Increase Fish Production Research Articles

Balık Yemlerinde Kullanılan Yem Katkı Maddeleri

Feed Additives in Aquafeeds Aquaculture production was realized as 212.000 tons in Turkey and approximately 66 million tons in the world in 2012 respectively. In aquaculture production, the main objective is to obtain maximum yield with minimum cost. In recent years, feed additives are widely used in order to increase fish production. While additives added to fish diets increase digestibility, but they reduce anti-nutritional effects of the fish diets. In addition, the feed additives play roles for fish gaining resistance against diseases. Probiotics to be used as feed additives should not be in pathogenic nature and they should not produce toxic subs- tances. Moreover, they should maintain viability during their storage and their high nutritional interaction with fish feed is more desirable. Some studies demonstrated that the use of enzymes and plant extracts in diets increased live fish weight and voluntary feed intake. In this study reviewed the specific literatu- re investigating probiotics, enzymes and plant feed additives in fish diets.

IMPROVEMENT OF SEED PRODUCTION AND QUALITY GROUPER BY HYBRIDIZATION PROGRAM

Several types of grouper hybrid seeds can now be massively produced in a hatchery. Hybrid seeds can increase diversification of aquaculture species and potential to increase fish production. Therefore, an improvement in hybrid seed production both in high quantity and quality is very important. This research was conducted to produce massively cantik grouper hybrid seeds i.e.,a crossbreed between female tiger grouper (Epinephelus fuscoguttatus) and male marbled grouper (Epinephelus microdon). This research examined the cantik grouper seed production compared with the production of tiger grouper and marbled grouper fingerlings. The research results showed that cantik hybrid grouper seeds production had higher survival rate (24.59%) than tiger grouper (17.44%) and marbled grouper (4.63%). The total length of the seed at the age of 45 days for cantik grouper was 3.59 ± 0.21 cm, tiger 3.24 ± 0.55 cm, and batik 2.61 ± 0.42 cm, respectively. Seed abnormality for cantik grouper was 4.13%, tiger grouper 30.21%, and marled tiger 0.57%, respectively. Based on genetic variation analyses, the cantik grouper had a closer genetic relationship with the marbled grouper compared with the tiger grouper. Keywords: Marbled grouper, hybridization program, seeds production, quality

IMPROVEMENT OF SEED PRODUCTION AND QUALITY GROUPER BY HYBRIDIZATION PROGRAM

<p>Several types of grouper hybrid seeds can now be massively produced in a hatchery. Hybrid seeds can increase diversification of aquaculture species and potential to increase fish production. Therefore, an improvement in hybrid seed production both in high quantity and quality is very important. This research was conducted to produce massively cantik grouper hybrid seeds i.e.,a crossbreed between female tiger grouper (Epinephelus fuscoguttatus) and male marbled grouper (Epinephelus microdon). This research examined the cantik grouper seed production compared with the production of tiger grouper and marbled grouper fingerlings. The research results showed that cantik hybrid grouper seeds production had higher survival rate (24.59%) than tiger grouper (17.44%) and marbled grouper (4.63%). The total length of the seed at the age of 45 days for cantik grouper was 3.59 ± 0.21 cm, tiger 3.24 ± 0.55 cm, and batik 2.61 ± 0.42 cm, respectively. Seed abnormality for cantik grouper was 4.13%, tiger grouper 30.21%, and marled tiger 0.57%, respectively. Based on genetic variation analyses, the cantik grouper had a closer genetic relationship with the marbled grouper compared with the tiger grouper.</p> <p>Keywords: Marbled grouper, hybridization program, seeds production, quality</p>

Assessment of water quality, macroinvertebrate biomass and primary productivity of small water bodies for increased fish production in the Lake Victoria basin, Kenya

