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Fecundity & Histology

Why is the Multispecies Research Group studying the fecundity of Atlantic Menhaden?

Atlantic Menhaden Brevoortia tyrannus support fisheries that yield the largest landings by volume on the U.S. East Coast and fulfill a critical ecological role as a forage species. The spawning reference point of the stock assessment model that is routinely applied to this species requires information on total annual fecundity. The goal of this study was to generate a contemporary, histology-based evaluation of the reproductive biology and fecundity of female Atlantic Menhaden.

The reproductive biology and fecundity of female Atlantic Menhaden

Objectives
  • Collect female Atlantic Menhaden over all seasons & from throughout the Mid-Atlantic Bight
  • Process ovaries using standard histological techniques. Information on maturity stages, spawning mode, seasonality & frequency.
  • Count ova based on histological findings
  • Model fecundity as a function of size & age.
Sample Area

menhaden_fecundity_samplearea.jpg

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Capture locations of female Atlantic Menhaden from fisheries-dependent gear (green hues) and fisheries-independent gear (orange hues), 2013–2019. ALOSINE, alosine staked gill-net survey; ChesMMAP, Chesapeake Bay Multispecies Monitoring and Assessment Program; NEAMAP, Northeast Area Monitoring and Assessment Program.
Laboratory Processing & Supplies:

Laboratory processing of each fish includes: fork length, whole & eviscerated weight, sex, macroscopic maturity classification, paired ovary weight, scale and otolith removal.

 Laboratory Processing Supplies:Female Atlantic Menhaden ready for ovary removal and workup. Image credit: Joel Hovanesian

  • Analytical Balance - minimum of 0.001 g to a maximum of 410 g
  • Fish Measuring Board
  • Hubco labels
  • Soil sample bags – ovary preservation
  • Screw top vials – otolith storage
  • Sample envelopes – Fish Scales
  • Scalpel + blades
  • Tissue Processing Embedding Cassettes
  • Tissue-Tek Marking Pencils
  • Plastic 1 gallon jugs for sample storage
  • Chemicals used for preservation:
    • Normalin
    • 10% Neutral Buffered Formalin
    • 70% Ethanol
Histology Laboratory Supplies:
  • Lab tissue processor - Thermo Excelsior ES
    • Ethanol
    • Xylene
    • Paraffin Wax
  • HistoStar™ Embedding Workstation
    • Paraffin Wax
  • Histology embedding molds
  • Razor scraper
  • Tanner Scientific TN6000 Manual Precision Microtome 
  • High Profile disposable Microtome Blades
  • Sharps container
  • Lighted tissue flotation water bath
  • Gelatin
  • Styrofoam Tray
  • Crushed Ice
  • Frosted microscope slides
  • Forceps
  • Paint brushes
  • Slide drying rack
  • Slide warmer
  • Kimtech wipes
  • Microscope slide boxes
Staining Supplies:

Stained Atlantic menhaden Ovary

  • Lab Coat
  • Nitrile Gloves
  • Shandon Varistain Gemini automatic stainer
  • Chemicals for staining:
    • Xylene
    • 100% ethanol
    • 95% ethanol
    • Hematoxylin
    • Acid Alcohol
    • NaHCO2
    • Eosin Y
  • Laboratory Fume Hood
  • Glass coverslips
  • Permount Mounting Medium
  • Kimtech wipes
  • Cotton Swabs
  • Aluminum slide trays
  • Drying Oven
Histological Interpretation Supplies:
Compound Microscope and software
  • Analytical Balance - minimum of 0.001 g to a max. of 410 g
  • Spoonula
  • Custom made grid for counting / measuring eggs
  • Glycerin to separate eggs
  • Compound microscope
  • NIS Elements software