15.98% = DEPLETED
How It’s Calculated
FINDEX is a novel way to gauge whether a species’ abundance is trending up or down. The calculations compare the desired condition of a fish stock with its existing condition. Specifically, FINDEX measures the gaps between either Target or Threshold biological reference values necessary for population recovery and the most recent, or “Terminal”, estimates of those values. Biological reference points vary among species depending upon the available data.
The “gaps” between the Target and Terminal values are reported as ratios. For example, if the Terminal and Target values are the same, there would be no gap, and the ratio would be 1.0. The multiplier on our barometer would set the FINDEX value at 100% in this example.
For Striped Mullet, the FINDEX gap assessment compared Target and Terminal values of Fishing Mortality (F35%) and Spawning Stock Biomass (SSB35%) from the most recent stock assessment model developed by the NC Division of Marine Fisheries. The Terminal year in the stock assessment model was 2019.
Here is the FINDEX formula used for Striped Mullet:
- (0.619 x 0.258) x 100 = 15.98%
- FINDEX = 15.98%
- 15.98% = DEPLETED
What does Depleted mean?
FINDEX designation as “Depleted” is assigned to any stock with a value less than 50%. Depleted indicates that the stock is overfished and severely impaired. Striped Mullet are being removed too rapidly from the stock, and the estimated number of spawning females in the population (Spawning Stock Biomass) is well below threshold and target levels for a sustainable fishery.
Stock assessment results predict continued declines in Striped Mullet recruitment and Spawning Stock Biomass, and an increase in fishing mortality. Also of concern is the lack of fish older than age 3 observed in North Carolina’s monitoring programs; Striped Mullet can live to approximately 15 years.
Note there is a significant time lag associated with updates to stock assessments for most of North Carolina’s fisheries. Periods between updates are usually 5 years, and sometimes 10+ years. For this reason, FINDEX calculations may not accurately describe current conditions – instead, FINDEX evaluates the most recent scientific data available. Striped Mullet data has been updated through 2019.
Commercial Striped Mullet Trends
The graph below illustrates commercial harvest trends for Striped Mullet from 1985 through 2020. In 2020, 610 commercial fishers recorded 9,073 trips harvesting 1,229,464 pounds of Striped Mullet valued at $651,104. Estuarine and ocean gill nets are the primary gear used to harvest Striped Mullet, valued for their roe. On Bogue Banks (Carteret County) a fall stop net fishery is allowed in the Atlantic Ocean. Supporting data was sourced from the North Carolina Department of Environmental Quality.
Recreational Striped Mullet Trends
Striped Mullet is not a popular target species for recreational anglers in North Carolina. However, recreational anglers will use cast nets to collect juvenile Striped Mullet (called “Finger Mullet”) as bait to catch other species. Data collection programs rarely encounter coastal anglers fishing for Striped Mullet, so the available data is scattered and imprecise.
Did you know?
- White Mullet can be differentiated from Striped Mullet by their lack of stripes and the presence of a distinct gold spot on the gill cover
- Adult Striped Mullet migrate in the fall from NC freshwater and estuarine waters to the Atlantic Ocean to spawn
- Up to 4 million eggs have been observed in a single female Striped Mullet
- Striped Mullet are capable of full osmoregulation, meaning they can tolerate salinities ranging from entirely freshwater to full seawater strength
- The diet of Striped Mullet is primarily bottom muck and surface scum – feeding habits of fishes referred to formally as “herbivorous detritivores”
- Mullet “jump” to move air into the upper portion of the pharynx to aid respiration
2022 Harvest Seasons for Striped Mullet
- The recreational limit for Striped Mullet is currently 200 fish per day (Striped Mullet and White Mullet combined). There is no size limit as harvest is focused on small fish used as bait.
- No annual quota exists for commercial landings of Striped Mullet. Proclamations for Striped Mullet can be found here.
FINDEX provides the most recent stock status updates for a variety of North Carolina’s finfish species. As new data is made available, FINDEX values will be revised. If you’re interested, FINDEX can be delivered to you each month if you subscribe to Think Coastal.
Formed in 2017, the N.C. Marine and Estuary Foundation and its brand “Think Coastal” were established to support world-class fisheries and thriving coastal economies. In achieving this goal, the N.C. Marine and Estuary Foundation equips citizens, researchers, legislators, policymakers, stakeholders, and other organizations with high-quality scientific information to help solve challenging fisheries issues.
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