AbstractThis study investigated the suitability of small water bodies (SWBs) in the Lake Victoria basin, between November 2010 and October 2011 for increased food production through aquaculture. Sampling sites were stratified in terms of water availability and altitude. Low‐altitude sites were represented by Yenga and Mauna dams in Siaya County, while high‐altitude sites were represented by Kesses and Kerita dams in Uasin Gishu County. Variations in selected water quality parameters, nutrients, primary productivity (PP) and macroinvertebrate biomass of SWBs were investigated. The measured biological and water quality parameters measured in this study included PP of phytoplankton, macroinvertebrate biomass of the most abundant taxon, temperature, dissolved oxygen concentration, biochemical oxygen demand, pH, total nitrogen concentration and total phosphorus concentration. Descriptive statistics of mean and standard error of the mean were conducted for water quality parameters and nutrient levels. The general linear model was used to test for significant difference in nutrients and physicochemical parameters, both within and between the SWBs. anova was used to test for any significant differences in both PP and biomass within and between the dams. PP and macroinvertebrate biomass were sufficiently high to support fish production, while all water quality parameters and nutrients were within acceptable ranges to support the life of the mostly cultured species. Based on the results of this study, the stocking of phytophagous and benthophagous fish is recommended as a means of exploiting the food resources and increasing fish production in these areas.

Fermentasi Ampas Kelapa menggunakan Trichoderma viride, Bacillus subtilis, dan EM4 terhadap Kandungan Protein Kasar dan Serat Kasar sebagai Bahan Pakan Alternatif Ikan <br><i>[Fermentation Of Coconut Dregs Using Trichoderma viride, Bacillus subtilis, And EM4 Against Crude Protein And Crude Fiber As An Alternative Feed Ingredients For Fish]<i>

Abstract Feed plays an important role in fish farming. Feed requirements achieve 60-70% of the cost of fish farming operations. Availability of feed with quality and sufficient quantity is aimed in increasing fish production. A very high feed prices due to artificial feed ingredients used are expensive and required in large quantities. Therefore, it is necessary to find alternatives to fish directly or indirectly obtaining appropiate and adequate nutrition needs to grow. The raw material content used for feed is coconut dregs (Cocos nucifera). The availability of the coconut dregs is abundant and potensial for fish feed ingredients. The coconut dregs is also one type or plantation waste which still has potential to be processed into the manufacture of fish feed. The coconut dregs flour can be processed by fermentation to improve quality. This study was aimed to determine the increase in crude protein content and a decrease in crude fiber content of coconut dregs fermented with Trichoderma viride; Bacillus subtilis and EM4. The research method was an experiment with Completely Randomized Design (CRD). The treatments used without the addition of microbes (P0), Bacillus subtilis 6% (P1), Trichoderma viride 6% (P2), and EM4 6% (P3) with 5 repeatitions each. The parameters observed were the content of crude protein and crude fiber after 7 days of fermentation. Data analysis used Analysis of Variance (ANOVA) and to determine the best treatments using Duncan Multiple Distance Test with 5% confidence interval. The results indicated that coconut dregs fermented with Bacillus subtilis (P1), Trichoderma viride (P2), and EM4 (P3) produced the difference of crude protein and fiber. The best treatment on the increase in crude protein content was Bacillus subtilis (P1) of 7.5564%. The best treatment on the decrease in crude fiber content was EM4 (P3) of 22.3967%. However, the results of the flour fermented coconut dregs can not be used as an alternative feed material because the fermented coconut dregs is not qualified for fish feed. This is due to a lack of crude protein and high crude fiber content.

Florfenicol depletion in edible tissue of rainbow trout, Oncorhynchus mykiss (Walbaum), and sea bream, Sparus aurata L.

An increase in fish production has consequently brought an increase in infectious diseases in fish farms. The use of chemotherapic drugs is the most effective instrument against common bacterial agents. The number of registered drugs for use in aquaculture is limited and often veterinary practitioners resort to the off-label use of chemotherapic agents authorized for different food-producing animal species. Florfenicol is well known for its outstanding effect against various pathogenic bacteria affecting fish, and therefore, it may be a useful drug for off-label use in aquaculture. The aim of this study was to evaluate the depletion of florfenicol and its major metabolite, florfenicol amine, from the edible tissue of two fish species, rainbow trout and sea bream, following treatment with medicated feed at a dosage of 10mgkg(-1) of bwday(-1) , for 10 consecutive days. At prefixed time points after the end of administration (0.25, 1, 2, 3, 4, 6, 7, 10, 14 and 21days after treatment), edible tissues (muscle plus adherent skin) from 15 individuals in each group were collected and analysed by HPLC, to determine concentration of the drug in the tissue. On the basis of the obtained concentrations, withdrawal times of florfenicol in the two species were calculated. The results indicate that a drug withdrawal time of 500°C-day, as established by Directive 2004/28/EC, for off-label drug use is more than satisfactory to guarantee the healthiness of fish products against the risk of drug residues.

