_(4).png){kind=logo}
Research Article
Jul 06, 2013
Effect of Diplostomum Species on Length–Weight Relationship of Farmed Nile Tilapia in Kibos Area, ... , Kisumu City, Kenya
Diplostomum species metacercariae are parasitic trematodes that pose significant economic threat to fish farming world– wide. Nile tilapia ranks the most commercialized fish in Kenya besides being a cheap source of highly nutritive protein. However, low production of pond reared Nile tilapia in western Kenya poses threats to initiatives by the Kenyan government to revamp the economy of residents in this region. Diplostomiasis infection has been scantly reported in the region, however, comprehensive studies on the effect of Diplostomum spp. on the health status of farmed fish is lacking. This study examined the influence of Diplostomum parasites on the length-weight relationships and condition factor of farmed tilapia in Kibos area near Kisumu City. 326 fish samples were collected from three fish farms between December, 2011 and February, 2012. The values of the regression co-efficient obtained for the length-body weight relationship in all the farms was around the hypothetical value ‘3’ whereas the correlation co-efficient was greater than 0.9. This suggests an isometric growth form in all the sampled specimens. The condition factor computed exhibited values significantly greater than Kn = 1.0. There was no significant statistical difference (p>0.05) between parasitized and non-parasitized fish. Thus, it is clear the specimens were healthy and fingerlings (< 5cm) from the farms could be used for commercial production
_(4).png){kind=logo}
Research Article
Jun 09, 2013
Spatio-temporal Variation in Distribution and Relative Abundance of Mid-Atlantic Bight Fishes and ... Invertebrates off the Coast of New Jersey (USA)
Commercial and recreational fisheries within the Mid-Atlantic Bight are an important component of the local and national economy. In 2010, commercial fisheries in New Jersey ranked sixth in value ($177,935,588) and eighth in landings (73,406 mt) in the United States. The estimated number of recreational fishing trips in New Jersey ranged from 5.4 million (2009) to 7.4 million (2007) during 2003 through 2010. Because fish communities and the habitats they rely upon can be negatively impacted by anthropogenic activities, descriptive baseline information on the coastal beach fish community beyond the surf zone must be available to marine resource managers so they can make informed decisions. Given this management need to facilitate objective informed marine resource decision-making, the main goal of this investigation was to provide a descriptive profile of the New Jersey coastal fish and invertebrate community. The specific objectives were to assess fish and invertebrate population dynamics by identifying trends (or lack thereof) in spatio-temporal variation in relative abundance and distribution for the most numerically dominant and economically valuable fish and invertebrate species found off the coast of New Jersey. The findings showed that annual relative abundance was stable among species, but there were temporal and spatial differences in overall fish and invertebrate relative abundance among specific species. In addition, results demonstrated there was a seasonal difference in species composition. Overall, butterfish and scup were the most numerically dominant species and relative abundance generally increased from spring to summer. Most fish showed a negative binominal distribution and the highest densities for butterfish and scup occurred at depths between 10 and 20 m.
