Development of an Automatic Distribution System for Live Feed, Microdiets and Prophylactic Treatments for Sturgeon Larvae and Early Juveniles

Final Report

Acadian Sturgeon and Caviar Inc

AIMAP 2011-M01

Executive Summary

Acadian Sturgeon and Caviar Inc was founded in Carters Point, New Brunswick, Canada in 2005 with the aim of producing sturgeon and caviar in aquaculture. We started by producing and selling, all over the world, live sturgeon (fertilized eggs, larvae and juveniles) from both local species, Atlantic (Acipenser oxyrhynchus) and shortnose sturgeon (Acipenser brevirostrum), for aquaculture, restocking (Baltic Sea) and research. Efficient production of juvenile sturgeon is not only important for exports but also for producing our grow-out livestock for developing the aquaculture meat and caviar production.

In order to address and solve the problems related to live feeding, prophylactic (salt) treatments and weaning on artificial micro diets, we proposed to purchase and modify an automated microdiet dispenser (AMD) system from the Department of Fisheries, Western Australia with the goal of optimizing the feeding and treatment processes, and increasing sturgeon juvenile production.

The Project objectives were:

• To modify the AMD system to also distribute live feed, microdiets and prophylactic treatments for sturgeon larvae and early juveniles;
• To test the efficiency of the automatic system by comparing it with manual feed and treatment distribution methods; and
• To determine the optimal parameters (frequency amounts) for automatic distribution of live feed, microdiets and prophylactic treatments.

We modified the AMD and transformed it in an integrated distribution system for live feed, microdiets and prophylactic treatments, with touch screen controllers that can control each 18 separate dry feeders and 6 separate controllers for peristaltic pumps (18 peristaltic pumps maximum).

Moreover, this Project provided the first comparison between the continuous and discontinuous feeding during the early life stages of Atlantic and shortnose sturgeon under a commercial hatchery environment and supports the notion of the importance of the continuous feeding during larval and early juvenile stages of sturgeon. While comparing the effectiveness of a continuous automatic feeding versus a manual discontinuous feeding during the larval and early juvenile rearing we found significantly higher survival (P<0.05) for larvae and early juveniles fed under a continuous feeding regimen as compared to discontinuous manual feeding. The findings support the notion of the importance of the continuous feeding during the larval and early juvenile culture of the Atlantic sturgeon.

We have optimized most of the technological parameters for growing larval and juvenile Atlantic and shortnose sturgeon (feeding rates, feeding frequencies etc.) but experiments will be conducted on continuous basis to adapt those parameters to different ages of fish and temperature conditions.

This new equipment is now sold on the global market and we determined that it has important positive impacts on efficiency of larval and juvenile growing, not only for sturgeon, that includes: improved general productivity; improved tank hygiene and survival; improved growth and quality of the live sturgeon produced for sale and for our own stocks; reduced labor costs; and reduced effluent pollution by reducing overfeeding.

In conclusion we are very happy with the installation and functioning of the newly developed feeding system and we consider that it is the most advanced and complex feeding system for larvae and small juveniles available in the world.

We acknowledge the financial support from DFO Aquaculture Innovation & Market Access Program (AIMAP) and the National Research Council -IRAP for this Project.

Introduction / Background

Acadian Sturgeon And Caviar Inc was incorporated in March 2005 in Carters Point, New Brunswick with the aim of producing sturgeon and caviar in aquaculture. Our business strategy, designed to help overcoming the long time necessary until obtaining the caviar from aquaculture, includes generating quick cash flow by selling live sturgeon, caviar and meat from wild sturgeon as well as meat from the male aquaculture fish. Those activities not only generate early cash flow but also help develop our markets (Canadian and international) for our upcoming aquaculture production and position our products and brand in the markets. Since 2005 we have been producing and selling worldwide, live sturgeon from the two native species we work with (Atlantic sturgeon – A. oxyrhynchus and shortnose sturgeon – A. brevirostrum) as stocking material for aquaculture, restocking, ornamental and research.

Species diversification of the aquaculture industry is a top priority for the Canadian government, scientists and aquaculturists in order to ensure the continued growth and stability of this important industrial cluster to Canada (Price Waterhouse Coopers, 2002).