STOCK ENHANCEMENT IN INDONESIAN LAKE AND RESERVOIRS FISHERIES

A total water surface area of lakes and reservoirs of Indonesia is 2.3 million hectares. To increase fish production in Indonesian lakes and reservoirs, fish stock enhancement were practiced. A review on fish stock enhancement in Indonesian lakes and reservoirs was conducted. Some species used in stock enhancement were reviewed, and the causes of program success or failure were analyzed in an attempt to determine the best approach for future stocking. Since 2000 the success of the project on<br />fish stock enhancement were supported by basic research on diet, ecological niche, life cycle and behavior of the species stocked. Recent successes in fish stock enhancement are mainly determined by species which can be reproduced naturally in the water bodies. Nile tilapia (<em>Oreochromis</em> <em>niloticus</em>), Siamese cat fish (<em>Pangasionodon hypophthalmus</em>) and small carp (bilih, <em>Mystacoleucus padangensis</em>), an endemic species are the species have best performances in the increasing fish production<br />significantly. Milk fish (<em>Chanos chanos</em>) stock enhancement can be used to mitigate the negative impact of cage culture in the reservoir. While grass carp (<em>Ctenopharyngodon idellus</em>) has been successful in controlling aquatic weed, Eichhornia crassipes in some lakes. Management of fish stock<br />enhancement including providing quality and quantity of seeds, regulating of fish catch, developin g of market system, institution and fisheries co-management have supported a steady yearly increase in yield. The governments should take the initiative in protection of genetic diversity, especially in stock enhancement of lakes inhabited by endemic and or threatened species, such as lakes in Sulawesi and Papua Island.

Indonesia

Khalwan, Irianto A, Rachmawati FN. 2012. Effect of Bacillus sp. supplementation through periphyton to total blood profile and intestinal microbial of common carp (Osphronemus gouramy). Bioteknologi 9: 35-40. Fish is a nutritious food which has high demand in Indonesia. Therefore, increasing fish production is needed. Fish farming faces constraints due to high feed price and diseases. Feed requirements could reach 60-70% of the fish production cost. However, fish infectious diseases have significant effect on profit gain for fish farmers. To overcome these problems, it is necessary to find an alternative of natural food which does not harm to the environment and improve the immunity of fish by utilizing biofilms that supplemented with beneficial bacteria. Supplementation of beneficial bacteria is expected to enrich the composition of periphyton and function as decomposer and help the digestibility of feed through enzymatic activity and stimulate the immune response e.g. through increasing the number and activity of kidney macrophages and increasing white blood cells. Probiotic bacteria used in this study was Bacillus sp. Experimental design used in this study to determine the effect of supplementation of Bacillus sp. and length of time of periphyton biofilm administration to intestine microorganism and blood profile of giant gouramy. This research used Split Plot Design (SPD). Data were analyzed using analysis of variance (ANOVA). The results showed that the total number of intestinal microbial populations and the total number of leukocytes among fish fed with periphyton supplemented and not supplemented with Bacillus sp. had no significant differences, while the length of periphyton biofilm supplementation had significant effect. Feeding with periphyton biofilm supplemented with Bacillus sp. for 21 days had the best response to giant gouramy immune based on the blood profile.

