Discover the types of records that are useful for tracking and improving a farm’s efficiency and performance.
SFR = Specific Feed Rate
How many kilograms of feed to offer per kg of biomass per day?
FCR = Feed Conversion Rate
How well does the feed I give turn into biomass?
SGR = Specific Growth Rate
What percent increase in body weight do my fish show each day?
This section covers the types of records that are useful for tracking and improving a farm’s efficiency/performance. While every farm has a unique mix of challenges and resources, the data recording system described here should provide a strong foundation to any farm’s data set. Types of data points can be separated into several categories:
Inputs are characterized as the resources one invests in the production process. In the aquaculture context, the primary inputs are stock (the number of eggs/animals, as well their average weight and associated biomass), feed and any chemicals used.
Inputs - Stock
When eggs (or fish) first arrive on the farm, an input code should be generated that will be associated with the stock throughout the production cycle. An input code should contain as much information as possible about the origin of the eggs or fish, taking a form such as “supplier – date received – incubator/rearing unit”. Additional information, such as the strain or variety of the species being raised should also be collected and either attached to the input code or noted alongside the input for reference later. Assigning an input code to every batch of eggs or fry that enter your facility will allow for proper traceability should any issues arise in production where you must isolate a group of fish that may have encountered a virulent pathogen, been exposed to a feed having manufacturing or storage defects, or received a particular medicinal treatment.
Inputs - Feed
When feed first arrives on a farm from the manufacturer, the following information should be recorded:
Feed type (it is best to use a product code supplied by the manufacturer, if available)
Amount of feed
Any associated lot or batch number (there can be multiple lot or batch numbers associated with a single shipment)
As feed is provided to a group the amount, type and batch number of the feed used should be recorded each day per rearing unit. Recording this information enables the calculation of daily feeding rates (as a % of fish body weight) and feed conversion ratios (FCR) as well as proper inventory management and feed traceability.
Economic FCR (EFCR) is a very practical metric, and is calculated as follows:
EFCR = (Total Feed Used During Period) ÷ (Final Biomass – Initial Biomass) or (Total Feed Used During Period) ÷ (Change in Biomass from Start to Finish)
Goals for an EFCR depend on many factors:
If any health issues arise in the stock that are suspected to be feed-related, having a record of what exact batch of feed was being used for the stock allows for speedier identification of issues in either the manufacturer’s production process, transport conditions or the feed storeroom on site. A feed records sheet can be generated for either a single day’s feedings or for a series of days. Using a format that allows for multiple days of feed records has the advantage of allowing a reviewer to see any trends in appetite (up or down) as well as reducing the total amount of paper records generated.
Keeping track of feed types and amounts used on a farm will help with feed ordering in the future, analysis of performance indicators such as FCR, and inventory management.
Inputs – Chemicals
There are often a variety of chemicals used in the production of trout with purposes ranging from hormone enhancement to parasite removal. Whenever applying or using a chemical, the following information should be recorded (as well as any other information required by the governing body/agency in charge of monitoring the use of the chemical):
Transfer records relate to the movement of stock, feed, or other production inputs from one location to another. Transfers of feed, medicinal products or any other consumptive input can be recorded simply by generating a sheet where one lists the source location, destination, and amount transferred. Transferring stock from one unit to another is a bit more complex, and requires that the following information be recorded:
Group or lot name indicated clearly
Date of transfer
Average weight of stock
Outputs of a farm are mostly classified in terms of biomass exiting the population in the form of mortality, culling, sale, or harvest. When recording mortality, a simple table of how many individuals expired on a given date per rearing unit is appropriate. Any culling should be recorded with an average weight, number and total biomass of fish culled from the population. Astute farmers will also include in their culling summary a breakdown by percentage of why these fish were culled (type of deformity, poor condition factor, etc.).
