Coastal Longline Survey - North Carolina
The North Carolina Coastal Longline Survey (NC-CLS) is a National Marine Fisheries Service funded fishery-independent survey conducted by the North Carolina Division of Marine Fisheries (NCDMF) since 2007. As a program component of SEAMAP South Atlantic, the NC Coastal Longline survey is designed to provide a repository of long-term fishery-independent data on the distribution, relative abundance, catch per unit effort, and size distribution of adult red drum in Pamlico Sound, North Carolina. Additionally, the survey provides information on the relative abundance, size distribution, sex, and maturity of multiple species of small and large coastal sharks occurring in Pamlico Sound.
Survey Design
The study area is divided into twelve similarly sized regions ranging from Gull Island (North of Avon, NC) to the mouth of the Neuse River. These regions are based on prior NCDMF red drum sampling and were chosen to optimize sampling efficiency (Figure 1). A stratified-random sampling design is utilized to select sample grids (one square nautical mile) within each sampling region. Sampling occurs annually over three continuous 4-week periods from mid-July to mid-October and each region is sampled six times. Each year 72 random samples (12 regions x 3 periods x 2 samples per grid = 72 samples) are taken.
All stratified-random sampling begins no sooner than an hour prior to sunset and continues into the night. Soak times are kept to approximately 30 minutes to standardize effort and ensure red drum are tagged in good condition. All random samples are conducted using a 1,500-meter bottom longline, with 100 hooks per set, that is retrieved using a hydraulic reel. The hooks are baited with cut striped mullet, but in the event mullet is not available squid is used. Catch per unit effort (CPUE) is calculated as the number of red drum captured per 100 hooks. Environmental and habitat data is recorded during the haul back of each main line and includes location, duration/soak time, gear parameters, sediment size, bottom composition, depth (m), surface and bottom temperature (°C), surface and bottom salinity (ppt), surface and bottom dissolved oxygen (mg/L), weather description, wind direction, wind speed (knots), and location (lat-longs in degrees, minutes seconds) of tagged and released fish.
All red drum captured are measured (FL and TL) to the nearest millimeter and the presence or absence of ‘drumming’, indicative of males only, is noted. A fin clip taken from the caudal fin is removed for genetic analysis. Red drum that will be released are tagged using either a stainless-steel dart tag (>550 mm FL) or an internal anchor tag (<550 mm FL). In addition, all released red drum are implanted with a Passive Integrated Transponder (PIT) tag in the musculature just below the junction of the first and second dorsal fins. Double tagging red drum allows long-term tag retention rates to be determined. Additionally, the PIT tags allow recaptures in the survey to be documented, even if the external tag is not present. A systematic random subsample of red drum is retained for age (otoliths), sex determination, maturity information, genetic data, and diet analysis.
In addition to red drum, other finfish and shark species captured in the survey are enumerated and measured with pertinent biological data recorded. Coastal shark species that are in good condition are tagged as part of the National Marine Fisheries Service Cooperative Shark Tagging Program.
Data Acknowledgement, Caveats, and Protocols
For guidance on data acknowledgements, caveats, and a more detailed description of the methods used, please see the Data Acknowledgment, Caveats, and Protocols: NC-CLS. This document provides critical information regarding the use of NC-CLS data and should be read in full before querying this data. Each requestor is solely accountable for any further analysis, manipulation, or presentations. It is also the responsibility of the data user to cite and acknowledge SEAMAP and the North Carolina Longline Survey.