"Net-Pen Aquaculture - Fish Species Net-Pen aquaculture refers to the use of net pens and cages which may be submerged,suspended or floating enclosures used to hold the culture stock (Fernandez-Reiriz, 2015).Aquaculture fish species cultured in pens, cages or any other enclosures produce wastes thatmove down the sea and cause negative effects to the benthic organism (Fernandez-Reiriz,2015). These wastes include dissolved nitrogenous and phosphorus wastes, the solid faecalparticles as well as the uneaten feed particles that lead to eutrophication and other effects onthe benthic environment(Naylor et al., 2000 and Folke et al., 1994).Fish species of the highestvalue and market demand are the mostly cultured in net pens particularly salmonfish(Burridge et al., 2010).Better Management Practices employed in minimizing the benthicimpacts of net pens and cages should include the following considerations and components.The selection or location of the site, Feed Management, Solid Waste Management andDisposal, Escape Management, the Operation and Maintenance of the Aquaculture facility,Health management, and Record Keeping.Site selection is of paramount importance. Kapetskyet al.(2013), noted that although theUnited States has the ideal zones both economically and environmentally for establishing netpen culture, that there has been no expansion occurring in this finfish aquaculture industry.Naylor et al.( 1998, 2000) and Naylor and Burke (2005), stated that the reason might be dueto the environmental concerns expressed regarding the nature of the net-pen aquacultureindustry in general and specifically salmon. selection of the site is critical to decreasingdamage as a result of potential environmental consequences that may impact optimal fishhealth and production One of the better Management Practices to reduce benthic use of integrated multi-trophicaquaculture is using the blue mussle (Mytillus edulis) (Fernandez – Reiriz, 2015). Theorganic dissolved and particulate fish wastes are fed on by the blue mussel thereby reducingon the quantity of wastes deposited in the environment by net pen aquaculture (McDonald etal, 2011; Nelson et al, 2012). Blue mussels can be cultured below the fish cages successfullyas naturally they prefer lower regions of the sea or waters (Neoriet al, 2004). Cranford et al(2013) confirms the ability of blue mussels to clear fish wastes and their integration orinclusion in netpen aquaculture makes it it sustainable. Both bio chemical andecophysiological studies suggestabsorption of fish wastes by theseblue mussels and this isfurther enhanced by the fact that they aggregate in their culture which increases on theirnumberper area of the cage or enclosures (Lander et al, 2012). This reduces on thesediments deposited on seabed (Fernandez – Reiriz, 2015). Use of such bio species to migratenetpen aquaculture impacts on the environment has been recommended (Meoriet al, 2004).Use of copper alloy mesh net pens instead of nylon nets is a recent innovation and kkkcanreduce benthic impact of net pen aquaculture (Ayer et al, 2016). Copper alloy mesh nets arestronger against wave action, they don’t require periodical painting andm cleaning, theyconsiderably reduce bio foulling unlike the nylon nets (Braithwaite et al, 2007; Fitridgeet al,2012). The active ingredients of paint used on nylon based metals whose high concentrationis toxic to the benthic organisms especially the photoplankton the primary producers of theocean (Cid et al, 1995). Plants have been discovered to reduce diversity of benthic life belowand near nets and cages of nylon types (Lejuene et al, 2006), Franklin etal, 2001).Hornbergeret al (2000) urgued that copper and found in paint reduces reproductive potential-1 -1 of benthic life when their concentration goes beyond a range of 24ugg – 287ugg . Thecopper alloy mesh nets preventbiofoulling of water by staying clean and reducing their dogging withorganic matter thereby not requiringanti foullant application (Gonzalez et al,2013; ICA, 2012). This leads to improved water circulation which prevents incidences verylow dissolved oxygen that would affect benthic organisms (Ayer et al, 2016). Since Copperalloy mesh nets can be recycled then they are environmentally sustainable.Another better Management is the application of a comprehensive modelling strategy in netpen aquaculture siting and waste management (Punchanget al, 2000). The comprehensivemodelling strategy assesses the factors that determine waste settlement and movement(Punchang et al, 1997). The system provides useful data necessary for decision making forwater parameters like tidal action, storms speed and seasons, wave action, velocity of solidwaste settling to the sea bottom, rate of sediment decay, resuspension rates of the depositedsolid wastes, and diversity of benthic flora and fauna (Gillibrand and Turrell, 1997). Value ofsuch parameters are applied in the siting of net pens for example, very low wave velocitymeans that all released wastes shall just settle below the pens and such an area coul beavoided (Dean and Dalrymple, 1984). Dudley et al (1998) described the use of this model asa sustainable tool in the aquaculture industry. Results from the model can further aid in thedetermination of benthic oxygen demand which level should not go below and should bemonitored (Punchanget al, 2000).Use of vaccination programs in net pen aquaculture to reduce on the quantity of antibioticsusage in the therapy of bacterial infections (Press and Lillehaug, 1995). Vaccination of fishrefers to introduction of attenuated micro organisms into the body of the fish purposely tostimulate immunity against such a micro organism hence preventing the disease (Leong andFryer, 1993). Vaccination