Coastal engineering investigation at Jupiter Inlet, Florida

A fixed-bed hydraulic model of Jupiter Inlet, Florida, was constructed for the purpose of testing measures designed to remedy problems of sediment erosion and deposition in the inlet area. Both tide-induced flows as well as waves were simulated in the model which was built on an undistorted scale of 1:49. Model verification was based on prototype measurements of waves, tides and currents. Results have been interpreted in terms of the influence of various proposed remedial schemes on flow velocity magnitude, distribution and wave height at various locations within the study area. A stability parameter has been utilized for evaluating the degree of sediment erosion or deposition at a given location. Various structural solutions were examined in the model. It is proposed that, in the initial phase of solution implementation, sediment removal/nourishment methods be used primarily to mitigate the existing problems. New structures, as per model test results, should be installed under subsequent phases, only if sediment management procedures do not prove to be adequate. The currently followed procedure of periodic sand trap dredging may be extended to include the new dredging/nourishment requirements. (PDF contains 245 pages.)

Pilot investigation of remote sensing for intertidal oyster mapping in coastal South Carolina: a methods comparison

South Carolina’s oyster reefs are a major component of the coastal landscape. Eastern oysters Crassostrea virginica are an important economic resource to the state and serve many essential functions in the environment, including water filtration, creek bank stabilization and habitat for other plants and animals. Effective conservation and management of oyster reefs is dependent on an understanding of their abundance, distribution, condition, and change over time. In South Carolina, over 95% of the state’s oyster habitat is intertidal. The current intertidal oyster reef database for South Carolina was developed by field assessment over several years. This database was completed in the early 1980s and is in need of an update to assess resource/habitat status and trends across the state. Anthropogenic factors such as coastal development and associated waterway usage (e.g., boat wakes) are suspected of significantly altering the extent and health of the state’s oyster resources. In 2002 the NOAA Coastal Services Center’s (Center) Coastal Remote Sensing Program (CRS) worked with the Marine Resources Division of the South Carolina Department of Natural Resources (SCDNR) to develop methods for mapping intertidal oyster reefs along the South Carolina coast using remote sensing technology. The objective of this project was to provide SCDNR with potential methodologies and approaches for assessing oyster resources in a more efficiently than could be accomplished through field digitizing. The project focused on the utility of high-resolution aerial imagery and on documenting the effectiveness of various analysis techniques for accomplishing the update. (PDF contains 32 pages)

Investigation of unusual mortalities of bottlenose dolphins along the mid-Texas coastal bay ecosystem during 1992

An investigation was conducted into the deaths of more than 220 bottlenose dolphins (Tursiops truncatus) that occurred within the coastal bay ecosystem of mid-Texas between January and May 1992. The high mortality rate was unusual in that it was limited to a relatively small geographical area, occurred primarily within an inshore bay system separated from the Gulf of Mexico by barrier islands, and coincided with deaths of other taxa including birds and fish. Factors examined to determine the potential causes of the dolphin mortalities included microbial pathogens, natural biotoxins, industrial pollutants, other environmental contaminants, and direct human interactions. Emphasis was placed on nonpoint source pesticide runoff from agricultural areas, which had resulted from record rainfall that occurred during the period of increased mortality. Analytical results from sediment, water, and biota indicated that biotoxins, trace metals, and industrial chemical contamination were not likely causative factors in this mortality event. Elevated concentrations of pesticides (atrazine and aldicarb) were detected in surface water samples from bays within the region, and bay salinities were reduced to <10 ppt from December 1991 through April 1992 due to record rainfall and freshwater runoff exceeding any levels since 1939. Prolonged exposure to low salinity could have played a significant role in the unusual mortalities because low salinity exposure may cause disruption of the permeability barrier in dolphin skin. The lack of established toxicity data for marine mammals, particularly dermal absorption and bioaccumulation, precludes accurate toxicological interpretation of results beyond a simple comparison to terrestrial mammalian models. Results clearly indicated that significant periods of agricultural runoff and accompanying low salinities co-occurred with the unusual mortality event in Texas, but no definitive cause of the mortalities was determined. (PDF file contains 25 pages.)

Preliminary investigation on growth responses of Cyprinus carpio L. fed on locally formulated artificial diets

The growth rate and feed conversion ratios of the common carp, Cyprinus carpio were measured for five test diets in 14-day replicate laboratory studies. The young carp were fed with artificial test diets with crude protein contents ranging from 14.50 to 21.42 per cent. Within this range of feed characteristic optimum growth rates were obtained with diets containing 20.25 and 21.42 per cent crude protein. The study of the effect of varying ration levels showed that growth rates increased with increases of ration size, but the food conversion efficiency and protein efficiency ratios decreased markedly as ration size was increased

