Chapter 14: in the Coos Estuary Jenni Schmitt, Colleen Burch Johnson - South Slough NERR Dungeness Crabs: The Dungeness fishery is sustainably managed, allowing for continued stable Dungeness populations on the west coast in general. Red Rock Crabs: Red Rock crabs appear to have a healthy resident population in Coos Bay, although their populations are largely unstudied.

Other Crabs: More information is Subsystems: CR- Coos River, CS- Catching Slough, HI- Haynes Inlet, IS- Isthmus Slough, needed to properly assess these LB- Lower Bay, NS- North Slough, PS- Pony Slough, SS- South Slough, UB- Upper Bay populations. Shore crabs appear abundant despite the introduction of the Atlantic mud crab. The status of subtidal crabs, pea crabs and kelp crabs has not been recently assessed.

Crabs in the Coos Estuary 14-1 Chapter 14: estuary (Groth et al. 2013). Much of the infor- Crabs in the Coos Estuary mation for the Other Crabs data summary is older, the most current being from deRivera This chapter includes three data et al. in 2005.

summaries: Dungeness Crabs, Red Information in crab data summaries was Rock Crabs, and Other Crabs – derived from a variety of sources including each describing the most current theses (e.g., Dunn 2011), agency reports (e.g., research on the status and trends Ainsworth et al. 2012), peer review literature (e.g., Shanks 2013), and personal communica- (where the data allow) of crab pop- tions with various researchers. ulations in the Coos Estuary. Data Gaps and Limitations The South Slough and Lower Bay are the two Data: Due to their economic most studied subsystems for all crab popula- importance, Dungeness crabs are the most tions and the only subsystems where infor- studied of the crab species. However, ques- mation is reported for red rock crabs ( tions remain about how Dungeness crabs use productus). Although Dungeness crabs (Can- estuaries. cer magister) are mainly found in the Lower Bay and South Slough subsystems, Dungeness For example, the migration of Dungeness crab populations have been studied in all sub- between the estuary and the ocean is largely systems except Pony Slough, Coos River and unstudied, although preliminary results from Catching Slough. Information about “Other Groth et al. (2013) suggest seasonal move- Crabs” comes mainly from studies focusing ment of Dungeness crabs in and out of the on South Slough and the Lower Bay, and from Coos estuary. limited studies in the Upper Bay, Isthmus Slough and Coos River subsystems. Another Dungeness crab-related question Oregon State University is investigating While all three crab-related data summaries (with ODFW), is the possibility of genetically include current and historical data, informa- different subpopulations of Dungeness crab tion for Dungeness and red rock crabs is by far –important for understanding how to keep the most current. For example, recent creel the Dungeness crab fishery sustainable since surveys have been conducted by the Oregon harvesting selectively among crab subpopula- Department of and Wildlife (ODFW) to tions can affect genetic characteristics within help understand Dungeness crab population a population and ultimately reduce the fisher- trends (Ainsworth et al. 2012), and a new, ies’ productivity. (ODFW 2013). though preliminary ODFW study informs us of red rock population structure in the Coos