_(4).png){kind=logo}
Research Article
May 20, 2013
Spatial and Temporal Patterns in Abundance and Distribution of Juvenile Ladyfish (Elops saurus) in ... Florida Waters (USA)
Relative abundance and distribution are two of the most important life-history characteristics that fishery managers use to make informed decisions, such as identifying nursery grounds or protecting specific habitats. Many researchers have already estimated the relative abundance and distribution of various commercially and recreationally important species (e.g., permit [Trachinotus falcatus], tarpon [Megalops atlanticus], and bonefish [Albula vulpes]) found within and outside of the United States. Unfortunately, comparative information for ladyfish (Elops saurus) is limited and nonexistent for most regions of the world. Given the need to examine the early life-history of ladyfish in more detail, and at a finer scale, the specific objectives of this study were to evaluate the annual relative abundance and distribution (spatial and temporal) of juvenile ladyfish in nine distinct Florida estuaries (USA). Findings showed that juvenile ladyfish recruitment and abundance in Florida waters varied seasonally and annually. Also, the results indicated that juvenile ladyfish recruited into secluded freshwater sites from latewinter to summer depending on the estuary. Annual juvenile ladyfish abundance demonstrated an alternating pattern, and the findings showed that the estimated annual abundance had increased in Tampa Bay and in the Indian River Lagoon during 1987 through 1995. Results also showed that juvenile ladyfish were unevenly distributed throughout Florida estuaries; juvenile ladyfish distribution was skewed towards a limited number of specific locations. It was evident that juvenile ladyfish did not recruit to a wide-variety of habitats; they required specific micro-habitats. In summary, juvenile ladyfish were collected primarily at specific stations located near, or adjacent to, freshwater input or protected bayou areas during late-winter through early summer months
_(4).png){kind=logo}
Research Article
May 20, 2013
Evaluation of Growth Response and Food Utilization Efficiency in Tilapia, Oreochromis mossambicus ... (Peters), Fingerlings Fed Supplemented Dietary Protein Levels with Varying Feeding Rates in Concrete Tanks
A four weeks laboratory feeding trial was conducted to assess the effect of dietary crude protein levels of 32.68% as basal protein diet (BPD) and 22.40% as low protein diet (LPD) fed at different feeding rates on growth performance, feed and nutrient utilization of tilapia, Oreochromis mossambicus. Fish were reared utilizing outdoor concrete tanks of 1 3 1 3 1 m. The results showed that growth performance of tilapia fingerlings was significantly (p , 0.05) increased at the higher dietary protein levels. Feed efficiency was significantly (p , 0.05) reduced in terms of protein efficiency ratio (PER) and specific growth rate (SGR) at the LPD tested. Further, the results clearly showed that fish growth was best at the BPD level tested. Furthermore, in term of percentage weight gain and daily weight gain, there was a progressive improvement in the growth responses with increasing dietary feeding rates at LPD levels, while weight increment in fish fed with BPD achieved a mean final weight of 41.11 g, LPD at 6% body weight of 29.55 g, LPD at 8% body weight of 31.50 g and LPD at 10% body weight of 33.02 g, respectively. Protein, lipid and moisture content were influenced significantly by dietary protein levels. There was a significant increase in muscle protein and a decrease in lipid content with increasing dietary protein. The growth performance of O. mossambicus fingerlings was monitored under laboratory conditions.
_(3).png){kind=logo}
Research Article
May 19, 2013
Commercial Fishery Catch Characteristics and Population Assessment of the Shortfin Mako Shark (Isur ... us oxyrinchus) in the Western North
Pelagic sharks, an oceanic group of sharks, are an incidental bycatch in many global pelagic longline commercial fisheries, including the U.S commercial longline fishery that operates in the western North Atlantic Ocean. Shortfin mako shark (Isurus oxyrinchus) is one of the only pelagic sharks that have any economic value. Similar to other sharks, the shortfin mako shark is slow-growing, late-to-mature, and has a low fecundity, which makes this species vulnerable to overexploitation. In 2002, the International Union for Conservation of Nature (IUCN) classified the shortfin mako shark as Lower Risk (Near Threatened [NT]) on its annual Red List of Threatened and Endangered Species. Given the current conservation status and the general paucity of data on the status of the shortfin mako shark population, the objectives of this study were to characterize the commercial pelagic longline shortfin mako catch and assess its population in the western North Atlantic Ocean using a simple production model. Commercial data indicated that pelagic longline fishing effort has decreased with time, but most of the fishing effort continued to be in the Gulf of Mexico. Catches of shortfin mako shark have decreased over time, but observer data showed that larger animals were taken in the fishery. Overall, the Schaefer model was generally the least sensitive to varying K values, more sensitive to F values, and the most sensitive to r values.
_(4).png){kind=logo}
Research Article
May 07, 2013
Do Rainbow Trout and Their Hybrids Outcompete Cutthroat Trout in a Lentic Ecosystem?
