Who We Are
The Fishery Biology Program is located at the Woods Hole Massachusetts Laboratory of the National Marine Fisheries Service (NMFS), Northeast Fisheries Science Center (NEFSC). We are one of three programs in the Population Biology Branch of the Fisheries and Ecosystems Monitoring and Analysis Division.
The group was established in 1965 as the Age and Growth Unit. The Unit
was initially responsible for performing routine age determinations for
haddock, Melanogrammus aeglefinus, and yellowtail flounder, Limanda
ferruginea, from the waters of the northwest Atlantic Ocean off the
coast of the United States. During this time, and through the 1970s, validation
studies were carried out, new sample processing and aging techniques were
developed, and many other species were added to the list. The Age and Growth
Unit gradually evolved into a group that studies not only fish growth,
but basic biology of fish and shellfish. In 1978, the Unit's name was changed
to the Fishery Biology Investigation and then Program in 1998 to reflect
the changes in its responsibilities and the Center's organization, however,
we are still often referred to as "Age and Growth".
Current Staff
| Front Row (Seated): |
| Kathy Lang, Research Fishery Biologist |
| Nancy Munroe, Biological Science Laboratory Technician (Fisheries) |
| Daphne Cassidy, Biological Science Laboratory Technician (Fisheries) |
| Second Row (Seated): |
| Sandy Sutherland, Fishery Biologist |
| Blanche Jackson, Biological Science Laboratory Technician (Fisheries) |
| Grace Thornton, Biological Science Laboratory Technician (Fisheries) |
| Third Row (Standing): |
| Nina Shepherd, Biological Science Laboratory Technician (Fisheries) |
| Bill Duffy, Biological Science Laboratory Technician (Fisheries) |
| Sarah Pregracke, Biological Science Laboratory Technician (Fisheries) |
| John "Jay" Burnett, Research Fishery Biologist, Program Chief |
| Liz O'Neill, Biological Science Laboratory Technician (Fisheries) |
What We Do
The mission of the Fishery Biology Program is to quantify fundamental demographic characteristics of marine fish and invertebrate populations. Those results are used in stock assessment analyses, in models designed to guide management decisions, and related research. The Program focuses on basic biological processes (particularly growth and reproduction) which are essential to understanding the population dynamics of exploited stocks.
Our current approach is to:
- Compile data and develop information relative to fish and shellfish growth and maturation
- Validate aging methods and develop and improve aging techniques
- Support age structure exchanges and aging workshops to ensure comparability between age readers, both within and between labs
The Fishery Biology Program ages about 35-50,000 fish per year. We age
18 species (26 stocks) of fish and shellfish from samples collected during
research vessel surveys and 14 species (21 stocks) from the commercial
fishery.
Click here to read about our new and improved sectioning technique.
Click here to access Templates for Calculating Aging Precision.
NEWS!
Click here to see results of the group's Quality Assurance and Quality Control efforts.
Click here to estimate fish ages and weights based on lengths.
How We Age Fish
The choice of an age determination method for a given species involves deciding on an appropriate aging structure (scales, otoliths, vertebrae, spines, etc.) and processing method (impressions, thin sections, etc.) for that structure. The next step is validation, in which the marks used to age fish are verified to occur once per year and at approximately the same time each year. Common validation techniques include direct methods such as tag/recapture studies, including marking with chemicals such as oxytetracycline, calcein, and others; and indirect techniques such as back-calculation, marginal increment analysis, edge progression analysis, length frequency-year class progression analysis, radiometric/isotope analysis, elemental analysis, and others.
To age a fish, an age reader must identify the annual growth marks (annuli)
on the structure chosen. In temperate waters, fish growth is fast during
the summer months when water temperatures are warm, and slow during the
cold winter months. A year of growth is defined as one summer zone plus
one winter zone. These zones are identified on scales as areas of wide
(summer) and narrow (winter) circulus spacing. On otoliths, these zones
are identified as alternating opaque and translucent bands when viewed
microscopically.
In 1988, the Fishery Biology Program developed and published
a set of detailed descriptions of the age determination methods we routinely
use. These descriptions are being updated and will be reprinted here in
their entirety. The descriptions are designed for use primarily by fishery
biologists and professional age readers and students but may be of general
interest.
Click here to browse through the Aging Manual
See which species we age and the structures we use to age them.
Why We Age Fish
Basic biological data are the foundation on which all assessments of fisheries resources are built. These include parameters such as the size and age composition of the population and catch (both landed and discarded), growth rates, and maturation. The most thorough assessments include age specific estimates of stock biomass, mortality rates, and predictions of future stock conditions. These require knowledge of the size and age composition of the catch and indices of relative abundance by age. Rates of growth, mortality (due to natural causes and fishing), and reproduction can only be calculated if changes in maturity or size (and numbers) at age can be monitored over time. Fish age is also a critical correlate to many biological and pathological processes.
What Is Done With Our Age Data
The NEFSC collects samples from three primary sources. In order to obtain unbiased estimates of the age composition of a fish population, samples from research vessel surveys are analyzed. These surveys are generally conducted four times each year in order to monitor the abundance and to follow the seasonal progression of growth and maturation of most species inhabiting the waters off the northeast coast of the United States.
Samples are also collected from commercial and recreational fisheries in order to estimate the age composition of the removals from the population. These samples are collected from the docks (the landed portion of the catch) and directly from fishing vessels (to estimate the age composition of the discarded portion of the catch).
Age and length data are then utilized in models that allow assessment scientists to estimate the biomass of fish and shellfish populations at age and to examine the potential effects of continuing removals from those populations. The Resource Evaluation and Assessment Division of the NEFSC publishes annual updates of the assessments of the fish and shellfish resources off the northeast coast of the United States. The document also includes descriptions of the methods used to analyze fish populations. If you are interested in viewing this document to learn more about assessment methods used at the NEFSC or the status of a particular species click here.