Sturgeons are some of the most highly valued fish in the world. One mature fish produced in aquaculture could easily be sold at the farm gate for $2000 as we sell their caviar at the farm gate for a minimum price of $1,300 per kg. Demand for caviar and meat is extremely high and will become higher as stocks continue to be fished (2004 FAO report on sturgeon world markets and industry - Fabio Carocci, updated 2009).

Despite this opportunity on the world market, sturgeon aquaculture only started to be developed a few years ago. There are only three sturgeon farms in operation in Canada and there is a huge potential for growth in this sector.

Two species of sturgeon are native in Atlantic Canada, namely shortnose sturgeon (A. brevirostrum) and Atlantic sturgeon (A. oxyrhynchus). Acadian Sturgeon and Caviar Inc are developing both these species for aquaculture.

As the demand for live sturgeon (not only for export, but also for aquaculture in Canada) increases every year, we need to increase productivity and production capacity of our sturgeon hatchery.

One of the major constraints in developing a viable sturgeon aquaculture industry in Canada is larval rearing and early juvenile production. Once the larva hatches from the egg and depletes its yolk-sac reserves, its survival depends not only on the culture system and management regimes but also on the nutritional input provided by exogenous feeding.

Most of the sturgeon are fed a natural diet, usually Artemia (brine shrimp), for the first 3 to 6 weeks of their life following which they are gradually weaned onto an artificial microdiet. Before we started this Project, Artemia feeding in our hatchery was carried out manually (at intervals of two hours from 6 AM to 10 PM). This tedious and labor intensive practice was adapted to keep Artemia available at the density of minimum 1/ml for growing larvae as well as to reduce the waste which can greatly enhance the water quality. However, this practice could not be extended during the night due to labor costs.

Moreover, survival of larvae and early juveniles is greatly influenced by tank hygiene during this sensitive period. Overfeeding is the main cause for deteriorating of hygiene conditions in tanks. If we could distribute smaller amounts of feed during day and night (sturgeon are more active during the night period) we could improve those conditions.

Weaning sturgeon from live feed to artificial diets is also a very sensitive period (Ware et al 2006). Mortalities during this period can reach 100%. Weaning is performed over a 3-week period to allow fish to modify their digestive tract enzyme composition to be able to digest dry feed. During this time the dry feed proportion should be gradually increased while decreasing the proportion of live feed. We considered that an automatic distribution would greatly increase the accuracy and results of this process.

Last but not least, after the initiation of exogenous feeding we perform preventive (prophylactic) treatments with salt that also require a large amount of labour. Those treatments are regularly performed once a day for 30 minutes every day and could be easily replaced by an automatic distribution system.

Project Rationale and Objectives

In order to address and solve the problems related to live feeding of sturgeon, prophylactic treatments and weaning on artificial micro diets mentioned above, during this Project we developed an integrated automatic system that we can program to optimize those important technological processes.

We tried unsuccessfully in the past to acquire such a system but there was nothing available commercially anywhere in the world. The live feeding is mostly performed manually or semi-automatically with frozen live feed. The microdiets are distributed either manually or by using very limited types of feeders (vibratory, auger, belt or drum feeders - Aquatic EcoSystems, Florida USA) that are not very accurate.

That is why we purchased and modified an automated micro diet dispenser (AMD) system from the Department of Fisheries, Western Australia. The DFO Saint Andrews Biological Station purchased one such system in 2009 but they only use it for distribution of micro diets. We adapted this system to also distribute live feed and treatments, adaptation that was performed for us by the Australian producer of the dry feed AMD system.

We tested this new equipment and technology to check its impacts on our technology, that included:

• improved general productivity;
• improved tank hygiene and survival;
• improved growth & quality of the live sturgeon produced for sale & our own stocks;
• reduced labour costs; and
• reduced effluent pollution by reducing overfeeding.

We first tested the efficiency of this new system by comparing it with regular hand feeding. Then we determined the optimal parameters for the automatic distribution of live and dry feed, microdiets and prophylactic treatments by determining the optimum feeding amounts and frequency, weaning rate and use of enrichments for the production of sturgeon.

