Wet Lab Sample Processing
Samples collected in the Fisheries Assessment and Monitoring Program (FAMP) provide fishery-independent data that helps determine the population status of marine organisms throughout Alabama’s coastal waters. These data are available to fisheries managers to use in the analysis of growth, determination of seasonal and geographical distribution, assess changes in population structures, and correlate abundance with some abiotic factors for all Alabama marine fauna. Bi-weekly data collection began in 1977 for shrimp and crabs. Monthly sampling for all penaeid shrimp, callinectes crabs and finfish species started in October 1980. In 1998, the program shifted to an interagency program with ADEM; water quality parameters and the number of sites sampled were expanded but effort was reduced to one sampling regime per quarter. After determining that quarterly sampling did not provide a suitable sample size and distribution to accurately observe trends, monthly sampling was resumed in October 2000. Given the revisions of the SEAMAP program and the importance for similar sample collection/processing throughout the Gulf, AMRD adjusted the FAMP program in order to produce data complementary to SEAMAP protocols beginning in May 2010. Therefore, current protocols require each sample to be sorted by species, determine species-specific total weight/abundance, and weigh/measure up to 20 individuals of each species.
Sample sites were selected at the beginning of the program to be most representative of the marine fauna found in Alabama waters. Sample locations are distributed throughout the Mississippi Sound, Mobile Bay, the Perdido system, Little Lagoon, and Alabama’s territorial. Three methods of sample collection are employed within these areas to target a wide range of fauna throughout their life history. Beam plankton trawls are used to target early life history stages of organisms utilizing nearshore habitats, seine hauls are used to target juvenile organisms utilizing shoreline habitats, and otter trawls are used to target juvenile and adult stages occurring within deeper water habitats.
For further information regarding seine, BPL, and otter trawl sample processing contact Craig Newton.
|Brown Shrimp||Greater Blue Crab||Juvenile Atlantic Croaker|
Otolith Lab Sample Processing
Target fish (those deemed to be commercially and/or recreationally important) are brought back to the laboratory for further processing. Target fish are measured down their centerline, weighed, otoliths extracted, sex is determined, and if female then the ovaries are weighed. The otoliths are extracted because this bony structure is the most reliable way to determine a fish's age.
Otoliths are located in the otic capsule of the head and are used by the finfish to interpret sensory information regarding movement, orientation, momentum, and sound. Daily growth of the otoliths lay down rings. Times of slower growth, associated with cooler months, causes rings to lay down in a more compact manner forming dark (opaque) rings. These thick rings are referred to as annuli. Faster growth periods, associated with warmer months, cause rings to lay down farther apart giving a translucent appearance. One translucent and one opaque ring are equivalent to one year's growth.
Otoliths must be thinly sectioned and mounted on a microscope slide to determine the number of annual growth zones present. AMRD personnel use a Hillquist Thin Section Machine and shave the otolith down to less than 1cm of thickness and cover the sectioned otolith with a clear liquid to prevent moisture from the air deteriorating the otolith section. After the otolith has been sectioned and mounted on a slide a Gulf States Marine Fisheries Commission (GSMFC) trained otolith reader will determine the age of the fish. The age of the fish can then be correlated with the length and sex to help determine size and creel limits.
Otoliths are processed at both the Gulf Shores and Dauphin Island offices. For further information regarding otolith collection and processing contact Jaime Miller.
|Extracted Otolith from a Red Drum||Otolith Processing||Section Red Drum Otolith|