Growth and Reproduction of Southern Flounder (\u3ci\u3eParalichthys lethostigma\u3c/i\u3e) in the North-Central Gulf of Mexico

Southern Flounder Paralichthys lethostigma is the most commonly harvested flatfish in the north-central Gulf of Mexico (GOM) and supports a major inshore recreational fishery, yet knowledge of the species’ life history is greatly limited. The objective of this research was to describe the growth and reproduction of Southern Flounder in the Mississippi stock. Fish were collected during September 2014 to March 2016 using primarily recreational fishing techniques. Otoliths (n = 313) were sectioned to estimate age, and multiple length-at-age models were fit to total length (TL, mm) and age estimate (y) data. Gonadal tissue samples (n = 221) were preserved for histological analysis and used to classify reproductive phases. Length-at-age model fit was evaluated using Akaike information criteria, revealing that the three-parameter von Bertalanffy growth function best described the female-specific data (L∞ = 509 mm, k = 0.70 y-1, t0= -0.46 y). By fitting a logistic model to binomial maturity data, the mean length-at-50% maturity was estimated as 303 mm TL and mean age-at-50% maturity was estimated as one year for females. Histological indicators and gonadosomatic index (GSI) data were used to estimate that the spawning season lasts from November to January, and to classify Southern Flounder as batch spawners. These results will inform future stock assessments and management decisions for the GOM Flounder fishery

The Hidden Cost of Overfishing To Commercial Fishermen: A 2009 Snapshot of Lost Revenues

Ocean fish populations are a vital renewable resource for human populations, providing food,employment and recreation, as well as contributing to global biodiversity. Unfortunately, due to overfishing, environmental degradation, climate change and other stressors, many fish stocks worldwide are in considerable decline.Biological overfishing occurs when fishing rates exceed population growth rates. The resulting declines in fish populations can impact the economy at large. This study analyzes one important component of the costs of overfishing: forgone revenues from lost commercial fisheries harvests due to years of continuedstock depletion, or historic overfishing. It estimates the present annual forgone revenue of overfishing for three regions in the United States: New England, the South Atlantic and the Gulf of Mexico. These regions were chosen for analysis because they are grappling with the effects of historic overfishing and therefore have a significant number of overfished stocks. The 20 stocks included in this analysis are federally managed stocks particular to each region that are included in the Fish Stock Sustainability Index and are currently classified by the National Marine Fisheries Service as "overfished." A stock that is classified as overfished is defined as having a biomass level below a biological threshold specified in its fishery management plan.Overfishing means fewer fish are available to catch in future years. The annual forgone revenue of historic overfishing, therefore, is an estimate of the value of lost catch in a given year due to overfishing. To arrive at the catch loss for each fishery, we first estimated the potential landings of each overfished stock as if it were at healthy levels, and compared those estimates directly to current landings values. We measured potential landings for each fish stock on the basis of optimal yield, and examined four approximations of optimal yield. Our estimates of commercial catch losses are for 2009, the most recent year for which all necessary data were available.Based on our estimates, the aggregate catch loss summed over all three regions in 2009 was $164.2 million. Under a less-conservative approximation of optimal yield, commercial catch loss across all three regions in 2009 was estimated at$222.5 million. Across all three regions, we demonstrated that only 20 to 29 percent of potential landings in 2009 were realized in actual landings. We found the commercial catch loss ($149 million) to be greatest in New England, where there are more overfished species than in any other region in the United States. In the Gulf of Mexico and South Atlantic regions, where large catch allocations are apportioned to recreational fishing, and therefore not accounted for in this analysis, commercial catch losses were lower but still significant. Commercial catch loss in the Gulf of Mexico and the South Atlantic regions were$12.3 million and $2.9 million, respectively.Our estimates of losses resulting from historic overfishing apply to commercial landings only, and do not account for the backward-linked economic impacts of commercial harvest, nor the forward-linked economic activity that would have resulted from the processing and retail sale of these potential catches. Additionally, there are further economic losses beyond the commercial sector in other industries, such as recreational fishing, and there are costs associated with negative impacts to food security, biodiversity and other ecosystem services that are not addressed in this analysis. Commercial catch losses are onesignificant component of the total economic costs of overfishing. Estimates of commercial catch loss we find in this study provide a strong economic argument in support of maintaining healthy fish populations and avoiding delays in rebuilding stocks currently subject to overfishing and/or classified as overfished.

