Part B: Overfished in Georges Bank
Legend has it that Atlantic cod were once so abundant on the Georges Bank that men could scoop them from the sea with baskets. Unfortunately, this is no longer the case. Over the last several decades, Georges Bank has experienced significant declines in fish catch as a result of overfishing and ecosystem degradation by certain types of fishing gear. Do these declines in catch mean that fish species in this region are overfished?
- For a species to be considered overfished, the population size must be below a level determined by scientists to be healthy. Look at the graph below of Georges Bank Atlantic Cod recruitment and biomass.
- Recruitment is the number of young fish that are just starting to be caught in fishing gear in a given year, or the number of fish that are reaching a particular size or age.
- Biomass is the total weight of a population of fish.
- Spawning Stock Biomass (SSB) is the total weight of all sexually mature fish in the population.
- NOTE: Stock biomass values along the y-axis are reported in 1,000s of metric tons (mt).
Graph courtesy of NOAA.
Stop and Think
1: Describe the trends you see in Georges Bank Atlantic Cod Spawning Stock Biomass from 1978-2004. Are there steady trends or distinct turning points?
2: What do you think are the long-term consequences of declining Spawning Stock Biomass?
A stock is considered to be overfished or overexploited if Spawning Stock Biomass falls below the Minimum Stock Size Threshold (MSST, or SSBTHRESHOLD). This value is usually 1/2 the stock biomass level that can produce Maximum Sustainable Yield (SSBMSY).
Answer the following question to check your understanding of the information provided in the Georges Bank Atlantic Cod Trends in Recruitment and Biomass graph above.
- According to the Northeast Fisheries Science Center, SSBMSY for Georges Bank Atlantic cod is 217,000 mt. During which years was Georges Bank Atlantic cod overfished?
SSB was less than 108,500 mt for all years shown in the graph. Therefore, Georges Bank Atlantic cod was overfished during this entire time period.
- Read the History of the groundfishing industry in New England to learn about the many factors contributing to the overfishing and overfished status of New England groundfish species.
Check your understanding of the history of New England ground fishing.
- Summarize how the ground fishing industry in New England changed over the course of the 20th century.