Predation pressure induced by seasonal fishing moratorium changes the dynamics of subtropical Cladocera populations

Seasonal fishing moratorium with selective fish harvesting is a common means of increasing fish production in Asia. Such manipulation might be expected to lead to a seasonal variation in abundance and composition of fish and predation pressure on zooplankton, and consequently a seasonal change in the Cladocera populations. In this study, we examined the seasonal dynamics of cladocerans in a subtropical plateau lake in southwestern China, Lake Erh, in which a fishing moratorium was implemented in spring and early summer. Cladocerans showed a bimodal seasonal distribution linked to variations in predation pressure induced by the seasonal fishing moratorium. When predation was low in winter because of cool water temperatures and decreasing fish density, Daphnia galeata appeared in the water column and increased towards spring. The cladoceran peaked in the middle of the fishing moratorium, coinciding with a clear water phase. The feeding rate increased with temperature in the late moratorium, allowing planktivorous fish to strongly suppress large daphnids. Small cladocerans benefited from the reduced competition with large daphnids by increasing their numbers rapidly, which resulted in a second peak of cladocerans in the fishing season.

Impacts of aquaculture extension activities on female fish farmers in different areas of Bangladesh

The study was an initiative to assess the impacts of training supports under aquaculture extension activities provided to the female farmers involved in pond fish culture in comparison to the male farmers from different areas of Bangladesh. It is also identified that constraining factors affect the participation of female farmers in fish culture after receiving training supports under aquaculture extension program. The mean baseline fish production by the female farmers was 3.8 ± 1.2 kg/dec and after getting training supports it increased to 6.8 ± 2.1 kg/dec, which was significantly (p < 0.001) higher (78%) in comparison to their baseline. Overall, there was increased fish production in the ponds of the trained female farmers in comparison to their baseline year (before trained) fish production in ponds; however, their fish production was lower than that of the male farmers who received the similar sort of supports. Different factors were related to the low level of involvement of females in fish culture and the low level of fish production was related to households, social and cultural reasons. Females were busy in managing usual household works especially taking care of their children and having limited time to make regular contact with extension officers. Low level of literacy, socio-cultural barriers, higher dependency on their male counterparts, their less ability to take decision, and comparatively their poor health condition are factor constraints for their active involvement in aquaculture.DOI: http://dx.doi.org/10.3329/bjz.v39i2.10591 Bangladesh J. Zool. 39(2): 213-221, 2011

IMPROVING WATER QUALITY AND PRODUCTIVITY OF TILAPIA (Oreochromis niloticus) USING CONSTRUCTED WETLAND

Organic and inorganic pollutants such as N, P, and heavy metals are a serious problem in water bodies (lake, reservoir, river, and stream) and have deleterious effects to pond productivity and human health. These pollutants produced from anthropogenic activities (i.e. industrial, agricultural, and settlement) are released into the water bodies and causing poor water quality. Constructed wetland (CW) is one of the technologies that have the capability to solve such problems. The purpose of this experiment was to examine the efficiency of constructed wetland in terms of reducing pollutants from the stream as a water resource for aquaculture area and increasing fish production. Two kinds of treatments were set up: one fish pond culture with constructed wetland and the other one without constructed wetland (control). Each treatment consisted of three replications. The result showed that water quality in the fish pond with CW was better than the control. Constructed wetland were able to reduce ammonia (NH3-N), nitrite (NO2-N), nitrate (NO3-N), TN, phosphate (PO4-P), TP, Cu, Pb, and As concentrations to 15.00%-88.27%, 9.52%-72.73%, 11.11%-57.14%, 20%-66.67%, 24.44%-80.77%, 12.04%-77.95%, 50.00%-100%, 56.25%-100%, and 46.83%-100%, respectively. Nile tilapia cultured in pond using CW was higher than the control in terms of total length, body weight, and survival rate. The t test revealed that nile tilapia (Oreochromis niloticus) cultured in pond with CW and the control has significant difference (P<0.01) in terms of total length, body weight, and survival rate. This is the evidence that constructed wetland technology is very useful on improving water quality and increasing pond productivity of nile tilapia cultured in the freshwaterpond.

