Progress Report
Hatchery Production of Mutton Snapper (Lutjanus analis)
and other High Value Marine Food Fish
DOC / NOAA / NMAI Grant No. 06RG-0068
Institutions:
Principal Investigator:
Daniel D. Benetti, Ph.D.
Collaborators:
Jorge Alarcón , Owen Stevens, Gill Banner-Stevens, William Matzey (ACFK, Inc.)
Brian O’Hanlon and Joseph Ayvazian (Snapperfarm),
José Rivera (NOAA)
Natalia Strattman and
Federico Rotman (RSMAS -
Bong Kim (
Hatchery Production of Mutton Snapper (Lutjanus analis)
and Other High Value Marine Food Fish
DOC / NOAA / NMAI Grant No. 06RG-0068
1. Summary
The successful development of breeding programs and larval husbandry techniques for mutton snapper (Lutjanus analis) and cobia (Rachycentron canadum) were achieved during the reported period (September 2001 to August 2002). In this project, we proposed to conduct research encompassing all stages of the operation from broodstock management to spawning, larval rearing, and nursery techniques. We report successful capture, transport, sampling, prophylaxis, quarantine, environmentally conditioned and hormonally induced spawning, larval rearing and fingerling production of both cobia and mutton snapper
Poor water quality was identified as the main cause of low fertilization rates of spawns and premature larval mortality during 2000 and 2001. Chemical water treatment protocols were implemented starting in 2002. Changes in water quality parameters lead to a higher number of spawns with higher fertilization rates and subsequent improved larval survival, indicating that water quality was the cause of low fertilization rates in previous years. A breeding program was successfully established for mutton snapper and cobia, where the captive broodstock populations produced an unprecedented number of viable spawns both within and outside the natural spawning seasons for these species. There has been also national and international recognition of these accomplishments (see Appendix).
Results from previous years combined with this year’s research efforts demonstrated that viability of spawns and quality of the eggs are mainly affected by broodstock nutrition and water quality parameters. Additional factors linked to spawning success were social behavior, culture conditions, the use of artificial substrate, and techniques used for handling spawns and broodstock fish. The most important improvements in the development of broodstock management techniques were in broodstock nutrition, in the long- term biological control of ectoparasites by the introduction of neon gobies, Gobiosoma oceanops, and in water quality monitoring and treatment.
Success of the developed and implemented maturation technology is attested by the unprecedented number of over 50 recorded hormonally and naturally induced spawns, resulting in the production of millions of eggs and subsequent production of tens of thousand post-larvae and fingerlings of mutton snapper and cobia. In 2002, the first commercial shipments for both L. analis, and R. canadum fingerlings were recorded in the United States and the Western hemisphere. Specifically, a total of over 200,000 cobia fingerlings measuring 5 cm in length (2 inches) were produced using the technology developed in this project. This resulted in the shipment of more than 20,000 cobia juveniles (measuring 12 cm or 4-5 inches) in the Summer and Fall of 2002. Approximately 10,000 mutton snapper fingerlings were produced as well. In 2002, approximately 30,000 juveniles were shipped from the Aquaculture Center of the Florida Keys (ACFK) hatchery for growout operations in offshore cages and recirculating systems within the US, giving birth to a new industry.
A detailed, comprehensive, and organized account of the work conducted at the Aquaculture Center of the Florida Keys from 1999 to 2002 has been described in the numerous publications which have been generated by this project (thesis, peer review, articles, news releases, relevant pictures/tables/graphs, etc. – see Appendix). ACFK and RSMAS-University of Miami acknowledged receiving partial funding from NOAA / Sea Grant and NMAI since 1999. This funding has been instrumental in assisting us in the development of a new industry in the U.S.
2. Major accomplishments and milestones
The most important accomplishments of this project during its first year (October 2001- September 2002) were:
3. Specific topics
3.1. Spawning, larval rearing and fingerling production of cobia, Rachycentron canadum
The first spawnings, larval rearing production trials of cobia, Rachycentron canadum, conducted at Aquaculture Center of the Florida Keys, Inc. (ACFK), are reported herein.
During the spring and summer of 2002, environmentally-conditioned and hormone-induced spawnings of cobia (Rachycentron canadum) were successfully obtained, generating millions of fertilized eggs. Eggs for the larval rearing trials were obtained from tank spawnings of wild broodstock fish collected from November 2001 to April 2002 off Marathon, Florida. Eggs hatched in less than 24 hours at 26-28 oC and larvae began feeding 2-3 days post hatch (DPH). Larval rearing was initially conducted in twelve 20-ton tanks using a “pseudo-mesocosm” system, as proposed in the original grant. However, initial observations clearly indicated that at least for cobia, a high flow, high volume, low stocking density, high food density system with a heavy use of wild zooplankton (particularly copepods of the genus Acartia) in addition to enriched rotifers and Artemia is ideal for producing large numbers of fingerlings. Larval feeds consisted of microalgae, Isochrysis galbana (C-Iso strain, originally isolated from Turks and Caicos), rotifers, Brachionus rotundiformis (formerly s-strain), wild zooplankton, Artemia nauplii, and enriched metanauplii. Cobia exhibited very fast growth rates of growth and development throughout the larval rearing and nursery stages. Larvae showed pigmentation and melanophores from the moment of hatching, and at 11 DPH larvae were well pigmented and developed, with presence of red blood cells, indicating that gill respiration is already taking place at this early stage. Survival rates during the larval stage ranged from 10-60 and were relatively high compared to other pelagic marine fish larvae. A combination of enriched Artemia and imported marine fish starter diets were used for weaning two to three-week-old post-larvae onto dry feeds. Approximately 100,000 cobia fingerlings measuring 5 cm (2 inches) were produced in each of two larval rearing trials during the Summer 2002. Even though tens of thousands of post-larvae were weaned at the ACFK facilities, weaning still presents the greatest challenge. Heavy mortalities experienced during the weaning and nursery stages were attributed to cannibalism as well as poor water quality parameters related to the scarcity of well water used at the hatchery. Improved water quality, higher flow rates. and continuous grading of fingerlings by size are required to improve survival rates of cobia fingerlings during the nursery stage.
