Aspects of the biology and population dynamics of freshwater mussels in Lake Kariba and Lake McIlwaine

The essential aim of this study was to provide a broad foundation of biological knowledge upon which a programme of mussel utilization and management could be built. Results of the study are presented in three main sections. Part 1 describes the stock of Lake Kariba and Lake McIlwaine; part 2 describes various aspects of the breeding biology of the three species; and part 3 presents the results of morphological, biochemical and age analyses - aspects which are used for initial standing crop and production calculations. The final discussion concludes the thesis with a general examination in ecological terms of the factors which have influenced the development and nature of the mussel faunas of the two lakes under consideration.

Biological characteristics and mortality of western butterfish (Pentapodus vitta), an abundant bycatch species of prawn trawling and recreational fishing in a large subtropical embayment

The western butterfish (Pentapodus vitta) is numerous in the bycatch of prawn trawling and recreational fishing in Shark Bay, Western Australia. We have thus determined crucial aspects of its biological characteristics and the potential impact of fishing on its abundance within this large subtropical marine embayment. Although both sexes attained a maximum age of 8 years, males grow more rapidly and to a larger size. Maturity is attained at the end of the first year of life and spawning occurs between October and January. The use of a Bayesian approach to combine independent estimates for total mortality, Z, and natural mortality, M, yielded slightly higher point estimates for Z than M. This result indicates that P. vitta is lightly impacted by fishing. It is relevant that, potentially, the individuals can spawn twice before recruitment into the fishery and that 73% of recreationally caught individuals are returned live to the water.

Freshwater Biological Association 1929-1979. The first fifty years

Booklet telling the story of the FBA from its founding in 1929 until its Golden Jubilee in 1979. The booklet aimed to produce a readable account of those aspects of freshwater biology that have been among the main themes of the Association's research, as well as some aspects of its history and the philosophy guiding its foundation. The publication includes many images of the FBA's work and history as well as images and illustrations on lake ecology and applied science.

Getting it right: incorporating social aspects into MPA planning and implementation

This brochure summarizes a series of case studies done in nine countries—Brazil, India, Indonesia, Mexico, Senegal, South Africa, Spain,Tanzania and Thailand—on the role of communities in the planning and implementation of marine protected areas (MPAs). The studies demonstrate that communities can be powerful allies in efforts for conservation and management of coastal and marine resources. They also underline the need for systematic attention, capacity building, funding and other resources for effective implementation of Programme Element 2 on governance, participation, equity, and benefit sharing of the Programme of Work on Protected Areas (PoWPA) of the Convention on Biological Diversity (CBD).

Studies on certain aspects of eutrophication of fresh water ponds at Barrackpore

In the present study, non-conservative abiotic parameters and biological conditions were utilized to portray the causes, consequences and magnitude of anthropogenic eutrophication in 4 fresh water perennial community ponds at Gangetic West Bengal, India. In order to classify the ponds, a single criterion basis was adopted and more emphasis given to the species of plankton which are biological indicators of eutrophication. Besides this, various abiotic parameters were also studied. On the basis of results obtained, 4 ponds have been classified as "Eutrophic, Tropical Bacillariae".

Training aspects for a trawling fishery

Trawling experiments carried out by the United Nations Development Programme Project and the Uganda Department of Fisheries, strongly suggest that the trawling method of fishing, if introduced on Lake Victoria, would bring about a tremendous increase in fish production from the lake. It is recognised, however, that before trawling is introduced, its economic, social, technical, biological and manpower implications must be carefully analysed. I now propose to discuss the training aspects of a trawl fishery on Lake Victoria.

Some major unsolved aspects of the dynamics of African fisheries as related to questions of rational development and management

Studies of fish and fisheries in Africa fall in to four phases: the period of fisheries expeditions, ecological investigations, the development phase, and the period of mechanized exploitation. There is need to establish the taxonomic status and ecology of the varied components of the potentially important Haplochromis in Lake Victoria. A comprehensive study of their bionomics and life history, population structure, natality, recruitment and mortality coefficients should be undertaken. Emphasis lo be laid on the study of the ecology, especially breeding behaviour of the economically important c1upeids (Stolothrissa tanganciae and Limnothrissa miodon), in Lake Tanganyika. A comprehensive investigation into the migratory and shoaling behaviour of the Lake Victoria Tilapia to be initiated. Pre-impoundment studies to be undertaken to assess effects of hydroelectric projects of fisheries. Studies on parasites of economically important fishes to be stepped up to assess pathological effects and the biological basis for their control. The role of predators, e.g., Hydrocyon, Lates and Micropterus salmoides in commercial fish populations should be evaluated, and the knowledge gaincd used to effectively manage the fisheries in favour of the more desirable fish stocks.

Aspects of the biology of the Lake Tanganyika sardine, Limnothrissa miodon (Boulenger), in Lake Kariba

Juveniles of limnothrissa miodon (Boulenger) were introduced into the man-made Lake Kariba in 1967-1968. Thirty months of night-fishing for this species from Sinazongwe, near the centre of the Kariba North bank, from 1971 to 1974 are described. Biological studies were carried out on samples of the catch during most of these months. Limnological studies were carried out over a period of four months in 1973. Limnothrissa is breeding successfully and its number have greatly increased. It has reached an equilibrium level of population size at a lower density than that of Lake Tanganyika sardines, but nevertheless is an important factor in the ecology of Lake Kariba. The growth rate, size at maturity and maximum size are all less than those of Lake Tanganyika Limnothrissa. A marked disruption in the orderly progression of length frequency modes occurs in September, for which the present body of evidence cannot supply an explanation.