Pengaruh Fermentasi Limbah Rumput Laut Gracilaria sp. dengan Bacillus subtilis Terhadap Populasi Plankton Chlorophyceae <br><i>[Effect Of Waste Seaweed Fermentation Of Gracilaria sp. With Bacillus subtilis Against On Plankton Populations Of Chlorophyceae]<i>

Abstract One of Indonesia's marine living resources is seaweed. There are about 18,000 species of seaweed around the world and 25 species of which have high economic value. In indonesia, there are 555 types of seaweed and four types of which are known as export commodities, that is Euchema sp., Gracilaria sp., Gelidium sp. and Sargasum sp. One type of algae is much cultivated in the waters of Indonesia is Gracilaria sp. Seaweed is widely cultivated because it has an important role in the effort to increase fish production and preservation of biological resources. However, sometimes the other result are found a lot of waste of seaweed in the field. Utilization of seaweed waste of Gracilaria sp. can be applied into organic fertilizer that is through a biological fermentation process using microbial proteolytic. The aims of the study to determine the effect of the waste seaweed fermentation of Gracilaria sp. with Bacillus subtilis on plankton populations of Chlorophyceae. The research was perform in August 2011 at the Laboratory of Fisheries Education, Faculty of Fisheries and Marine, University of Airlangga, Surabaya. The design of experiments in this study using Completely Randomized Design (CRD) with 6 treatments and 4 replications. The treatments were: (A) control, (B) 10ml/l of seaweed waste liquid without fermentation, (C) 5ml/l of seaweed waste liquid using fermentation, (D) 10ml/l of seaweed waste liquid using fermentation, (E) 15ml/l of seaweed waste liquid using fermentation, (F) 20ml/l of seaweed waste liquid using fermentation. The main parameter is plankton populations of Chlorophyceae, while supporting parameter water quality. Data analysis using analysis of variance (ANOVA), when there is a difference followed by Duncan's Multiple range test. The results showed that the utilization of waste seaweed of Gracilaria sp. Using fermentation with isolated bacterial of Bacillus subtilis produce significantly different population (p <0.05) and D the treatment that is 10ml/l of seaweed waste liquid using fermentation, showed the highest cell density of 264,252 cells / ml. Based on the results of Duncan's Multiple range test showed that the D treatment give the best effect among all of the treatments. Water quality parameters during the study remained within the tolerance limit for the growth of Chlorophyceae, pH 7-8 and the water temperature ranges between 2729o C.

Using Instream Water Temperature Forecasts for Fisheries Management: An Application in the Pacific Northwest1

Huang, Biao, Christian Langpap, and Richard M. Adams, 2011. Using Instream Water Temperature Forecasts for Fisheries Management: An Application in the Pacific Northwest. Journal of the American Water Resources Association (JAWRA) 47(4):861-876. DOI: 10.1111/j.1752-1688.2011.00562.x Abstract: Water temperature is an important factor affecting aquatic life within the stream environment. Cold water species, such as salmonids, are particularly susceptible to elevated water temperatures. This paper examines the potential usefulness of short-term (7 to 10 days) water temperature forecasts for salmonid management. Forecasts may be valuable if they allow the water resource manager to make better water allocation decisions. This study considers two applications: water releases from Lewiston Dam for management of adult Chinook salmon (Oncorhynchus tshawytscha) in the Klamath River and leasing water from agriculture for management of steelhead trout (Oncorhynchus mykiss) in the John Day River. We incorporate biophysical models and water temperature distribution data into a Bayesian framework to simulate changes in fish populations and the corresponding opportunity cost of water under different levels of temperature forecast reliability. Simulation results indicate that use of the forecasts results in increased fish production and that marginal costs decline as forecast reliability increases, suggesting that provision and use of such stream temperature forecasts would have potential value to society.

Institutional Arrangements in Seasonal Floodplain Management under Community-based Aquaculture in Bangladesh

Seasonal floodplains under private and public ownership in the Indo-Ganges river basin provide food and income for millions of people in Bangladesh. Floodplain ownership regimes are diverse, covering the whole spectrum from public to private ownership. The paper compares community-based fish culture projects in these floodplains and analyzes the institutional arrangements of three different Floodplain Management Committees (FMC). The paper aimed to understand the complex institutional relations that govern ownership, access, and control of the floodplains under community-based fish culture (CBFC) to increase fish production and the livelihoods of the poor. We followed the stakeholders representing the various institutions and organizations such as the Department of Fisheries (DoF), Department of Land (DoL), and FMC. Other important stakeholders were the lease-holders of public water bodies in the floodplains, private landowners, seasonal, and professional fishers. The analysis demonstrates a significant increase of benefits to all stakeholders, including the poor, through the sharing of benefits derived from their involvement in the project. The willingness of different social classes to work together, the adoption of new technologies, and the societal embeddedness of local government institutions appear to be important inputs for policy making.

