Policymakers in the northern Gulf of America have proposed various spatial closures in recent years as a management tool for the Gulf Menhaden Brevoortia patronus fishery. In this work, we aim to understand how the seasonal movement of the stock will impact the efficacy of spatial restrictions by examining the short-term impacts of simulated area closures of 1.6, 3.2, and 4.8 km adjacent to land on the commercial Gulf Menhaden fishery using commercial logbook data from 2006 to 2009 and 2011. We used bootstrap resampling (n = 1,000) of trip-level data to describe five descriptive metrics. These were the mean set-specific catch per unit effort (CPUE, metric tons, mt set-1), the mean number of sets deployed on each trip, the mean trip-specific CPUE (mt minute-1), the median distance (km) traveled to the first set, and the median distance (km) traveled among subsequent sets (for trips with at least two sets). We explored the impacts of closures by comparing the month-specific distributions of the descriptive metrics from all trips to those calculated using only those trips with all sets outside of a particular restricted area. Using the simulation, we evaluated the resulting spatial differences in fishing effort that would occur. The results of the simulation indicated that, in all restriction scenarios for all months, the spatial restrictions served to increase the travel distance to the first set and to reduce the mean number of sets taken. Set-specific and trip-specific CPUE are reduced in the restriction scenarios. We found that the reduction of total harvest (mt) for the 1.6 km restriction regime was 4.3 to 7.2%, 9.1 to 12.0% in the 3.2 km restriction regime, and 12.7 to 15.4% in the 4.8 km restriction regime. This work provides information about the impacts on the fishery that result from area closures. Such information is necessary to evaluate the efficacy and impacts of spatial closures for the Gulf Menhaden fishery.

Southern Flounder, Paralichthys lethostigma, is an important fish in the northern Gulf of America and has declined throughout its range. In this work, we evaluate a spatially-and temporally-integrated per-recruit model by incorporating information on movement dynamics and spatial differences in fishing pressure. A total of n = 80 Southern Flounder were tagged in Saint Louis Bay, Mississippi with acoustic transmitters. We classified n = 11 individuals as migrators, these individuals exhibiting movement to offshore spawning locations, and n = 16 individuals as residents, these individuals overwintering in inshore habitats. Incorporating the total proportion of migrators, timing of egress from inshore habitats, and differences between inshore and offshore fishing pressure into the spatiotemporally integrated per-recruit model resulted in changes to reference points. In the traditional per-recruit model, at Mississippi's current minimum size limit of 305 mm, F0.4 = 0.41 y-1 and Fmax = 0.78 y-1; at a size limit of 381 mm, reference points increase to F0.4 = 0.64 y-1 and Fmax = 1.12 y-1. Under the current 305 mm size limit, F0.4 = 0.41 y-1 and Fmax = 0.78 y-1 in the traditional model, while F0.4 = 0.27 y-1 and Fmax = 0.52 y-1 in the integrated model. These contrasts indicate that the stock is more vulnerable when movement is explicitly considered in the model. The results of both traditional and spatiotemporally integrated per-recruit models indicate that changes to the current management regime could benefit the Southern Flounder stock.

The northern Gulf of Mexico (nGOM) is a taxonomically rich ecosystem. Previous work based on a meta-analysis of stomach contents data has shown the trophic connectivity of predators and prey to be substantial. However, the trophic dynamics of many economically and ecologically important species are still not well understood. Sportfish, such as Spotted Seatrout (Cynoscion nebulosus), Red Drum (Sciaenops ocellatus), and Southern Flounder (Paralichthys lethostigma), support recreational fisheries throughout the region. Gulf Menhaden (Brevoortia patronus), a high biomass forage fish with the region's largest commercial fishery, is considered an important forage species. In this study, we use information from meta-analysis of stomach contents and stable isotope analysis to investigate the importance of prey taxa, including Gulf Menhaden, for nGOM nearshore predators. Stomach contents and stable isotope analyses are generally evaluated independently, with stomach contents used to directly identify trophic interactions, while stable isotopes of carbon (δ13C) and nitrogen (δ15N) provide insight into a consumer's long-term feeding habits. We used a multispecies trophic model, EcoDiet, developed by Hernvann et al. (2022), that integrates information of both stomach contents and stable isotopes into a single framework to estimate trophic link probabilities and diet proportions. Data in the model include n = 41 predators, n = 173 prey, and n = 497 unique predator and prey interactions. The results indicate that nGOM nearshore predators are generalists using the diverse prey base, and in concordance with previous findings, there is no single Menhaden-dependent predator. Our findings better quantify the trophic interactions of the highly diverse nGOM region and have important implications regarding future ecosystem modeling and management considerations for the Gulf Menhaden stock.

