Food and Agriculture Organization of the United Nations Fisheries and for a world without hunger Aquaculture Department Cultured Aquatic Species Information Programme Morone hybrid (genus Morone, hybrids) I. Identity V. Status And Trends a. Biological Features VI. Main Issues b. Images Gallery a. Responsible Aquaculture Practices II. Profile VII. References a. Historical Background a. Related Links b. Main Producer Countries c. Habitat And Biology III. Production a. Production Cycle b. Production Systems c. Diseases And Control Measures IV. Statistics a. Production Statistics b. Market And Trade Identity Morone genus Morone, hybrids [Moronidae] FAO Names: En - Striped bass, hybrid, Fr - Bar d'Amérique, hybride, Es - Lubina estriada, híbrida Biological features The fishes that make up the hybrids of the genus Morone are all within the Moronidae family, which is a small group of freshwater (white bass and yellow bass) and anadromous estuarine (striped bass and white perch) and marine percoids (striped bass) found naturally from the Mississippi River drainage system to the East Coast of the United States and Canada. Also included in this family are the European-North African species of Dicentrarchus represented by two species (D. labrax and D. punctatus). There is only one reported case of intentional congeneric cross hybridization between the two genera and the offspring were not viable or were triploids. The general features of Morone include having a medium to large size; the body is either moderately deep or elongate and terete or compressed dependent on the species (in striped bass the body depth is less than of body length, and it is more than in the other species and hybrids; the mouth is moderate to large with a terminal lower jaw jutting forward of the snout; opercules have at least one well-developed spine; maxillary teeth are small and there are one to two hyoid tooth patches on the tongue; scales are ctenoid and the lateral line is complete extending into the caudal fin; there may or may not be several lateral stripes found on the fish that FAO Fisheries and Aquaculture Department may be complete or broken in appearance; dorsal fins are separate or slightly joined with fin spines stout that vary among species but typically are 7-8 in first dorsal and one anterior in second dorsal that may be joined or separate, there are 3 spines in the anal fin of varying length that is species dependent; the caudal fin is emarginated or forked dependent on the species; and, the pelvic fin is thoracic with the pectoral fins located high on the side. The hybrids of Morone are intermediaries of the parental species and typically deeper in body than striped bass with 7-8 broken stripes laterally found on the sides. Size differences are significant in that the white bass, white perch, and yellow bass are small; maturing in the 0.5 kg range with record fish being approximately 3 kg, 1.38 kg, and 1.36 kg, respectively. Netted striped bass, however, have been reported in the range of 54.5 kg with the record fish caught on fishing tackle being 31.8 kg for a freshwater system and 37.2 kg for saltwater: over 10 times the size of white bass. The record hybrid fish caught by angling was 12.5 kg. Images gallery Hybrid eggs 2.5 hours post fertilization. Larval hybrid striped bass at hatch. Photo by R. M. Harrell Photo by R. M. Harrell First feeding larvae. Photo by R. M. Harrell Fingerlings. Photo by R. M. Harrell (modified) Live harvested hybrid striped bass. Photo by D. W. Webster Profile Historical background Although one of the pure parents of hybrid Morone, striped bass, have been artificially cultured since the 1880s, Morone aquaculture really did not become established as a science until the 1960s. Prior to that time, production was essentially dependent on one hatchery system in the coastal area of the Roanoke River, North Carolina in the United States This hatchery was dependent on collecting naturally-ovulating female striped bass and spermiating males on the spawning grounds just below the hatchery location. By 1962 hormone-induced spawning of striped bass was successful in South Carolina, and by 1965 the first Morone hybrid was artificially made by combining the eggs of striped bass with the sperm of white bass FAO Fisheries and Aquaculture Department creating a palmetto bass. The original objective to produce the hybrid was to provide a fish that could occupy the open-water areas of these new reservoirs the same way white bass typically do, but had the potential to obtain the size of a striped bass and create an open-water fishery. Coupled to this logic was the failure of striped bass to do well in the relatively shallow, warm-water, man-made reservoirs; which is prime habitat for the white bass. Management biologists were hoping to capitalize on the anticipated increased vigor often found in hybrid crosses, and they were looking for a fish that would be