Fisheries and Resources Monitoring System

Black seabass - Southeastern Atlantic coast of USA
Marine Resource  Fact Sheet
Status of stocks and resources 2019
Black seabass - Southeastern Atlantic coast of USA
Fact Sheet Citation  
Owned byFood and Agriculture Organization (FAO) – More
Related observationsLocate in inventorydisplay tree map
FAO Names: en - Black seabass, fr - Fanfre noir, es - Serrano estriado
Geographic extent of Black seabass - Southeastern Atlantic coast of USA
Main Descriptors
Considered a single stock: Yes        Spatial Scale: National
Management unit: Yes        Reference year: 2016
Biological State and Trend
State & Trend Descriptors
Exploitation rateF2014−2016/FMSY = 0.64Not applicable
Abundance levelSSB2016/MSST = 1.15Not applicable
FAO Categories
Exploitation stateMaximally sustainably fished

A recent assessment of black seabass (Centropristis striata) in USA South Atlantic waters indicated that the stock was not overfished nor undergoing overfishing. 
Habitat and Biology
Climatic zone: Tropical; Temperate.   Vertical distribution: Demersal/Benthic.  

Water Area Overview
Spatial Scale: National

Geo References
Resource Structure
Considered a single stock: Yes

Data up to 2016. The United States of America reports 100% of total landings in FAO Area 31. The catch-age model included data from fishery independent surveys and from five fleets that caught black sea bass in southeastern U.S. waters: commercial lines (primarily handlines), commercial pots, commercial trawls, recreational headboats, and general recreational. The model was fitted to data on annual landings (in units of 1000 lb whole weight), annual discard mortalities (in units of 1000 fish), annual length compositions of landings, annual age compositions of landings, annual length compositions of discards, two fishery-independent indices of abundance (MARMAP blackfish/snapper traps and SERFS combined chevron traps and videos), and two fishery-dependent indices (commercial lines and headboat). Data used in the model are tabulated in §2 of this report.
Assessment Model
Type:  Age-structured
Beaufort Assessment Model (BAM)

The primary model used in the SEDAR25 benchmark and the update - and updated here - was the Beaufort Assessment Model (BAM), a statistical catch-age formulation. A base run of BAM was configured to provide point estimates of key management quantities, such as stock and fishery status. Uncertainty in estimates from the base run was evaluated through a mixed Monte Carlo/Bootstrap (MCB) procedure.
Overall Assessment Results

Total and Spawning Biomass - Estimated biomass at age followed a similar pattern as abundance at age (Figure 18; Table 7). Total biomass and spawning biomass showed similar trends—general decline from early 1980s until the mid-1990s, a relatively stable period from 1993–2006, and an increase followed by a decline since 2007 (Figure 19; Table 8). The decrease in biomass at age is less noticeable than in abundance at age due to the larger size of the older fish. - Fishing Mortality, Landings, and Discards - The estimated fishing mortality rates (F) generally increased through the early 2000s, reaching a peak in 2006. Since then, the fishing mortality due to landings have all decreased (Figure 26). The general recreational fleet has been the largest contributor to total F (Table 10). Estimates of total F at age are shown in Table 11. In any given year, the maximum F at age (i.e., apical F) may be less than that year’s sum of fully selected Fs across fleets. This inequality is due to the combination of two features of estimated selectivities: full selection occurs at different ages among gears and several sources of mortality have dome-shaped selectivity. Table 12 shows total landings at age in numbers, and Table 13 in weight. In general, the majority of estimated landings were from the recreational sector, i.e., headboat and general recreational fleets (Figures 27, 28; Tables 14, 15). Estimated discard mortalities occurred on a smaller scale than landings (Figure 29; Tables 16, 17). - Status of the Stock and Fishery - Estimated time series of stock status (SSB/MSST and SSB/SSBMSY) showed general decline until the mid-1990s and some increase since (Figure 36, Table 8). The increase in stock status appears to have been initiated by strong year classes in 2008 and 2010, and perhaps reinforced by management regulations. Base-run estimates of spawning biomass have remained near MSST and below SSBMSY since the early 1990s, increased substantially from 2008 to 2012, and then decreased again in the last three years. Current stock status was estimated in the base run to be SSB2016/MSST = 1.15 and SSB2016/SSBMSY = 0.71 (Table 18), indicating that the stock is not overfished, but is below SSBMSY for the stock. Uncertainty from the MCB analysis suggested that the estimate of SSB relative to SSBMSY is robust, but that the status relative to MSST is less certain (Figures 37, 38). More specifically, about 99.8% of MCB runs indicate the stock is below SSBMSY, but only 23.4% of the MCB runs indicated an overfished status. Age structure estimated by the base run showed fewer older fish in the last decade than the (equilibrium) age structure expected at MSY (Figure 39), however with improvement in the terminal year (2016), particularly for ages younger than six. The estimated time series of F /FMSY suggests that overfishing has been occurring throughout most of the assessment period (Table 8), but with much uncertainty demonstrated by the MCB analysis (Figure 36). However, the fishery benchmark is based on the last three years of selectivity and fishing mortality, and may not be appropriate to compare to earlier years as the selectivity and the proportional contributions of the fleets to the total fishing mortality have changed through time. Current fishery status in the terminal year, with current F represented by the geometric mean from 2014–2016, was estimated by the base run to be F2014−2016/FMSY = 0.64 (Table 18), and only 5.2% indicated that overfishing is still occurring (Figures 37, 38).
Scientific Advice

