Hypoxia and Sturgeons: report to the Chesapeake Bay Program Dissolved Oxygen Criteria Team

In this essay, three lines of evidence are developed that sturgeons in the Chesapeake Bay and elsewhere are unusually sensitive to hypoxic conditions: 1. In comparison to other fishes, sturgeons have a limited behavioral and physiological capacity to respond to hypoxia. Basal metabolism, growth, and consumption are quite sensitive to changes in oxygen level, which may indicate a relatively poor ability by sturgeons to oxyregulate. 2. During summertime, temperatures >20 C amplify the effect of hypoxia on sturgeons and other fishes due to a temperature*oxygen "squeeze" (Coutant 1987)- In bottom waters, this interaction results in substantial reduction of habitat; in dry years, nursery habitats in the Chesapeake Bay may be particularly reduced or even eliminated. 3. While evidence for population level effects by hypoxia are circumstantial, there are corresponding trends between the absence of Atlantic sturgeon reproduction in estuaries like the Chesapeake Bay where summertime hypoxia predominates on a system-wide scale. Also, the recent and dramatic recovery of shortnose sturgeon in the Hudson River (4-fold increase in abundance from 1980 to 1995) may have been stimulated by improvement of a large portion of the nursery habitat that was restored from hypoxia to normoxia during the period 1973-1978. (PDF contains 26 pages

Recovery and status of shortnose sturgeon in the Hudson River

Shortnose sturgeon (Acipenser brevirostrum), an endangered species, has experienced a several-fold increase in abundance in the Hudson River in recent decades. This population growth followed a substantial improvement in water quality during the 1970s to a large portion (c. 40%) of the species' summertime nursery area. Age structure and growth were investigated to evaluate the hypothesis that improvements in water quality stimulated population recovery through increased survival of young of the year juveniles. Specimens were captured using gill nets bi-monthly from November 2003 to November 2004 (n = 596). Annuli in fin spine sections were used to generate estimates of sturgeon age. Based upon a marginal increment analysis, annuli were determined to form at an annual rate. Age determinations yielded a catch composed of age 5-30 years for sizes 49-105cm Total Length (n = 554). Individual growth rate (von Bertalanffy coefficients: TL, = 1045mm, K = 0.07) for the population was similar to previous growth estimates within the Hudson River as well as proximal estuaries. Hindcast year-class strengths, based upon a recent stock assessment (Bain et al. 2000) and corrected for gill net mesh selectivity and cumulative mortality indicated high recruitments (28,000-43,000 yearlings)during 1986-1992, which were preceded and succeeded by c.5-year periods of lower recruitment (5,000-1 5,000 yearlings). Recruitment patterns were corroborated by trends in shortnose sturgeon bycatch from a Hudson utilities-sponsored monitoring program. Results indicated that Hudson River shortnose sturgeon abundance increased due to the formation of several strong year-classes occurring about five years subsequent to improved water quality in important nursery and forage habitats in the upper Hudson River estuary. (PDF contains 108 pages.

Demographic assessment of the blue crab (Callinectes sapidus) in Chesapeake Bay using extractable lipofuscins as age markers

The blue crab (Callinectes sapidus) plays an important economic and ecological role in estuaries and coastal habitats from the Gulf of Mexico to the east coast of North America, but demographic assessments are limited by length-based methods. We applied an alternative aging method using biochemical measures of metabolic byproducts (lipofuscins) sequestered in the neural tissue of eyestalks to examine population age structure. From Chesapeake Bay, subsamples of animals collected from the 1998–99 (n=769) and 1999–2000 (n=367) winter dredge surveys were collected and lipofuscin was measured. Modal analysis of the lipofuscin index provided separation into three modes, whereas carapace-width data collected among the same individuals showed two broad modes. Lipofuscin modal analysis indicated that most adults (carapace width >120 mm) were <2 years old. The results indicate that use of extractable lipofuscin can provide a more accurate and better resolved estimation of demographic structure of blue crab populations in the field than size alone

The Use of Extractable Lipofuscin for Age Determination of Crustaceans: Reply to Sheehy (2008)