By implementing this automatic feeding system in our technology our expectation was to greatly improve the larval and early juvenile sturgeon quality and quantity at much lower cost and increase sustainability of our juvenile production.

Project Objectives:

• To modify the AMD system to also distribute live feed, microdiets and prophylactic treatments for sturgeon larvae and early juveniles;
• To test the efficiency of the automatic system by comparing it with manual feed and treatment distribution methods; and
• To determine the optimal parameters (frequency amounts) for automatic distribution of live feed, microdiets and prophylactic treatments.

This Project contributes to the development of Atlantic and shortnose sturgeon in Canada and of the Canadian aquaculture industry in general by allowing for diversification, expansion and therefore sustainability.

By developing this automatic feeding system we will offer it for adoption for other sturgeon farms or for other species of fish. This could have a high impact on sustainable production of fish in aquaculture through increased productivity, reduced production costs and increased production of high quality juveniles.

Methodology

The following methodology was applied in order to achieve each objective:

Modifying and installing the microdiet automatic distribution system

Objective: Modifying and installation of the microdiet automatic distribution system to also distribute live feed, microdiets and prophylactic treatments for sturgeon larvae and early juveniles.

Methodology:

• Purchasing of two Australian automatic microdiet distribution systems and modifying the programming of their PLC to also control peristaltic pumps for the distribution of liquid solutions (Artemia, salt);
• Installing a quick connect distribution system for distributing Artemia and prophylactic treatments; the system consists of 0.38” ID tubes that will be continuously flushed with fresh water from the header tanks and allows the injection of Artemia or prophylactics (salt) in a “Y” connection for each row of tanks; this system is secured on an aluminum structure installed above the tanks; and
• Modifying the existing Artemia production system to accommodate the automatic distribution (2 large hoppers for Artemia storage and enrichment, transfer pumps, larger Artemia production tanks; heating, light and aeration system).

Testing automatic system efficiency comparing with manual feeding

To begin the experimental part a preliminary experiment on the ingestion rate of Artemia nauplii during larval stages of the Atlantic and shortnose sturgeons was performed using the following methodology:

• Treatments: 4 densities of Artemia, namely 5/100 ml, 10/100ml, 20/100ml and 40/100ml with 5 replicates per treatment.
• Experimental unit: transparent plastic cup each holding 100 ml of water and one larva.
• Experimental design: The larvae at different stages (1 week, 2 weeks, 3 weeks, 4 weeks and 5 weeks old) were obtained from an operational tank at Acadian Sturgeon Hatchery and starved for 24 hours prior to the exposure. They were then allowed to feed on the newly hatched Artemia nauplii for 24 hours. The amount consumed was determined by the difference between the initial and final number of nauplii (only intact individuals were considered as still available).

Objective: Test the efficiency of the automatic system by comparing it with manual feeding and treatment distribution methods.

Methodology:

• Two trials were conducted to compare the automatic and manual distribution methods – one for shortnosed and one for Atlantic sturgeon.
• Treatments: automatic and manual feeding, Replicates for each treatment: 3 
• Experimental unit: round flow through tank each stocked with 5000 juveniles in about 250 litres of water.
• Growth: 30 individual juveniles were randomly sampled weekly from each tank (each experimental unit) and preserved in a formalin solution. The total length of each individual was measured under the dissecting scope.
• Survival: Daily count of dead larvae/juveniles was conducted during routine maintenance and % survival was calculated for each experimental unit on a weekly bases. At the end of the experiment, all living juveniles were counted to report the final survival for each replicate.

Optimizing the feeding and treatment parameters

Objective: Determine the optimal parameters (frequency, amounts, live feed enrichments) for automatic distribution of live feed, microdiets and prophylactic treatments.

Methodology:

Determining the optimum feeding ratio for 1-5 g juveniles

• Treatments: feeding at 7%, 5% and 3% of body weight per day.
• Replicates for each treatment: 3
• Experimental unit: square tanks using flow through system each stocked with 1000 Atlantic sturgeon juveniles (in about 200 liters)
• Sampling: at least 30 individual juveniles were randomly sampled from each tank (each experimental unit) photographed and weighted. Sampling was done weekly.
• Survival: dead juveniles were removed from each tank and recorded daily.
  
