A better understanding of trophic interactions between hardhead catfish (Ariopsis felis) and gafftopsail catfish (Bagre marinus) is crucial for developing multi-species management strategies for the ...northern Gulf of Mexico (GOM). These two species are often aggregated in food web models; however, limited data are available to substantiate this approach. Therefore, the present study aimed to describe the dietary habits of hardhead catfish and gafftopsail catfish using analysis of stomach contents aided by DNA barcoding. Hardhead (n = 693) and gafftopsail (n = 655) catfish were sampled in the northern GOM from 2015–2019 using both fisheries-dependent and -independent techniques. The average percent number (%N), average percent mass (%M), prey specific number (%PN), prey specific mass (%PM), and prey-specific index of relative importance (%PSIRI) were computed to quantify prey species. The stomach content analysis identified distinct differences in diet between hardhead and gafftopsail catfish. Crustaceans were the most important prey for hardhead catfish, while gafftopsail catfish showed a significantly broader dietary breadth and were primarily piscivorous. Multivariate analyses indicated that the location of capture explained the greatest amount of diet variability for both species. These findings address fundamental knowledge gaps regarding the dietary habits of hardhead and gafftopsail catfish in northern GOM ecosystems.
Atlantic tarpon (Megalops atlanticus, hereafter tarpon) are facing a multitude of stressors and are considered Vulnerable by the IUCN; however, significant gaps remain in our understanding of tarpon ...space use and movement. From 2018 to 2019, citizen scientists facilitated tagging of 23 tarpon with SPOT tags to examine space use and movement across the northern Gulf of Mexico. Movement‐based kernel densities were used to estimate simplified biased random bridge‐based utilization distributions and a joint move persistence model was used to estimate a behavioral index for each fish. Tarpon showed consistent east–west movement from the Alabama/Florida border to Louisiana, and utilization distributions were highest in the Mississippi River Delta. Move persistence was highest in Alabama and Mississippi and lowest in Louisiana. Our examination of tarpon space use and movement indicates that Louisiana is a critical, yet understudied, part of their range.
In the northern Gulf of Mexico, batoids are caught as bycatch in the shrimp trawl fishery and targeted by recreational bowfishers. The vulnerability of these batoid species to overexploitation is ...primarily dictated by their life history strategies. Lessa’s butterfly ray,
Gymnura lessae
, is a sexually dimorphic piscivorous batoid ranging from the northern Caribbean Sea to Massachusetts. Species in the family Gymnuridae have small, poorly mineralized centra; as a result, age and growth has only been described in one species,
G. altavela
. In this study, we examined size at maturity, reproduction, sex-specific growth (using Electronic Length Frequency Analysis), instantaneous natural mortality, and age at maturity of
G. lessae
in the northern Gulf of Mexico. Overall, 552
G. lessae
were sampled from 2016 to 2018, of which 322 were male and 230 were female. Estimated disc width at 50% maturity was 340.0 mm and 461.4 mm for males and females, respectively. Sex-specific von Bertalanffy growth parameter estimates were
DW
∞
= 427.1 mm,
k
= 1.34 year
−1
, and
t
0
= −0.35 years for males, and
DW
∞
= 882.2 mm,
k
= 0.40 year
−1
, and
t
0
= −0.56 years for females. Instantaneous natural mortality was higher for males (1.48) than females (0.48). Most age-0 males (93.8%,
n
= 16) and 30.7% of age-0 females (
n
= 13) appeared to mature fast enough to mate just 1 year after birth. Our results indicate that
G. lessae
is fast growing, quick maturing, and relatively fecund in the northern Gulf of Mexico and is thus at low risk of overexploitation.
Reservoirs are mostly managed at local scales as spatially independent units. A basin‐scale perspective may increase awareness at a broader scope and generate insight not evident at local scales. We ...examined the array of reservoir attributes and fisheries in the Mississippi Basin to identify management opportunities. The basin is the third largest in the world and includes over 1,700 reservoirs >100 ha, the most of any river basin. Our bird's‐eye view shows a piecemeal approach where reservoirs are mostly administered at the local level. Basin‐wide or catchment coordination to holistically address problems that recur across the basin is mostly lacking. A basin‐wide coordination arrangement could facilitate various facets of reservoir management. We reviewed governance arrangements in major river basins across the globe and concluded that the basin‐wide administrative layer we encourage for the Mississippi Basin may already exist in some basins but may not be directly applicable everywhere.
Two different methods, metagenetics and free‐otolith identification, were used to identify prey in the stomach contents of 531 Gymnura lessae captured by trawling in Mobile Bay, Alabama 2016–2018. ...Both methods were found to produce analogous results and were therefore combined into a single complete dataset. All prey were teleosts; the families Sciaenidae and Engraulidae were the most important prey (prey specie index of relative importance 89.3% IPSRI). Multivariate analyses indicated that the diet of G. lessae varied with sex and seasonality. Specifically, variability was probably due to morphologically larger females consuming larger teleost prey species compared with males, whereas seasonal variability was probably due to changes in the available prey community composition. The findings indicate that both metagenetics and free otolith identification, used independently or complementarily, offer robust means of characterising dietary habits for teleost‐specialised species such as G. lessae, which may play an important role in the structure and maintenance of coastal food webs such as those in Mobile Bay.
