Age and Growth

  • Atlantic croaker (Micropogonias undulatus) Otolith
    Atlantic croaker (Micropogonias undulatus) Otolith  are one of the most abundant inshore demersal fishes along the southeastern coast of the United States. This species has been reported to live over 15 years old.  
  • Atlantic croaker (Micropogonias undulatus)
    Atlantic croaker (Micropogonias undulatus)  This sectioned croaker otolith is 6 years old. The oldest Atlantic croaker aged by our surveys: ChesMMAP Survey 18 years old, NEAMAP Survey 12 years old  
  • Black drum (Pogonias cromis) Otolith
    Black drum (Pogonias cromis) Otolith  are a long-lived fish and are the largest member of the family Sciaenidae on the Atlantic coast.  
  • Black drum (Pogonias cromis)
    Black drum (Pogonias cromis)  This sectioned black drum otolith is 41 years old. The oldest black drum aged by ChesMMAP was 54 years old.  
  • Black seabass (Centropristis striata) Otolith
    Black seabass (Centropristis striata) Otolith  are protogynous hermaphrodites that is, initially they are females, but larger fish reverse sex to become males. Black seabass are reported to live as long as 20 years, however, individuals longer than 15 inches, the size of an approximately 8 year old fish, are uncommon. (Source: Fishes of the Chesapeake Bay)  
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  • Bluefish (Pomatomus saltatrix) Otolith
    Bluefish (Pomatomus saltatrix) Otolith  are a migratory pelagic species that primarily travels in schools. A highly sought after recreational finfish. Reported to live more than 12 years.(Source: Fishes of the Chesapeake Bay)  
  • Bluefish (Pomatomus saltatrix)
    Bluefish (Pomatomus saltatrix)  This sectioned bluefish otolith is 1 year old. The oldest bluefish aged by our surveys: ChesMMAP 2 years old, NEAMAP 5 years old.  
  • Butterfish (Peprilus tricanthus) Otolith
    Butterfish (Peprilus tricanthus) Otolith  are a pelagic schooling species, typically found over sandy bottoms in near shore and offshore waters. Maximum age suspected to be 6.  
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  • Kingfish (Menticirrhus) Otolith
    Kingfish (Menticirrhus) Otolith  are members of the Sciaenidae family and are known to live for at least 4 years.  
  • Kingfish (Menticirrhus)
    Kingfish (Menticirrhus)  This sectioned kingfish otolith is 2 years old. The oldest kingfish aged by the ChesMMAP survey was 7 years old.  
  • Red drum (Sciaenops ocellatus) Otolith
    Red drum (Sciaenops ocellatus) Otolith  is an important recreational finfish that may travel in large schools. Red drum may live as long as 35 years.(Source: Fishes of the Chesapeake Bay)  
  • Red drum (Sciaenops ocellatus)
    Red drum (Sciaenops ocellatus)  This sectioned red drum otolith is 8 years old. The largest red drum aged by the ChesMMAP survey was 30 years old.  
  • Scup (Stenotomus chrysops) Otolith
    Scup (Stenotomus chrysops) Otolith  are abundant fishes which prefer hard-bottom and submerged structures. Scup may attain 15 years of age (Source: Fishes of the Chesapeake Bay)  
  • Scup (Stenotomus chrysops)
    Scup (Stenotomus chrysops)  This sectioned scup otolith is 9 years old. The oldest scup aged by our surveys: ChesMMAP 2 years old, NEAMAP 4 years old  
  • Sheepshead (Archosargus probatocephalus) Otolith
    Sheepshead (Archosargus probatocephalus) Otolith  prefer high-relief, hard-bottom areas. An excellent food fish that has been reported to live as long as 35 years. (Source: Old Dominion University's Center for Quantitative Fisheries Ecology)  
  • Sheepshead (Archosargus probatocephalus)
    Sheepshead (Archosargus probatocephalus)  This sectioned sheepshead is 8 years old. The oldest sheepshead aged by the ChesMMAP survey was 26 years old.  
  • Spot (Leiostomus xanthurus) Otolith
    Spot (Leiostomus xanthurus) Otolith  one of the Chesapeake Bay's most important commercial and recreational species. Spot have been reported to 6 years old. (Source: Old Dominion University's Center for Quantitative Fisheries Ecology)  
  • Spot (Leiostomus xanthurus)
    Spot (Leiostomus xanthurus)  This sectioned spot otolith is 1 year old. The oldest spot aged by the ChesMMAP survey was 4 years old.  
  • Striped bass (Morone saxatilis) Otolith
    Striped bass (Morone saxatilis) Otolith  Important recreational and commercial finfish. Females grow larger than males, and most fish older than 11 years are females, with ages exceeding 30 years reported.  
  • Striped bass (Morone saxatilis)
    Striped bass (Morone saxatilis)  This sectioned striped bass otolith is 4 years old. The oldest striped bass aged by our surveys: ChesMMAP 20 years old, NEAMAP 21 years old  
  • Summer flounder ( Paralichthys dentatus) Otolith
    Summer flounder ( Paralichthys dentatus) Otolith  recreationally and commercially important flat fish. Excellent food fish. Known to live at least 12 years.  
  • Summer flounder (Paralichthys dentatus)
    Summer flounder (Paralichthys dentatus)  This sectioned summer flounder otolith is 3 years old. The oldest summer flounder aged by our surveys: ChesMMAP 12 years old, NEAMAP 13 years old  
  • Weakfish (Cynoscion regalis) Otolith
    Weakfish (Cynoscion regalis) Otolith  a member of the family Sciaenidae that often occur in schools and frequent shallow, sandy bottom areas. Known to live at least 12 years. (Source: Fishes of the Chesapeake Bay and NEFSC)  
  • Weakfish (Cynoscion regalis)
    Weakfish (Cynoscion regalis)  This sectioned weakfish otolith is 2 years old. The oldest weakfish aged by our surveys: ChesMMAP 6 years old, NEAMAP 4 years old.  
  • White perch (Morone americana) Otolith
    White perch (Morone americana) Otolith  a member of the family Moronidae. White perch are ubiquitous in estuaries and freshwater ecosystems. White perch may live as long as 17 years (Source: Fishes of the Chesapeake Bay)  
  • White perch (Morone americana)
    White perch (Morone americana)  This sectioned white perch otolith is 6 years old. The oldest white perch aged by the ChesMMAP survey was 17 years old.  
  • Winter flounder (Pseudopleuronectes americanus) Otolith
    Winter flounder (Pseudopleuronectes americanus) Otolith  the most common near-shore (shallow-water) flounder. Important U.S.commercial and recreational fisheries exist from the Gulf of Maine to the the Mid-Atlantic Bight. Winter flounder have been know to reach 15-20 years of age. (Source: NOAA NEFSC)  
  • Winter flounder ( Pseudopleuronectes americanus)
    Winter flounder ( Pseudopleuronectes americanus)  This sectioned winter flounder otolith is 3 years old. The oldest winter flounder aged by the NEAMAP survey was 19 years old.  
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Why is ageing fish important?      

