Selection of efficient hanging ratios of gillnet on fish catch in Lake Kainji, as means of alleviating poverty among artisanal fishermen in Nigeria

Five experimental gillnet each measuring 50mx 3m nylon multi filament netting of 3" by210/2 mesh size were constructed using 40%, 45%, 50%, 55% and 60% hanging percentages, the report was carried out at Yunawa fishing village on the eastern bank of Lake Kainji. The nets were set over night (6 hours approximately). Between April-July 2004, the fish caught by the five nets were recorded taking into consideration the three mode of capture i.e. enmeshing entanglement and wedging Weight number and percentage mean weight and number based on species at five different hanging ratios were analyzed in general 50% hanging ratio was found to be the best followed by 40% among others. There was significant difference (P<0.05) in the mode of capture for both hanging ratios. Most of the fish were caught by entanglement i.e. about 83% of the catch was by entanglement while 505 hanging ratio was the best considered after the report. The occurrence of species of the five hanging ratios has significant difference (P<0.05) in terms of catch by weight and number

Promoting women participation in fish culture enterprises - as a means of poverty alleviation in Nigeria

One major aspect of the poverty status in Nigeria is the high rate of unemployment with the attendant economic in capacity, which in turn is responsible for the persistent problem of malnutrition over the decades. This paper is focused on how women can be empowered for better productivity in fish culture enterprises, seeing that women have been active in different aspects of agricultural production. They also sustain more than half of the developing countries such as Nigeria. Some problems being encountered by would be women fish farmers and suggestions on how women participation in fish and shellfish culture enterprises can be enhanced are proffered. The major ones being those sustainable policies by the Government State ADPs and NGOs are applied to ensure adequate motivation of women for fish culture enterprises

An identification key of the most important German freshwater teleost fishes by means of their eggs [Translation from: Archiv fur Hydrobiologie 83(2), 200-212, 1978]

The fetal and larval development of many freshwater fish is already relatively well covered. Coverage of the morphology of fish-species' eggs is very sparse. For this reason the authors have attempted to prepare a key on fish eggs which covers the bulk of German Teleostei fish. The key also includes a discussion of problems of categorization and terminology.

Trapping success and population analysis of Siren lacertina and Amphiuma means

Siren and Amphiuma are two poorly known genera of aquatic salamanders that occur in the Southeastern United States. A primarily bottom-dwelling existence makes these salamanders difficult to detect with conventional sampling methodologies. Therefore, the current status of their populations is unknown. I compared the capture success of modified crayfish traps and plastic minnow traps in capturing these salamanders. In addition, a mark-recapture study of S. lacertina (Greater siren) and A. means (Two-toed amphiuma) was conducted at Okefenokee National Wildlife Refuge (southern Georgia) and at Katharine Ordway Preserve (north-central Florida) from August 2001 until September 2002. Crayfish traps were much more successful than minnow traps in catching siren and amphiuma. Crayfish traps yielded 270 captures for an overall capture success of 16%, whereas minnow traps yielded only 13 captures for an overall success rate of 0.05%. In addition, several marking techniques were evaluated, and of these, only passive integrated transponder (PIT) tags were retained for the duration of the study. Therefore, I recommend this marking technique for long-term monitoring of S. lacertina and A. means. Several variables were found to have significant effects on capture rates of salamanders. A. means were most often captured in summer and the number of captures was positively correlated with water temperature, water level, and rainfall. S. lacertina were most often captured during winter and spring. Number of captures was negatively correlated with water temperature, while no relationship was found with water level or rainfall. Trap day and baiting had no significant effect on number of A. means or S. lacertina captured. Recapture probabilities of both species were low, 0.025-0.03 for S. lacertina and 0.08-0.11 for A. means. Monthly survival rates were high, 0.77-0.97 for A. means and 0.88-1.00 for S. lacertina. Density estimates of 1.3 salamanders/m2 (S. lacertina) and 0.28 salamanders/m2 (A. means) were obtained for Lake Suggs using Jolly-Seber models. Siren and amphiuma make up a substantial part of wetland biomass and can impact many other wetland species. Thus, more attention must be focused on evaluating and monitoring their populations.

Age validation of Dover sole (Microstomus pacificus) by means of bomb radiocarbon

We used bomb radiocarbon (14C) in this age validation study of Dover sole (Microstomus pacificus). The otoliths of Dover sole, a commercially important fish in the North Pacific, are difficult to age and ages derived from the current break-andburn method were not previously validated. The otoliths used in this study were chosen on the basis of estimated birth year and for the ease of interpreting growth zone patterns. Otolith cores, material representing years 0 through 3, were isolated and analyzed for 14C. Additionally, a small number of otoliths with difficult-to-interpret growth patterns were analyzed for 14C to help determine age interpretation. The measured Dover sole 14C values in easier-to-interpret otoliths were compared with a 14C reference chronology for Pacific halibut (Hippoglossus stenolepis) in the North Pacific. We used an objective statistical analysis where sums of squared residuals between otolith 14C values of Dover sole and the reference chronology were examined. Our statistical analysis also included a procedure where the Dover sole 14C values were standardized to the reference chronology. These procedures allowed an evaluation of aging error. The 14C results indicated that the Dover sole age estimates from the easier-to-interpret otoliths with the break-and-burn method are accurate. This study validated Dover sole ages from 8 to 47 years.

Age and growth of three species of Lake Victoria fish determined by means of otolith daily growth rings

The sagittal otoliths of Lates niloticus, Haplochromis obesus, and Oreochromis niloticus from Lake Victoria were examined for daily growth rings using scanning electron microscopy. In the three species the increments were clear and thick enough to allow future studies with light microscopy. The daily nature of the increments seems supported by the rhythmic growth that were found.

Preliminary studies on the effect of irradiation as a means of preservation of fish and shellfish

Preliminary investigations on the effect of irradiation on commercially important fish and shell fish like silver pomfret, Bombay duck and prawns were conducted. Irradiated samples had an extended storage life compared to their respective controls even though yellowish or brownish discoloration occurred earlier in irradiated fish. Irradiation enhanced the rate of drip formation. Brine treatment prior to irradiation retarded this rate. Pre-blanching was found to further extend the storage life of irradiated fish.