An oceanic whitetip shark swims near the surface of the water. Photo courtesy of John Carlson.
Fisheries Biology - Age and Growth Data Sources and Uses
Data on fishes' age and growth are crucial for stock assessment models.
Collecting Samples for Stock Assessments
While some sampling is conducted "in house" via port sampling in the Panama City area and small-vessel fishery-independent surveys, our bioprofiles program is largely responsible for processing biological samples obtained from several other state and federal programs. Fishery-dependent programs that have contributed "dockside" samples include:
- Head Boat Survey (run out of NOAA Fisheries’ Beaufort, North Carolina laboratory).
- Trip Interview Program (run out of NOAA Fisheries’ Miami, Florida laboratory).
- Florida Fish and Wildlife Research Institute.
- Marine Recreational Fisheries Statistics Survey (run out of NOAA’s Southeast Fisheries Science Center).
- Augmented sampling at recreational marinas (run out of our Panama City Laboratory).
In addition to "dockside" sampling, we also conduct collaborative studies involving "at-sea" sampling from fishery observers aboard fishing vessels (shark bottom longline observer program and Galveston observer program) and from scientific fishery surveys. These collaborating studies have included NOAA Fisheries’ Pascagoula, Mississippi Laboratory reef fish and long-line surveys, NOAA Fisheries’ Pascagoula/Panama City fishery reserve study, and the U.S. Geological Survey's fishery habitat characterization studies.
For formal assessments, the biological data, including age, size, sex, maturity, and reproductive status, are then used in models that enable assessment scientists (primarily NOAA Fisheries’ Sustainable Fisheries Division in Miami, Florida) to estimate population parameters and assess fishery impacts. Because it is commonly recognized that biological data (and resulting parameters) can vary due to natural conditions and from process error, bioprofile program investigators most familiar with the data and their sources (e.g., by gear, fishery type, and locations), work as interactively as possible with the end users conducting the assessments.
Ageing Studies
Information on the age of fish is crucial to conduct population analysis for stock assessment. Otoliths or other hard part derived age data is used to estimate the age and growth patterns of the catch and to estimate longevity. Age-structured stock assessment models are used to estimate stock status and to determine if a stock is overfished or undergoing overfishing,as required by national standards and spelled out within the Magnuson-Stevens Fishery Conservation and Management Act. The MSA governs much of what we do in the fishery science and management business. Therefore, ageing fish is an important activity for the goal of maintaining sustainable fishery harvests.
Methods and structures used for age determination vary among species. For example, otoliths from some species can be aged whole, saving time and cost in processing. Some species such as grey triggerfish are aged from dorsal spine sections; however, most aging will be based on sagittal otoliths by taking transverse sections through the focus in the dorso-ventral plane using a petrographic-type saw. Increasingly, as new species are assessed, we are required to find innovative and efficient ways to age larger numbers of fish.
Validation of ageing methods is conducted to ensure that ages estimated from otoliths or other hard-parts are assigned accurately. Otolith stable isotope analysis is used to determine the population structure of highly sought after species such as bluefin tuna and red snapper. Since the 1980s, our laboratory's focus has been on species managed largely from federal waters within the Gulf of Mexico and has included several reef fishes (snappers and groupers) and certain coastal pelagic species (mackerels). In recent years, highly migratory species have been aged to contribute to International Commission for the Conservation of Atlantic Tunas assessments. As the number of species being managed grows, our list also grows and we strive to coordinate with other federal, state, and university laboratories to efficiently divide up the workload and keep up QA/QC standards.
Reference
- Baremore, I.E. and D.M. Bethea. 2010. A guide to otoliths from fishes of the Gulf of Mexico. NOAA Technical Memorandum NMFS-SEFSC-599, 102 p.
Other Fish Biology Research in the Southeast
While our bioprofiles program focuses on basic biological processes (particularly age, growth and reproduction) related to stock assessment needs, our laboratory’s biologists are also involved in studies of comparative life history, population age and size structure across spatial and habitat gradients, stock delineation, and recruitment and reproductive variability. Methods studies are also conducted and include aspects of gear selectivity, evaluation of growth models, validation of ageing accuracy, new techniques in sample processing, and tests of precision for age and reproductive estimations.
More Information
An oceanic whitetip shark swims near the surface of the water. Photo courtesy of John Carlson.
