56.4% = DEFICIENT
How It’s CalculatedFINDEX is a novel way to gauge whether the status of a population is trending up or down. Management of most fish and shellfish species in North Carolina is guided by stock assessment models developed by various groups of scientists. The calculations in our FINDEX metric measure the gap between the desired condition of a stock (the Target reference value) and the existing condition (the most recent data year in the model called the Terminal value) as determined in each stock assessment. The gaps between Target and Terminal values are calculated as ratios. For example, if the Target and Terminal values are the same, there would be no gap and the ratio would be 1.0. The multiplier on our FINDEX barometer would set the FINDEX value at 100% in this example and assign a stock status designation of “Stable.” Categories on our FINDEX barometer are measurable as they track the extent of the gap either above or below the “Stable” designation. For Blue Crab, the FINDEX gap assessment compared Target and Terminal values of Fishing Mortality (F) and Average Spawner Abundance (ASA) from the stock assessment developed by the NC Division of Marine Fisheries. The Target value for Average Spawner Abundance was established at 73 million mature Blue Crab females. The Terminal year (the most recent data year) in the stock assessment model was 2016. FINDEX recognizes that Fishing Mortality (lower is better) and Average Spawner Abundance (higher is better) are inversely related, so we adjust our gap calculations whenever the two ratios are considered together.
Here's the FINDEX formula used for Blue Crab:
- (0.824 x .685) x 100 = 56.4%
- FINDEX = 56.4% for 2016
- 56.4% = DEFICIENT
What Does Deficient Mean?FINDEX designation as “Deficient” is assigned to any stock with a value between 50 and 99%. In the case of Blue Crab, Terminal values of both Fishing Mortality and Average Spawner Abundance failed to meet the established Target values. Note there is a considerable time lag associated with updates to the Blue Crab stock assessment. For this reason, FINDEX calculations may not accurately describe current conditions – instead, FINDEX evaluates the most recent scientific data available (2016 in the case of Blue Crab).
FINDEX Status Over TimeThe stock assessment model for Blue Crab provides point estimates of Fishing Mortality and Average Spawner Abundance for each year covered in the data set. We’ve compared the Target reference values to these annual point estimates and calculated the ratios (gaps) for each data year through the period 1995–2016. Applying the FINDEX gap assessment to the entire time series provides the following stock status trendline:
Commercial Blue Crab TrendsThe graph below illustrates commercial harvest trends for Blue Crab from 1985 through 2021. In 2021, 539 commercial fishers recorded 29,982 trips in pursuit of hard Blue Crabs with another 13,164 trips reporting harvest of peeler and soft crabs. Combined harvest of hard, peeler, and soft crabs in 2021 was 12,819,824 pounds valued at $23,950,761. Supporting data was sourced from the North Carolina Department of Environmental Quality.
Commercial Blue Crab Harvest
No Data Found
Recreational Blue Crab Trends
The Marine Recreational Information Program that is used to estimate harvest and discards of North Carolina’s recreational fisheries does not capture Blue Crab data. However, the NC Division of Marine Fisheries conducts an annual mail survey of anglers who have purchased a Coastal Recreational Fishing License to estimate Blue Crab harvest in the recreational sector.
This data program has limitations, especially considering an individual does not need a fishing license to keep Blue Crabs. The estimated recreational harvest of Blue Crab from the mail survey averaged 82,178 (27,393 pounds) between 2011 and 2021. Annual estimates of Blue Crab harvested by holders of a Recreational Commercial Gear License are currently unknown.
2023 Harvest Seasons for Blue Crab
- The recreational limit for Blue Crab is currently 50 per day, with a minimum size limit of 5-inch carapace length.
- Blue Crabs cannot be possessed during the month of January north of the Highway 58 Bridge, or from March 1 through March 15 south of the Highway 58 Bridge.
- Commercial fishing operations for Blue Crab typically use a gear referred to as a “Crab Pot”. Crab Pots accounted for almost 96% of all Blue Crab landings in 2021. Proclamations for Blue Crab that outline the various commercial harvest restrictions can be found here.
Did you know?
- Most Blue Crabs landed commercially in North Carolina come from Albemarle Sound. In 2021, more than 5.3 million pounds of hard Blue Crabs were sold from this region, with over 275,000 pounds of soft and peeler crabs harvested as well. Currituck Sound and Pamlico Sound both supported Blue Crab landings in excess of 1.2 million hard crabs in 2021.
- A Blue Crab shell is called a “carapace”. The abdomen or underside of the crab is called an “apron”.
- Male and Female crabs can be distinguished by the shape of the apron. A male crab has a “T-shaped” apron, whereas a female crab has a triangular apron.
- A male crab is called a “Jimmy” and a female crab is called a “Sook”. “Sponge Crabs” are female crabs carrying an egg mass which typically varies in color from black to bright orange.
- Blue Crabs grow by shedding their shell during a process called “molting”. Prior to becoming mature, a Blue Crab might molt as many as 20 times.
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, new FINDEX profiles can be delivered to you directly if you subscribe to our newsletter.
Formed in 2017, the N.C. Marine and Estuary Foundation was 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.