THE VALUE OF IN‐STREAM WATER TEMPERATURE FORECASTS FOR FISHERIES MANAGEMENT

Water temperature is an important factor affecting aquatic life within the stream environment. Cold water species, such as salmonids, are particularly susceptible to elevated water temperatures. This paper examines the economic value of short‐term water temperature forecasts for salmonid management. Forecasts may have economic value if they allow the water resource manager to make better water allocation decisions. This study considers two applications: water releases for management of Chinook salmon in the Klamath River and leasing water from agriculture for management of steelhead trout in the John Day River. We incorporate biophysical models and water temperature distribution data into a Bayesian framework to simulate changes in fish populations and the corresponding benefit from recreational fishing and opportunity cost of water under different temperature forecast accuracies. Simulation results indicate that use of the forecasts results in increased fish production and that marginal costs decline and net benefits increase as forecast accuracy increases, suggesting that provision and use of such stream temperature forecasts would have value to society.(JELQ22, Q25, Q28, Q50)

Legacy of New York State's Watershed Surveys, 1926–1939

AbstractOn 16 June 1926, A. L. Hazzard was casting flies into Dyke Creek, upper Genessee River, and reeled in two common shiners. That was the beginning of the watershed surveys of New York, which involved scores of individuals and stretched over 15 years. The state legislature authorized surveys of the aquatic life in streams and lakes with a $15,000 appropriation “to determine the most practical methods of increasing fish production.” Under the leadership and insight of Emmeline Moore, the surveys accomplished this mission by providing a basis for assessing the need and appropriateness of what previously had been a general stocking program. Groundwork for the surveys began under John Titcomb, and his writings and management activities influenced Dr. Moore. Her approach led to more than a refinement of stocking policy; she and her staff recognized the importance of assessing watersheds as systems and that policies affecting game fish required information on more than just the game fish. Staff conducted synoptic surveys of biota, assessed chemistry and hydrology, and paid particular attention to pollutants. The importance of vouchering specimens was recognized, and the surveys provided a steady stream of specimens that were used in several taxonomic studies. Finally, Titcomb and Moore recognized that in order to affect change in stocking policy, states needed well‐trained biologists knowledgeable in all aspects of freshwater ecology. So, the surveys became the training school for a suite of biologists that dominated fisheries science in universities and in management agencies in the mid‐ and late 20th century. Perhaps the most important legacy of these surveys is not the reports, illustrations, specimens, or input from the well‐trained fisheries scientists; it is a way of thinking about aquatic resources and the role of the manager in developing them

Livestock waste-menace: Fish wealth-solution

A review of the use of livestock wastes for sustainable fish wealth creation was done, using information from literature and data from field observation and experimentation. Livestock wastes including animal manure and poultry by-products, which are a menace to the environment, are sources of wealth creation in fish farming. In Nigeria, about 932.5 metric tonnes of manure is produced annually from the well established livestock industries which keep expanding at the rate of 8% year -1 . Nigeria is the largest importer of frozen fish in the world with a fish demand of between 106,200 - 128,052 metric tonnes year -1 . This situation calls for increased fish production which can be achieved through the effective utilization of livestock wastes. Properly treated animal manure can serve as organic fertilizer/feed component. Consequently, there is enhanced fish farming profitability, efficient resources utilization and conservation of environment due to waste management. Key words: Wastes, manure, fish, plankton, livestock, fertilizer, feed

Food sources and intake of n‐6 and n‐3 fatty acids in low‐income countries with emphasis on infants, young children (6–24 months), and pregnant and lactating women

