Impacts of climate change and variability on fish value chains in Uganda

This study examines the vulnerability of fish pr oduction in Uganda, particularly as it r elates to the predicted impacts from climate change, using the concept of the value chain. The value chain approach has been recommended as a useful tool to study specific challenges facing a sector resulting from various drivers of change, including climate. Critically, such analyses can reveal context-specific response strategies to enhance a sector (Jacinto and Pomer oy 2010). The specific purpose of the study was to identify curr ent and potential impacts of climate change and corresponding adaptation strategies in fish value chains. The study builds upon information fr om earlier value chain analyses on fisheries and aquaculture production in Uganda to provide a more in-depth understanding of issues facing the fish industry, in particular, those to be incorporated in the CGIAR Resear ch Program Livestock and Fish.

The structure and margins of the Lake Chilwa fisheries in Malawi: a value chain analysis

Small freshwater pelagic fisheries in closed lakes are very important to millions of people in sub-Saharan Africa providing livelihoods and nutritional security. However, returns from these fisheries have been shown to �uctuate in response to climatic variability. In order to understand the impact of these fluctuations on the livelihoods of people dependant on these fisheries, there is a need for information on how the fish value chain is organized and how it functions in response to variation in supplies. The results will feed into strategies that build resilience in fishing households against the uncertainties arising from unstable ecosystems. The Lake Chilwa fishery value chain is composed of fishers, processors, traders, fish transporters, boat owners, owners of fish processing shades, fisheries associations, gear owners, gear makers, firewood sellers, and traders of fishing gear and equipment. The value chain employs many people and local authorities can consider using this information in the design of rural development strategies for employment generation in small-scale fishing communities. The findings from this study have a number of implications for the improvement of the livelihood of fishers and enhancing their capacity to mitigate against the effects of climate change.

Benthic invertebrates that form habitat on deep banks off southern California, with special reference to deep sea coral

There is increasing interest in the potential impacts that fishing activities have on megafaunal benthic invertebrates occurring in continental shelf and slope ecosystems. We examined how the structure, size, and high-density aggregations of invertebrates provided structural relief for fishes in continental shelf and slope ecosystems off southern California. We made 112 dives in a submersible at 32−320 m water depth, surveying a variety of habitats from high-relief rock to flat sand and mud. Using quantitative video transect methods, we made 12,360 observations of 15 structure-form-ing invertebrate taxa and 521,898 individuals. We estimated size and incidence of epizoic animals on 9105 sponges, black corals, and gorgonians. Size variation among structure-form-ing invertebrates was significant and 90% of the individuals were <0.5 m high. Less than 1% of the observations of organisms actually sheltering in or located on invertebrates involved fishes. From the analysis of spatial associations between fishes and large invertebrates, six of 108 fish species were found more often adjacent to invertebrate colonies than the number of fish predicted by the fish-density data from transects. This finding indicates that there may be spatial associations that do not necessarily include physical contact with the sponges and corals. However, the median distances between these six fish species and the invertebrates were not particularly small (1.0−5.5 m). Thus, it is likely that these fishes and invertebrates are present together in the same habitats but that there is not necessarily a functional relationship between these groups of organisms. Regardless of their associations with fishes, these invertebrates provide structure and diversity for continental shelf ecosystems off southern California and certainly deserve the attention of scientists undertaking future conservation efforts.

Reference area as a factor affecting potential yield estimates of coral reef fishes

A compilation of 48 estimates of Caribbean and Pacific coral reef fish catches, ranging from 0.1 to 23.7 t km super(-2) year super(-1), obtained from coral reef areas ranging from 0.1 to nearly 4-10 super(5) km super(2), are used to show that observed catches, and hence potential yield estimates, depend strongly on the reference area. The implications for coral reef fisheries assessments are discussed.

Aquaculture of a high-value freshwater fish in [Malaysia] : the marble or sand goby (Oxyeleotris marmoratus, Bleeker)

The article highlights the aquaculture of marble or sand goby (Oxyeleotris marmoratus) in Malaysia. Topics discussed are: breeding, hatchery and nursery techiques, nutrition, growout techniques, and diseases.

The introduction of exotic fish in Sri Lanka with special reference to tilapia

Introductions of exotic finfish between 1948 and 1953 are reported in this paper, with a brief reference to earlier and later introductions. Exotic fish were introduced principally to develop the potential for aquaculture in fresh and brackish waters in order to increase the availability of fish for rural communities through the biological control of aquatic vegetation. The algal feeding tilapia (Sarotherodon mossambicus) has created a new food industry in inland and brackishwaters. It has supplemented marine fishery production in a community where animal protein intake consists mainly of fish. It is also being cultured in flooded rice fields and used in the control of malaria. This excellent table fish has not had any adverse environmental impact.

Comparison of some traits of economic importance in tilapias (Orechromis niloticus and Sarotherodon galilaeus) with particular reference to their culture in Ghana

This study was conducted to determine which of the two major tilapia species in freshwater capture fisheries in Ghana, Oreochromis niloticus or Sarotherodon galilaeus, is more suitable for breed improvement and pond culture. It compares traits of economic importance, including seed output, specific growth rate, survival and sex ratios following androgen sex reversal. The results of the study showed that the aquaculture potential of S. galilaeus compares favorably with that of O. niloticus. However, S. galilaeus may be preferred because the males and females have an equal growth rate, which allows for manual sorting to raise both sexes in monosex culture, an inexpensive appropriate technology that an ordinary smallscale fish farmer can apply.

