Hi, I’m Elizabeth Lee, and I am an Oregon State University master’s student with Dr. Kathleen O’Malley in the State Fisheries Genetics Lab at Hatfield Marine Science Center in Newport, Oregon. My first quarter as Malouf Scholar has been quite busy, but before I dive into my Fall quarter, let me provide a little background on my research.
When you think of the Oregon Coast, what comes to mind? Maybe rocky coastlines? Tides pools? Seals? Beaches? Boats? Seafood? Dungeness crab?
If “Dungeness crab” didn’t come to mind, you need to spend more time along the Oregon Coast! Dungeness crab (Cancer magister) is Oregon’s most valuable single-species commercial fishery. Its cultural, historical, economical, and ecological importance along the Oregon coast is prominent.
In 2017, 20.4 million pounds of Dungeness crab were landed by commercial fishing vessels in Oregon, totaling $62.7 million in ex-vessel value. These may seem like large numbers to you, but I will argue, that from the perspective of my discipline, there’s another aspect of Dungeness crab that’s even bigger. The genome of the Dungeness crab.
Let’s take a trip back to Biology 101, remember all the ‘A’s, ‘T’s, ‘G’s, and ‘C’s that make up your DNA? These ‘A’s, ‘T’s, ‘G’s, and ‘C’s (or bases) pair-up to form the double stranded structure that holds the blueprints that makes each of us unique (or DNA). The complete DNA blueprints (or genome) of the Dungeness crab is over 2 billion base pairs long! And, every cell in its shell-encrusted body has a copy of these 2 billion base pairs. So, although we catch tens-of-millions of pounds of Dungeness crab per year in Oregon, the genetic composition that makes a Dungeness crab a Dungeness crab, is even larger!
Considering the importance of Dungeness crab along the West Coast, one would assume we know a lot about the Dungeness crab’s genome and genetics. But in fact, we do not. The O’Malley Fisheries Genetics Lab undertook one of the first large-scale genetics projects on Dungeness crab. They sampled over 7,000 adult Dungeness crab off the coasts of Washington, Oregon, and California to understand the population genetic structure, genetic connectivity, and genetic diversity of Dungeness crab within the California Current System (Jackson et al. 2017)
By determining the pattern of ‘A’s, ‘T’s, ‘G’s, and ‘C’s within the crab genome, we can study the genetic structure, genetic connectivity, and the genetic diversity of the population. These findings are informative for managers and conservationists. Defining the population genetic structure of Dungeness crab is important for determining how groups of crab in the ocean are connected and allows managers to define stocks within the fishery. Assessing the genetic diversity within and among populations provides insight into the species ability to respond to environmental changes.
In their coast-wide population genetics study, Jackson et al. (2017) found that Dungeness crab were highly connected genetically within the California Current System. Interestingly, they found inter-annual variability in the degree of genetic connectivity. This suggests that inter-annual variations in oceanographic conditions are affecting the genetic population structure of Dungeness crab. Specifically, the strength and timing of coastal upwelling, the timing of spring transition, and the phase of the Pacific Decadal Oscillation that effects of the strength of the off-shore current systems.
So, how is it that these large-scale oceanographic conditions might be affecting the bottom-dwelling Dungeness crab? Because of the complex life cycle of Dungeness crab.
Before Dungeness crab become 6 ¼-inch-bottom-dwelling (benthic) harvestable organisms in the ocean, they spend 3-4 months as very small, floating (pelagic) larvae within the water column. The pelagic larvae are moved offshore and are dispersed for 3-4 months along the west coast by the ocean currents. The time-period the larvae spend in the ocean current systems and the strength of the ocean currents influence where the larvae finally land on the bottom at the completion of their 3-4 month ocean journey. When the Dungeness crab larvae land along our coasts, we call this process recruitment. After recruitment, the juvenile crabs grow into bottom-dwelling adult crabs.
As a graduate student, I am studying the genetic structure and diversity of Dungeness crab larvae that are recruiting to our Oregon Coast. By combining this genetic information with information about the oceanographic conditions and ocean currents along our coast, we can better understand the inter-annual variability that is observed within the adult Dungeness crab genetic population structure. The findings of my research can inform scientists and managers about the population of Dungeness crab off our coasts. Our genetic research is one of the many research projects that can help us tackle the complex questions of ‘how’ and ‘why’ the Dungeness crab fishery and population changes from year-to-year.
I am looking forward to keeping you all updated on my Dungeness crab genomics research this year. And in the meantime, I am enjoying the start of the 2018 Dungeness crab commercial season in Newport, Oregon!
Jackson, T. M., Roegner, G. C., & O’Malley, K. G. (2017). Evidence for interannual variation in genetic structure of Dungeness crab (Cancer magister) along the California Current System. Molecular ecology.
Rasmuson, L. K. (2013). The biology, ecology and fishery of the Dungeness crab, Cancer magister. In Advances in marine biology (Vol. 65, pp. 95-148). Academic Press.
Wild, P. W., & Tasto, R. N. (Eds.). (1983). Life history, environment, and mariculture studies of the Dungeness crab, Cancer magister, with emphasis on the central California fishery resource. State of California. The Resources Agency. Department of Fish and Game.