Low trophic-level fishes provide a link to higher trophic-level animals, including birds, mammals, and economically valuable fishes. Despite their role, the dry energy density (DED) of these fishes and its variability have not been described in the northern Gulf of Mexico (nGOM). To address this, we describe species-specific DED for four fish species in the nGOM: Atlantic Croaker (Micropogonias undulatus), Gulf Menhaden (Brevoortia patronus), White Trout (Cynoscion arenarius), and Bay Anchovy (Anchoa mitchilli). We investigated the impacts of body length, life stage (juvenile and adult), month of collection, and river discharge from the Mississippi River to determine the response of DED for Atlantic Croaker and Gulf Menhaden. Using bomb calorimetry, we found that the DED of Atlantic Croaker ranged from 3021 to 6445 calories/g (mean = 4524 +/- 646 calories/g SD, n = 129), Gulf Menhaden DED ranged from 2578 to 6821 calories/g (mean = 5069 calories/g +/- 794 SD, n = 193), White Trout DED ranged from 3118 to 4581 calories/g (mean = 4120 calories/g +/- 358 SD, n = 30), and Bay Anchovy DED ranged from 3925 to 4387 calories/g (mean = 4261 +/- 126 calories/g SD, n = 74). The mean DED of Gulf Menhaden and Atlantic Croaker varied and was at a minimum during the fall. The DED of Gulf Menhaden and Atlantic Croaker were linearly, positively, and significantly (alpha = 0.05) related to fork length (R-2 = 0.23 and R-2 = 0.32, respectively). The flow rate of the Mississippi River was not a significant predictor of the DED of juvenile or adult Gulf Menhaden but was a significant predictor of the DED of adult Atlantic Croaker (p < 0.001, R-2 = 0.04). The species-specific energy density values and the variations due to the month of collection, environmental conditions, and physiological variation will serve to inform ecosystem models.

Discards from commercial fisheries have been linked to detrimental effects on ecosystems and stocks of living marine resources. Understanding spatial and temporal patterns of discards may assist in devising regulatory practices and mitigation strategies and promote sustainable management policies. This study investigates data from bycatch monitoring programs using a machine learning approach. We used a gradient boosting classifier for describing catch and bycatch patterns in the U.S. Mid-Atlantic Black Seabass (Centropristis striata), Summer Flounder (Paralichthys dentatus), Scup (Stenotomus chrysops), and Longfin Squid (Doryteuthis pealeii) fisheries. We used oceanographic, biological, spatial, and fisheries data as explanatory model features. We found positive associations between target species volume and bycatch. Although we found that sea surface temperature and year were important model features, the direction of impact of those predictors was variable. From our findings, we conclude that machine learning approaches are promising in supplementing traditional methodologies, especially with the increase in data availability trends.

Red drum Sciaenops ocellatus are conspicuous members of the ichthyofauna in the coastal zone of the northern Gulf of Mexico and support a popular inshore recreational fishery. Red drum exhibits differences in distribution where younger fish (age ≤ 4 years, y) are found primarily in inshore estuarine locations, and older individuals are generally found in offshore locations near Mississippi’s barrier islands. In this study, we evaluate stable isotope values of carbon and nitrogen in muscle tissue of red drum to (1) understand how these vary with the location (bearing) of capture, age (y), and total length (TL, mm), (2) describe how patterns of isotopic niche space and overlap vary with age group, and (3) evaluate if location category (estuary and island) of capture could be predicted using a machine learning approach. We found that patterns of δ13C and δ15N were variable with bearing, TL, and age. Contrasting patterns of age-specific δ13C and δ15N values are evident in younger fish (age ≤ 2 y and age 3 to 4 y). Fish from estuaries had lower δ15N and lower δ13C. To understand age group–specific patterns of isotopic niche space and overlap, we employed a bootstrapping algorithm using SIBER and nicheRover. We observed a minimum overlap of isotopic niche space between the age group comprised of age 1 to 6 y individuals and the age group comprised of age 7 + y individuals. The area of the isotopic niche space was greatest for the age group comprised of age 1 y individuals and for the age group comprised of age 1 to 7 y individuals. To understand if the location category of capture could be predicted, we constructed a random forest model. We found that the variables δ13C, δ15N, and TL are the most important predictors of the location category of capture. The out-of-bag error rate for the classification was 5