Biological reference points for managing kingfish, Scomberomorus commerson, in Oman

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. On the other hand, both F sub(50) and F sub(rep) provided acceptable results, suggesting reduction on the current fishing mortality by 17-40%.

Background Concepts for a Rotating Harvesting Strategy with Particular Reference to the Mediterranean Red Coral, Corallium rubrum

A simple cohort model was used as the basis for selecting the appropriate periodicity and number of separate unit areas in a rotating harvest scheme for a sedentary species, the red coral, Corallium rubrum, in the General Fisheries Management Council for the Mediterranean area. The rotation period in years, and hence the minimum number of unit areas involved, was determined on the basis of the time to maximum biomass by a simple calculation of the yield-per-recruit type, requiring a knowledge of natural mortality and growth rates. Other criteria may be more important, however, and in general for a long-lived species, will result in shorter rotation periods. These criteria may include economic factors, criteria based on the preferred size or quality of product, or criteria that take into account the cumulative risk of illegal fishing of closed areas with time, hence the growing cost of enforcement as harvestable product accumulates. For red coral, although maximum biomass is predicted to be reached after some 15-44 years, the above considerations suggest that a rotation period ofsome 9-15 years would be close to optimal, taking into account a range ofthe above considerations. This article discusses the relative merits of rotating harvest schemes in contrast to quota management for sedentary and semi-sedentary resources or geographically isolated substocks ofa mobile resource, and concludes that this approach may have considerable potential as an alternative approach to resource management.

Episodic variations in stream water chemistry associated with acid rainfall and run-off and the effect on aquatic ecosystem, with particular reference to fish populations in N.W. England

This is the episodic variations in stream water chemistry associated with acid rainfall and run-off and the effect on aquatic ecosystems, with particular reference to fish populations in North West England produced by the North West Water Authority in 1985. This report looks at the biological, physical and chemical information collected over a five year period from over 100 sites on upland streams in the North West Region of which drained rocks of low buffering capacity. In both Lake District and South Pennine sites striking differences were found between the composition of invertebrate communities inhabiting acid-stressed and less acid-stressed streams. Electric fishing surveys showed that acidic streams (geometric mean pH <5.5) generally had abnormally low densities of salmonids ( < 0 .2m2) and that 0+ fish were very few or absent. The latter indicates recruitment failure. Salmon were more sensitive than trout to low pH.

A report on the strategic stock assessment survey of the Colton Beck catchment 1994 with particular reference to salmonids

This is the report on the strategic stock assessment survey of the Colton Beck catchment in 1994 with particular reference to salmonids in Colton Beck, River Ea, River Gilpin and Rusland Pool. This report forms one part of the third year of a triennial survey programme for the South West Cumbria and South Cumbria catchments. It was produced by the National Rivers Authority in 1994. Colton Beck had excellent densities of sea trout (Salmo trutta) and a small population of salmon (Salmo salar) in its lowest reaches. The total productivity was very good throughout the catchment. Stocking of sea trout fry in 1993 has enhanced the population with survivors through to parr probably adding to the scoring of double class A at two sites in the survey in 1994. Stocking was not undertaken in 1994, but the population appears to be maintaining itself at a very high level.

A report on the strategic fisheries stock assessment survey of the minor catchments in South West Cumbria 1996 with particular reference to salmonids

This is the report on the strategic fisheries stock assessment survey of the minor catchments in South West Cumbria 1996 with particular reference to salmonids, produced by North West Water in 1994. The 1996 Minor Catchment survey indicates variations in salmonid production within these catchments. Survey results indicate that production may be reaching its limit in certain areas whilst others are underachieving and others are unsuitable for salmonid production. Trout production within the catchments is higher and more widespread than that of salmon. Water quality levels vary considerably between catchments and intra-annually within individual catchments. The need for selective habitat surveys, with a view to habitat improvement schemes (H.I.S) is discussed. This report formed a basis for subsequent reports, thus, allowing data comparisons and analysis of production level fluctuations. It was the most extensive assessment of these catchments to date, taking into account comparisons with the new National Database on salmonid production in England and Wales.

A report on the strategic fisheries stock assessment survey of the River Winster 1995 together with a coarse fish survey in 1994 and reference to the 1995 drought

This is the report on the strategic fisheries stock assessment survey of the River Winster 1995 together with a coarse fish survey in 1994 and reference to the 1995 drought, produced by the Environment Agency North West in 1996. Salmonid production within the Winster catchment was dominated by trout although good densities of salmon juveniles were found on some main river sites. Despite suffering drought conditions for much of 1995, only salmon fry production appeared to have been affected. Coarse fish populations once found in the lower reaches of the Winster appear to have declined to very low levels with no fish sampled. This may be partly due to broken tidal gates allowing saline intrusion. It seems that the lower river was suited to the development of a recreational coarse fishery, now that the gates have been repaired. This report completes the strategic stock assessment surveys planned for the period 1992-1995. It represents the last major catchment that was surveyed to determine the current status of fisheries in the South and South West Cumbria areas.

Report of 1996 survey of Trout Beck with particular reference to spawning gravel quality and invertebrates as a food source for salmonids

This is the Report of 1996 survey of Trout Beck with particular reference to spawning gravel quality and invertebrates as a food source for salmonids produced by the Environment Agency North West. Whilst the main River Derwent is quite a high profile salmon fishery, Trout Beck is not a significant fishery in its own right, but serves to maintain the genetic integrity of the wild populations of trout and salmon in the catchment by providing a unique habitat. This survey addressed the invertebrate food availability, and additionally looked at the substrate to try to determine whether the bed type might actually be unsuitable for spawning, especially in view of the previously mentioned silt inputs.