Aquacultural Engineering 49 (2012) 18–22 Contents lists available at SciVerse ScienceDirect Aquacultural Engineering j o ur nal homep age : www .elsevier.com/locate/aqua- online Cost analysis of a mobile fish nursery system for growing hybrid striped bass (Morone chrysops × M. saxatilis) fry Pratikshya Sapkota, Carole Engle ∗ , David Heikes, Nathan Stone Aquaculture/Fisheries Center, Mail Slot 4912, University of Arkansas at Pine Bluff, 1200 North University Drive, Pine Bluff, AR 71601, USA a r t i c l e i n f o Article history: Received 14 August 2011 Accepted 24 January 2012 Keywords: Mobile fish nursery system Hybrid striped bass fingerlings Investment costs Hybrid striped bass economics a b s t r a c t Broodstock used to produce hybrid striped bass can now be spawned throughout the year, but year- round supply of fingerlings has been limited due to low survival of fry stocked in ponds in late summer. A mobile fish nursery system was developed at the University of Arkansas at Pine Bluff to culture fry under protected conditions by filtering out large zooplankton and providing fry with the appropriate size of live rotifers until they are large enough to escape predators in the pond. Economic engineering techniques were used to estimate the investment, annual fixed, and operating costs associated with such a mobile fish nursery system for the experimental unit and for a larger commercial-scale unit. Total investment cost for a commercial scale system was estimated to be $41,390. Components were identified that contributed the most to investment cost, suggesting cost-reducing alternatives. Annual costs were sensitive to the number of annual production cycles, pump capacity utilization, and the survival rate. Study results suggest production targets and management strategies for economically feasible adoption of this technology. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Commercial production of hybrid striped bass (Morone chrysops x M. saxatilis) in the U.S. doubled from 1994 to 2005 (Carlberg et al., 2007) and hybrid striped bass were considered to be a species poised to capture a substantial share of the U.S. market. How- ever, growth of the industry tapered off and reached a plateau. While a number of factors likely have contributed, one constraint to expansion of the hybrid striped bass industry is that fingerlings are not available year-round. Broodstock can be spawned year- round through advances in spawning techniques, but survival of fry stocked in late summer is much lower than when stocked in the spring (personal communication, Mike Freeze, Keo Aquacul- ture). Thus, pond production of hybrid striped bass fingerlings is constrained by season and geography and is limited to the period from April to early June in the southern and eastern United States (Ludwig and Lochmann, 2009). Low survival of hybrid striped bass fry stocked in late summer may be due to lack of natural food of an appropriate size or to the presence of large zooplankton like cyclopoid copepods which feed on small fry (Valderrama et al., 2000). In late summer, zooplankton blooms in ponds may lack the small rotifers needed as food and con- tain large zooplankton that feed directly on the hybrid striped bass fry. Hybrid striped bass fry are small (3–5 mm long) and require live ∗ Corresponding author. Tel.: +1 870 575 8523; fax: +1 870 575 4637. E-mail address: cengle@uaex.edu (C. Engle). food, primarily small rotifers (Core, 2004). Fry growth and survival depend directly upon the number of zooplankton of appropriate size available in the system, as long as water quality parameters remain within acceptable ranges (Ludwig, 2004). A mechanism to facilitate an assured supply of live food (rotifers) of appropriate size that provides a proper water quality envi- ronment for hybrid striped bass fry in the late summer may be advantageous. Such a system would need to remove the large zoo- plankton that prey on fry, concentrate the live rotifers deemed necessary to ensure growth, and provide adequate water quality conditions to ensure survival of hybrid striped bass fry in late sum- mer. Studies have been conducted to find ways to improve survival and growth of fry of different fish species in a variety of green water nursery systems (Palmer et al., 2007). Robinson et al. (1989) reared channel catfish fry for seven days in fiberglass tanks with water recirculation. Similarly, Morrison et al. (1995) reared channel cat- fish fry in a floating in-pond raceway. Cyprinid larvae were reared in a flow-through cage within ponds (Lirski et al., 1979), while van der Meeren and Lønøy (1998) reared fry of saithe (Pollachius virens L.) and two wrasse species (goldsinny, Ctenolabrus rupestris L.; and corkwing, Crenilabrus melops L.) in 5.3 m 3 plastic bag mesocosms. An outdoor mobile fish nursery system was developed by the University of Arkansas at Pine Bluff to culture fry under protected conditions until they are large enough for pond rearing. The objec- tive of the system was to provide the capacity to rear fry in late summer months to extend the pond fingerling production season through the end of the summer. Preliminary trials with goldfish, 0144-8609/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaeng.2012.01.004