The goals of this study were to generate baseline population dynamics parameters for Gulf of Mexico crevalle jack Caranx hippos and examine the foraging habits of Mississippi and Alabama crevalle ...jack. Specimens were collected from Mississippi, Alabama and Florida, and age was estimated from sagittal otoliths. Stomachs from some specimens were retained for dietary analyses. Age classes spanned 0–20 years. Overall growth was best represented by the logistic growth model, whereas sex‐specific growth was best represented by a version of the von Bertalanffy growth function that allowed L∞ to vary by sex while holding k and t0 constant between sexes. Fishes were more important to crevalle jack diet than invertebrates, and diet varied among locations and years. These findings will address fundamental knowledge gaps to inform age‐based stock assessments for crevalle jack and ecosystem approaches to fisheries management in the Gulf of Mexico.
In the southeastern USA and the Gulf of Mexico (GOM), Atlantic Tripletail Lobotes surinamensis are increasingly targeted by recreational anglers, indicating that stock status should be assessed. A ...critical need for such assessments is age‐specific data; however, previous studies have drawn conflicting conclusions regarding the most appropriate structure for aging. Moreover, growth parameters and mortality rates for GOM Atlantic Tripletail are unknown. Therefore, the goals of this study were to (1) evaluate sagittal otoliths and first dorsal spines as aging structures; (2) model combined and sex‐specific growth; and (3) estimate mortality rates for GOM Atlantic Tripletail. From 2012 to 2019, Atlantic Tripletail (N = 230, including a near‐record‐size specimen) were collected from the north‐central GOM via hook and line and were aged using otoliths and first dorsal spines. Total length ranged from 212 to 940 mm, and age ranged from 0.07 to 5.27 years. Otoliths produced higher percent agreement (95.0%) and lower average percent error (3.0%) between readers compared to spines (82.9% and 6.5%, respectively). The von Bertalanffy growth parameters differed slightly between the otolith‐based data (mean asymptotic length L∞ = 762.42 mm, Brody growth rate coefficient k = 0.69 year−1, and hypothetical age at which length equals zero t0 = −0.58 year) and spine‐based data (L∞ = 718.83 mm, k = 0.79 year−1, and t0 = −0.56 year). For both otolith‐ and spine‐based sex‐specific data, the best‐fitting version of the von Bertalanffy growth function permitted L∞ to vary by sex. Chapman–Robson estimates of instantaneous total mortality rate and total annual mortality rate were 1.15 and 68.66%, respectively. Based on empirical, life history‐based methods, the instantaneous natural mortality rate was estimated at 0.75–0.97 and the instantaneous fishing mortality rate was estimated at 0.18–0.45, suggesting low levels of exploitation. These growth parameters and mortality estimates will provide information for future stock assessments, thereby ensuring sustainability of the GOM stock of Atlantic Tripletail.
A better understanding of trophic interactions between hardhead catfish (Ariopsis felis) and gafftopsail catfish (Bagre marinus) is crucial for developing multi-species management strategies for the ...northern Gulf of Mexico (GOM). These two species are often aggregated in food web models; however, limited data are available to substantiate this approach. Therefore, the present study aimed to describe the dietary habits of hardhead catfish and gafftopsail catfish using analysis of stomach contents aided by DNA barcoding. Hardhead (n = 693) and gafftopsail (n = 655) catfish were sampled in the northern GOM from 2015–2019 using both fisheries-dependent and -independent techniques. The average percent number (%N), average percent mass (%M), prey specific number (%PN), prey specific mass (%PM), and prey-specific index of relative importance (%PSIRI) were computed to quantify prey species. The stomach content analysis identified distinct differences in diet between hardhead and gafftopsail catfish. Crustaceans were the most important prey for hardhead catfish, while gafftopsail catfish showed a significantly broader dietary breadth and were primarily piscivorous. Multivariate analyses indicated that the location of capture explained the greatest amount of diet variability for both species. These findings address fundamental knowledge gaps regarding the dietary habits of hardhead and gafftopsail catfish in northern GOM ecosystems.
NOvA is a long-baseline neutrino oscillation experiment that measures oscillations in charged-current \(\nu_{\mu} \rightarrow \nu_{\mu}\) (disappearance) and \(\nu_{\mu} \rightarrow \nu_{e}\) ...(appearance) channels, and their antineutrino counterparts, using neutrinos of energies around 2 GeV over a distance of 810 km. In this work we reanalyze the dataset first examined in our previous paper Phys. Rev. D 106, 032004 (2022) using an alternative statistical approach based on Bayesian Markov Chain Monte Carlo. We measure oscillation parameters consistent with the previous results. We also extend our inferences to include the first NOvA measurements of the reactor mixing angle \(\theta_{13}\) and the Jarlskog invariant. We use these results to quantify the strength of our inferences about CP violation, as well as to examine the effects of constraints from short-baseline measurements of \(\theta_{13}\) using antineutrinos from nuclear reactors when making NOvA measurements of \(\theta_{23}\). Our long-baseline measurement of \(\theta_{13}\) is also shown to be consistent with the reactor measurements, supporting the general applicability and robustness of the PMNS framework for neutrino oscillations.
PDF