A statistical investigation of fish prices in Nigeria

The main objective of this study is to describe and characterize the behaviour of fish prices in Nigeria. Drawing upon aspects of the data from a nationwide fish survey in 1980/81 and on various secondary data, the study analyses the pattern of fish price movement and makes projections of fish prices in Nigeria till 2002 A.D. It is concluded that unless efforts are directed at stemming inflation in fish prices, prices paid by fish consumers in Nigeria will be more than doubled within the next two decades

A preliminary investigation into the effects of a sex-reversal androgen, methyltestosterone, on food utilization and growth of Sarotherodon niloticus (L) fry

Three groups of Sarotherodon niloticus fry were fed for 8 weeks on diets either treated with 17- & methyltestosterone (MT), alcohol (CA), or untreated (CO). Growth rate and food utilization in the different groups were compared. Results indicate that the best growth, Feed Conversion Ratio (FCR), Protein Efficiency Ratio (PER) and Mean Growth Rate (MGR) were obtained with the MT diet. There was no significant difference (P 0.05) in growth and food utilization of the CA and CO fry, nor in the mortality rate of the 3 treatments. The androgen, methyltestosterone promotes growth and protein anabolism without producing toxic effects in S. niloticus

An investigation of the organization of canoe fisheries in Nigeria: A case study of Ilaje/Esedo local government area of Ondo State

The effects of some socio-economic variables on the performance of artisanal fishermen were investigated. The variables include the age-structure of the fishermen, level of investment, educational background, membership of co-operative societies and marketing arrangements. All these variables were found to be crucial to productivity in the artisanal fishing sector

A preliminary investigation into the post harvest losses of fish in Shiroro Lake area

The findings are presented of a study conducted to assess the post harvest losses in Shiroro Lake, Nigeria. The major objectives were to identify and quantify the types of losses, to provide recommendations that would enhance formulation of policy guidelines for utilization and exploitation of the declining fishery resources of the lake

An investigation of the effect of replacing fish meal with soyabean meal, groundnut cake and blood meal at varied proportion on growth and food utilization of the Clarias anguillaris fingerlings fed in outdoor hapas

Fingerlings of Clarias anguillaris obtained from a homogenous source through induce breeding and each with a mean weight of 2.8g were stocked in ten hapas each measuring 1.0x1.0m in outdoor concrete tank and were fed for eight (8) weeks. Results shows that the best growth rate was recorded among fingerlings fed fish meal as the only protein source (TD5) while DT2 containing soya bean, groundnut cake (40%), blood meal as the protein sources came next. The growth rate of fingerlings fed DT2 (40 % groundnut cake, 10% soyabean meal and 10% blood meal) was higher than those fed DT4 containing 10% fish meal but lower than those fed DT5 which has fish meal as its sole source of protein (53.0%). Analysis of various growth parameters like SGR, FCR and PER. shows that DT5 was the overall best diet but there was no significant statistical difference in weight gained by fish fed the five diets (P <0.05)

A preliminary investigation into the effect of different storage methods on the keeping quality of smoked Oreochromis niloticus

The study was carried out to asses the nutritional qualities of smoked O. niloticus and to discover the best methods of storage to minimize spoilage and infestation of smoked fish. Result showed that the protein contents in A and D decreased while the protein contents of b and C increased. The lipid content increased only in A while it decreased in B-C and D. The moisture content generally increased over the period of storage and there was an increase in ash content only in C while it decreased in A, B and D. The samples packed in polythene bag suffered about 35% mould infection and a few were attached by rodents with some fouling. Samples packed in jute bag were in good condition but were slightly attached by insect. All samples packed in carton and basket were still in good state but there were insect attack in those packed in carton

An investigation into the value of yam (Dioscorea rotundata) peels as energy source in the diet of Oreochromis niloticus fry fed in indoor glass aquaria

The study was designed to investigate the value of the peels of yam (Dioscorea rotundata) as energy source in the diet of Oreochromis niloticus fry and to investigate the level of inclusion of this peels that will give optimum growth performance. Four diets, three levels of yam peels and a control, was prepared and tested on O. niloticus fry (mean weight of 0.27g) for ten weeks. Fifteen (15) O. niloticus fry were grouped in each of the glass aquaria, measuring 60x30x3Ocm and with a maximum capacity of 52 liters of water. The fry were fed twice daily at 10% biomass. The fry were weighed weekly to determine weight increment or otherwise and the quality of feed was adjusted accordingly. DTl (70% yam peels and 30% yellow maize) in the carbohydrate mixture gave the best performance. The fry fed this diet, gained a mean weight of 1.20g for the period of the experiment. The poorest performance in terms of growth was from fry fed the control diet (100% yellow maize in the carbohydrate mixture). Fry fed this diet gained mean weight of 0.80g for the duration of the experiment. Analysis of the various growth indices like SGR, PER, FCR and NPU shows that DTl was the overall best diet with an SGR value of I. 92 and FCR of 54.10. The difference in weight gain by fry fed the three levels of yam peels diet and the control diet (100% yellow maize) was not statistically significant (P>0.05)

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

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