The Red Snapper Lutjanus campechanus is a structure-associated species occurring across a wide depth range in the northern Gulf of Mexico. We used the random forest machine learning algorithm to understand which habitat and individual fish characteristics could predict reproductive parameters of female Red Snapper. We evaluated fish captured from 2016 to 2018 on three artificial structure types with various structure heights at depths of 100 m or less. Overall, we found that depth and month were important predictors for most reproductive parameters, but the type of structure (artificial reefs, oil platforms, and rigs-to-reefs structures) was not important. Maturity was correctly classified in 88.9% of the cases when using the random forest ensemble model, with important predictors including FL, depth, structure height, and month of collection. Spawning seasonality (measured as gonadosomatic index [GSI]) was correctly classified in 59.5% of the cases when using histology reproductive phase, FL, month, and depth variables. Reproductively active or inactive females were correctly classified in 89.3% of the cases using GSI, month, FL, and depth, while females in the developing versus spawning capable phases were correctly classified in 82.2% of the cases using GSI, FL, month, and depth. Histological indicators that show potential spawning within a 36-h period were correctly classified 61.5% of the time, with the best predictors being depth, FL, GSI, and month. Stepwise regression indicated that month was the only factor that significantly predicted contrasts in relative batch fecundity, with significantly greater values in August compared to all other months. Our findings suggest that female Red Snapper reproductive effort is not consistently or well predicted by artificial structure type or height but that a combination of fish FL, month, and depth can predict reproductive characteristics of female Red Snapper.

Enhanced product yields, reduction in throughput time, improved cost-effectiveness and product quality are examples of benefits gained by delaying apoptotic cell death in bioreactors. To examine the effect on recombinant protein production, bcl-x(L) was overexpressed in a CHO cell line secreting humanized monoclonal antibody directed against the alpha1beta1 integrin. When cell lines overexpressing bcl-x(L) were compared to the parent, cell viability was increased by 20% and titers by 80%. Total viable cell densities were similar and specific productivities were enhanced by almost two-fold on scale-up to bioreactors. Comparison in a chemically defined media demonstrated an even greater sustained viability in bcl-x(L) expressing cells by 50% and up to 90% increase in titer with no impact on product quality. Caspase 3 activities were monitored as a marker for apoptotic cell death. In the presence of Bcl-x(L), caspase activities were reduced to background levels. The role of Bcl-x(L) in protecting cells from premature death was further examined in studies performed in the presence of NaBu, at concentrations known to trigger cell death. Results demonstrated that cells expressing bcl-x(L) retained 88% cell viability with >2 fold increase in titer. Bcl-x(L) was similarly overexpressed in a different CHO cell line producing a humanized mAb against the chemokine MCP1. Once again, production titer was increased by 80% and viability by 75%. Together the studies have shown that overexpression of bcl-x(L) in production cell lines was able to significantly increase the titer by enhancing both the specific activity and total cell viability while maintaining product quality.

The quantification of niche diversity and niche overlap is useful for understanding the impacts of fisheries regulation and management. In this work, we evaluate isotopic niche size and overlap at the guild and species levels. Specifically, we analyzed guild- and species-specific isotopic niche space and niche space overlap using the SIBER and nicheROVER packages, and we evaluated length-specific and geographic contrasts in isotopes for fishes in the north-central Gulf of Mexico. Stable carbon and nitrogen isotope values (delta C-13 and delta N-15) of fish species were compared among four ecotype-based fish guilds: estuarine, coastal migratory pelagic (CMP), reef, and large offshore pelagic (LOP). Significant differences in the mean stable isotope values were found among fish guilds. Estuarine guild species exhibited the highest delta C-13 variability, and Red Drum Sciaenops ocellatus were the most isotopically diverse. Variability of delta C-13 for CMP fish was comparable to that of some estuarine species, whereas reef and LOP fish were less variable. Fishes within the LOP guild had the largest delta N-15 range. Reef guild fishes had the smallest isotopic niche space and LOP guild species consistently had the largest, although no species in any guild occupied as large of an isotopic niche space as Red Drum. Distinct and well-separated isotopic niches were also observed between most estuarine species and CMP species; however, high niche overlap was observed for species within the reef and LOP guilds. We found a positive relationship of delta N-15 and fish TL for Red Drum, Blackfin Tuna Thunnus atlanticus, and Yellowfin Tuna T. albacares, and we found that delta N-15 values for Red Drum and Red Snapper Lutjanus campechanus showed distinct isotope differences between geographic areas. This study provides data not only on how species within and without ecotypes interact but also on the variability of their interactions, all of which can inform ecosystem-based fisheries management models.

