January 13, 2021 — The following was released by Sustainable Fisheries UW:
Commercial fishing is vital to global food production. Wild-caught fish contain every essential amino acid, require no land or freshwater, and are a renewable resource when managed sustainably. In addition to providing access to healthy, low-impact protein, the seafood industry is worth over a trillion dollars annually and employs 40 million people—ensuring its sustainability is vital to economies all over the world. We explain seafood industry regulations in our section on fishery management—but first, the fundamental key to understanding sustainable seafood is grasping the science of catching fish.
Fisheries are composed of fish stocks and the fishing fleet that catches them. A fish stock is simply a harvested population. It refers to one specific species in one particular place, like Gulf of Maine cod. A fishery is the intersection of a stock (or group of stocks) and the means of harvest. Fishing fleets can use several different methods to capture fish, each method describes the fishery and guides management.
A fishery is sustainable when the amount harvested does not compromise future harvests.
Fishery science is the process that answers that question, primarily through stock assessments. A stock assessment uses several different kinds of data to understand the health of a stock and determine how much can be fished. You can think of the data as the A,B,Cs of stock assessments – abundance, biology, and catch.
- Abundance is how many fish are in the population; estimates of abundance are made based on samples that are gathered using various methods.
- Sampling can also collect biological data such as: age and length from which we can estimate levels of natural mortality and fishing mortality. Together, these data help estimate the reproductive rate of a population, which in turn allows us to predict how many fish will be around next year.
- During sampling, environmental data like temperature, salinity, dissolved oxygen and other ecological variables are also collected.
- Catch data are our historical records of how many or what weight of fish was caught during a calendar year or a fishing season.