Integrating Porpoise and Cod Management: A Comparison of Days-at-sea, ITQs, and Closures

The purpose of this study is to determine if management measures based on effort reductions, in particular days-at-sea (DAS) controls, can approach a harbor porpoise individual transferable quotas (ITQ) program in terms of efficiency. The intent is to expand discussions of combining fishery-porpoise management actions. The New England sink gillnet fishery is examined by using a numerical bio-economic model. Year-round and seasonal surcharges in combinations with overall DAS reductions are investigated. Results indicate that several programs for marine mammal protection can achieve the same conservation outcome with modest differences in industry profits. At the industry level, the program selection decision may then rest on the goal of cod management, since reductions in cod landings are much greater under the DAS year-round (59–63%) versus seasonal (39–46%) programs. Significant differences in vessel profits, however, may make consensus on the appropriate program difficult.Fisheries management, individual transferable quotas, protected species, marine mammals, turtles, bycatch, Environmental Economics and Policy, Research Methods/ Statistical Methods, Q220, Q280, Q570, Q580,

Seasonal prediction of bottom temperature on the Northeast U.S. Continental Shelf

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Chen, Z., Kwon, Y.-O., Chen, K., Fratantoni, P., Gawarkiewicz, G., Joyce, T. M., Miller, T. J., Nye, J. A., Saba, V. S., & Stock, B. C. Seasonal prediction of bottom temperature on the Northeast U.S. Continental Shelf. Journal of Geophysical Research: Oceans, 126(5), (2021): e2021JC017187, https://doi.org/10.1029/2021JC017187.The Northeast U.S. shelf (NES) is an oceanographically dynamic marine ecosystem and supports some of the most valuable demersal fisheries in the world. A reliable prediction of NES environmental variables, particularly ocean bottom temperature, could lead to a significant improvement in demersal fisheries management. However, the current generation of climate model-based seasonal-to-interannual predictions exhibits limited prediction skill in this continental shelf environment. Here, we have developed a hierarchy of statistical seasonal predictions for NES bottom temperatures using an eddy-resolving ocean reanalysis data set. A simple, damped local persistence prediction model produces significant skill for lead times up to ∼5 months in the Mid-Atlantic Bight and up to ∼10 months in the Gulf of Maine, although the prediction skill varies notably by season. Considering temperature from a nearby or upstream (i.e., more poleward) region as an additional predictor generally improves prediction skill, presumably as a result of advective processes. Large-scale atmospheric and oceanic indices, such as Gulf Stream path indices (GSIs) and the North Atlantic Oscillation Index, are also tested as predictors for NES bottom temperatures. Only the GSI constructed from temperature observed at 200 m depth significantly improves the prediction skill relative to local persistence. However, the prediction skill from this GSI is not larger than that gained using models incorporating nearby or upstream shelf/slope temperatures. Based on these results, a simplified statistical model has been developed, which can be tailored to fisheries management for the NES.This work was supported by NOAA's Climate Program Office's Modeling, Analysis, Predictions, and Projections (MAPP) Program (NA17OAR4310111, NA19OAR4320074), and Climate Program Office's Climate Variability and Predictability (CVP) Program (NA20OAR4310482). We acknowledge our participation in MAPP's Marine Prediction Task Force

An Evaluation of a Reduced Bar Spacing Turtle Excluder Device in the U.S Gulf of Mexico offshore Shrimp Trawl Fishery

Shrimp are the most economically valuable internationally-traded seafood commodity, and wild-caught, trawled shrimp make up almost half of the ~6.6 million metric tons of annual global production. Shrimp trawling is responsible for one-third of the world’s total fisheries bycatch, leading many to consider shrimp trawling to be the single most destructive fishing practice in the world. Though the bycatch of large marine animals can be significantly reduced by use of turtle excluder devices (TEDs) on shrimp trawls, current TED designs are ineffective at reducing the capture of smaller organisms which represent a large portion of the total bycatch. To further reduce bycatch in the United States Gulf of Mexico shrimp trawl fleet, a variety of bycatch reduction devices (BRDs) are currently being used in conjunction with TEDs. I evaluated the efficiency of a new TED design, intended to reduce bycatch and maintain target shrimp catch. The new TED model is characterized by 5-cm spacing between flat bars, as opposed to the current industry standard of 10-cm spacing between round bars. Comparative towing experiments under standard commercial shrimp trawling operations in waters off of Georgia, Texas and Mississippi during the summer of 2012 demonstrated shrimp losses or gains of -4.32%, +6.07%, -1.58% respectively and an overall reduction in the capture weight of sharks (41.1-99.9%), rays and skates (76.5-93.4%) and horseshoe crabs (100%). These experiments were limited in time and space, and therefore not fully representative of fishing conditions throughout the year, but this study demonstrates the new TED’s effect on the catch rates of target shrimp and bycatch. This thesis research should lead to a broader understanding of the benefits of using reduced spacing flat bar TEDs in the U.S. shrimp trawl industry