Sales and harvests should be well accounted, as they represent the cash inflow to the farm and will be used to extrapolate important metrics that guide production decisions in the future. In addition to the standard data points of average weight, number of fish and biomass sold/harvested, one should record the price per piece or weight (in unit of preference, pounds, or kilograms). Keeping record of biomass, average weight and population harvested or sold will allow calculations at a later date of several important production figures: FCR, SGR, survival, average price, and ultimately the cost to produce a given piece or pound/kilogram of harvestable product. Any harvest that does not remove all the stock in a given unit should result in an adjustment of number of fish and biomass in the remaining population, meaning less feed will be provided to this unit.
Table 1. Examples of SFR table. (Remember: these values are percentage.)
A practical scenario
For a tank with 13 degree water, 20,000 fish in it averaging 30 grams - how much feed should you give per day?
If the rate of feed you calculate exceeds safe levels, you need to either reduce the biomass in the tank or lower the feed rate (and lower your growth expectations).
EFCR: A practical scenario
This means for every kg of biomass produced, it took 1.18 kg of feed to generate it.
While each farm may have indicators that they watch more closely than others, there are a few that are common to all farmers and should be accounted for monthly and yearly. Feed conversion ratio (FCR) is a metric that describes how much feed is required to produce a given pound, kilogram or other unit of weight/mass of product. There are two main types of FCR calculation: Economic FCR and Biological FCR. Economic FCR divides total feed use by current biomass of a group, while Biological FCR divides total feed use by the current biomass and all biomass lost due to mortality, predation, escape and culling. Specific growth rate (SGR) relates the weight gain as a percentage of the average individual in a population over a specified time period. Typically, this percentage gain is evaluated on a per day basis and the SGR can be evaluated over days, weeks, months, or any other unit of time one prefers. It is important to track SGR as it can be compared to benchmark performance either on one’s own farm or against other farms’ performances. Making this comparison allows the producer to determine if stock is underperforming and, if so, what changes could be made in their production process to bring stock up to expectation.
Specific Growth Rate (SGR)
This contrasts with the Absolute Growth Rate, which says the actual weight the individual gains in one day (2g per day, 10g per day, etc)
Specific Growth Rate = (102 – 100) ÷ 100 = .02, or 2.0%
Absolute Growth Rate = (102 – 100) ÷ 1 day = 2g per day
Specific Growth Rate: Multiple Days
SGR gets more complicated when you consider multiple days, and the formula becomes:
SGR = ln(Final Weight ÷ Initial Weight) x (100 ÷ # days of growth)
“ln” stands for Natural Logarithm, which you can research if you need help understanding. It is a common function that appears on phone calculators as well as in Excel.
SGR: a practical scenario
Interrelationship between SGR, SFR and FCR
SGR = SFR÷FCR
It’s that simple. In practice, this means I can increase my growth rate by either feeding more or by feeding more efficiently
Survival as a metric indicates the percentage of individuals surviving from the original input stock. A producer should track survival throughout the grow-out of a population to determine where the largest challenges to survival occur (typically in the earliest stages of production) so that when changes are made to the production process, they can determine if this change positively or negatively affects survivability.
The environment in which stock is grown has a tremendous impact on stock performance. While each site is different and will need to watch some parameters more closely than others, there are several environmental metrics that are common and germane to all aquaculture production. Temperature and dissolved oxygen levels are at the forefront of necessity in environmental monitoring as they have the largest effect on the success of a given population. Records should be kept at least daily for each of these figures in a simple table to be able to track changes over time and adapt production processes when environmental conditions become unfavorable. Several other parameters to monitor include:
Figure 1: Relationship between the ammonia/ammonium ratio and pH
Figure 2. Reaction of ammonia excreted into water by fish
Though record keeping is often one of the more mundane activities to perform on a farm, it is highly important to the short- and long-term success of a production operation. Proper record keeping enables the understanding of the enterprise’s productivity, offering insight into how operations can be improved or amended to achieve desirable results. Diligent record-keeping not only maintains the economic health of an operation but also the general health of the animals for which it is responsible. Keeping and monitoring records can help diagnose production issues before they arise to keep everything, and everyone, healthy, happy and thriving.