AFSC/RACE/SAP/Swiney: Effects of holding space on juvenile red king crab growth and survival

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Alaskan waters

Note: Dataset migrated by Dan Woodrich (AFSC data management coordinator) on 12/16/2021. Contact: Daniel.woodrich@noaa.gov

Swiney, K. M., W. C. Long, and S. L. Persselin. 2013. The effects of holding space on juvenile red king crab, Paralithodes camtschaticus (Tilesius, 1815), growth and survival. Aquaculture Research 44(7): 1007-1016.

Manuscript produced from this data

Ovigerous red king crab were captured with commercial crab pots in Bristol Bay, Alaska, in November 2008. Crab were shipped in coolers with seawater-soaked burlap bags and ice packs to the Alutiiq Pride Shellfish Hatchery in Seward, Alaska. Larvae hatched from these females between 22 March and 12 April 2009 and were reared for mass culture at the hatchery. In July 2009, juvenile crab were placed in seawater with net substrate in two 3.8 L insulated containers and then packed in a cooler with ice packs and shipped to the Alaska Fisheries Science Center’s Kodiak Laboratory seawater facility in Kodiak, Alaska. Upon arrival at the laboratory, crab were placed in holding tubs acclimated to the ambient seawater temperature. Prior to beginning the experiment, crab were held communally in a 2480 L tank with unfiltered, flow-through ambient seawater with net substrate, and fed twice per week a diet of frozen Artemia (Brine Shrimp Direct, Ogden, Utah, USA), frozen bloodworms (Brine Shrimp Direct, Ogden, Utah, USA), frozen Cyclop-eeze (Argent Laboratories, Redmond, Washington, USA), Cyclop-eeze flakes and a gel diet of “Gelly Belly” (Florida Aqua Farms, Inc., Dade City, Florida, USA) enhanced with Cyclop-eeze powder and pollock bone powder (U. S. Department of Agriculture, Agricultural Research Service, Kodiak, Alaska, USA).

To examine the effects of holding-cell size on growth, survival, and intermolt duration, three treatments were tested. Individual holding cells were constructed from PVC pipe of 20 mm, 40 mm, and 77 mm inner diameters cut to 77 mm in length with 750 micron nylon mesh glued to the bottom of each cell (Table 1). Each treatment had 30 replicates placed randomly on plastic grating raised off of the bottom of a rectangular 0.3 m deep x 0.9 m wide x 1.8 m long fiberglass tank. Three PVC pipes with holes drilled on the sides and bottoms were placed beneath the grating to distribute sand-filtered, flow-through, ambient seawater below the cells. To ensure adequate circulation was occurring prior to beginning the experiment, food coloring was placed in each holding cell. All visible dye was flushed out of all of the cells within 6 hours. A temperature logger was placed in the tank and it recorded temperature at half-hour intervals throughout the experiment.

In September 2009, crab 158 to 179 days old and 32.1 mg to 99.6 mg wet mass were randomly placed in the holding cells with one crab per cell and the experiment was run for 274 days. During the experiment, crab were fed a gel diet of Gelly Belly enhanced with Cyclop-eeze powder and pollock bone powder three times per week. Cells were cleaned prior to feeding. Each cell was checked daily, mortalities and molting events were recorded, and the exuvia and mortalities were removed and stored in individually labeled containers with filtered seawater and placed in a refrigerator until growth measurements could be made. To examine growth, carapace length (CL) (straight-line distance from the posterior margin of the right eye orbit to the medial-posterior margin of the carapace) and carapace width (CW) (greatest straight-line distance across the carapace excluding spines) measurements were made on the exuvia and mortalities. A ratio of CL/CW was calculated to determine if crab shape was affected by holding cell size. To standardize these measurements, carapaces were carefully removed from all exuvia and mortalities and photographed under a dissecting scope using a darkfield adapter. Measurements were made using Image-Pro Plus v. 6.00.260 imaging software (Media Cybernetics, Inc., Bethesda, Maryland, USA). Occasionally, part of a carapace was broken so only one or none of the measurements could be made. To determine the relationship of holding cell area to crab size we area and CL is crab carapace length.. Additionally, 7 days after each molt, crab were carefully blotted dry with a paper towel and weighed. Missing or regenerating limbs were recorded. Wet masses of crabs missing or regenerating limbs were excluded from the analysis. At the termination of the experiment, all surviving crab were sacrificed by being placed in a freezer. The crab were then thawed, and the carapaces were removed, photographed and measured as described above.