Aspects of the fishery and biology of the African catfish Clarias gariepinus (Burchell, 1822) amidst environmental changes in Lake Wamala (Uganda)

Environmental changes are some of the factors that affect fisheries and biological characteristics of fishes. The African catfish Clarias gariepinus (Burchell, 1822) has biological characteristics that enable it to persist under various stressful environmental conditions. However, few studies have examined how the African catfish responds to conditions created by a changing climate. The study examined some of the fishery and biological characteristics of African catfish in Lake Wamala (Uganda) to provide an understanding of their response to changing climatic conditions using data for the period 1950 - 2013. Temperature around the lake increased by 0.02ºC/year since 1980, commensurate with the regional trend, while rainfall was above average since 1996, except in 2004 and 2008. Lake depth was strongly positively correlated with rainfall (r =0.83, n= 6, p<0.05) up to 2000, after which, lake depth decreased amidst increase in rainfall. The contribution of African catfish increased from 20% to 85% and 17% to 78% respectively to commercial and experimental catches respectively between 1975 and 2013 despite the decrease in lake depth. The modal total length, condition factor, food, and fecundity did not change. Only size at first maturity decreased from 37.5 to 30 cm TL in females and 39.5 to 34.2 cm TL in males between 1999/2000 and 2012/2013. The biological characteristics of the African catfish were comparable with those of the same species in other lakes and remained relatively stable. The results suggested that the African catfish has the capacity to persist and/or adjust appropriately under conditions created by climate variability and change, and if properly managed, can sustain the fisheries of Lake Wamala.

Hydrologic aspects of freshening upper Old Tampa Bay, Florida

Upper Old Tampa Bay, a 17-square mile area of Old Tampa Bay, Florida, has been proposed for conversion to a fresh-water lake. The amount of runoff to the proposed lake and its chemical quality are both adequate to freshen and sustain a fresh-water lake in this part of the bay. During 1950-66 runoff to the proposed lake, including discharge from Lake Tarpon, would have averaged 134 mgd (million gallons per day) and would have displaced the volume of the proposed lake at normal pool stage (2.5 feet above mean sea level) about 1.7 times per year. Without discharge from Lake Tarpon, the volume of the proposed lake would have been displaced 1.2 times. If the lake level was initially at a normal pool stage during a critically dry year, such as 1956, the proposed lake would have declined 0.25 to 0.5 foot below the minimum design level, (1.5 feet above mean sea level). (44 page document)

Biological Studies. Annual Report, Part 5, September 1972

(54 page document)

Review of river fisheries valuation in West and Central Africa

This paper provides a review of the valuation of river fisheries in West and Central Africa. It is the general perception that, compared to the biological and ecological aspects of river fisheries, this particular subject area has received relatively little attention. Economic valuation is concerned with finding expression for what is important in life for human society. It should, therefore, be a central and integral part of government decision-making and policy. The review started with concepts and methods for valuation. Three main types of valuation techniques were identified: conventional economic valuations, economic impact assessments and socioeconomic investigations, and livelihood analysis. On the basis of a literature review, valuation information was then synthesized for the major regional river basins and large lakes, and also used to develop a series of national fisheries profiles. To supplement this broad perspective, a series of case studies are also presented, which focus in particular on the impact of changes in water management regime. Finally, the paper presents an assessment of the three main types of valuation methodology and a set of conclusions and recommendations for future valuation studies.

A report of biological observations at Topanga artificial reef and Santa Monica Bay artificial reef

(Document pdf contains 25 pages)

Biological surveys of five southern artificial reefs: Oceanside #1, Oceanside #2, Carlsbad, Pacific Beach, and Mission Bay

(Document pdf contains 19 pages)

Observations of the biological communities at Bolsa Chica artificial reef

Bolsa Chica Artificial Reef (BCAR) was constructed in November 1986 with 10,400 tons of concrete rubble and eight concrete and steel barges. Prior to any additional augmentation of BCAR, the u.s. Army Corps of Engineers and the California Coastal Commission required the California Department of Fish and Game (CDFG) to survey the bioloqical communities on and around BCAR. In April 1992, qualitative surveys of the biological communities were conducted on one of the eight modules at BCAR and at a nearby sand-only site. One of the modules, Module D, located in 90 feet of water (MLLW), was surveyed for fish, macroinvertebrates, and turf community organisms (small plants and sessile animals). Twelve species of fish were observed, including kelp bass (Paralabrax clathratus) and barred sand bass (P. nebulifer). Eight macroinvertebrate species were observed, rock scallops (Crassedoma giganteum) being the most abundant. The turf community was comprised of thirteen invertebrate taxa, among which erect ectoprocts (Bugula spp.) were the most numerous. Two species of foliose red algae (Rhodymenia pacifica and Anisocladella pacifica) were also observed. The reef has reached an advanced stage of successional development with fish and invertebrate communities diverse and well established. However, due,.to its depth and the turbidity of surrounding waters, this reef is not likely to ever support a diverse algal community. The diversity and abundance of fish and macroinvertebrates were, as to be expected, much lower in the nearby sand-only site. Only two species of fish and seven macroinvertebrate species were observed. Of these, only the sea pen, Stylatula elongata, was common. Overall, when compared to nearby sand-only habitats, Bolsa Chica Artificial Reef appears to contribute substantially to the local biological productivity. In addition, the concrete rubble used in BCAR' s construction appears to be performing as well as the quarry rock used in all of CDFG's experimental reefs. (Document pdf contains 22 pages)