The heterogeneous mixture of metabolic by-products termed lipofuscin (LF) or age pigments has long been known to accumulate in post mitotic cells with increasing age. In crustaceans several approaches have been developed over the years to track LF accumulation and provide a proxy for chronological age. Histological approaches have been traditionally used for LF determination of crustaceans (e.g. Sheehy et al. 1994, Mar Biol 121:237-245), but over the last decade extraction approaches for neural tissues have been introduced (Ju et al. 1999, Mar Ecol Prog Ser 185:171-179) and tested (Ju et al. 2001, Mar Ecol Prog Ser 224:197-205; 2003, Fish Bull 101:312-320) for the crab Callinectes sapidis. In developing the extraction approach we have followed the most rigorous age validation steps available to us and carefully reported accuracy, precision, and bias estimates. In the present paper, we welcome the opportunity to respond to the individual concerns of Sheehy (2008, Mar Ecol Prog Ser 353:303-306) that (1) extractable LF remains unidentified, (2) extracted LF is not correlated with in situ LF, and (3) protein normalization does not produce a reliable assay. We argue that the fundamental issue of an incomplete characterization of LF as an ageing structure pervades most, if not all invertebrate fishery applications. We show positive correlation between the 2 methods, despite the lack of each to fully characterize the structurally complex products generated and sequestered in neural tissues. New information is presented on the ability of extractable LF to follow age in small macrozooplankton, suggesting the broad applicability of the extraction aging approach to small crustaceans. Dependent upon species and availability of known age animals for calibration, both histological and extraction approaches can be an effective method for age determination in crustaceans if they meet the requirements of validation, precision and bias estimations that typify rigorous age determinations in fisheries science

Growth Rate Variability and Lipofuscin Accumulation Rates in the Blue Crab Callinectes Sapidus

To better understand growth and age-pigment (lipofuscin) accumulation rates of the blue crab Callinectes sapidus under natural conditions, juveniles (33 to 94 mm carapace width) were reared in outdoor ponds for over 1 yr. Growth rates, measured by carapace width, during summer and fall exceeded all those reported in the literature; the initial carapace width of 59 ± 14 mm (mean ± SD) increased to 164 ± 15 mm within a 3 mo period. No growth occurred during winter months (November to April) at low water temperatures. Growth rates of crabs in ponds were substantially higher (von Bertalanffy growth parameter K = 1.09) than those of crabs held in laboratory environments, and than rate estimates for natural populations of mid-Atlantic blue crabs. Model comparisons indicated that seasonalized von Bertalanffy growth models (r2 \u3e 0.9) provide a better fit than the non-seasonalized model (r2= 0.74) for pond-reared crabs and, by implication, are more appropriate for field populations. Despite growth rates that varied strongly with season, lipofuscin (normalized to protein concentration) accumulation rate was nearly constant throughout the year. Although the lipofuscin level in pond-reared crabs was significantly correlated with size (carapace width), it was more closely correlated with chronological age. Lipofuscin accumulation rates were also similar to those observed for laboratory-reared crabs, despite very large differences in growth rates and temperature regimes. The constancy of normalized-lipofuscin accumulation rates of blue crabs across seasons and environmental conditions suggests that lipofuscin concentration can be a more robust indicator of age than carapace width alone

Use of Extractable Lipofuscin for Age Determination of Blue Crab Callinectes Sapidus

The blue crab Callinectes sapidus is an economically and ecologically important species in many temperate estuaries, yet stock assessments have been limited to length-based methods for demographic analyses. We evaluated the potential of age pigments (lipofuscins) sequestered in neural tissue of eye-stalks and brains to estimate the age of blue crabs collected from Chesapeake Bay and Chincoteague Bay. The rate of lipofuscin accumulation was determined using crabs of known age reared in the laboratory. Age pigments were extracted from neural tissues (eye-stalk or brain), quantified, and normalized to protein content to allow comparisons across tissue types and crab sizes. Field-collected blue crabs (35 to 185 mm carapace width) contained highly variable levels of age pigments (coefficient of variation = 58 %). Lipofuscin level was significantly related to carapace width, but not significantly different between gender or sampling location. In juveniles (40 to 70 mm carapace width) reared for 6 mo, the age pigments showed no significant change during the rapid summer growth period, but significantly increased during fall (after 3 mo). Lipofuscin contents in known-age reared crabs were positively related to chronological age. Modal analysis of lipofuscin for field-collected adult males provided separation of multiple modes, whereas carapace width showed only a single broad mode. These results confirm the potential use of lipofuscin for age estimation of blue crabs

“We Are Asking Why You Treat Us This Way. Is It Because We Are Negroes?” A Reparations-Based Approach to Remedying the Trump Administration’s Cancellation of TPS Protections for Haitians