TEMPORAL AND SPATIAL MANAGEMENT TOOLS FOR MARINE ECOSYSTEMS: CASE STUDIES FROM NORTHERN BRAZIL AND NORTHEASTERN UNITED STATES

Anthropogenic interventions and actions upon the marine habitat pose threats to a range of species of economic and conservation concern. The dynamic nature of marine ecosystems offers a difficult challenge to incorporate spatial and temporal distributions of different species, and the interactions among species and human activities into a formal management framework. Each country has its own priorities when it comes to management of the marine resources (e.g. conservation, food security, sustainable fisheries, and optimization of revenue). Therefore, a key hurdle is to create tools adequate for use within an Ecosystem Approach to Management (EAM) and Ecosystem-based Management (EBM) framework, that meet local and regional needs. Models can provide insights regarding ecosystems dynamics and generate tools for management applications, including the estimation of optimal conditions and frameworks, assessing current conditions relative to baselines, exploring the effects of potential management decisions and delimiting areas where monitoring efforts of species of concern or “choke species” should be concentrated. The present work focuses on all these elements with the aim to provide modeling and visualization capacity to management decision making. My dissertation had two main objectives, divided in two case studies in distinct geographic and data availability settings. The first was to develop spatial models to promote the adequate monitoring of species of conservation concern (SOC) within a data-limited setting in two multiuse marine protected areas (MPAs) in the Amazon Delta, Northern Brazil by: 1) collecting SOC available data; 2) developing GIS-based suitability models; and 3) generating baseline knowledge for future management strategies of SOCs. The second objective was to study alewife (Alosa pseudoharengus) role within a data-rich setting in the Northeast U.S. large marine ecosystem (NEUS LME) and the Gulf of Maine (GOM) marine ecosystem by: 1) developing food-web based ecosystem models; 2) assessing the impacts of anadromous forage fish restoration; 3) testing riverine and marine-based management strategies to promote their recovery. For the data-limited studies, I found that extreme data scarcity impeded our ability to develop a model for the Environmental Protection Area (EPA) of Algodoal-Maiandeua, Northern Brazil. However, it allowed us to show preliminary data of sea turtles’ observations and fixed fishing gears in the EPA, giving basis to the future develop of spatially explicit models. While for the second multiuse MPA, the Soure Marine Extractive Reserve (MER), we were able to successfully develop a spatial explicit suitability model focused on monitoring priority areas for SOCs. Our results show that 30% of the MER is under medium, high and extremely high monitoring priority, allowing more effective development of monitoring design for SOCs. For the data-rich setting, I found that the full restoration of alewife in the NEUS LME could lead to a 50% potential biomass increase for small pelagics, 26% for fisheries target species, and approximately 69% for SOCs. This provided a more stable picture for the middle trophic level forage species and lead to major potential biomass changes for SOCs. I also found that fishing effort reduction alone did little to promote alewife recovery in the GOM marine ecosystem. However, when river to ocean connectivity was added to fishing effort reductions. The alosine (alewife, blueback herring, and American shad) group showed a major response. As a whole, my dissertation captures a range of management approaches from data-limited to data-rich systems, using modeling approaches to optimize decision making

Climate-Driven Stock Shifts And Expansions In The U.S. Northeast Shelf: Identifying Challenges, Opportunities, And Barriers Through Fishermen And Manager Perspectives

Climate-driven warming in the U.S. Northeast Shelf (NES) has led to changes in the spatial distributions of many marine resources. Shifts and expansions of commercially important fish stocks pose major challenges to fishermen and fisheries managers in this region. American lobster (Homarus americanus) in the Gulf of Maine (GOM) is one of these impacted stocks and is projected to continue its shift towards more northern and offshore areas. Continued ocean warming could potentially reduce the GOM lobster stock by up to 60% over the next several decades. Given Maine’s reliance on its lobster fishery—which contributes over 80% of the value of Maine’s commercially harvested marine resources—building climate resilience into the fisheries social-ecological system is critical. Southern New England (SNE) serves as an example of a region that has already experienced much of the changes posed to impact the GOM. Through semi-structured interviews with SNE and GOM fishermen and a focus group of NES fisheries managers, black sea bass (Centropristis striata) was identified as a potential opportunity for fishermen to adapt to climate-driven changes. However, existing barriers—such as permitting, quota allocations, and bycatch regulations—prohibit the region’s fishermen from actualizing emerging opportunities. Results indicated that these barriers are not insurmountable and implementing “social-ecological management” approaches could provide viable pathways to facilitate opportunities and bolster climate resilience in the GOM