Support for the Slope Sea as a major spawning ground for Atlantic bluefin tuna: evidence from larval abundance, growth rates, and particle-tracking simulations

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hernandez, C. M., Richardson, D. E., Rypina, I. I., Chen, K., Marancik, K. E., Shulzitski, K., & Llopiz, J. K. Support for the Slope Sea as a major spawning ground for Atlantic bluefin tuna: evidence from larval abundance, growth rates, and particle-tracking simulations. Canadian Journal of Fisheries and Aquatic Sciences, 79(5), (2021): 814-824, https://doi.org/10.1139/cjfas-2020-0444.Atlantic bluefin tuna (Thunnus thynnus) are commercially and ecologically valuable, but management is complicated by their highly migratory lifestyle. Recent collections of bluefin tuna larvae in the Slope Sea off northeastern United States have opened questions about how this region contributes to population dynamics. We analyzed larvae collected in the Slope Sea and the Gulf of Mexico in 2016 to estimate larval abundance and growth rates and used a high-resolution regional ocean circulation model to estimate spawning locations and larval transport. We did not detect a regional difference in growth rates, but found that Slope Sea larvae were larger than Gulf of Mexico larvae prior to exogenous feeding. Slope Sea larvae generally backtracked to locations north of Cape Hatteras and would have been retained within the Slope Sea until the early juvenile stage. Overall, our results provide supporting evidence that the Slope Sea is a major spawning ground that is likely to be important for population dynamics. Further study of larvae and spawning adults in the region should be prioritized to support management decisions.Ship time was supported by NOAA, the Bureau of Ocean Energy Management, and the US Navy through interagency agreements for Atlantic Marine Assessment Program for Protected Species (AMAPPS). CMH and JKL received funding from the Woods Hole Oceanographic Institution’s Ocean Life Institute (#13080700) and Academic Programs Office. CMH was additionally supported by the Adelaide and Charles Link Foundation and the J. Seward Johnson Endowment in support of the Woods Hole Oceanographic Institution’s Marine Policy Center. IIR, KC, and JKL were supported by a US National Science Foundation (NSF) grant (OCE-1558806). JKL was additionally supported by the Lenfest Fund for Early Career Scientists and the Early Career Scientist Fund at Woods Hole Oceanographic Institution

Evaluating a microalga (Schizochytrium sp.) as an alternative to fish oil in fish-free feeds for sablefish (Anoplopoma fimbria)

Alternative feeds are critical for the sustainable expansion of the marine finfish aquaculture industry. The industry uses wild-caught forage fish as a primary ingredient in farmed fish feeds. Alternative ingredients are needed to safeguard fisheries\u27 sustainability and future aquaculture development. While there have been successes in alternative feeds, it is necessary to improve the existing options and identify alternative ingredients with higher concentrations of omega-3 polyunsaturated fatty acids (PUFAs). This study was designed to test a microalga, Schizochytrium sp., as a feed ingredient for sablefish (Anoplopoma fimbria) using six test diets. There were two fish-ingredient control diets: +FM+FO, which contained both fishmeal and fish oil, and −FM+FO, which contained fish oil, but no fishmeal. The remaining four diets contained alternative lipids and were completely fish-free. FF Flax contained flax oil as the only lipid source replacing fish oil. FF LowSc, FF ModSc, and FF HighSc contained a low, moderate, and high level of Schizochytrium sp. to replace fish oil, with flax oil content decreasing as the microalga increased. After a 20-week trial, sablefish growth differed across the feed treatments, with fish fed the high microalga-inclusion diet (FF HighSc) performing similarly to fish fed the fish-ingredient controls. Fulton\u27s K condition factor, dry feed intake (DFI), and lipid productive value (LPV) were also influenced by treatment. For the four fish-free diets, specific growth rate increased with increasing inclusion of Schizochytrium sp. in the feed. Fillet fatty acid profiles were similarly influenced by diet treatment, generally reflecting the fatty acid profiles of the feed. Total fillet PUFAs were higher in sablefish from the fish-free treatments than the control treatments, with DHA increasing with increasing inclusion of dietary Schizochytrium. In contrast, EPA was higher in fillets from both fish-ingredient control treatments compared to fillets from the fish-free treatments, yet EPA remained higher than expected in sablefish fed the fish-free diets. Histologic evaluation of sablefish distal intestine and liver demonstrated that the microalga-inclusion diets were well tolerated and did not cause histomorphological changes in the tissues. These results suggest Schizochytrium sp. can increase PUFA concentrations in fish fillets without compromising fish health and growth, making it a viable ingredient for alternative sablefish feeds

