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Shellfish Assessment Program - Habitat Research

Upper Thermal Tolerance in Red and Blue King Crabs

Photo of a red king crab in holding cell during thermal tolerance experiment
Red king crab in an individual holding cell during a thermal tolerance experiment.
Graph of red and blue king crab mortality after 24 hour exposure to a range of temperatures. 
			Click image to enlarge.
Proportional mortality for red and blue king crab after 24h exposure to a range of temperatures. Points represent the mean mortality 1 standard error. Lines are the best fit models. Click image to enlarge.

Red and blue king crabs (Paralithodes camtschaticus and P. platypus) are commercially important in Alaskan waters and, although they are very similar in many ways, have generally non-overlapping distributions.

Thermal tolerance is likely important for many aspects of their life history, including growth and survival, and may explain distributional differences between the two species. With expected increasing global temperatures, understanding the thermal tolerance of crabs will help predict how populations may respond to a changing climate.

To understand their thermal tolerance, researchers Ben Daly (formerly with the Shellfish Assessment Program) and Chris Long, did a series of experiments to understand at what temperatures these crabs start being stressed.

Crabs did not start dying until more than 23°C and 20°C for red and blue king crab respectively. However, both species showed reduced growth or other signs of stress at temperatures above about 12°C.

In general, red king crab had a about a 3°C higher tolerance than blue king crab. This work will help understand how these species will respond to warming temperatures.

Shellfish Assessment Program - Habitat Research PAST RESEARCH

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