more tolerant of warmer temperatures, lower oxygen concentrations, and smaller sized reservoirs (<500 ha) that had been proven to be barriers in establishing inland striped bass populations. Ultimately, it was confirmed that hybrid Morone did indeed exhibit hybrid vigor, had excellent potential for management, and they produced an exceptional recreational fishery. Today, with the exception of Alaska and Idaho, 48 of the 50 States have natural or introduced populations of striped bass or its hybrids. These fish are a popular recreational fish and over 200 million fingerlings (40-125 mm) are produced annually in the United States for stocking. Aquaculture for hybrid Morone food-fish production began in the United States in the 1970s when in 1973 the first commercial hybrid striped bass production facility was started. They produced about 9 000 kg but failed in 1974. In 1977 a second farm was established and produced around 13 200 kg, but it also failed within three years. By 1980 several farms were in operation and in 2000 annual production was approaching 5 000 tonnes. Production in Asia began in 1996, while production in Europe began in 2004. Main producer countries Many countries have produced hybrid Morone, but the United States is the most significant producer. The other main countries involved in hybrid Morone production include Mexico, Portugal, France, Germany, Italy, Israel, South Vietnam, China, Taiwan, and Russia. According to FAO statistics (2013) the producers countries are United States, Israel and Italy, as shown in the map below. Main producer countries of striped bass, hybrid (FAO Fishery Statistics, 2013) Habitat and biology The various hybrids of Morone have different requirements for larval-rearing, and are strongly linked to the female parent of the cross. Once the fish are readily accepting artificial diets the production methods are similar regardless of the parental species. Production is divided into different phases; hatchery (seed supply), fingerling production (nursery), and grow-out (ongrowing). FAO Fisheries and Aquaculture Department Morone are eurythermic (4–30 oC). Fingerling production and grow-out to market-size fish allows for much more flexibility in biological requirements, while larval rearing is more exacting. All Morone are dioecious, group-synchronous, iteroparous, spring spawners mostly in freshwater tributaries and in coastal areas above the tidal zones. Spawning is usually initiated with increasing spring water temperature and ranges from 12–24 oC with peak spawning being around 18–20 oC. All Morone spawn in freshwater. Traditionally, wild-caught fish from natural spawning grounds were used as broodstock for all Morone culture including making hybrids. Because the females were naturally close to spawning only administration of ovulatory hormones, such as human chorionic gonadotropin, was needed to stimulate ovulation. However, in recent years, the life cycle has been closed and using a combination of maturation hormonal implants and photoperiod manipulation, most Morone can be induced to spawn at least twice per year. In nature, striped bass and white perch are pelagic spawners while the other Morone spawn near shore, usually around vegetation and/or rocky substrates. Striped bass, white perch, and hybrid eggs are non-adhesive and demersal with a specific gravity greater than freshwater. White bass and yellow bass eggs are adhesive. Mature striped bass eggs are about 1.5 mm in diameter while white bass eggs are about 0.75 mm. A water flow of approximately 30 cm/sec is required for keeping the striped bass and palmetto bass eggs in suspension. Egg development is fast and usually requires about 36 hours to hatch at 20 oC. Newly hatched larval striped bass (prolarvae) are typically 4–7 mm in total length (TL) while white bass larvae are considerably smaller (ca. 3–5 mm TL). The larvae of hybrids are closer to that of striped bass than white bass but are highly dependent on the female of the cross. Larval Morone have a yolk sac that contains a large oil globule that helps maintain buoyancy in the water column. Mouth parts are typically developed by 3–5 days post-hatch and they begin feeding on small zooplankton. Rarely do first-feeding larval Morone accept artificial food. Therefore most the nursery production of fingerlings is usually a separate segment of the aquaculture of the species and their hybrids and is conducted in outdoor pond systems where natural zooplankton populations are manipulated and managed. Due to size differences of the larvae and exacting live food size requirements rarely are there completely closed life-cycle operations. Larval white bass, white perch, yellow bass and hybrids of these crosses with the female being the parent require very small zooplankton (i.e., rotifers) for first feeding. Larval striped bass and palmetto bass hybrids can be started on first instar nauplii of Artemia.