There is a considerable knowledge gap regarding the ecology and biogeography of blennies (Family Blenniidae) in Pakistan. To address this, we performed an extensive coastal survey from Pakistan's Sindh and Balochistan provinces in 2018 and 2019. The goal of the survey was to inventory the presence of members of rockskippers of the family Blenniidae, provide detailed description of the collected specimens, and describe otolith shape and camouflage efficiency in natural and captive environments. We focused our analysis and description on six species of the family Blenniidae (n = 53) including Antennablennius bifilum (n = 12), Blenniella cyanostigma (n = 12), Istiblennius edentulous (n = 17), Istiblennius spilotus (n = 1), Pereulixia kosiensis (n = 9), and Praealticus striatus (n = 2). Sagitta otoliths (right side) were extracted and detailed descriptions are provided. Camouflage efficiency was categorized as immediate, moderate, or low for each species. This was done by making visual observations of individuals in natural and captive environments. This study documents, for the first time, the presence of six rockskipper from the study area and the camouflage capacity of different species. These data enhance information about ornamental fishes in the region to promote conservation and management.

Biological data that are collected in commercial port sampling programs are a critical component of the assessment and management of Gulf MenhadenBrevoortia patronusand Atlantic MenhadenBrevoortia tyrannus. The menhaden port sampling program represents one of the longest continuous commercial sampling efforts in the United States; however, this sampling program has not been evaluated recently to determine whether the program adequately characterizes the size and age structure of the catch despite significant changes in the spatial extent and magnitude of the fisheries in the last three decades. We conducted a simulation study to evaluate current menhaden fishery sampling targets and to examine the relative performance of a suite of alternative targets. To simulate data collection, we conducted a bootstrap analysis of the observed port sampling data. These observations were resampled with replacement across a range of current and alternative combinations of number of trips and fish sampled per trip. At the current target for sampling intensity and allocation, the mean sample weight and proportions at age for ages 2 and 3 are well characterized in both the Gulf and Atlantic menhaden fisheries. The proportions of age-1 fish in the catch differed by stock and region, with samples from the northern Atlantic regions displaying the greatest uncertainty overall. The proportions of age-4 and older fish were poorly characterized in both fisheries, which is likely due to their rarity in the population (Gulf) and lack of spatial overlap between the fishery and the stratified distribution of menhaden by age along the coast (Atlantic). Our results indicate that reducing the number of fish that is sampled per trip from the current target of 10 to as few as four would have a minimal effect on estimates of mean size and proportions at age in the catch. Increasing the number of sampled trips will not greatly improve the characterization of catch size or age composition.

The identification of anthropogenic and environmental drivers on length-at-age of fish stocks is important to understanding ecosystem dynamics and harvest intensity. We evaluated coastwide annual growth of n = 187,115 Atlantic Menhaden (Brevoortia tyrannus) and n = 299,185 Gulf Menhaden (B. patronus), using samples collected from the North, Mid-, and South Atlantic from 1961 to 2016 and across the Gulf of Mexico from 1977 to 2016. Using hierarchical models of age 1 growth and age 2 growth, we evaluated a suite of candidate predictors including fishery landings, easterly (U) and northerly (V) wind velocity, river discharge, juvenile abundance, and the Atlantic Multi-decadal Oscillation (AMO). We found age 2 growth rates were smaller than age 1 growth rates for both species and that Atlantic Menhaden growth rates were 3-4 times greater than Gulf Menhaden. Age 1 growth rate of Atlantic Menhaden was positively affected by landings lagged by one year, indicating a density-dependent mechanism. In addition, AMO (negative effect), and wind U (positive effect) and wind V (negative effect) in the North Atlantic region were significant factors influencing coastwide age 1 Menhaden growth. Wind V (negative effect) and AMO (positive effect) influenced age 1 Gulf Menhaden growth. No environmental factors were found to have an effect on age 2 Atlantic Menhaden growth, and AMO was the only significant predictor (weak negative effect) of age 2 Gulf Menhaden growth. Fishing pressure was the primary influence on age 1 Atlantic Menhaden growth, whereas age 1 Gulf Menhaden growth was primarily influenced by environmental conditions.