3.2. Methods for environmentally and hormonally induced spawnings of mutton snapper on- and off-season, with application to cobia and other marine fish species.
Mutton snapper (Lutjanus analis) broodstock were kept in 50,000 liter recirculating tanks since Summer 2000 at the Aquaculture Center of the Florida Keys and conditioned to spawn through the manipulation of water temperature during Spring 2001, and the Spring, Summer, and Fall of 2002. The tanks were stocked with 8-20 adult fish at an approximate male to female ratio of 2:1 and equipped with artificial substrate (Aquamats) to reduce aggressiveness and stress. As broodstock nutrition has a direct effect on egg quality and fertility levels, special attention was given to the broodstock diet. A combination of fresh frozen sardines, squid, and shrimp were alternated and supplemented with a especially formulated moist pellet enriched with vitamin and mineral mixes to add up to approximately 2% of the fishes’ body weight per day. Stress levels were further reduced through the introduction of neon gobies (Gobiosoma oceanops) into the system for long-term biological control of ectoparasitic infestations through symbiosis.
Voluntary spawning events routinely occurred when water temperature was increased from 22 °C to 24-24.5 °C (figure 1). In 2002, natural spawnings occurred even when the fish were exposed to temperatures below 23°C, on- and off-season. Consistent supply of fertilized eggs of mutton snapper through environmentally conditioned tank spawnings on and off-season has been achieved in 2002. This was an unprecedented accomplishment. More than 50 voluntary spawnings occurred in 2002, with fertilization rates ranging from 0 to over 90%. Most of the spawnings had high fertilization rates (>90%). The number of eggs collected during the spawning events widely ranged from 20,000 to 1.5 million, averaging 400,000 eggs per spawn. Similar methodology has been successfully used with broodstock cobia, Rachycentron canadum, as previously reported.
Hormonally induced tank spawning of broodstock L. analis kept captive for over one year have also been achieved. Both Human Chorionic Gonadotropin (HCG) and Salmon Gonadotropin Release Hormone Analog (GnRH-a) were used to induce final maturation resulting in millions of eggs in every spawning event.
Figure 1. Temperature cycle used for conditioned spawning of broodstock mutton snapper Lutjanus analis
3.3. Growth, survival and feed conversion rates of cobia, Rachycentron canadum, juveniles raised in a floating net cage in an saltwater lake in the Florida keys.
An experimental trial was conducted in the Summer and Fall 2002 to assess the growth, survival and food conversion rates hatchery reared cobia (Rachycentron canadum) juveniles in a floating net cage. One thousand fingerlings produced at ACFK were stocked in a circular high density extruded polyurethane (HDEP) floating net cage moored in a 7-acre saltwater lake in the Florida Keys. The dimensions of the cage used are 10m diameter x 7 m deep (600 m3). The cage was fitted with a 1/2” mesh size (stretched). Fish were fed extruded pellets (AquaXcel, Burris) containing 53% crude protein and 10% crude fat. Estimated food conversion ratio (FCR) to date is 0.75. Fish grew from an average weight of 10.62 g and length of 12.95 cm at 59 days post hatch to 1008 g (over 1 kilogram) and 47.7 cm at 167 days post hatch. Estimated survival rate to date is over 90%.
Water quality parameters (temperature, salinity, D.O., TAN, pH and S2, were routinely measured at the surface, 3.3 m and 7.5 m depth. The saltwater lake is stratified at approximately 10 m. Below the stratification layer, water quality deteriorates considerably and a significant drop in dissolved oxygen level is observed. Besides, the water in the lake is almost static. Current measurements conducted using a surface drifter indicate a maximum wind and tide driven surface current of less than 0.1 knot (< 5 cm/sec). High levels of sulfur and ammonia coupled with anoxic conditions below the stratification layer clearly indicate that water quality parameters in the lake are inadequate for marine fish culture. For this reason, cobia were stocked at low stocking density (1.6 fingerlings/ m3). Notwithstanding the poor water quality parameters, cobia exhibited extraordinary rates of growth and FCR, with virtually no mortality being recorded. Nevertheless, as evident from low dissolved oxygen readings from water samples at the cage site, cobia juveniles quickly outgrew the system’s environmental conditions and the cage biomass had to be thinned out (50% of the fish were harvested and transferred at this stage).