14-2 Crabs in the Coos Estuary An ongoing ODFW study samples Dungeness Non-Indigenous Crabs crabs in the Yaquina and Alsea estuaries, While there is mention in this chapter of a collecting data on carapace width, weight, non-indigenous crab species (Atlantic mud sex, epifaunal growth on carapace, missing crab— Rhithropanopeus harrisi), the status appendages, parasite presence, and evidence of non-native crab populations in the Coos of pitting (injuries), thus providing important estuary, including invasive species such as the abundance and health information (ODFW European green crab () are 2013). A similar study in the Coos estuary discussed in full in Chapter 17: Non-Indige- could provide insight into the use of habitats nous and Invasive Species. by Dungeness crabs locally. References Red Rock Crab Data: Even though red rock Ainsworth, J. C., M. Vance, M. V. Hunter, and crabs are recreationally harvested, this native E. Schindler. 2012. The Oregon recreational crab has been largely unstudied. However, Dungeness crab fishery, 2007-2011. [Oregon ODFW is now gathering much-needed infor- Department of Fish and Wildlife Information mation (e.g., growth rates) that may contrib- Report 2012-04, Marine Resources Program]. Newport, OR. ute to our understanding of how red rock crabs use the Coos estuary. deRivera, C. E., G. M. Ruiz, J. Crooks, K. Was- son, S. Lonhart, P. Fofonoff, B. Steves, S. Rum- rill, M. S. Brancato, S. Pegau, D. Bulthuis, R. K. Other Crabs Data: More information is Preisler, C. Schoch, E. Bolwby, A. DeVogelaere, needed on other crabs in the Coos estuary. M. Crawford, S. Gittings, A. Hines, L. Takata, K. The most comprehensive targeted study is Larson, T. Huber, A. M. Leyman, E. Collinetti, T. Queen’s thesis from 1930 which provides an Pascot, S. Shull, M. Anderson, and S. Powell. 2005. Broad-scale nonindigenous species excellent historic baseline for other crabs in monitoring along the West Coast in National the Coos estuary but is obviously of limited Marine Sanctuaries and National Estuarine use for understanding the status of current Research Reserves. [Report to National Fish & crab populations. Most needed is informa- Wildlife Foundation]. 126 pp. tion characterizing the current distribution, Dunn, P. H. 2011. Larval biology and estuarine productivity, and habitat usage by the large ecology of the Nemertean egg predator Car- variety of non-Dungeness crabs that use the cinonemertes errans on the Dungeness crab, Cancer magister. [PhD Thesis]. University of Coos estuary – especially subtidal crabs, pea Oregon. crabs (Pinnixa faba), and kelp crabs (Pugettia producta), about which there is especially Groth, S., S. Yamada, E. Post, and J. Heinrich. limited information. 2013. Mark recapture of red rock crab, Cancer productus, in Coos Bay, OR. [Poster session presented at Towards an Estuarine Ethic: inte- grating science and stewardship]. 36th Annual Meeting of the Pacific Estuarine Research Society: 2013, April 4-7. Delta, BC.

Crabs in the Coos Estuary 14-3 Oregon Department of Fish and Wildlife (ODFW). 2013. Oregon Dungeness Crab Re- search and Monitoring Plan. Available online http://www.dfw.state.or.us/MRP/shellfish/ commercial/crab/docs/ODFW_Dungeness- CrabResearchMonitoringPlan2013.pdf

Queen, J. C. 1930. Marine decapod crustacea of the Coos Bay, Oregon district. [MS Thesis]. University of Oregon, Department of Biology.

Shanks A. L. 2013. Atmospheric forcing drives recruitment variation in the Dungeness crab (Cancer magister), revisited. Fisheries Ocean- ography 22(4): 263-272.

14-4 Crabs in the Coos Estuary How the Local Effects of Climate Change Could Affect Crabs in the Coos Estuary There are several climate-related changes expected on the Oregon coast that have the potential to affect crab populations in the Coos estuary:

„„ Ocean acidification is expected to cause a multitude of effects on crabs including low molt success rate and decreased larval survival.

„„ Warming oceans, sea level rise, and hypoxia events are all likely to stress crab populations, most likely causing a shift in range, distribution, and habitat use. Kelp Crab Photo: „„ Increasing ocean temperatures will also Scott Groth likely affect survivorship of multiple crab

species. Juvenile Red Rock Crab Photo: ODFW „„ Changes in ocean currents are expected to affect recruitment of larvae to the estuary Porcelain Crab and alter nutrient availability. Photo: UC Berkeley

With Oregon’s Dungeness crab (Cancer estimated 30 species of crab living in our magister) fishery certified sustainable by the estuary. Climate-related changes will likely Marine Stewardship Council, one naturally come from the increasing acidification and wonders whether the fishery can remain temperature of ocean and estuary waters, sustainable and robust should permanent hypoxia (low dissolved oxygen levels) in ocean climate-influenced changes take place in the and estuary waters, sea level rise, and change Coos estuary and nearshore ocean. Scientists in oceanographic conditions, each of which are also concerned about climate-related are discussed below. effects on habitats associated with the other