The Atlantic chub mackerel (Scomber colias) stock is commercially exploited throughout the Atlantic and Mediterranean and has been recently targeted by a small, but emerging, fishery off the Northeast coast of the United States.Recent efforts by the Mid-Atlantic Fishery Management Council to manage the Northwest Atlantic stock have necessitated the description of its life-history characteristics.The objectives of this study were to evaluate the utility of ageing methods, describe the length-at-age and weight-at-length relationships, and compare estimated growth parameter values to those reported from other regions.We found that whole otoliths provided the most precise method for age determination of Atlantic chub mackerel.Age estimates were derived for adult (n = 422) and larval fish (n = 60).Parameter estimates of individual growth models were determined using a Bayesian framework.The length-at-age relationship was described using four non-linear candidate growth models, which were fit to total length (TL, cm) and age estimates (y).We found that the three-parameter VBGF (L ∞ = 33.56cm TL, k = 1.75 y -1 , t 0 = 0.07 y) was the best candidate model to describe the length-atage relationship.A power function was used to describe the weight-at-length relationship from 1 136 individuals (a = 0.0258, b = 2.72).We found that individuals exhibit a greater rate of growth and reach smaller average maximum length when compared to published estimates in other regions.The rate of increase of weight relative to length was found to be significantly lower than that reported in other regions.These results can be used to inform assessment of the Atlantic chub mackerel stock in the Northwest Atlantic.

Here, we describe the trophic structure of the La Paz Bay, Baja California Sur, Mexico, and evaluate the role of weak trophic interactions in the ecosystem using a suite of topological indices. We used information derived from published and unpublished stomach contents analysis studies from the region to construct an unweighted and directional trophic network (comprising 250 nodes and 1528 associated interactions) to assess the impact of predators in three scenarios. Each scenario simulated the removal of weak interactions corresponding to removal of those nodes with trophic contributions less than 5%, 10%, and 15%. In each removal scenario, the nodes phytoplankton and zooplankton exhibited the greatest betweenness and closeness centrality, suggesting that they are critical groups in the structure of the web, especially in the transference of indirect effects to the largest number of possible nodes in the network. The multiphyletic nature of the phytoplankton and zooplankton, and their ubiquity in diets served to increase their connectivity to all taxonomic groups. We note the presence of numerous weak interactions (67% of taxa have weak trophic interactions) and speculate that this characteristic confers ecological resilience in the Bay of La Paz coastal marine ecosystem.

The Red Drum Sciaenops ocellatus stock is heavily targeted in the Gulf of Mexico (GOM) by recreational fishers and supports a small commercial fishery in Mississippi. Despite their popularity, little recent work has been done to describe their life history. In this work, we describe sex-specific growth and reproductive dynamics of Red Drum collected from the northern GOM from September 2016 through October 2017. We evaluated seven candidate growth models and found that the three-parameter von Bertalanffy growth function (VBGF) was the best candidate length-at-age model. No significant difference in growth between sexes was observed with the three-parameter VBGF, despite the female-specific curve having a larger mean asymptotic length than the male-specific curve. All seven candidate growth models predicted similar mean length-at-age estimates, and four of them exhibited significant differences in sex-specific mean length at age, with females reaching a larger length at age than males after age 5. There was no significant difference between the sex-specific weight-at-length relationships. Red Drum are batch spawners that spawn in northern GOM coastal waters during August and September. We estimated 3.7d between spawns and 10.5 spawning events per female in 2017. Nearly 20% of fish collected during the spawning season were sexually mature but reproductively inactive, indicating the possibility of skipped spawning. The age at 50% maturity was around 3years (length at 50% maturity=670mm TL) in both sexes, but fish were not spawning capable until age 4.5 (703mm TL) in males and age 5.8 (840mm TL) in females. Furthermore, elevated gonadosomatic indices were not observed until around age 5-6. The updated life history information presented in this work helps to address current data limitations and provides critical information for future assessments of Red Drum stocks in the northern GOM.