Much has been written about introduced rainbow trout interbreeding and outcompeting native cutthroat trout. However, the specific mechanisms by which rainbow trout and their hybrids outcompete cutthroat trout have not been thoroughly explored, and most of the published data is limited to lotic ecosystems. Samples of Snake River cutthroat trout (Oncorhynchus clarkii bouvieri), the rainbow-cutthroat hybrid, the cutbow trout (Onchorhynchus mykiss x clarkii), and rainbow trout (Oncorhynchus mykiss), were obtained from a lentic ecosystem (Eleven Mile Reservoir, Colorado) by creel surveys conducted from May to October, 2012. The total length and weight of each fish was measured and the relative condition factor of each fish was computed using expected weight from weight-length relationships from the Colorado Division of Parks and Wildlife (CDPW). Data from the CDPW collected from 2003 – 2010 in the same lentic ecosystem were used to compute relative condition factors for additional comparison, as was independent creel survey data from 2011. The data was also compared with minimum, 25th percentile, mean, 75th percentile, and maximum weight-length curves generated from independent North American data. Cutthroat trout were plump: the mean relative condition factor of the cutthroat trout was 112.0% (± 1.0%). Cutbow hybrid trout were close to the expected weights with a mean relative condition factor of 99.8% (± 0.6%). Rainbow trout were thinner with a mean relative condition factor of 96.4% (± 1.4%). Comparing mean relative condition factors of CDPW data from earlier years and plotting the 2012 data relative to percentile curves also shows the same trend of cutthroat trout being plumper than expected and rainbow trout being thinner than the cutthroat trout, with the hybrid cutbow trout in between. This data supports the hypothesis that rainbow trout do not outcompete cutthroat trout in lentic ecosystems. Comparison with data from three other Colorado reservoirs also shows that cutthroat trout tend to be more plump than rainbow trout and their hybrids in sympatric lentic ecosystems.
_(3).png){kind=logo}
Research Article
Apr 28, 2013
Estimating Largemouth Bass Age: Precision and Comparisons among Scales, Pectoral Fin Rays, and Dor ... sal Fin Spines as Nonlethal Methods
Scales are commonly used to age largemouth bass since the samples are easy to extract and process. Yet, scale annuli are often difficult to interpret among the largest (and presumably oldest) individuals. The goal of this study was to determine whether a more precise nonlethal structure could be used to age largemouth bass. We examined scales, pectoral fin rays, and dorsal fin spines from largemouth bass collected from six glacial lakes in northern Indiana. Collectively, 861 structures were aged by three analysts and post-concert reads concluded with 85%, 94%, and 99% agreement for scales, pectoral fin rays, and dorsal fin spines, respectively. Pre-concert exact (± 0 years) percent agreement among age analysts was highest for dorsal fin spines (27%) followed by pectoral fin rays (23%) and scales (2%). Mean coefficient of variation was lowest among dorsal fin spines (16%) followed by pectoral fin rays (22%) and scales (37%). Scales exhibited the most variability and bias, while dorsal fin spines were the least variable and most unbiased structure. We encourage researchers to use scales for younger fish and dorsal fin spines for larger fish when both: (1) nonlethal methods and (2) a higher standard of precision are sought to evaluate specific management objectives.
_(4).png){kind=logo}
Research Article
Apr 23, 2013
Utilization of Tigernut (Cyperus esculentus L.) Meal as Dietary Supplement by African Catfish (C ... larias gariepinus Burchell, 1822)
Two hundred and fifty five Clarias gariepinus fingerlings with average body weight of 5.01.0g were allotted to five isoproteic diets (CP540%) in which tigernut replaced maize at 0%, 25%, 50%, 75% and 100% respectively. The catfish fingerlings were divided into five groups of 45 fish per treatment and fed at 3% biomass for 20 weeks. Result showed significant (p,0.05) differences in feed intake and specific growth rate but no significant (p.0.05) differences in feed conversion ratio (FCR) and body weight changes among the dietary treatments. This indicates that tigernut meal can be tolerated as replacement for whole maize in African catfish diets without compromising production/yield.