Crabs in the Coos Estuary 14-5 Ocean Acidification

Increasing acidic conditions in the ocean are Ocean Acidification expected to have major consequences for Since the late 18th century, the average invertebrates with shells or exoskeletons, such as crabs. For example, adverse effects of open ocean surface pH levels worldwide ocean acidification were found in laboratory have decreased by about 0.1 pH units, a experiments by Long (2013) who found that decrease of pH from about 8.2 before the only 25% of female red king crabs (Paralith- industrial revolution to about 8.1 today. odes camtschaticus) molting in acidified -wa A 0.1 change in pH is significant since it ter were able to molt successfully, while 100% of those in the control group (standard ocean represents about a 30 percent increase in salinity) successfully molted. ocean acidity (the pH scale is logarithmic, meaning that for every one point change Long also made the surprising observation in pH, the actual concentration changes by that for many crab species — including a factor of ten). Scientists estimate that by Dungeness crab — calcium content in freshly 2100 ocean waters could be nearly 150% molted crab exoskeletons is higher in acidi- fied water than those molting in standard sea more acidic than they are now, resulting water. Long suggests this is most likely due to in ocean acidity not experienced on the ability of many crab species to increase earth in 20 million years. The best Pacific their internal pH during a molt cycle; the Northwest ocean acidification data we increased pH range between their bodies and have so far are from the Puget Sound area the more acidified water could lead to a high- er calcium content in exoskeletons. However, where pH has decreased about as much this physiological process comes at a high en- as the worldwide average (a decrease ergetic cost, seen in the drastic depletion of ranging from 0.05 to 0.15 units). lipid reserves in molting adults, leaving them depleted of a major energy source required Sources: Feely et al. 2010, NOAA PMEL for proper growth. In further experiments, Carbon Program 2013 Long saw survival of red larvae de- crease by 13% in acidified water.

Intertidal crabs live in a constantly fluctu- es are temporary and only last until the next ating environment as the relatively stable high tide. Ceballos-Osuna et al. 2013 found conditions of high tide give way to stressful that the intertidal porcelain crab (Petrolisthes low tide conditions. Changes in oxygen and cinctipes) had 30% reduced survival of juve- pH can be drastic and occur very rapidly in niles when continuously exposed to low pH shallow isolated tide pools, but these chang-

14-6 Crabs in the Coos Estuary waters. Therefore, intertidal organisms that are presently tolerant to brief changes in pH Increasing Ocean Temperatures could still be detrimentally affected by ocean Worldwide, ocean temperatures rose at acidification. an average rate of 0.07° C (0.13° F) per decade between 1901 and 2012. Since Increasing Ocean Temperatures 1880, when reliable ocean temperature One consequence of a warming ocean may observations first began, there have been be decreased stability in ocean habitats, and no periods with higher ocean temperatures thus decreased survivorship of multiple crab than those during the period from 1982 – species. Brown and Terwilliger (1999) found 2012. The periods between 1910 and 1940 that Dungeness crab megalopae and first instar juveniles are more temperature sensi- (after a cooling period between 1880 and tive than older crabs, in part because they are 1910), and 1970 and the present are the spawned in stable ocean conditions before times within which ocean temperatures moving to the warmer and more fluctuating have mainly increased. temperatures in estuaries during their adult stage. Destabilizing the ocean conditions Describing how the worldwide trend would likely have deleterious effects on the translates to trends off the Oregon coast crab’s sensitive younger stages. Brown and is a complicated matter. Sea surface Terwilliger also noted that survival at all temperatures are highly variable due to larval stages decrease as water temperatures coastal upwelling processes and other approach 20° C (68° F). To put this in perspec- climatic events that occur in irregular tive, ocean waters near Coos Bay ranged be- cycles (e.g., El Niño events). We do have 27 tween 8.6° and 18.2° C (47.5° and 64.8° F) in 2011 (NOAA National Data Buoy Center n.d.), years (1967-1994) of water temperature suggesting that further research is needed to data collected from near the mouth of understand how rising ocean temperatures the Coos estuary that indicate through over the next several decades could ultimate- preliminary analyses a very weak trend ly stress crab juveniles past their limit in the towards warming water temperatures. Coos estuary. Fifteen years (1995-2010) of data from multiple stations further up the South Others have documented temperature-re- Slough estuary show very little water lated stresses on crab physiology and life histories. For example, Wild (1980) found that temperature change. increases in water temperature decreased Sources: USEPA 2013, SSNERR 2013, Cornu hatching success of Dungeness crab eggs, es- et al. 2012 pecially when temperatures over 13° C (55° F) were reached. On average, 685,000 eggs per

