Written by Industry Expert, David Beasley, Fisheries Biologist
Understanding Relative Weights
If you have ever had a fisheries biologist sample your fishery using an electrofishing boat, you have seen lengths and weights of individual fish recorded. Variation of the length-weight relationship is an indication of health, fatness, and wellbeing of an individual.
One method fisheries biologists use to measure the health of a fishery is to determine the relative weight of individual fish. Relative Weight (Wr) is the ratio of the actual weight of a fish to what a healthy fish of the same length should weigh, called the standard weight (Ws). Fish with high relative weights are fat while those with low relative weights are thin. When Wr values are well below 100 for an individual or size-group, it typically indicates that problems exist within the habitat or the predator/prey ratio.
Knowing the overall condition of fish in your waterbody is important to fisheries managers. Fish with a high Wr indicate a waterbody with conditions ideal for growth, such as good fish habitat and edible size food. The opposite is also true. Fish with poor Wr indicate an environment often lacking in habitat and little food availability.
Being able to evaluate and monitor the health and condition of your fish is essential in helping biologists make fisheries management decisions for your lake or pond.
Contact the experts at 888-480-LAKE (5253) for all of your lake, pond and fisheries management needs.
David Beasley is a Fisheries Biologist with SOLitude Lake Management. Since 1998, SOLitude Lake Management has been committed to providing full service lake and pond management services that improve water quality, preserve natural resources, and reduce our environmental footprint. Services are available throughout the Eastern United States. Fisheries management consulting and aquatic products are available nationwide. Learn more about SOLitude Lake Management and purchase products at www.solitudelakemanagement.com.