This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Southern Flounder Paralichthys lethostigma is the most commonly harvested flatfish in the north‐central Gulf of Mexico (GOM), yet knowledge of this species’ growth and reproduction is limited for the Mississippi region. Given the offshore spawning migrations and likely mixing between state‐managed units of the GOM Southern Flounder stock, small‐scale environmental influences may constitute a major driver of life history dynamics during early life residency in nearshore estuaries. Therefore, estimates of local demographic characteristics are needed for effective fishery management. Here, we describe critical life history traits of Southern Flounder, including estimation of growth rates and maturity. The three‐parameter von Bertalanffy growth function best described female‐specific growth: mean asymptotic length L∞ was 514 mm TL, mean growth coefficient k was 0.67 year–1, and mean theoretical age at zero length t0 was –0.50 years. The estimated female‐specific mean length at 50% maturity (L50) was 303 mm TL, and the female‐specific mean age at maturity was 0.96 years. Although we observed significant differences between L50 estimates in the GOM, length‐at‐age parameter estimates were similar to those reported for other areas of the GOM. Both individual growth and length‐at‐maturity estimates were significantly different from those reported for the Atlantic, suggesting basin‐level differences in population characteristics, with faster growth and earlier maturation in the GOM. Histological indicators and gonadosomatic index data indicated that the spawning season in the north‐central GOM occurs from November to January and that Southern Flounder are batch spawners with asynchronous oocyte development. Our study provides a description of growth and spawning dynamics that will contribute to future stock assessment efforts focused on the Southern Flounder fishery in Mississippi and the GOM.
Spotted Seatrout Cynoscion nebulosus are a highly valued recreational inshore species in Mississippi coastal waters. The accurate description of the length-at-age relationship is critical for assessment efforts of the stock. Because Spotted Seatrout exhibit small-scale movements, the stocks in the Gulf of Mexico are managed as statespecific units. Therefore, local demographic estimates of length at age are needed for assessment. We estimated the length-at-age relationship of Spotted Seatrout in Mississippi by using tag recapture records and otolith-derived age estimates. Three nonlinear length-at-age models were fit to sex-aggregated, tag recapture data and four nonlinear length-at-age models were fit to sex-specific, otolith-derived age data. For each suite of models, model support was determined using Akaike information criteria. The Francis (1988a) GROTAG method had the greatest support of the three models fit to the tag recapture data, and the resulting parameter estimates from the model were L 1 D 550.8 mm and k D 0.45/year. The three-parameter logistic model had the greatest support of the four models fit to the otolith-derived age data for both males and females and the resulting parameter estimates of L 1 were 605.3 mm TL for females and 574.9 mm TL for males. The results of this study indicate that (1) the Francis (1988a) GROTAG model was the best-supported method for the determination of the von Bertalanffy growth function parameters from tag recapture information, and (2) the von Bertalanffy growth function may not be the best model to describe the length-at-age relationship of Mississippi's Spotted Seatrout. This work highlights the utility of using multiple sources of length-at-age information and fitting multiple models to enhance both the description of the length-at-age relationship and to determine biases that occur in both.
The Spotted Seatrout Cynoscion nebulosus is the most popular target of recreational inshore fisheries in Mississippi coastal waters. The Gulf of Mexico (GOM) stock of Spotted Seatrout is composed of spatially distinct substocks, and each state imposes unique bag and size limits. In Mississippi, the stock is managed using minimum length limits and daily bag limits. We used two methods to evaluate the efficacy of length restrictions and fishing mortality (F) levels: (1) a per‐recruit model simulation to evaluate the effects of proposed management actions on reproductive output and yield, and (2) an evaluation of how management regimes impact relative stock density (RSD). Relative stock density has been widely used as a management tool in recreational and generally freshwater fisheries but has not been widely employed in informing management of marine stocks. We used demographic information from fisheries‐independent sampling and length‐specific natural mortality estimates to construct both models. Our analysis suggested that decreased F, increased minimum length limits, and slot limits that include intermediate upper length limits could increase RSD measures for GOM Spotted Seatrout. We found that for all management regimes examined, local demographic properties of Spotted Seatrout may preclude large proportions of trophy‐length (≥686 mm TL) individuals. Per‐recruit modeling and RSD analysis are complementary approaches to inform management, as they consider spawning stock biomass, yield, and the maximization of angler satisfaction. Received October 6, 2015; accepted June 8, 2016 Published online September 13, 2016
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.