Crabs in the Coos Estuary 14-7 crab hatched in 10° C (50° F) water, while only 14,000 per crab hatched at 16.7° C (62° F) Sea Level Rise (Wild 1980). Normal development from egg to larvae in Oregon takes place between 10° Our local NOAA tide station in Charleston and 13.9° C (50° and 57° F)(Rasmuson 2013). has documented an average rate of sea level rise (SLR) of 0.84 mm (0.03 inches) Stillman (2003) reported that thermal stress per year averaged over the past 30 years from global climate change may already be (0.27 feet in 100 years). The rate of SLR affecting intertidal species such as porcelain is expected to accelerate over time. crabs (Petrolisthes cinctipes). This has been For example, according to the National seen in Monterey, California with a decline in Porcelain crab abundance of over the past Research Council (2012), predicted 60 years, corresponding to a rise in water SLR rates for the area to the north of temperature. Stillman suggests that those California’s Cape Mendocino (the study’s species that have evolved to survive high closest site to the Coos estuary), are temperatures for short periods of time, such reported as high as +23 cm (9 inches) by as intertidal crabs, are already near the limit 2030; +48 cm (19 inches) by 2050; and of their maximal temperature and will there- +143 cm (56 inches) by 2100 . fore be particularly susceptible to sustained increases in water temperature. Sources: NOAA Tides and Currents 2013, NRC 2012 Another likely outcome of warming oceans is a shift in the timing of larval development. cooler habitats, changing the population This means that the evolutionarily estab- dynamics in the estuary and nearshore ocean lished timing of crab larvae development may (McConnaughey and Armstrong 1995). Espe- no longer remain in sync with the seasonal cially apparent will be population changes in blooms of their planktonic food sources species where the Coos estuary is near the (Pörtner and Farrell 2008). Moreover, warm- Northern or Southern extent of their range. er ocean waters are expected to change the (e.g., the pygmy rock crab, Cancer oregonen- community composition of the nearshore sis). ocean, including upper trophic food web organisms (e.g. salmonids), which rely on crab larvae as a main component of their diets Hypoxia Events (Pörtner and Farrell 2008). Hypoxic conditions can stress crabs, especially subtidal populations, which are not regularly A warming ocean is also likely to cause a shift exposed to low oxygen conditions. Increas- towards the poles in all invertebrate species ing temperatures compound the effects of as well as a vertical shift towards deeper, hypoxia. In turn, hypoxic events can reduce