With increasing interest in the potential effects of n-6 and n-3 fatty acids in early life, there is a need for data on the dietary intake of polyunsaturated fatty acids (PUFA) in low-income countries. This review compiles information on the content in breast milk and in foods that are important in the diets of low-income countries from the few studies available. We also estimate the availability of fat and fatty acids in 13 low-income and middle-income countries based on national food balance sheets from the United Nations' Food and Agriculture Organization Statistical Database (FOASTAT). Breast milk docosahexaenoic acid content is very low in populations living mainly on a plant-based diet, but higher in fish-eating countries. Per capita supply of fat and n-3 fatty acids increases markedly with increasing gross domestic product (GDP). In most of the 13 countries, 70-80% of the supply of PUFA comes from cereals and vegetable oils, some of which have very low α-linolenic acid (ALA) content. The total n-3 fatty acid supply is below or close to the lower end of the recommended intake range [0.4%E (percentage of energy supply)] for infants and young children, and below the minimum recommended level (0.5%E) for pregnant and lactating women in the nine countries with the lowest GDP. Fish is important as a source of long-chain n-3 fatty acids, but intake is low in many countries. The supply of n-3 fatty acids can be increased by using vegetable oils with higher ALA content (e.g. soybean or rapeseed oil) and by increasing fish production (e.g. through fish farming).

Fish use of artificial dike structures in a navigable river

AbstractArtificial structures have been used to potentially increase fish production by providing cover, feeding and spawning areas. In some rivers, the United States Army Corps of Engineers has constructed dikes to provide additional habitat for river fishes and to mitigate for navigation impacts to young fishes. This study was designed to test whether such structures function as viable habitats as evidenced by increased abundances relative to reference areas lacking artificial dike structures. Dikes and reference sites in the Kanawha River, West Virginia were sampled 21 times between July 2002 and October 2003. We found a difference in taxonomic composition among fish using dikes relative to reference areas. Artificial dike structure use was most important among Centrarchidae species, especially juveniles, including black bass and several species of Lepomis. Further, distribution of fish between areas with and without dikes appears most affected by water temperature in 2002 and by short‐term river flow in 2003. These patterns suggest these artificial structures are viable mitigation measures that target and benefit fish of economic interest. Copyright © 2009 John Wiley & Sons, Ltd.

Aquatic Community Responses to Salmon Carcass Analog and Wood Bundle Additions in Restored Floodplain Habitats in an Alaskan Stream

AbstractLand use activities often directly and indirectly limit the capacity of freshwater habitats to produce fish. Consequently, habitat creation and enhancement actions are often undertaken to increase the quantity and quality of resources available to aquatic communities within these impaired systems, with the intent to increase fish production. The objectives of this study were to (1) determine whether aquatic community colonization and development could be accelerated through additions of woody debris bundles and marine‐derived nutrients (via salmon carcass analog pellets) and (2) measure how aquatic communities (biofilm, invertebrates, and fish) respond to these additions after the creation of off‐channel (alcove) fish habitat in a stream in south‐central Alaska. Biofilm, invertebrates, and juvenile coho salmon Oncorhynchus kisutch were sampled in four treatments (control, wood, analog, and analog plus wood). Biofilm chlorophyll‐a concentrations were 4–10 times higher in analog‐enriched treatments than in the control and wood treatments. No treatment effects were detected in benthic invertebrate density; however, treatment differences were detected in coho salmon diets, with nearly twice the amount of invertebrate abundance and biomass (primarily various dipteran, ephemeropteran, and plecopteran larvae) in the analog and analog plus wood treatments compared with the control and wood treatments. Juvenile coho salmon density and biomass were significantly higher in the wood treatment than in the analog plus wood treatment, and fish in the control showed possible signs of density‐dependent limitation. Further, body condition of juvenile coho salmon was highest in the two analog‐enriched treatments at the end of the study; juveniles in these habitats showed nearly two times the condition increase of fish inhabiting the control and wood treatment alcoves. These results demonstrate that the combination of salmon carcass analog and woody debris bundle additions aids in the short‐term development of aquatic communities in newly created off‐channel habitats, providing a boost in limited resources such as food and shelter.