_(4).png){kind=logo}
Research Article
Apr 23, 2013
Potentials of Kunnu Waste as Dietary Supplement for African Catfish Fingerlings
A 72 days feeding trial was conducted on African catfish (Clarias gariepinus) fed on five diets (CP540%) in which maize was replaced with kunnu waste at 0%, 25%, 50%, 75% and 100% respectively. Fingerlings of C. gariepinus were assigned to the five diets in a completely randomized design at 36 fish per treatment in Hapa nets suspended in an outdoor concrete tank; experimental fish were fed at 5% biomass daily. Results on performance and feed utilization showed linear correlation between specific growth rate and body weight gain (p.0.05). However, feed intake increased with increased dietary levels of kunnu waste (p,0.05). The best feed conversion ratio (FCR) was obtained from the control group while the poorest was recorded at 100% replacement (p.0.05). This finding indicated that C. gariepinus can tolerate kunnu waste as dietary replacement for maize without adverse effect on performance
_(4).png){kind=logo}
Research Article
Apr 16, 2013
Measuring Body Size in Small Marine Fishes: A Comparison of Three Non-intrusive Methods
Studies of non-intrusive techniques are important in fisheries biology, because research methods may inadvertently cause damage to the study organisms. In addition, current effects of human–environment interactions coupled with future trends in global climate change likely will lead to increased monitoring of fish population dynamics. The aim of this study is to analyze the effectiveness of three simple non-intrusive techniques to accurately obtain body length measurements of anemonefish and other small fishes. Frequently used catch and re-capture methods are stressful to fishes, and can alter their behaviors upon release, thus negatively impacting field ecological studies. Alternate methods to non-intrusive sizing of reef fishes are needed, and these methods should be compared to determine the most effective and efficient means of collecting the targeted data. Three non-intrusive techniques were employed to obtain accurate fork length (FL) measurements of the twoband anemonefish, Amphiprion bicinctus. Comparison of these methods revealed that fish lengths from visual estimates by self-contained under water breathing apparatus (SCUBA) divers did not differ significantly from those estimated using both video-mirror and Tps-mirror techniques (ANOVA, F(2,60) 5 1.572; p 5 0.22). Under laboratory conditions, fish sizes from manual measurements also did not differ significantly from those obtained using either mirror method (ANOVA, F(2,81) 5 0.489; p 5 0.61), demonstrating that the mirror techniques accurately assess fish size under both laboratory and field conditions. These methods were not effective in identifying or tracking individual fish among years in the field, due to high rates of fish mobility and turnover. However, they were useful in determining short-term anemonefish migration among sea anemone hosts.
_(4).png){kind=logo}
Research Article
Apr 14, 2013
Assessment of Probiotic Application on Natural Food, Water Quality and Growth Performance of Salin ... e Tilapia Oreochromis mossambicus L. Cultured in Concrete Tanks
The effects of different levels of commercial probiotics BZT® BIO-AQUA on water quality, phytoplankton populations and total production were evaluated in saline tilapia Oreochromis mossambicus production tanks. The experiment consisted of 4 treatments with three replicates utilizing twelve 1m3 outdoor concrete tanks. All tanks were stocked with graded, nursed all-male tilapia fingerlings O. mossambicus (5.79–6.31 1 0.52g/fish) for a 60 days culture period. Variations in phytoplankton populations were recorded throughout the experiment among treatments. O. mossambicus associated with probiotics to their tanks has a higher significant effects (p 0.05) on final weight, % weight gain, SGR% and FCR than in control treatment, respectively. O. mossambicus average body weight (ABW) was higher (p 0.05) and tend to grow with time for overall treatments with better performance in probiotics treated fish. Water quality was better in treatments of O. mossambicus associated with probiotics and suggesting providing further control on water quality, growth performance and phytoplankton production, specifically when applied.
_(3).png){kind=logo}
Research Article
Mar 20, 2013
Morphogenesis, Pathogenesis, Detection and Transmission Risks of White Spot Syndrome Virus in Shri ... mps
Among the important challenges to shrimp aquaculture worldwide are diseases caused by viruses, in particular by White Spot Syndrome Virus (WSSV) whose genome of 305 kb has been recently sequenced. WSSV, also dubbed White Spot Bacilliform Virus (WSBV), is a major shrimp pathogen with a high mortality rate and a wide host range. The sequencing and characterization of different strains of WSSV has begun to reveal aspects of its biology, virulence and pathogenesis. Knowledge on these aspects is critical for developing effective control methods. The socioeconomic impacts of the diseases caused by the WSSV have been catastrophic in some shrimp producing countries of Asia and the Americas. Thus, these diseases were listed by the World Animal Health Organization (or Office International des Epizootics, OIE) as posing a significant threat to cultured and wild crustaceans as a consequence of international trade or movement of infected organisms. The aim of this review is to present a state-of-the-art knowledge in different aspects of WSSV like morphogenesis, pathogenesis, transmission risks, detection, bio-inoculation studies, and international rules and standards.