14-8 Crabs in the Coos Estuary the thermal tolerance of some crabs. This References problem will be particularly relevant to inter- Brown, A. C. and N. B. Terwilliger. 1999. tidal crabs, which are sometimes living near Developmental changes in oxygen uptake Cancer magister the limit of both their thermal and hypoxia in (Dana) in response to changes in salinity and temperature. Journal tolerance (Metzger et al. 2007). of Experimental Marine Biology and Ecology 241(2): 179-192. Sea Level Rise Ceballos-Osuna L., H. A. Carter, N. A. Miller, Drowned river valleys, such as the Coos and J. H. Stillman. 2013. Effects of ocean estuary, provide valuable intertidal habitat acidification on early life-history stages of the intertidal porcelain crab Petrolisthes cinctipes. to numerous crab species. If sedimentation Journal of Experimental Biology 216(8): 1405- rates do not allow intertidal marshes to keep 1411. pace with sea level rise, many of these areas may be lost due to rising sea levels, especially Cornu, C. E., J. Souder, J. Hamilton, A. Helms, R. Rimler, B. Joyce, F. Reasor, T. Pedersen, E. where no low elevation lands exist for the Wright, R. Namitz, J. Bragg, and B. Tanner. marshes to migrate to (McConnaughey and 2012. Partnership for Coastal Watersheds Armstrong 1995). State of the South Slough and Coastal Fron- tal Watersheds. [Report prepared for the Partnership for Coastal Watersheds Steering Change in Oceanographic Conditions Committee]. South Slough National Estuarine Changes in oceanographic conditions, such as Research Reserve and Coos Watershed Asso- ciation. 225 pp. local wind patterns, ocean currents or other weather cycles, raise questions about how Feely, R. A., S. R. Alin, J. Newton, C. L. Sabine, the local effects of long term climate change M. Warner, A. Devol, C. Krembs, and C. Maloy. 2010. The combined effects of ocean acidi- will affect the distribution of pelagic larvae, fication, mixing, and respiration on pH and the timing of spring transition and the -re carbonate saturation in an urbanized estuary. cruitment of crabs into the Coos estuary. It is Estuarine, Coastal and Shelf Science 88(4): unclear what exact effects these changes will 442-449. have on the planktonic larval phase of crabs, Long, C. W., K. M. Swiney, and R. J. Foy. 2013. but it is likely recruitment will be altered Effects of ocean acidification on the embry- (McConnaughey and Armstrong 1995). Shifts os and larvae of , Paralithodes in the timing or strength of spring transition camtschaticus. Marine Pollution Bulletin 69(1- 2): 38-47. will also alter nutrient availability for larvae, affecting their health and survival (McCon- McConnaughey, R. A., and D. A. Armstrong. naughey and Armstrong 1995). 1995. Potential effects of global climate change on Dungeness crab (Cancer magis- ter) populations in the northeastern Pacific Ocean. Canadian Special Publication of Fisher- ies and Aquatic Sciences 121: 291-306.

Crabs in the Coos Estuary 14-9 Metzger, R., F. J. Sartoris, M. Langenbuch, and Stillman, J. H. 2003. Acclimation Capacity

H. O. Pörtner. 2007. Influence of elevated CO2 Underlies Susceptibility to Climate Change. concentrations on thermal tolerance of the Science 301(5629): 65. edible crab . Journal of Ther- mal Biology 32(3): 144-151. United States Environmental Protection Agen- cy (USEPA). 2013. Climate change indicators National Oceanic and Atmospheric Admin- in the United States. Available online http:// istration National Data Buoy Center. n.d. www.epa.gov/climatechange/science/indica- Umpqua Offshore, OR station 46229. Avail- tors/oceans/sea-surface-temp.html able online http://www.ndbc.noaa.gov/sta- tion_page.php?station=46229 Wild, P. W. 1980. Effects of Seawater Tem- perature on Spawning, Egg Development, National Oceanic and Atmospheric Adminis- Hatching Success, and Population Fluctua- tration Pacific Marine Environmental Labora- tions of the Dungeness Crab,Cancer Magis- tory (PMEL) Carbon Program. 2013. What is ter. CalCOFI Report 21: 115-120. Available Ocean Acidification? Available online http:// online http://www.calcofi.org/publications/ www.pmel.noaa.gov/co2/story/What+is+- calcofireports/v21/Vol_21_Wild.pdf Ocean+Acidification%3F

National Oceanic and Atmospheric Adminis- tration Tides and Currents. 2013. Mean Sea Level Trend 9432780 Charleston, Oregon. Accessed 22 June 2015. Available online http://tidesandcurrents.noaa.gov/sltrends/ sltrends_station.shtml?stnid=9432780

National Research Council. 2012. Sea-Level Rise for the Coasts of California, Oregon, and Washington: Past, Present, and Future. Wash- ington, DC: The National Academies Press. 201 pp.

