Preliminary investigation into implication of a single cell organism in fish feed bouyancy and flotation

Two Isocaloric Isoproteic 30% crude protein diets were formulated for Clariid catfish and Tilapia with wheat grain starch (WGS) and cassava tuber starch (CTS) incorporated at 10 percent as binding agents. Saccharomyces cerevisiae was included at 2% as floating additive. The water stability, nutrient retention and flotation of pelleted feeds were observed for 60 minutes. There were generally decreasing trends in stability and retention at increasing time of immersion in water. The lipid retention was higher (P>0.05) than proteins in both diets. WGS diet was better (P>0.05) than CTS diet in flotation, which has attributed to the presence of gluten protein in wheat products. It is envisaged that a break through in floating feed development in Nigeria aquaculture would save the Nigeria economy from extruded (floating) feed importation

The economic contribution of whalewatching to regional economies: Perspectives from two National Marine Sanctuaries

Whenever human beings have looked out on the sea, they have seen whales. First from the shore and later from ships when humanity entered the ocean realm as seafarers, we have responded to seeing these creatures with awe and wonder. Even when we hunted whales, a period well chronicled both in history and in literature, the sight of a whale brought an adrenaline rush that was not totally linked to potential economic gain. The first trips on boats specifically to watch, rather than hunt, whales began around 45 years ago in Southern California where the migrating gray whales, seen in the distance from land, drew vessels out for a closer look. Since that time whalewatching has boomed, currently conducted in over 40 countries around the world, including Antarctica, and estimated by economists at the Whale and Dolphin Conservation Society to have a 1999 worldwide economic value of around $800 million USD. The economic contribution to local coastal communities is particularly significant in developing countries and those where declining fish populations (and in some cases like the Japanese, international bans on whaling) have driven harvesters to look for viable alternatives. Clearly, whalewatching is now, in many places around the world, a small but thriving part of the regional economy. Like in the days of whaling, we still get the rush, but for some, money is back contributing to the physiological response. (PDF contains 90 pages.)

Re-emphasizing the importance of Lake Chad fisheries in Nigerian economy: Borno State experience

Nigeria with an estimated population of about 120 million people requires about 2.3 million metric tonnes of fish and fisheries product for good health at the recommended 19 kg/caput/year by FAO. Lake Chad fisheries resource of Borno State is a blessing in disguise to the Nigerian economy. It has potential to produce over 300,000 metric tonnes of fish protein annually, representing about 12.2% of the total fish demand of Nigerians. In spite of this laudable potential Lake Chad fisheries resources of Borno State declined in the past two decades due, largely, to lack of/or inadequate attention by the government, private and commercial organization, lack of social economics and infra-structural facilities for rational exploitations and management of its resources. This paper re-emphasizes the importance of Lake Chad Fisheries of Borno State in the Nigerian economy. The fisheries resources, the environment, the exploitation, the potential marketing, the role of law enforcement and foreign agencies, the constraints and potentials are discussed. Nigeria can derive a substantial proportion of its fish demand from Lake Chad fisheries of Borno State alone just with the adoption of some proffered strategies including combined efforts of the private and public sectors in the rational management of the fisheries resource of Lake Chad

Hatchery construction and its feasibility in the Nigerian economy

Aquaculture drive in the Niger Delta has necessitated the springing up of various forms of hatcheries in Nigeria in the area. The hatchery level is high as most fish farmers now want to produce their own fingerlings for the stocking of their production ponds for culture to market (table) size. The paper shows that there is a lot of market in the Niger-Delta for fresh fish. Majority of the numerous fish farmers are not well empowered to breed and produce fish seeds especially species most loved and eaten. The rising cost of materials in the Nigerian economy has become a bottleneck in the construction of more fish hatcheries for fingerling production. However, the assistance of multinationals has become very necessary to enhance its feasibility to encourage better involvement in the fish hatchery works. One remarkable area where assistance is being felt by the communities in the Niger-Delta is in fish farming and more so in the supply of fish fingerling to top fish farmers by The Shell Petroleum Development Company of Nigeria Limited (SPDC), a multinational oil company in the area. Few fish farmers have benefited from this. If more hatcheries are available to service and provide the needed fingerlings to stock the available water bodies such as, home backyard ponds, the 0.74 million hectares of brackish water, 1.01 million hectares of perennial swamps, and other marginal land available for aquaculture and properly managed, it will yield between 2.5 and 10 metric tones of fish depending on the species stocked and bred

Investigation of nematode Eustrongylides larvae infections in mudfish Clarias gariepinus and C. anguillaris from Bida floodplain of Nigeria

