Hybrid Striped Bass

From Dr. Doug Holland's notes (Brunswick Community College) on Hybrid Striped Bass, with some modifications for this blog.

Largest Pond Farm
Top to bottom: white bass, striped bass and hybrid striped bass (Bodie bass)
Source: NC Wildlife
Various hybrids of the striped bass have shown improvement in survival, improved growth, greater resistance to disease, and tend to be hardier under culture conditions than wild striped bass.

-The two most common crosses are:

"original cross" - striped bass (Morone saxatilis) female X white bass (Morone chrysops) male
-R.E. Stevens, SC, 1965, (Also known as the "Palmetto Bass".)

"reciprocal cross" - white bass female x striped bass male.
-Bayless, SC, 1966 (Also known as the "Sunshine Bass".)

The "original cross" remains the most popular and numerous in commercial culture. Newly hatched fry are larger and have higher survival rates in pond fingerling production than do the "reciprocal cross," therefore fingerling production is more profitable.

Hybrid striped bass are produced in all types of systems, including:
1. Open static pond culture (NC)
2. Cage culture (very limited)
3. Raceway & tank culture using flow-through water (FL, CA, MS, etc.)
4. Intensive recirculating systems (mixed results)
Hybrid fingerlings are traditionally produced in fresh water. But growout to food size is done in both fresh and brackish water, and is also possible in saltwater. Striped bass are anadromous. They spawn in freshwater and move into saltwater as adults.

"Striped bass (Morone saxitilis) are one of 7 anadromous species found in the Cape Fear River system. Due to dramatic drops in the population, a coast wide moratorium on striped bass fishing was imposed from 1985 to 1990. Although striped bass populations in other N. C. drainages have rebounded, the Cape Fear River striped bass population has not (Mallin et. al. 1998,1999,2000). Although declines in water quality and the introduction and possible predation and competition by nonnative catfishes are probably contributing to the problem, one specific culprit could be competition from hybrid striped bass. [...] Hybrid striped bass are a hybrid of striped bass (Morone saxatalis) and white bass (Morone chrysops). They have been stocked as a put and take fishery in Lake Jordon nearly every year since 1983. The hybrids are introduced to the Cape Fear River by flooding events. Through competition, hybrids utilize the resources normally available to striped bass (Patrick and Moser 2001). Hybrids do not reproduce and so the resources they keep from striped bass are not converted into reproduction. As a result of competition with hybrids, striped bass may not be as healthy and in turn, not produce as many juveniles. Tag and recapture data from studies conducted in this drainage suggested that hybrids conduct a spawning run with true striped bass as has been documented in other systems (Patrick and Moser 2001, Bishop 1967). Due to competition with true striped bass for food resources and spawning habitat, hybrid striped bass are likely having a negative impact on the striped bass population in the Cape Fear River system. Catch-per-unit-effort data showed a statistically significant drop in the fall gill net samples (Figure 32). While commercial landings of striped bass in North Carolina have shown a gradual increase since 1990. Landings in the Cape Fear System remain low and this is the only river in North Carolina that stocks hybrid striped bass. Although the hybrid striped bass population appears to be decreasing, future surveys should examine whether this trend continues."
From Anadromous Species of the Cape Fear River System, UNC, Wilmington

Phases of Hybrid Striped Bass Production:

1. Phase I fingerling production
-Generally to about 2" (1-2.5")

2. Phase II fingerling production
-Range from 3 to 10 inches (average 4-6")

3. Phase III or Foodfish Production
-Range from 0.7 to 4 lbs (most desirable market size is 1.5 to 2 lbs).

The production of phase I and phase II hybrid bass is covered in Hatchery Management I and II.

Production of Market-Size or Phase III Fish

Pond Culture
Since the late 1970's, production of large striped bass has been in practice at the Edenton National Fish Hatchery, where they have used pond culture to produce, maintain and spawn domesticated striped bass broodstock from five different Atlantic strains.

During the early 1980s attempts to produce stripers and hybrids in earthen ponds by some commercial farms in California, Maryland, and elsewhere was met with some success. In the late 1980s Carolina Fisheries was established in Aurora, NC to commercially produce market-size Hybrid Striped Bass in earthen ponds and was the first financially successful pond-based farm. It has been followed by many others in eastern North Carolina. In all twenty eight farms were established by 1998, thirty five by 2000.

In all, the largest pond-based farm is located in northern Mississippi, covering 600 acres (larger than all others combined).
Largest Pond Farm
"It may be the only farm-raised hybrid striped bass farm in Mississippi, but it is the largest such operation in the world."
From Nature’s Catch is largest striped bass farm in the world

Current Pond-culture Techniques
Earthen ponds should average about three acres in size, but can range between 1-5 acres and 4-8 ft. in depth. Production can be in fresh water, but minimum hardness and alkalinity values of water should be 100 ppm.

Weed control is an important contributing factor in good production, though management may be difficult in clear, hardwater ponds. Ponds should be filled during winter and fertilized in at the beginning of late winter and continued into early spring at high rates with liquid 10-34-0 or phosphoric acid to promote phytoplankton bloom to adequately shade the bottom.

Phase II fingerlings may be stocked after filling the pond. Generally they are more readily available in spring than any other time of the year. When temperatures are moderate, handling the fingerlings cause the fish less stress.

Ask for health certification by a qualified veterinary lab to make certain the fish are healthy, well graded, and sufficiently large enough to produce adequately sized marketable fish in one growing season. Though this may vary according to geography. Use the same method for estimating average size and numbers of fingerlings as outlined for catfish. In eastern North Carolina, a one hundred gram fish will grow to about 1.5 lbs in one growing season.