has been successful in aquaculture mainly against bacterial diseases particularly the control of vibriosis whichaffects salmon fish (Newman, 1993).Other diseases include, cold water vibriosis caused by vibrio Salmonicida, entric red mouthdisease caused by Yersinia rucken, furunculosis caused by Aeromonassalmonicida, (Pressand Lillehaug, 1995). Vaccines may be administered by injection using the widely acceptedmethod of intraperitoneal approach, immersion or oral administration (Guddingetal, 1999).Before the invention of vaccination technology, bacterial infections control program inaquaculture mainlydepended on antibiotic theraphy with its riskon the benthic environment(Hektoen et al, 1995). Excessive use of antibiotics is hazardous to the environment becausethey are residual in nature (Sorum, 2006, Boxall et al, 2004; Aarestrup, 2006). Antibioticsreach the benthic water region of the sea through fish excreta of urine and faeces (Hektoenetal, 1995). Antibiotics use negatively affects the biodiversity of zoo plantons andphytoplanktonsat sea bed (Chrstensenet al, 2006 and Lutshoft et al, 1999(. Increase invaccination use has had a gradual decrease anti biotic use in the aquaculture industry (Pressand Lillehaug, 1995).Waples et al. 2012 expressed concerns that the genetic diversity of the wild fish populationwould be affected by the possible escape of fish from the net-pens. Naylor et al. 1998, 2000and Adler et al. 2008 were explicit about the sustainability of the fishmeal and fish oil contentof the feed. The application of antibiotics (Smith and Samuelson 1996) and the possibletransmission of disease from the farmed fish to those of the wild stock (Johansen et al. 2011)are of interest also.Not only is this a topic of concern to the scientific society (Knapp et al.2007; Baron 2010; Knapp 2012) but the general public as well. And any negative impressiongenerated publicly decreases the acceptance for the various forms of aquaculture (Moffitt2006; Amberg and Hall 2008; Mazur and Curtis 2008). It is an arduous task to impress thepublic to appreciate the progress achieved in the net pen and other forms of aquaculture once a contrary viewpoint is established (Gibbs 2009; Chu et al. 2010). Alternately the high cost oflabor, operations and value of coastal lands along with the lengthy, tedious process toestablish a net pen culture proves prohibitive and is a deterrent to the United Statescompeting in the global farmed seafood market (Kite-Powell et al. 2013).Having proper feed management is essential. Most of the waste generated by a net pen farm iA major sustainability issue and a limitation to the production of carnivorous species inaquaculture is the use of fish oil and fish meal in aquaculture feeds (Naylor et al. 1998, 2000;Kristoffersson and Anderson 2006). Although fish meal or fish oil in the nutrition of anyanimal is not a requisite, it has been proven that raising fish, including carnivores, has morepractical advantages over terrestrial animals (NRC 1983,1984,2011). Fish meal and fish oilroutinely have been included in fish feeds since these ingredients meet the nutritionalrequirements of fish and has been proven to be cost-effective (Hardy and Barrows 2002).Farmed Atlantic salmon fed formulated feed that has no fish meal or fish oil achieve the samegrowth pattern similar to the result obtained when fed with feeds containing fish oil and fishmeal (Torstensen et al. 2008; Burr et al. 2012).Similar results obtained with Rainbow TroutOncorhynchus mykiss (Lee, K.J. et al. 2002; Barrows et al. 2007; Gaylord et al. 2007),Grouper Cromileptesaltivelis (Shapawi et al. 2007) and Cobia Rachycentroncanadum(Watson et al. 2012, 2013).Red Sea Bream Pagrus major (Takagi et al. 2000), White Sea BassAtractoscionnobilis (Trushenski et al. 2013), and the Pacific Whiteleg ShrimpLitopenaeusvannamei (Sookying 2010; Olmos et al. 2011).Using high feeding technologies that lower waste production from net pen aquaculture couldeffectively reduce the benthic impact of net pen aquaculture (Alanora, 1992). Demandfeeding and timer controlled feeding techniques results in lowest feed conversion ratios of1.08 (Madrid et al., 1990).Demand controlled feeding also enable fish to feed at a time thatwould yield the best food conversion efficiency (Spieler and Heilman,1999).Povision of feeds to fish when appetite is at its peak results in better growth performance(Noeskeet al.,1981).Low food conversion ratios means that less wastes will be produced and therefore lessimpact of the net pen aquaculture to the benthic organisms(Alanara,1992).References:Aaestrup, F.M. (2006). The origin, evolution, and local and global dissemination ofantimicrobical resistance ASM Press, Washington, D.C PP 339-359.Ayer, N, Martin, S, Dwyer, L.B, Gace, L and Laurin, L. (2016). Environmental performanceof copper alloy Net – pens: Lifecycle assessment of Atlantic salmon grow-out in copper alloyand nylon net-pens. Aquaculture 453:93-103.Adler, J., B. Campbell, V. Karpouzi, K. Kaschner, and D. Pauly(2008). Forage fish: fromecosystems to markets. Annual Reviews of Environment and Resources 33:153–166.Amberg, S. M., and Hall,T.E.(2008). Communicating risks and benefits of aquaculture: acontent analysis of U.S. newsprint representations of farmed salmon. Journal of the WorldAquaculture Society 39:143–157.Baron, N.(2010). Escape from the ivory tower: a guide to making your science matter. IslandPress, Seattle.Beveridge, M.(2004).Cage aquaculture, 3rd edition. Fishing News Books, Blackwell Science,London.Boyd, C. E., C.,Tucker, A.,McNevin, K.,Bostick, and Clay,J.(2007). Indicators of resourceuse efficiency and environmental performance in fish and crustacean aquaculture. Reviews inFisheries Science 15:327–360. "