Pörtner, H. O., and A. P. Farrell. 2008. Physiol- ogy and Climate Change. Science 322(5902): 690-692.

Rasmuson, L. K. 2013. The biology, ecology and fishery of the Dungeness crab, Cancer magister. Advances in Marine Biology 65: 95-148.

South Slough National Estuarine Research Reserve (SSNERR). 2013. [Unpublished raw data]. System-Wide Monitoring Program (SWMP). Available online http://cdmo.ba- ruch.sc.edu/

14-10 Crabs in the Coos Estuary Dungeness Crabs in the Coos Estuary

Summary: „„ Despite 90% of the legal-sized male Dungeness crab population being taken by commercial crabbing each year, ODFW data Adult indicate that the Dungeness crab Dungeness fishery remains sustainable. Crab

„„ Decadal variations in ocean currents along with the timing Dungeness of spring upwelling conditions Crab ultimately determine yearly adult Megalope Dungeness crab populations in the Coos estuary.

Recent Dungeness What’s happening? crab study locations. Oregon Department of Fish and Wildlife’s commercial Dungeness crab (Cancer magis- indicate that the Dungeness crab fishery has ter) landings data provide resource managers been healthy and robust for decades (Figure and scientists with a very reliable index of 1) despite the fact that commercial crabbers four year old adult Dungeness crab popu- harvest about 90% of the commercially avail- lations in Oregon estuaries (S. Groth and A. able male Dungeness crab population most Shanks, pers. comm., April 2012). These data years (Ainsworth et al. 2012).

Crabs in the Coos Estuary 14-11 Figure 1. Oregon commercial Dungeness crab landings (millions of pounds) by season (1947-48 through 2012-13 crab seasons). Graph ODFW 2001.

Figure 2 shows the number of commercial crab pots and vessels engaged in crabbing in Oregon between 1977 and 2012, illustrating relatively recently established crab fish- ery management measures. Limited entry to the fishery (limited number of permits issued) began during the 1995-96 season; limits on the

Figure 2. Number of active vessels and estimated number of pots used in Ore- number of crab pots used by gon’s commercial Dungeness crab fishery from 1977-78 to 2012-13 crab seasons. Graph ODFW 2001. permit holders began during the 2006-07 season. These measures help maintain the sustainability of We should note that some of the recent the commercial Dungeness crab fishery. increases in commercial landings may actually be due to long-term cyclical changes in North The recreational Dungeness crab fishery, Pacific climate, the latest cycle of which hap- another important element of the coastal Or- pened to benefit crab populations (A. Shanks, egon economy, also appears to be stable. This pers. comm., April 2012; see more in Why is it is good news since according to Dean Runyan happening?). and Associates (2009), recreational shellfish harvests contribute $172 million to Oregon’s

14-12 Crabs in the Coos Estuary Figure 3. Recreational Dungeness crab catch per person in Coos Bay 2008-2013. Graph: ODFW 2001.

recent years and Figure 4 shows where over 98% of the recreational crabbing effort takes place in the Coos estuary (Ainsworth et al. 2012).

According to Ainsworth et al. (2012) in their survey of Oregon’s Dungeness crab fishery for 2007-11, crabs harvested from the Coos estuary were among the largest of all bays surveyed (likely due to the greater ocean influence in the lower Coos estuary), with a mean weight of 643.5 g (1.42 lbs) averaged over four years of data. They note that while recreational crabbing effort has not changed significantly statewide since 1971, effort has actually decreased in Coos Bay. And despite that decrease in effort, Coos Bay’s recreation- Figure 4. Most popular crabbing locations in the Coos estuary. al crab harvests have increased. Over 40,000 Data: ODFW 2001. crabs were caught in Coos Bay in 1971, while economy. The Coos estuary is one of Oregon’s in more recent times (2007-2011) the rec- most popular clamming and crabbing des- reational catch averaged between 86,000- tinations. Recreational crabbing (mainly for 136,000 crabs per year (likely due to improve- Dungeness crabs) comprises a large percent- ments in fishing gear, changes in bait, and age of the recreational crab harvest in Coos larger and more efficient boats). Bay. Current Oregon Department of Fish and Wild- Figure 3 shows the relative stability of the life (ODFW) commercial crabbing regulations recreational crab catch in the Coos estuary in protect recreational crabbers’ share of the