Gulf Menhaden, Brevoortia patronus, in the northern Gulf of Mexico support a large commercial fishery and are thought to play an important trophic role in the coastal ecosystem. The temporal dynamics of both fatty acid and oil content have a direct impact on the value of Gulf Menhaden to predators and to the fishery. In this work, we describe how oil content of Gulf Menhaden varies with season, sex, age, condition, and tissue and investigate how fatty acid composition of mature (>= 137.5 mm FL) female tissues varies with season, month, and tissue type. We found pronounced temporal (January to October) variation in mean oil content ranging from 0.062 to 0.579 mg g(-1) that exhibited a significant (p < 0.001) seasonal pattern. We observed significant differences in oil content between tissue (muscle vs. ovary) of mature females and these exhibited a significant seasonal contrast, indicating that females were provisioning eggs in the fall. PERMANOVA analysis indicated the existence of significant differences (p < 0.001) in the composition of fatty acids of muscle tissue collected in different months. Mean eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and long chain polyunsaturated fatty acid (LC-PUFA) levels exhibited significant seasonal differences (p < 0.05), and in the case of DHA and LC-PUFA, both exhibited mean tissue-specific differences (p < 0.05). This work indicates that the value of Gulf Menhaden as prey and a fishery resource in the region varies during the year and we propose that trophic models of the Gulf of Mexico ecosystem should account for this variation. (C) 2018 The Authors. Published by Elsevier B.V.

The Atlantic and Gulf Menhaden stocks (Brevoortia tyrannus and Brevoortia patronus) support the second largest fishery by weight in the US and serve a critical ecological role as forage (Hartman & Brandt, 1995; NOAA Fisheries, 2016; Sagarese et al., 2016). Stock assessment and management of these important stocks have experienced thorough scrutiny from multiple perspectives (Hilborn et al., 2017; Pikitch et al., 2012). Therefore, we feel compelled to comment on Turner's (2017) paper titled “Smaller size-at-age menhaden with coastal warming and fishing intensity.” Our comment is based on three issues: misstatements regarding the stocks’ assessment and management, inappropriate analyses, and limited acknowledgment of alternative hypotheses for the putative patterns. Turner (2017) made several erroneous statements about US menhaden assessment and management. First, neither value described as “MSY” in Turner (2017) represents an accurate or reliable estimate of MSY for menhaden. The value labelled “MSY Atlantic” in Figure 1 and throughout the text is the total allowable catch, based on average landings from 2009 to 2011 (ASMFC, 2012). The value labelled “GOM MSY” in Figure 1 and throughout the text is the estimate of biomass at MSY (BMSY) generated by a surplus production model not adopted for use in management (SEDAR, 2013). Developing MSY estimates for forage fish such as menhaden is problematic (SEDAR, 2013) and currently is not accepted for determining stock status on either coast. The model used to assess both species, the NMFS Beaufort Assessment Model, is a statistical catch-at-age model that estimates spawner-per-recruit reference points for management (SEDAR, 2013, 2015). Additionally, landings of both species shown in Figure 1 were inflated by a factor of 1,000.1 Turner's conclusions regarding variation in size-at-age with fishing pressure (Figure 4, Table III) are not valid because incorrect estimates of menhaden MSY and landings were used in the analysis. Inappropriate analyses included treatment of the data and model choice. By using mean estimates of size-at-age, analyses artificially reduced the estimated inter-annual variance and ignored potentially confounding factors. Using mean estimates serves to allocate the error variation to the linear regression component of the model, inflating the amount of variance explained. Reanalysing the Gulf data, we find that Turner's model formulation inflates the variance explained from 292% to 1,267%. By including the full weight- and length-at-age dataset, R2 values range from <0.001 to 0.128 (Table S1). Such poor estimation of annual changes in length- and weight-at-age weakens support for Turner's conclusions. Also, menhaden demonstrate considerable spatial variation in their distribution by size and age that affects availability of older ages to the fishery. Proper interpretation of these fishery-dependent data must account for fleet dynamics, especially for Atlantic menhaden, which was historically caught coastwide but now between New Jersey and Virginia. Beyond treatment of data, we disagree with the use of a linear model to understand the inter-annual dynamics of length- and weight-at-age. A qualitative examination of the residual pattern indicates that a linear model does not properly incorporate the biological and environmental dynamics. Turner's paper interpreted results with a narrow view on possible factors affecting size-at-age over time and failed to fully acknowledge alternative hypotheses. Density dependence, fishing mortality, selectivity, and environmental factors all have the potential to influence size-at-age. Turner's finding that not all age classes decreased in size is an important piece of evidence. Broad-scale mechanisms such as density and environmental factors (i.e., temperature) would be expected to cause changes on all age classes, while factors only acting on specific age classes (i.e., fishing mortality) would be expected to cause changes on only impacted age classes. For example, Atlantic menhaden growth varies widely over time with large swings; these changes have been plausibly linked to density dependence (Schueller & Williams, 2017). Also, observed changes in size-at-age over time may simply be due to variation in fishing locations and concomitant changes in the frequency of older menhaden encountered by the fishery over time (SEDAR, 2013, 2015). Additionally, time-varying dome-shaped selectivity and biased growth estimates based on fishery-dependent samples (Schueller, Williams, & Cheshire, 2014) have led to inadequate samples of older age classes. For example, the number of age 4+ Atlantic menhaden samples collected has declined from an average of 4,338/year in the 1950s to 267/year from 1960+. Although we acknowledge the possibility that climate change may be affecting menhaden dynamics and growth, Turner's analyses are insufficient to draw definitive conclusions. We would like to thank referees for comments on previous drafts. This is Contribution Number 5455 of the University of Maryland Center for Environmental Science. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