This is the first report and record of the determination whether mudfish Clarias were infected with the larvae of the nematode Eustrongylides. Also, documented the assessment of the socio-economic perceptions of three groups of fisher folks on the economy of infected mudfish Clarias fishing activities. Fifty-six (67.5%) of 83 mudfish Clarias caught by artisanal fisher folks were examined for the presence of the larvae of the nematode Eustrongylides. All the 8 sampled fishing localities in Bida floodplain of Nigeria had a mean intensity and abundance of at least 3 and 1 worm per fish per site, respectively. Two hundred and one (96.2%) of 209 worms recovered were from the musculatures at different depths resulting in undulations on the skin surfaces as grub-like presentations. The three groups of fisher folks assessed encountered economic losses from nematode infected mudfish Clarias which attract much debates or rejections during marketing due to its aesthetically displeasing appearance, faster deterioration, higher fragility in smoked form coupled with poorer taste compared to the wholesome ones. Infected female mudfish Clarias had higher worm burden than the males, for each fishing locality

The effects of aquaculture on farm household economy: a case study in Omon District, Cantho Province, Vietnam

A study of the farming systems in the Mekong River Delta (Vietnam) indicate that fish culture brings to the household a higher level of net farm income and family labor use. In general, adoption of fish culture is strongly affected by: (1) decline of wildfish; (2) location of the farm; (3) farm size per person and available water bodies within the farm; (4) income of farm, excluding income from fish; (5) guidance from agricultural extension workers; (6) policies of local government on the development of agriculture including aquaculture.

Coupling ecology and economy: modeling optimal release scenarios for summer flounder (Paralichthys dentatus) stock enhancement

Increasing interest in the use of stock enhancement as a management tool necessitates a better understanding of the relative costs and benefits of alternative release strategies. We present a relatively simple model coupling ecology and economic costs to make inferences about optimal release scenarios for summer flounder (Paralichthys dentatus), a subject of stock enhancement interest in North Carolina. The model, parameterized from mark-recapture experiments, predicts optimal release scenarios from both survival and economic standpoints for varyious dates-of-release, sizes-at-release, and numbers of fish released. Although most stock enhancement efforts involve the release of relatively small fish, the model suggests that optimal results (maximum survival and minimum costs) will be obtained when relatively large fish (75–80 mm total length) are released early in the nursery season (April). We investigated the sensitivity of model predictions to violations of the assumption of density-independent mortality by including density-mortality relationships based on weak and strong type-2 and type-3 predator functional responses (resulting in depensatory mortality at elevated densities). Depending on postrelease density, density-mortality relationships included in the model considerably affect predicted postrelease survival and economic costs associated with enhancement efforts, but do not alter the release scenario (i.e. combination of release variables) that produces optimal results. Predicted (from model output) declines in flounder over time most closely match declines observed in replicate field sites when mortality in the model is density-independent or governed by a weak type-3 functional response. The model provides an example of a relatively easy-to-develop predictive tool with which to make inferences about the ecological and economic potential of stock enhancement of summer flounder and provides a template for model creation for additional species that are subjects of stock enhancement interest, but for which limited empirical data exist.

Age and growth of the estuarine dolphin (Sotalia guianensis) (Cetacea, Delphinidae) on the Paraná Coast, southern Brazil

Teeth of 71 estuarine dolphins (Sotalia guianensis) incidentally caught on the coast of Paraná State, southern Brazil, were used to estimate age. The oldest male and female dolphins were 29 and 30 years, respectively. The mean distance from the neonatal line to the end of the first growth layer group (GLG) was 622.4 ±19.1 μm (n=48). One or two accessory layers were observed between the neonatal line and the end of the first GLG. One of the accessory layers, which was not always present, was located at a mean of 248.9 ±32.6 μm (n=25) from the neonatal line, and its interpretation remains uncertain.The other layer, located at a mean of 419.6 ±44.6 μm (n=54) from the neonatal line, was always present and was first observed between 6.7 and 10.3 months of age. This accessory layer could be a record of weaning in this dolphin. Although no differences in age estimates were observed between teeth sectioned in the anterior-posterior and buccal-lingual planes, we recommend sectioning the teeth in the buccal-lingual plane in order to obtain on-center sections more easily. We also recommend not using teeth from the most anterior part of the mandibles for age estimation. The number of GLGs counted in those teeth was 50% less than the number of GLGs counted in the teeth from the median part of the mandible of the same animal. Although no significant difference (P>0.05) was found between the total lengths of adult male and female estuarine dolphins, we observed that males exhibited a second growth spurt around five years of age. This growth spurt would require that separate growth curves be calculated for the sexes. The asymptotic length (TL∞), k, and t0 obtained by the von Bertalanffy growth model were 177.3 cm, 0.66, and –1.23, respectively, for females and 159.6 cm, 2.02, and –0.38, respectively, for males up to five years, and 186.4 cm, 0.53 and –1.40, respectively, for males older than five years. The total weight (TW)/total length (TL) equations obtained for male and female estuarine dolphins were TW = 3.156 × 10−6 × TL 3.2836 (r=0.96), and TW = 8.974 × 10−5 × TL 2.6182 (r=0.95), respectively.