Whole-body transcriptome of selectively bred, resistant-, control-, and susceptible-line rainbow trout following experimental challenge with Flavobacterium psychrophilum

Genetic improvement for enhanced disease resistance in fish is an increasingly utilized approach to mitigate endemic infectious disease in aquaculture. In domesticated salmonid populations, large phenotypic variation in disease resistance has been identified but the genetic basis for altered responsiveness remains unclear. We previously reported three generations of selection and phenotypic validation of a bacterial cold water disease (BCWD) resistant line of rainbow trout, designated ARS-Fp-R. This line has higher survival after infection by either standardized laboratory challenge or natural challenge as compared to two reference lines, designated ARS-Fp-C (control) and ARS-Fp-S (susceptible). In this study, we utilized 1.1 g fry from the three genetic lines and performed RNA-seq to measure transcript abundance from the whole body of naive and Flavobacterium psychrophilum infected fish at day 1 (early time-point) and at day 5 post-challenge (onset of mortality). Sequences from 24 libraries were mapped onto the rainbow trout genome reference transcriptome of 46,585 predicted protein coding mRNAs that included 2633 putative immune-relevant gene transcripts. A total of 1884 genes (4.0% genome) exhibited differential transcript abundance between infected and mock-challenged fish (FDR \u3c 0.05) that included chemokines, complement components, tnf receptor superfamily members, interleukins, nod-like receptor family members, and genes involved in metabolism and wound healing. The largest number of differentially expressed genes occurred on day 5 post-infection between naive and challenged ARS-Fp-S line fish correlating with high bacterial load. After excluding the effect of infection, we identified 21 differentially expressed genes between the three genetic lines. In summary, these data indicate global transcriptome differences between genetic lines of naive animals as well as differentially regulated transcriptional responses to infection

Identification of larval sea basses (Centropristis spp.) using ribosomal DNA-specific molecular assays

This paper is not subject to U.S. copyright. The definitive version was published in Fishery Bulletin 106 (2008): 183-193.The identification of sea bass (Centropristis) larvae to species is difficult because of similar morphological characters, spawning times, and overlapping species ranges. Black sea bass (Centropristis striata) is an important fishery species and is currently considered to be overfished south of Cape Hatteras, North Carolina. We describe methods for identifying three species of sea bass larvae using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) assays based on species-specific amplification of rDNA internal transcribed spacer reg ions. The assays were tested against DNA of ten other cooccurring reef fish species to ensure the assay’s specificity. Centropristis larvae were collected on three cruises during cross-shelf transects and were used to validate the assays. Seventysix Centropristis larvae were assayed and 69 (91%) were identified successfully. DNA was not amplified from 5% of the larvae and identification was inconclusive for 3% of the larvae. These assays can be used to identify sea bass eggs and larvae and will help to assess spawning locations, spawning times, and larval dispersal.Collection of larvae at sea was supported by funding from the National Science Foundation through OCE 9876565 to C. Jones, S. Thorrold, A. Valle-Levinson, and J. Hare. Additional funding for this project was provided by Office of National Marine Sanctuaries and by Grays Reef National Marine Sanctuary

A Vulnerability Assessment of Fish and Invertebrates to Climate Change on the Northeast U.S. Continental Shelf