We evaluated the effects of multiple bottom-up processes on the relative condition (an index of length-specific weight) of adult Gulf menhaden Brevoortia patronus sampled from the US commercial fishery, from 1964 to 2011, in the northern Gulf of Mexico (NGOM). A series of Generalized Additive Models (GAMs) were constructed to examine the influence of Mississippi River Discharge (MRD), El Nino Southern Oscillation (ENSO), wind vector components, sea surface temperature (SST), and chlorophyll a concentration. Relative condition was positively correlated with MRD and highest during weak La Nina-like and moderate El Nino-like conditions. The effect of wind vector components was variable across the NGOM. This observation is likely due to geographic differences in wind-related transport of nutrient rich river plume waters Relative condition was highest at 24 degrees C and declined rapidly when SST was below 23 degrees C or above 29 degrees C Relative condition exhibited seasonal variability with increasing condition from August until November, likely caused by seasonal provisioning by individuals for winter spawning. We show that multiple bottom-up processes contribute to contrasts in the condition of Gulf menhaden in the NGOM and these results can be used to predict the response of Gulf menhaden to environmental variability.

Understanding geographic variation in growth dynamics is essential for the management of exploited fish populations because such variation can be used to define stock structure and influence perceptions of stock productivity. Sheepshead (Archosargus probatocephalus) is a species targeted by both commercial and recreational fisheries, and is distributed throughout the north and central Atlantic Ocean and Gulf of Mexico. We analyzed fishery-dependent and -independent length-at-age and weight-at-length data from Texas, Louisiana, Mississippi, Alabama, Florida, South Carolina, North Carolina, and Virginia to investigate the geographic variation in growth of Sheepshead. We constructed a series of von Bertalanffy growth functions (VBGF) and length-weight power equations using a Bayesian framework that included sex, latitudinal, and regional effects. Median posterior VBGF parameter estimates of asymptotic length (L-infinity) for females ranged from 561 mm fork length in the Virginia Chesapeake Bay to 418 nun in Florida Gulf coast, while the posterior median growth coefficient (k) ranged from 0.42 yr(-1) in Texas to 0.20 yr(-1) in the Florida Atlantic. Predicted length-at-age and weight-at-length varied considerably among States. Predicted length-at-age for age-1 and -5 individuals was greater in the Gulf of Mexico than the Atlantic. However, predicted length-at-age for older age classes was greater in the Atlantic. Predicted weight-at-length decreased along latitudinal gradients in the Atlantic and the lowest values were found in Mississippi. Given the impact of growth on fisheries reference points, such geographic variation in growth can inform the development of assessment efforts for Sheepshead in the Gulf of Mexico and Atlantic.