This Article places the Trump Administration’s decision to cancel TPS for Haitians within the longer history of U.S. racism and exclusion against Haiti and Haitians, observes the legal challenges against this decision and their limitations, and imagines a future that repairs the harms caused by past and current racist policies. First, this Article briefly outlines the history of exclusionary, race-based immigration laws in the United States, and specifically how this legal framework, coupled with existing anti-Black ideologies in the United States, directly impacted Haitians and Haitian immigrants arriving in the United States. Next, the Article provides an overview of the TPS decision-making process, the Trump Administration’s openly racist comments against Haitians and other people of color before and during the decision-making process to cancel TPS, and the departure from the established administrative process for TPS cancellation. The Article then reviews the legal challenges against TPS cancellation and the arguments that the decision violated the Equal Protection Clause and how such efforts reveal the limitations of litigation as a tool to achieve social justice. Looking towards the future, this Article discusses reparations and remittances as creative ways to repair some of the damage wrought by the United States’ history of racial discrimination in immigration and foreign policy against Haitians. Specifically, this Article explores three solutions: (1) recognizing the harms caused specifically to Haitians by the United States’ exclusionary foreign affairs and immigration policies; (2) using material and non-material forms of reparations, including extending TPS, offering a pathway for citizenship for TPS holders, or offering Haitian TPS recipients benefits to public programs; and (3) valuing the role remittances play in affirming Haitians’ autonomy and working towards eroding decades of imperialistic treatment of Haitians

Oceanic migration rates of Upper Chesapeake Bay striped bass (Morone saxatilis), determined by otolith microchemical analysis*

Oceanic incidence and spawning frequency of Chesapeake Bay striped bass (Morone saxatilis) were estimated by using microchemical analysis of strontium in otoliths. Otoliths from 40 males and 82 females sampled from Maryland’s portion of the Chesapeake Bay were analyzed for seasonal and age-specific patterns in strontium and calcium levels. The proportion of oceanic females increased from 50% to 75% between ages seven to 13; the proportion of oceanic males increased from 20% to ~50% between ages four to 13. Contrary to an earliermodel of Chesapeake Bay striped bass migration, results indicated that a substantial number of males undertook oceanic migrations. Further, we observed no mass emigration of females from three to four years of age from the Chesapeake Bay. Seasonal patterns of estuarine habitat use were consistent with annual spawning runs by striped bass of mature age classes, but with noteworthy exceptions for newly mature females. Evidence of an early oceanic presence indicated that Chesapeake Bay yearlings move into coastal regions—a pattern observed also for Hudson River striped bass. Otolith microchemical analyses revealed two types of behaviors (estuarine and oceanic) that confirm migratory behaviors recently determined for other populations of striped bass and diadromous species (e.g., American eels [Anguilla rostrata] American shad [Alosa sapidissima] and white perch [Morone Americana])

Identifying Important Juvenile Dusky Shark Habitat in the Northwest Atlantic Ocean Using Acoustic Telemetry and Spatial Modeling

Highly mobile species can be challenging for fisheries management and conservation due to large home ranges combined with dependence on discrete habitat areas where they can be easily targeted or vulnerable to anthropogenic disturbances. Management of the Dusky Shark Carcharhinus obscurus in the northwest Atlantic Ocean has been particularly challenging due to the species\u27 inherent vulnerability to overfishing and poorly understood habitat associations. To better understand habitat associations and seasonal distributions, we combined telemetry and remotely sensed environmental data to spatially model juvenile Dusky Shark presence probability in the northwest Atlantic Ocean. To accomplish this, 22 juvenile Dusky Sharks (107-220 cm TL) that were tagged with acoustic transmitters at different locations within the U.S. Middle Atlantic Bight region were tracked through networked arrays of acoustic receivers. Tag detections were summarized as daily presence records, and data describing environmental conditions, including depth, chlorophyll-a concentration, salinity, and sea surface temperature, were extracted at detection locations. These data were used in boosted regression tree models to predict juvenile Dusky Shark presence probability based on environmental parameters during fall 2017 and summer 2018. Telemetry observations and modeled presence probability showed consistent associations with temperatures between 16 degrees C and 26 degrees C and chlorophyll-a concentrations between 2 and 7 mg/m(3), which were associated with seasonal migration timing and monthly spatial distributions. Dusky Shark tag detections and predicted distributions during summer and early fall overlapped areas in the Middle Atlantic Bight that were affected by fisheries and potential offshore energy development. Our methodology provides a framework for assessing climate change effects on distribution

Assessment of Critical Habitats for Recovering the Chesapeake Bay Atlantic Sturgeon Distinct Population Segment

The states of Virginia and Maryland along with Virginia Commonwealth University (VCU), Virginia Institute of Marine Science (VIMS) and University of Maryland Center for Environmental Science (UMCES) partnered to assess critical habitat for recovering the Chesapeake Bay Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) distinct population segment. The primary objectives were to assess reproductive habitat in the James River, nursery habitat in the James and York Rivers and the degree of dependence of those populations to habitat in the Chesapeake Bay