  Determining the optimum Artemia feeding frequency for sturgeon larvae

• Treatments: feeding 1 min every 10 min, 1 min every 20 min and 1 min every 30 min
• Replicates for each treatment: 3
• Experimental unit: round tanks using recirculating system each stocked with 1000 Atlantic and shortnose sturgeon juveniles (in about 160 liters)
• Sampling: at least 30 individual juveniles were randomly sampled from each tank (each experimental unit) photographed and weighted. Sampling was done weekly.
• Survival: dead juveniles were removed from each tank and recorded daily.
  
  Determining the optimum feeding frequency for 0.5-2 g juveniles

• Treatments: 2 shots per 30 min, 4 shots per 60 min and 8 shots per 120 min
• Replicates for each treatment: 3
• Experimental unit: round flow through tank each stocked with 1000 juveniles (in about 250 liters)
• Sampling: at least 30 individual juveniles were randomly sampled from each tank (each experimental unit) and weighted. Sampling was done weekly.
• Survival: dead juveniles were removed from each tank and recorded daily
  
  Examining the effect of Artemia enrichment: 2 x 4-6 week trials (one for each species) on Artemia enrichment using the Ori-Green enrichment from Skretting

• Treatments: feeding 1 min every 10 min, with Artemia and enriched Artemia (2 treatments)
• Replicates for each treatment: 3
• Experimental unit: round tanks using recirculating system each stocked with 1000 Atlantic sturgeon juveniles (in about 160 liters)
• Sampling: at least 30 individual juveniles were randomly sampled from each tank (each experimental unit) and weighted. Sampling is done weekly.
• Survival: dead juveniles were removed from each tank and recorded daily.

Comparing the manual versus automatic prophylactic treatments

Objective: Comparison of manually and automatically applying prophylactic treatments with salt for young of the year shortnose sturgeon.

Methodology:

• Number of tanks / fish per tank: 9 / 150 fish each tank;
• Treatments: no salt, manual salt distribution, automatic salt distribution;
• Data collection: daily mortalities, bi-weekly weights and lengths for calculating the specific growth and condition factor, salt consumption.

Modifying and installing the microdiet automatic distribution system

As soon as the Project started we ordered the changes to the Australian AMD system to accommodate the control of peristaltic pumps for distribution of liquid diets and treatments. Dr Sagiv Kolkovski, Principal Research Scientist, Marine Aquaculture, Department of Fisheries, Western Australia (automatic feeding equipment producer in Australia) visited our facility after the installation of the systems in order to help start-up the system and solve any problems during the use of the system.

The 2 original AMD systems with touch screen controllers were modified to control each of the 18 separate dry feeders with 6 separate controllers for peristaltic pumps. Installation was performed during the period June 25 – July 10, 2011. During the same period we installed the dry feeders and also the distribution system for liquid diets and treatments on both the juvenile and larval systems designed so that the diets or treatments are automatically washed from the 3/16” lines by gravity feed water from the header tanks; in this way the Artemia would not stay into the lines between the feedings and create a bacterial hazard if they die due to low oxygen.

We designed and built two Artemia (brine shrimp) hatching systems (2 units x 6 hatching cones) that are modular, easy to operate and keep clean and easy to harvest. Before starting the actual experiments we tested the functions of each feeder or peristaltic pump, measured quantity of diet distributed per event or minute respectively and prepared the systems for the experimental phase.

Testing automatic system efficiency comparing with manual feeding

In the preliminary experiment designed to establish the target Artemia feeding rates for the larvae, we determined that at each developmental stage, the ingestion rate increased with increasing prey densities. Large variation in the ingestion rates by the larvae in the same developmental stage during the first 2 weeks for both Atlantic and shortnose sturgeons. For the first two weeks, 40 Artemia /100ml seems to be sufficient amount of the food however, it amount seems to be insufficient for the later stages of the development. In conclusion we decided to feed at satiation, minimum 40 Artemia /100 ml.

Although no significant difference in Standard Length (SL) was observed during the experiment, the larvae and early juveniles under the Automatic treatment had higher SL at the end of the trial. Survival was not significantly different during the first four weeks, however, was significantly higher under the Automatic treatment for the final two weeks of the trial.

