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Shellfish Assessment Program - Reproduction: Past Research


Primiparous and Multiparious Southern Tanner Crab Egg Development

Photo of southern Tanner crabs. The crab on top is recently mature (primiparous-brooding 1st egg 
			clutch). The southern Tanner crab on bottom is an older mature female (multiparous-brooding 2nd or 
			subsequent egg clutch).
The southern Tanner crab on top is recently mature (primiparous-brooding 1st egg clutch). The southern Tanner crab on bottom is an older mature female (multiparous-brooding 2nd or subsequent egg clutch).
Photo of a female southern Tanner crab brooding a clutch 
			of eggs
Female southern Tanner crab brooding a clutch of eggs.

Timing of egg extrusion, embryo development, timing and hatching duration, and incubation periods of primiparous (brooding 1st egg clutch) and multiparous (brooding 2nd or subsequent egg clutch) southern Tanner crabs were compared to determine if these variables differ between the two reproductive states.

Primiparous females extruded eggs on average 103 days earlier than multiparous females and embryos developed similarly between groups.

Both groups exhibited an embryonic developmental diapause (suspended development) at the gastrula stage; however, the length of diapause was approximately 6 months for the primiparous group and 3 months for the multiparous group. This diapause appears to synchronize hatching.

Hatching was relatively synchronous between the two groups, however the mean hatch date was 10 days earlier for primiparous females and on average, hatching took 7 days for primiparous females and 12 days for multiparous females.

Primiparous females have an average incubation period of 489 days which is 92 days longer than the average multiparous female incubation period of 397 days.

Results of this study clearly illustrate that reproductive cycles differ between primiparous and multiparous Tanner crabs which may result in different reproductive potentials.

Differences between primiparous and multiparous southern Tanner crabs must be understood and included in models for effective stock assessment and management.

        Photo of southern Tanner crab embryos
			stained with Bouin's Solution     Photo of southern Tanner crab embryos. 
			Dark brown spots are eyes, darker orange regions are yolk, and lighter orange/clear areas are the 
			embryos
        Southern Tanner crab eggs stained with Bouin's Solution so the embryos are easier to see. Click image to enlarge.     Southern Tanner crab embryos. Dark brown spots are eyes, darker orange regions are yolk, and lighter orange/clear areas are the embryos. Click image to enlarge.


Reproductive Dynamics and Life-History of Snow Crab in Eastern Bering Sea

Photo of digital camera being inserted into sled
The digital camera is set inside an aluminum housing with a quartz dome viewing port.
Photo of side view of the video camera sled
Side view of video camera sled

In 1991, scientists at the Shellfish Assessment Program used Remotely Operated Vehicles (ROV) and benthic camera sleds to conduct detailed studies of Tanner crab reproductive behavior in Chiniak Bay off Kodiak Island.

The sled carried a digital video camera, a 24 V battery, and two 150-W lights. Towed along the seafloor at up to 2 knots, it captured video of crabs and other marine life. The sled was used to cover several miles of seafloor per day in search of crab aggregates.

Aggregation behavior is common to many species of crustaceans including spiny lobsters (Panulirus interruptus), American lobster (Homarus americanus), and juvenile and adult red king crabs (Paralithodes camtschaticus).

Complex, high-density mating aggregations of southern Tanner crabs (Chionoecetes bairdi) observed at continental shelf depths (greater than 150 meters) had not been seen by scientists at the Shellfish Assessment Program prior to 1991.

Efforts were focused on determining the relationship between time of mound formation in the wild, larval release by crabs in the laboratory, and environmental changes, particularly tidal fluctuations.

This research was conducted in association with the Alaska Department of Fish and Game and the West Coast National Undersea Research Program.




                        Photo Tanner crab aggregate, which was was measured at 1-2 meters in diameter, 0.5-1.0 meters 
			high and containing approximately 100,000 crabs.           Photo of male Tanner crab mating with a female Tanner crab at the aggregation periphery.
                        Tanner crab aggregate was measured at 1-2 meters in diameter, 0.5-1.0 meters high and containing approximately 100,000 crabs.           Male Tanner crabs were found mating with females at the aggregation periphery.



Shellfish Assessment Program - Reproduction Research CURRENT RESEARCH


Related Publications

  • SWINEY, K. M. 2008. Egg extrusion, embryo development, timing and duration of eclosion, and incubation period of primiparous and multiparous Tanner crabs (Chionoecetes bairdi). Journal of Crustacean Biology 28(2):334-341.

  • STEVENS, B. G., J. A. HAAGA, and W. E. DONALDSON. 1994. Aggregative mating of Tanner crabs, Chionoecetes bairdi. Canadian Journal of Fisheries and Aquatic Sciences 51:1273-1280.


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