_(4).png){kind=logo}
Research Article
Feb 21, 2013
Ecological and Biodiversity Friendly Approach to Post Larval Shrimp (PLS) Collection in Ghana
A new approach to post larval shrimp (PLS) collection using a locally designed PLS trawler has been successfully tried in the Volta Estuary of Ghana for 3 years (2000, 2002 and 2005). The PLS trawler had 4 major components: the pulley system, the post larvae (PL) collector, the control room and a work space. The PL collector had an aperture area of 0.433m2 and a volume of 0.389m3 . Trawling for PLS was made at designated water depths at trawl speed of approximately 0.25 knots (0.128m/s). Each trawl session lasted for 10min and was replicated. The distance traversed by the PL collector in a trawl session was estimated at 77.07m and covered a swept area of 33.40m2 . The associated volume of water filtered through the PL collector was 33.38m³. The average number of PLS collected per trawl session ranged from 682 6 604 to 758 6 761 at high tide and from 324 6 273 to 414 6 248 at low tide. The ‘other larvae’ (OL) (by-catch discards) collected in the PL collector comprised of the larvacean, Oikopleura spp.; the chaetognatha, Parasagitta (Sagittidae) spp.; crab larvae and fish larvae. Mean OL numbers collected for each trawl session ranged from 295 6 188 to 349 6 292 at high tide and from 257 6 164 to 396 6 261 at low tide. Total PLS collected over 36 trawl months spread over a period of 3 years was 39,549. The corresponding OL numbers was estimated at 21,543. The OL (by-catch discards) to PLS ratio per trawl session was thus estimated at 54.47%. The comparatively low catches of the OL was attributed to the combined effect of the filtering efficiency of the 500µ mesh PL collector net, the ability of the PL trawler to sample at variable water depths and the relatively shorter time of 10min used in a trawl session. This method of PLS collection would provide a viable and reliable alternative to the marine resources (by-catch) destruction which accompanies wild PLS harvest and also ensure biodiversity preservation in the Ghanaian coastal region. The mode of operation of the PL trawler and its operational efficiency is presented and discussed
_(4).png){kind=logo}
Research Article
Feb 16, 2013
Influence of Live and Dry Diets on Growth and Survival of Chub (Leuciscus cephalus) Larvae
The effect of live and dry diets on the growth and survival of cultured chub (Leuciscus cephalus) larvae was measured from 5 days post-hatch and over a 24 days period. At its conclusion, larvae fed artificial dry diets were significantly shorter, weighed less and suffered higher mortality rates than those fed Artemia and a mixed diet of Artemia spp. and a commercial feed.
.png){kind=logo}
Research Article
Feb 16, 2013
Evaluation of antidiabetic activity of medicinal plant extracts used by tribal communities in rural ... areas of Warangal district, Andhra Pradesh, India
The prevalence of diabetes mellitus (DM) is increasing with ageing of the population and life style changes associated with rapid urbanization and westernization. Physalis minima is widely used in Indian medicine by the tribal communities to treat various diseases including diabetes. The present study was aimed at assessing the hypoglycemic effects of extracts from P. minima in alloxan-induced diabetic rats. The powdered plant parts were successfully extracted with boiling water using soxhlet extractor. The Wister strains of male albino rats were used for the present study. The antihyperglycemic activity of the crude aqueous extracts of P. minima different parts were studied in alloxan-induced diabetic rats. The toxicity study results showed that the medium lethal dose (LD50) of the extracts is higher than 1 g/kg body weight and hence, in a single dose administration, the plant extracts had no adverse effect. There is no significant level of reduction in fasting blood glucose level was noticed for the aqueous extracts of root and stem of P. minima. On chronic administration, the effect of P. minima flower and leaf causes a fall in fasting blood sugar of rats. These findings clearly established that the antidiabetic efficacy of the flower and leaf extract of P. minima are almost equal and both exhibited more potent antidiabetic activity by reducing the blood glucose level significantly than all other root and stem extracts.