Ageing fishes is a vital part of fish stock management. Ageing is also important for the monitoring of fish  populations and their reaction to environmental impacts such as fishing, natural mortality, and predation. This management will help aid in more long term monitoring and management of fish stocks to create sustainable fish stocks.

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Sample Area

Our sample area focuses on two survey areas of the Chesapeake Bay and the Northwest Atlantic Ocean from Cape Hatteras, North Carolina to Martha’s Vineyard, Massachusetts. The Chesapeake Bay is the east coast’s largest estuary which makes it an essential body of water to monitor. This coupled with the near shore survey in the Atlantic provides sample coverage for many commercially valued species which should all be carefully monitored.

Lab Processing

 

Age and Growth laboratory supplies
  • Dissecting microscope
  • Buehler low-speed Isomet saw
  • 3" or 4" diamond wafering blades 
  • Saw blades spacers
  • Hot plate
  • Crystalbond
  • Glass dish
  • Probe
  • Forceps
  • Paper mounting squares 
  • Slides
  • Slide box
  • Wet sand paper - 400 grit
  • Water bottle
  • Suction cups
  • Paper towels
Ageing Methods

A variety of methods are used to age fish. Scales, vertebrae, spines, opercula and otoliths are a few of the hard calcified structures that are commonly used to age fish. Scales and otoliths, the fish’s ear bones, are the two most common that our group samples.  Appropriate hard parts for ageing (otoliths, vertebrae, opercula or spines) are removed from each fish that is subsampled and brought back to VIMS for further analysis. Ageing structures are prepared according to methodology established by the NEFSC, Old Dominion University, and VIMS.

Typically, one otolith is selected and mounted on a piece of 100 weight paper with a thin layer of Crystal Bond. A thin transverse section is cut through the nucleus (core or focus) of the otolith, perpendicular to the sulcal groove, using two Buehler diamond wafering blades with approximately a 0.4-0.5mm spacer and a low speed Buehler Isomet saw. The resulting section is mounted on a glass slide and covered with Crystal Bond. If necessary, the sample is wet-sanded to an appropriate thickness before being covered. Some smaller, fragile otoliths are bifurcated and wet sanded to the appropriate thickness. Few particular species are read using the whole otolith. Sectioned otoliths are most commonly viewed using transmitted light under a dissecting microscope, while whole otoliths are viewed with reflected light on a black back-ground under a dissecting microscope. Other structures such as vertebrae, opercula, and spines are processed and read using the standardized and accepted methodologies for each. For all hard parts, ages are assigned as the mode of three independent readings. Ages are adjusted by a senior reader as necessary to account for the timing of sample collection and annuli deposition (mark formation). Any discrepancy amongst the three readers are flagged by the senior reader read a second time.

The samples processed allow us to determine the age of the fish when it was caught. With this data, we can get a clear picture of the age structure of the population present in the Chesapeake Bay, nearshore mid-Atlantic and southern New England.

Finfish Ageing Protocols