• Establish a more comprehensive sampling program for ages and lengths of fish captured by the recreational fleet in all regions of the South Atlantic. • Investigate discard mortality due to hooks in shallow waters (<10m). • For this assessment, the age-dependent natural mortality rate was estimated by indirect methods. More direct methods, e.g. tag-recapture, might prove useful. Some tag-recapture studies have demonstrated relatively high tag return rates for black sea bass, at least compared to those of other reef fishes of the southeast U.S. • Gather more depth data from private boat anglers. • Investigate the potential for a range shift in the black sea bass population, and the potential causes, such as climate change. • The following are from SEDAR25, and are still needed: • The assessment panel recommended increasing the number of age samples collected from the general recreational sector. • Black sea bass in the southeast U.S. were modeled in this assessment as a unit stock, as recommended by the DW and supported by genetic analysis (SEDAR 56-RD42). For any stock, variation in exploitation and life-history characteristics might be expected at finer geographic scales. Modeling such sub-stock structure would require more data, such as information on the movements and migrations of adults and juveniles, as well as spatial patterns of recruitment. Even when fine-scale spatial structure exists, incorporating it into a model may or may not lead to better assessment results (e.g., greater precision, less bias). Spatial structure in a black sea bass assessment model might range from the very broad (e.g., a single Atlantic stock) to the very narrow (e.g., a connected network of meta-populations living on individual reefs). What is the optimal level of spatial structure to model in an assessment of snapper-grouper species such as black sea bass? • The assessment time period (1978–2010) is short relative to some other assessments of South Atlantic reef fishes. Extending the assessment back in time might provide improved understanding of the stock’s potential productivity and therefore sustainable yield, assuming the historic productivity is still relevant. Such an extension would require historic landings estimates from all fleets in operation. Although historic estimates from the commercial sector are available, those from the recreational sector are not. Hindcasting the historic recreational landings might require the development of new methods, or at least analysis of existing methods. • Protogynous life history: 1) Investigate possible effects of hermaphroditism on the steepness parameter; 2) Investigate the sexual transition for temporal patterns, considering possible mechanistic explanations if any patterns are identified; 3) Investigate methods for incorporating the dynamics of sexual transition in assessment models. • In this assessment, the number of spawning events per mature female per year assumed a constant value of X = 31. That number was computed from the estimated spawning frequency and spawning season duration. If either of those characteristics depends on age or size, X would likely also depend on age or size. For black sea bass, does spawning frequency or spawning season duration (and therefore X) depend on age or size? Such dependence would have implications for estimating spawning potential as it relates to age structure in the stock assessment. • For this assessment, the age-dependent natural mortality rate was estimated by indirect methods. More direct methods, e.g. tag-recapture, might prove useful. Some tag-recapture studies have demonstrated relatively high tag return rates for black sea bass, at least compared to those of other reef fishes of the southeast U.S.

Management unit: Yes
Source of information
FAO. Western Central Atlantic Fishery Commission. 2019. Review of the state of fisheries and fisheries resources in the WECAFC region. Meeting document WECAFC/SAG/IX/2018/3 of the ninth session of the Scientific Advisory Group, Christ Church, Barbados, 19-20 November 2018.  Click to open
SEDAR. 2018a. South Atlantic Black Seabass. SEDAR 56 Stock Assessment Report. SEDAR, North Charleston SC. 164 pp.  Click to open
FAO. Western Central Atlantic Fishery Commission/FAO Commission des pêches pour l’Atlantique Centre-Ouest/FAO Comisión Central de Pesca para el Atlántico CentroOccidental. 2019. Report of the ninth session of the Scientific Advisory Group, Christ Church, Barbados, 19-20 November 2018. Rapport de la neuvième session du Groupe scientifique consultatif, Christ Church, Barbade, 19-20 Novembre 2018. Informe de la octava sesión del Grupo Asesor Científico, Christ Church, Barbados, 19-20 de Noviembre de 2018. FAO Fisheries and Aquaculture Report/Rapport sur les pêches et l’aquaculture/Informe de Pesca y Acuicultura. No. 1266. Bridgetown, 156 pp.  Click to open
All references to figures, tables and bibliography in the text are found within the source of information.
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