The Commission’s Fisheries Science Program coordinates activities of state and federal fishery management agencies in order to improve the scientific basis of fisheries management decisions. These activities vary depending on the priorities and changing needs of fisheries managers, but typically focus on broad scientific issues that can be applied to several species.
There are many factors affecting the growth of fish. Species grow at different rates and have different life spans. Examples of large, long-lived species include the Atlantic sturgeon, which lives up to 100 years and reaches 15 feet in length, and the spiny dogfish that may live to 50 years and reach four feet in length. At the other extreme, fishes like spot grow to only 16 inches in length and live only five years.
Fisheries biologists determine the age of a fish by counting annual markings of growth observed on one or more body parts. The most commonly used ageing structures are fish scales, otoliths (ear bones), opercula (gill plates), spines, and vertebrae. Annual markings form because a fish and its age structures grow at different rates during the warm (faster) and cool (slower) seasons, producing alternating translucent and opaque bands. These marks can be read in the same way that rings are counted to age trees.
Fish age information is the basis for determining how fast a species grows, how long it lives, when it matures, and how big it is at each age. Understanding how fast fish grow and when they mature allows scientists to develop harvest strategies that allow the population to successfully replace what was removed by fishing and natural causes. A variety of harvest strategies may be evaluated by comparing different gear sizes that capture different ages of fish. The gear size catching the preferred ages of fish may then be implemented to meet management goals. Age data also provide important information on the age structure of a fish population and whether that age structure is changing over time.
Unfortunately, obtaining quality age data is challenging and expensive. Ageing methods must be validated using controlled laboratory or tagging studies to confirm the observed markings are truly annual markings (annuli). Collecting age data requires a sampling program that adequately covers the fishery or stock, and staff and facilities to process samples.
To improve the availability of age data for use in fish stock assessments, ASMFC established an Otolith Collection Program. This effort coordinates age sampling among member states to achieve a broad representation of fish ages throughout a stock’s range. Biologists and cooperating anglers gather otoliths, scales, and additional information (length, weight, sex) from fish taken in the recreational fishery or during fishery-independent surveys. Sample collection and processing protocols have been developed by ageing experts and ASMFC Staff and distributed to cooperating agencies and angler groups.
The Commission also organizes workshops to address important questions related to fish ageing techniques. Several state agencies collect age samples for a species or group of related species and meet to compare methods. Ageing experts from each state review otolith processing procedures and exchange samples for age reading comparisons. The goal is to ensure age samples are being processed and read in a consistent manner coast wide, providing reliable data for use in assessments of finfish populations. To date, the Commission has conducted ageing workshops on American shad, American eel, Atlantic croaker and red drum, Atlantic striped bass, bluefish, tautog, and winter flounder.
Kristen Anstead, Ph.D., Stock Assessment Scientist
Assessment Science Committee, Laura Lee, Chair
Report of the Quality Assurance/Quality Control Fish Ageing Workshop (March 2016)
Atlantic Menhaden Ageing Workshop Report (June 2015)
River Herring Ageing Workshop Report (August 2014)
Proceedings of the 2013 Black Sea Bass Ageing Workshop (December 2013)
Tautog Ageing Workshop Report (May 2012)
Proceedings from the Winter Flounder Ageing Workshop (February 2012)
Bluefish Ageing Workshop Report (May 2011)
Proceedings from the Atlantic Croaker and Red Drum Ageing Workshop (October 2008)
Proceedings from the Atlantic Striped Bass Ageing Workshop (March 2003)
Testing the validity of Cating’s (1953) method for age determination of American shad using scales. Fisheries Research 30: 10-18.McBride, R.S., Hendricks, M.L., and Olney, J.E. (2005)
Proceedings of the Workshop on Ageing and Sexing American Eel (December 2001)
Tag and recapture data are valuable inputs to the stock assessments of several species managed by the Commission, including Atlantic striped bass, red drum, Atlantic sturgeon, weakfish, spiny dogfish, and coastal sharks. The Commission’s Interstate Tagging Committee (ITC) was created in 1999 to improve the quality and utility of fish tagging data. A subcommittee of ITC members with expertise in tagging program design was established to review and certify interested tagging programs. The certification process supports the promotion of effective tagging programs that can contribute to stock assessments. The ITC maintains a Cooperative Tagging Website and Registry that provides information on coastwide tagging programs. Anglers can search a database by fish species, tag type, and tag color in order to identify recovered tags. The tagging program certification application is also available on the tagging website.
Since 1988, the Commission has partnered with state and federal agencies and academic institutions on a Cooperative Winter Tagging Program led by the U.S. Fish and Wildlife Service. The program organizes scientist to conduct field tagging each winter in nearshore waters off Virginia and North Carolina. The program is designed to capture and tag striped bass on overwintering grounds, and has expanded tagging efforts to additional species throughout the years including Atlantic sturgeon, spiny dogfish, horseshoe crabs, and others. There is an annual winter cruise aboard a research vessel using an otter trawl to capture various species and, during some years, there are additional efforts on charter boat trips using hook and line to capture and tag striped bass. The fish are measured at the time they are initially tagged and then measured again during any subsequent recaptures to provide information on growth. The proportion of fish recaptured over different time periods provides information on survival and mortality. Tagged fish that are subsequently recaptured also provide scientists with data to better understand habitat preferences, seasonal movements and migrations, and stock boundaries.
Jeff Kipp, ASMFC Stock Assessment Scientist
Wilson Laney, U.S. Fish and Wildlife Coopertaive Winter Tagging Program Chief Scientist
Interstate Tagging Committee, Paul Caruso, Chair
In 2007, the Commission established the Fishing Gear Technology Work Group (FGTWG) with the charge of evaluating new gear innovations and associated research from the U.S. and around the world to assess their potential to reduce bycatch, discarding, and habitat alteration associated with Atlantic coast fisheries. The Workgroup, which consists of fishing gear experts from state agencies, academic institutions, and the National Marine Fisheries Service, is building on the Commission’s history of improving fishing gear to minimize impacts on ecosystems. Earlier efforts by Commission committees and workgroups contributed to implementation of the Nordmore grate, turtle exclusion devices (TEDs), and finfish bycatch reduction devices (BRDs) in a variety of fisheries along the Atlantic coast.
In 2008, the FGTWG identified priority fisheries and completed evaluations of gear technology to address issues in these fisheries. The Work Group’s findings are available in the 2009 FGTWG Report.
Jeff Kipp, Stock Assessment Scientist