Climate change and decadal variability are impacting marine fish and invertebrate species worldwide and these impacts will continue for the foreseeable future. Quantitative approaches have been developed to examine climate impacts on productivity, abundance, and distribution of various marine fish and invertebrate species. However, it is difficult to apply these approaches to large numbers of species owing to the lack of mechanistic understanding sufficient for quantitative analyses, as well as the lack of scientific infrastructure to support these more detailed studies. Vulnerability assessments provide a framework for evaluating climate impacts over a broad range of species with existing information. These methods combine the exposure of a species to a stressor (climate change and decadal variability) and the sensitivity of species to the stressor. These two components are then combined to estimate an overall vulnerability. Quantitative data are used when available, but qualitative information and expert opinion are used when quantitative data is lacking. Here we conduct a climate vulnerability assessment on 82 fish and invertebrate species in the Northeast U.S. Shelf including exploited, forage, and protected species. We define climate vulnerability as the extent to which abundance or productivity of a species in the region could be impacted by climate change and decadal variability. We find that the overall climate vulnerability is high to very high for approximately half the species assessed; diadromous and benthic invertebrate species exhibit the greatest vulnerability. In addition, the majority of species included in the assessment have a high potential for a change in distribution in response to projected changes in climate. Negative effects of climate change are expected for approximately half of the species assessed, but some species are expected to be positively affected (e.g., increase in productivity or move into the region). These results will inform research and management activities related to understanding and adapting marine fisheries management and conservation to climate change and decadal variability

Exploring the advantages and limitations of sampling methods commonly used in research facilities for zebrafish health inspections

Examining zebrafish populations for the presence of disease is an integral component of managing fish health in research facilities. Currently, many different strategies are used for zebrafish fish health inspections, which is a scenario that may result in subjective and biased diagnostic evaluations. The goal of this study was to compare the success of pathogen detection between a sample size of randomly selected fish ( n = 60) that provides 95% confidence in pathogen detection based on a presumed pathogen prevalence level ≥5%, and other subpopulations and sample numbers commonly submitted for diagnostic testing within a 1000 tank, 30,000 fish, recirculating research system. This included fish collected from a sump tank ( n = 53), sentinel fish ( n = 11), and fish that were found moribund or freshly dead ( n = 18). Additionally, five fish from each subpopulation were collected for histopathologic examination. A second study used retrospective data to examine pathogen distribution between systems ( n = 2−5) in multi-system facilities ( n = 5) using a sample size of 60 fish per system. For the pathogens detected, results supported the use of representative sample numbers rather than smaller numbers of populations considered more at risk. The exception to this is for the moribund/mortality group, which may be a resource for targeted surveillance of select pathogens. Each system within multi-system facilities should be considered separate units in terms of fish health inspections and biosecurity. Development of these evidence-based standards for fish health inspections in zebrafish systems enhances fish welfare, provides identification of potentially zoonotic pathogens, and ensures scientific integrity and reproducibility of research results.</jats:p

Proteomic characterization of the acute-phase response of yellow stingrays Urobatis jamaicensis after injection with a Vibrio anguillarum-ordalii bacterin

Systemic inflammatory responses of mammals and bony fish are primarily driven by coordinated up-regulation and down-regulation of plasma acute-phase proteins. Although this general principle is believed to be universal among vertebrates, it remains relatively unexplored in elasmobranchs. The objective of this study was to characterize acute changes in the plasma proteome of three yellow stingrays Urobatis jamaicensis following intraperitoneal injection with a commercial Vibrio bacterin. Changes in plasma protein levels were analyzed immediately prior to vaccination (time 0) and at 24 and 72 h post-injection by isobaric tags for relative and absolute quantitation (iTRAQ 4-plex) using shotgun-based nano liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis and de novo peptide sequencing. Pooled 2D-LC-MS/MS and de novo sequencing data revealed differential expression of 156 distinct plasma proteins between time 0 and at least one post-vaccination time point. Using 1.5-fold change in expression as physiologically significant, 14/156 (9.0%) proteins were upregulated in at least one stingray through at least one experimental timepoint. Upregulated proteins included complement factors, Mx-protein, hemopexin, factor X and prothrombin. Seventy-six of 156 (48.7%) proteins were downregulated in the acute-phase response, including transferrin, apolipoprotein B, heparin cofactor 2, alpha2-macroglobulin, and various growth factors. Other differentially upregulated or downregulated proteins included intracellular, cell binding and structural proteins, proteins involved in physiologic processes, and unknown/hypothetical proteins. Selected bioactive factors are discussed for their putative roles in the elasmobranchs acute-phase response. These findings contribute to our understanding of disease processes in elasmobranchs, immunologic phylogeny in vertebrates, and begin the search for potential biomarkers of disease in these ecologically important fish