For the Atlantic sturgeon the average survival was significantly higher for automatic feeding (74%) compared to that of 60% for manual feeding at the end of the experiment. Regarding growth, although not significant, at the end of the experiment, the juveniles under the automatic treatment were larger than those of the manual treatment (25mm for automatic versus 21mm for manual feeding). The outcome of this experiment was submitted as a short communication to the Journal of Applied Ichthyology in Jan 2013.

Optimizing the feeding and treatment parameters

The optimum Artemia feeding frequency for sturgeon larvae was 1 min every 10 min, and that is only possible using an automatic distribution system, like the one developed in this Project. This keeps the Artemia concentration practically constant during the day and night allowing satiation feeding for maximizing growth in larval sturgeon.

The optimum feeding ratio for juveniles (1-5 g) was 5% of the body weight. This is similar to the findings in the literature for sturgeon of similar weights. For 0.5-2 g sturgeon the average feeding ratio of 46% dry weight of the cultured fish body weight was higher compared to other treatments at the end of the experiment. However, this experiment should be repeated as we did not obtain a significant difference between the treatments.

Artemia enrichment with Ori-Green enrichment from Skretting for 4-6 weeks was not significantly different but we will re-do the experiment at a higher temperature as we believe that the enrichment was not done properly and that is the reason for the non-significant results.

Comparing the manual versus automatic prophylactic treatments

Results were not-significantly different, probably due to the laminar flows of salt water that is not mixing enough with the fresh-water in the present tank set-up. We will perform experiments again using an air diffusing system that will better mix the salt-water in the system. From the preliminary results we observed that we could probably reduce the concentration of salt by half while maintaining the same efficiency of the prophylactic treatments.

Communications

Results of this Project were published in:

• Hatchery International, November – December 2011; and
• Scientific paper submitted as a short communication to the Journal of Applied Ichthyology in Jan 2013.

A presentation will also be made at the 7th World Sturgeon Symposium, Nanaimo, BC July 2013 (“Comparison of continuous and discontinuous feeding regimens on the growth and survival of larval and early juvenile Atlantic sturgeon (Acipenser oxyrhynchus) under hatchery conditions”, Paymon Roustaian, Cornel Ceapa, Domika Clarke and Joel Chase.

Conclusion

In conclusion we are very happy with the installation and functioning of the newly developed feeding system and we consider that it is the most advanced and complex feeding system for larvae and small juveniles available in the world! This feeding system has increased the productivity of our technicians and reduced the use of the feed, reduced wasted feed etc.

Literature is quite limited on larval and early juvenile rearing of the Atlantic sturgeon. To the best of our knowledge, this is the first report on comparing continuous live feed delivery using an automatic feeding system and discontinuous manual feeding in the larviculture of the Atlantic sturgeon in terms of growth and survival in a commercial hatchery operation. Significantly higher survival and growth for Automatic treatment during the last two weeks of this study point to the importance of the continuous presence of the food for the growing larvae and early juveniles. The only other dietary work on growth and survival of first-feeding larval Atlantic sturgeon was conducted by Mohler et al (2000) who reported more than 90% survival in a 26 day trial when the larvae were continuously fed on Artemia nauplii. However, no comparison was made with manual discontinuous feeding in their work. Their higher survival rate may stem from shorter duration of their trail (26 day), temperature and stock related differences. Studies on larval and early juvenile nutrition of other sturgeons also point to the effectiveness of the continuous feeding during sturgeon early life histories (Ware et al., 2006).

We have optimized most of the technological parameters for growing larval and juvenile Atlantic and shortnose sturgeon (feeding rates, feeding frequencies etc.) but experiments will be conducted on continuous basis to adapt those parameters to different ages of fish and temperature conditions.

This Project provides the first comparison between the continuous and discontinuous feeding during the early life stages of the Atlantic sturgeon under a commercial hatchery environment and supports the notion of the importance of the continuous feeding during larval and early juvenile stages of Atlantic sturgeon. Further improvement on the automatic system based on the feeding rate and the frequency of feeding can further improve the outcome of the seed production in the sturgeon larviculture under practical hatchery condition.