Stocking rates can range between two and five thousand fingerlings per acre. Optimum results have been obtained by stocking between 3000-3500 per acre.

Acclimating Fish to Water
As with any species of fish, fingerlings should be acclimated to water temperature before stocking them into the pond. This involves pumping water from the receiving pond into the haul tank over a period of 20-30 minutes until temperature and pH are approximately equal. A difference in temperature which comes to more than 10°F, is considered large and a longer acclimation period is required. Three minutes for every degree up and 1.5 minute for every degree down.

Hybrid Striped Bass are normally fed a diet consisting of 38% protein and 8% fat, but better results have been achieved using a feed containing 40% protein and 10% fat. A feed that is a mixture of both floating and sinking pellets is best. Hybrid Striped Bass sometimes feed slower after satiation, and all-floating feed may end up going to waste on the embankment.

Feeding rate should be around 2% of body weight per day, depending on:
1. Age
2. Size
3. Water temperature
4. Time since last feeding
5. Water quality
The best method to determining appropriate feeding rate is by observing feeding activity and adjust accordingly.

Good water quality is crucial in production. Bass are less tolerant of poor water quality. Pay careful attention to DO (Dissolved Oxygen levels) which should never fall below 4ppm. The dissolved oxygen level should consistently be kept above 5ppm. Aeration capacity is required for production. A three acre pond should be outfitted with a 5 horsepower electric paddlewheel aerator. Variable horsepower aerators should be outfitted on larger or smaller ponds. Sometimes additional aeration is required, and is usually supplied with PTO-driven paddlewheels. Most farmers have one tractor with PTO paddlewheel for every four ponds on the farm.

Keep ponds salted to increase chloride levels up and prevent problems with nitrite.

To keep ammonia levels down and ponds cool during hot summer weather it may become necessary to frequently flush ponds. Hybrid Striped Bass is really more of a coolwater than a warmwater species.

Disease and Parasites
Yellow grub (Clinostomum complanatum), a digenetic trematode is the most economically devastating disease & parasite problem encountered. These parasites are characterized by their life cycle... having a definitive host (birds) a first intermediate host (snails) and a second intermediate host (fish).

Rams Horn Snail
Rams Horn Snail - An intermediate host in the life cycle of the Yellow Grub.
Photo by author, 2007

No effective FDA-approved treatment exists for yellow grub, though it may be controlled by eliminating the predatory birds (primarily cormorants and great blue herons) and/or the snails.
• Trained dogs can chase away birds or a depredation permit can be obtained to shoot them. By controlling weeds snails can be effectively reduced, particularly bottom-rooted macrophytes on which they feed. Introducing snail-eating fish is now one area of research being looked into.
• Snail numbers may be greatly reduced by draining and drying ponds annually. Quicklime (CaO) may be applied to remaining puddles or copper sulfate at 10 ppm to kill any remaining snails. Be aware both treatments will also kill any fish remaining in the puddles.

Ichthyophthirius multifiliis

ICHTHYOPHTHIRIUS MULTIFILIIS, or "ICH" for short, is one of the freshwater fish diseases. Ich is a waterborne microscopic parasite that reproduces in small colonies among the slime coat and/or skin of your fish. A common sign of beginning stages of Ich infection are what is called "flashing", where fish will swipe against aquarium decorations or the gravel at the bottom of the tank in an attempt to seemingly scratch themselves. Only one or two small colonies will appear at first, and be very difficult to identify until this infection advances to near maturity. The irritating Ich parasite, if untreated, will very rapidly overwhelm the fish with tiny white spots, making your fish seem as though they have been sprinkled with salt.
Source: http://www.fishtankguy.com/health.php

Ich (Ichthyophthirius multifiliis) is a protozoan parasite that sometimes causes devastating losses in commercial Hybrid Stripe Bass, and other species. This parasite is difficult to treat. The best prevention method is through the use of disease-free certification of incoming fingerlings and avoid use of water supplies containing wild fish.

Other common diseases include the bacterial diseases MAS (Aeromonas spp.) and columnaris (Flexibacter columnaris). Terramycin medicated feed is used to control these and other bacterial diseases, but is not specifically approved by the FDA for use on hybrid striped bass intended for use as human food.

Other disease problems have been reported but are either secondary (such as fungal diseases) or relatively rare.

Harvesting Hybrid Striped Bass
Hybrid Striped Bass are harvested using standard seining techniques. They are sorted by size and packed in 100 lb boxes on ice for shipment to East Coast markets, primarily Northeastern US and Florida. Some fish are sold live, to live-haulers for shipment to Asian-American markets in the Northeast.

Single-Pass Tank/Raceway Culture
Successful culture of Hybrid Striped Bass in single-pass tanks and raceways are nearly as lucrative as pond culture, depending on circumstances. Fish grown in these systems require the same basics in feed and water quality. Some advantages are the lack of problems with yellow grub, as long as the fingerlings are grub-free. There are better feed conversion than in ponds and harvesting is easier and less costly. Such factors help offset increased costs associated with intensive culture in tanks and raceways.

Recirculating System Culture
Sufficient attempts have been made to grow Hybrid Striped Bass in recirculating systems, but many failed due to problems associated with water quality and disease.

Cage Culture
Cage culture of Hybrid Striped Bass holds promise in locations where water quality is sufficient for good health and growth rates throughout the growing period. Feeding in brackish public waters is likely to cause degradation of water quality around the cages. If large numbers of fish are fed in many cages in a semi-closed brackish water body (such as a small sound or lagoon), a generalized reduction in water quality over the whole area is likely. Even if cage or net-pen culture is demonstrated to be technically and economically feasible, it may not be politically acceptable in many areas, and is likely to be regulated out of existence before it can get started.

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