boats are more efficient, catching about 25 kg of fish per day, compared to 10 kg caught by non-motorized vessels. The increase in use of illegal gears, motorized vessels and fishermen suggests that fishing for Nile perch is still profitable. P reviously driven by lucrative export prices for Nile perch, fishers now target undersize illegal Nile perch for the lucrative domestic and regional trade, which is estimated to exceed the export trade by volume and value. This shift in fishing for undersize Nile perch will effect government revenues earned from the export fishery. The Nile perch fishery over the last decade contributed 0.6% less to the Tanzanian GDP, similarly, a decrease in export trade of Nile perch from Uganda of 14% occurred between 2007 and 2008, resulting in a 0.1% decrease in GDP contribution. By not controlling fishing effort targeting illegal, undersized and immature Nile perch, economic and social hardships will worsen. Current fisheries management both regionally through the LVFO, and nationally amongst the riparian states is inadequate, with respect to Monitoring, Control and Surveillance (MCS). MCS is a collection of activities and tools intended to support fisheries management in fighting IUU fishing, and forms the framework on which accurate, informative and dynamic fisheries management decisions can be made. MCS is critical at all levels of fisheries management. Within the Lake Victoria region, co-management has been implemented through the establishment of Beach Management Units (BMU’s). A BMU is a community-based organization, which is legally accepted as a representative of a fishing community and is mandated on a voluntary basis to engage in MCS initiatives. Lake Victoria has 1 087 registe red BMU’s according to the harmonized BMU guidelines, agreed upon amongst the member states and the LFVO. Although the inclusion of community based management and MCS is critical in contributing to effective management of Lake Victoria’s fisheries resources, many challenges exist, including amongst others; geographical isolation of fishing communities, social issues (families of BMU members may partake in illicit activities), political interference (revenue collections, or election voting), corr uption, conflict of interests (BMU members are often fishmongers and fish traders) and lack of representation in higher management committees. Although advances in MCS technology have revolutionized fisheries management amongst many ESA-IO countries, the sharing of regional resources and capacity is fragmented and not effectively harnessed by the LVFO. Database management systems are not working effectively, data collecting, analyzing and dissemination are unreliable and time inefficient, respec tively and appropriate MCS tools for example net gauges are not available. The RWG-MCS reported that between 2004 and the end of 2008, a total of 4 605 suspects were apprehended, 12 126 beach seines, 9 550 small seine nets, 27 703 monofilament nets, 248 843 kilograms of immature Nile perch (249 tons) and 254 589 illegal gillnets were confiscated. These data are unreliable; furthermore they were not quantified in terms of definition of the item (how long were the nets that were confiscated 80 met er, or one kilometer, this has a profound effect on CPUE), of financial loss to fishers and traders versus the opportunity costs of MCS. The valve of court fines are insignificant especially if one considers the amount of uncontrolled fishing effort, uncontrolled illegal gears used in Lake Victoria, and the increasing value in the trade of immature fish on domestic markets. Also, there is no indication as to whether the court penalties and fines imposed on the same offences in the three partner states have any reference to the same severity across the region, or are recycled back into MCS initiatives. It is therefore difficult to determine whether the RWG-MCS interventions from 2004 to the end of 2008 were beneficial, as little to no comparative data exists. The LVFO depends highly on donor funds to support MCS and management initiatives, including training, capacity building and technical expertise. When donor funds are not available, regional MCS stagnates, which is a major concern. Operation Save the Nile perch is one such example. The EAC Council of Ministers in 2009 launched the ‘Operation Save the Nile Perch’ (OSNP), which required each of the three member states to contribute US$ 600 000. The goal of the initiative was to target illegal fishing and to curb the trade in undersize Nile perch currently threatening the economic integrity of Lake Victoria. The target of OSNP, as ratified by the Council of Ministers was to have fisheries illegalities in the lake, based on th e 2008 frame survey data as bench mark, reduced by 50% in June and 100% by December 2009. Currently as of 2011, Kenya has paid the required funds, with Tanzania only contributing 31% and Uganda zero resulting in less than half of the required funds paid in by from the member states. This undermines the legitimacy of ‘Operation Save the Nile Perch’ and political will and MCS operational capacity. The aim of this report was to assess the state of IUU in Lake Victoria, and to support the SMARTFISH programme in assisting the LVFO and established MCS committees to implement joint regional MCS trainings, by conducting a short cost benefit analysis of enhancing existing regional MCS initiatives and by evaluating past and present regional action plans to deter IUU fishing on Lake Victoria. An action plan was developed through a participatory workshop between the LVFO, national states and the MCS-RWG, held in Jinja, Uganda from the 5th to the 7th of October 2011.
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    Home Country Measures that Promote Responsible Foreign Agricultural Investment 2016
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    This paper summarizes the good practices by nine selected OECD countries that seek to promote responsible foreign investment in developing country agriculture, primarily by investors in their territory or jurisdiction. The study provides examples of the increasing trend of home countries in establishing binding legal norms and other mechanisms as safeguards that are relevant for agricultural investment. It finds that States apply some specific provisions to hold private corporate actors investin g in agriculture abroad accountable, for example in regard to bribery of foreign public officials. Investment home countries are also increasingly using safeguards relevant for agricultural investment for companies that are controlled by the State or seek its support. Furthermore, Public-Private Partnerships are increasingly used in development assistance projects as a means to promote responsible agricultural investment. In these cases, the safeguards usually imply the use of negotiated and app roved instruments such as the Voluntary Guidelines on the Responsible Governance of Tenure of Land, Fisheries and Forests in the Context of National Food Security (VGGT). The Principles for Responsible Investment in Agriculture and Food Systems (CFS-RAI), endorsed in 2014 by the Committee on World Food Security (CFS), will possibly become a major guidance instrument, given recent declarations by the G7 and G20.

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