Results confirm that R. canadum exhibits very good potential for commercial aquaculture development in net cages in the tropics, especially in offshore systems, where dissolved oxygen levels are always at or above saturation levels and water quality parameters are conducive to successful aquaculture of pelagic species.
3.4. Preliminary results of aquaculture performance of cobia (Rachycentron canadum) and mutton snapper (Lutjanus analis) in submerged cages off the coast of Culebra Island, Puerto Rico
Snapperfarm, Inc. joined efforts with the University of Miami's Rosenstiel School of Marine and Atmospheric Science (RSMAS) and the Aquaculture Center of the Florida Keys, Inc. (ACFK) to develop an offshore aquaculture demonstration project off the Island of Culebra in Puerto Rico. The University of Puerto Rico is conducting the environmental assessment of the project. Both cobia and mutton snapper exhibit very good potential for commercial aquaculture development in net cages in the SE U.S. and the Caribbean. Cobia exhibits extraordinary rates of development and growth both at the hatchery and growout level.
In June 2002, Snapperfarm installed two Ocean Spar SeaStation 3000 cubic meter submersible cage systems 3.7 km southwest of Culebra, Puerto Rico. This offshore site has a depth of 27-28 meters and currents running .2 to 1 knots. The water at the cage site is saturated with oxygen, has an average salinity of 36 ppt, an average temperature of 27° Celsius and the underwater visibility ranges from 15-36 meters. In August 2002 the cages were stocked with Cobia (Rachycentron canadum) and Mutton Snapper (Lutjanus analis) produced at the Aquaculture Center of the Florida Keys, Inc. (“ACFK”). An estimated 10,000 cobia and 7,500 mutton snapper were stocked in the two offshore cages.
The cobia are being fed Burris AquaXcel 5310 extruded pellets. The fish quickly moved up in feed sizes and rendered several thousand pounds of the smaller nursery diets useless. The fish also outgrew their nursery net fairly quickly. Within 3-4 weeks of stocking the fish were ready to be released into the main cage. However, due to the low stocking densities the decision was made to hold them in the 600 cubic meter nursery net for few extra weeks.
All of the cobia shipped to Puerto Rico were from the same spawn at ACFK. The spawning occurred on July 12, 2002. The fish were transported from Florida to Puerto Rico and stocked in the offshore cages at 2.5 to 3 grams between August 19, 2002 and September 5, 2002. On October 5, 2002 the cobia in the offshore cages were sampled for the first time. They averaged 140 grams and 26 centimeters with less than 0.5% mortality observed. The demonstration trial is ongoing. Continuing routine sampling of the fish are being conducted.
3.5. Logistics, costs and technicalities involved in transporting and stocking cobia and mutton snapper fingerlings in submerged offshore cages.
With the recent development of high quality marine finfish at the Aquaculture Center of the Florida Keys, Inc. (ACFK), and the potential development of future hatcheries in the US and Caribbean, methods for transporting fingerlings that are cost efficient and logistically possible will have to be developed. Potential problems can be identified in every step involved in transporting different finfish species from the hatcheries to their finally destination. Hatcheries are generally located afar from the growout operations, and shipping costs and logistics are proving to be a major obstacle for the economical viability of stocking offshore cages. The need to stock these grow out facilities is imperative to sustain existing farms and those that will develop in the next decade
Logistics, time frame, costs and technical aspects involved in the transportation and stocking of cobia and mutton snapper fingerlings from the ACFK in Florida, USA to Snapperfarm offshore cages off Culebra Island in Puerto Rico, USA, are reported herein. The cost to transport 22,930 fingerlings was $23,100. The purchase price for fingerlings was 50 cents each, whereas the transportation cost was $1.01 per fingerling. In some instances, transportation from the hatchery to the offshore cage site took over 24 hours. Some of the costs and time associated with current transportation methods can, in some cases, be drastically reduced. Land, sea and air methods used to pack, ship, transport and stock fingerlings of cobia and mutton snapper are discussed. Fingerlings where stocked in 1,000 m3 cardboard transportation boxes lined with triple polyethylene bags filled to 300 liters at the ACFK hatchery in the Florida Keys. They were then loaded into a truck, driven to Miami International airport in Florida, where they where flown to San Juan, Puerto Rico. Once in San Juan, boxes where inspected by Fish and Wildlife Service authorities, cleared customs, loaded on a flatbed truck, driven down to Fajardo, where they were transferred to a transportation tank on a boat, which finally took the fingerlings to the cage site. Once at the site, fingerlings where transferred from the transportation tank to the nursery nets inside the main cages using a pressure pump via a large diameter hose. Dissolved oxygen levels, temperature, stocking densities (biomass) and time are the most crucial parameters to be addressed. Results of these trials conducted in the Summer and Fall of 2002 indicate that novel approaches for transporting fingerlings need to be urgently addressed and developed.
4. Appendix (abstracts of thesis, abstracts of conference presentations, articles, news articles, peer review publications and relevant pictures/charts/tables)