Crabs in the Coos Estuary 14-13 Dungeness crab harvest (i. e., shorter seasons in) and then as pea-sized megalopae. Ulti- and larger size limit for commercial crabbers). mately, they develop into small juvenile crabs, Without this protection, the recreational fish- settle out of the water column, and begin ery would be greatly affected by the commer- living on intertidal and subtidal channel bot- cial crabbing industry (Ainsworth et al. 2012). toms, mudflats, and in eelgrass beds.

Why is it happening? Understanding both the larval and settled life stages of juvenile Dungeness crabs helps Dungeness crabs inhabit estuaries and off- us understand the status and trends of shore waters from Alaska to Monterey Bay, adult crab populations. Research conducted California (Ricketts et al. 1985). In the Coos locally by Shanks and Roegner (2007) linked estuary, they’re found in the South Slough, the number of Dungeness crab megalopae the lower and upper Coos estuary, and the settling in the Coos estuary with the num- Isthmus Slough (Figure 5)(Miller et al. 1990; ber of adult crabs caught locally four years deRivera et al. 2005; Ramsay 2012). later (simplistically, more megalopae = more adults). Further, they determined that the Like all crabs, young Dungeness crabs first live number of Dungeness crab megalopae set- in the water column as “planktonic larvae,” tling in the Coos estuary is correlated with first as crab zoea (2.1 mm-10 mm, 0.08 in-0.4 the timing of the spring transition, when low productivity wintertime ocean conditions off the Oregon coast shifts to high productivity summertime ocean conditions (productivity determined by north wind-driven upwelling in the summer and south wind-driven down- welling in the winter). Shanks and Roegner report that early spring transitions result in greater the numbers of megalopae settling, and four years later, more adult crabs avail- able for harvest.

Shanks (2013) has also described planktonic Dungeness crab larvae movement relative to Pacific Decadal Oscillation (PDO) patterns: patterns in which oceanic and ocean-related climate conditions shift every 20-30 years from cold phases to warm phases and back Figure 5. Study stations where Dungeness crabs were found again. during surveys . Data from deRivera et al. 2005, Ramsay 2012 and Miller et al. 1990.

14-14 Crabs in the Coos Estuary A cold phase of the PDO, which our region has been experiencing locally since 1999 (NASA JPL 2000), strengthens the south-flow- ing California Current. This causes megalopae to accumulate along the Washington and Oregon coasts, and thus creates extraordi- nary high returns of megalopae to the Coos estuary and surrounding area. During a warm phase of the PDO, the opposite occurs. Adult Dungeness crab populations are reduced in Oregon waters as the California Current is weakened, allowing the stronger, north-flow- ing Gulf of Alaska Current to pick up the meg- alopae and move them northwards. Shanks showed that cold phase PDO, paired with early spring transition and constant spring upwelling, creates conditions for the highest crab megalopae returns to the Coos estuary Figure 6. Trawl stations from Armstrong et al. 2003. Map shows partitioning of the Coos estuary into Lower Side Channel, Low- system. er Main Channel and Upper Estuary habitat types.

The quality and type of habitat where crabs to the estuary mouth, with cold summer settle out of the water column also influ- temperatures, high salinity, deep channels, ences adult crab populations. Armstrong et little ground cover, and few intertidal zones; al. (2003) determined juvenile Dungeness Upper Estuary is indicated by the warmest crab density and abundance by age class in summer temperatures, low salinities, mod- several Oregon and Washington estuaries erate amounts of intertidal habitat, and high while also considering the influences of water amounts of cover (mainly from shell and temperature, salinity, sediment composition woody debris). and habitat. They found the habitat with the highest juvenile crab density was what they In the Coos estuary, the Lower Side Channel called Lower Side Channel habitat, character- habitat averaged a juvenile Dungeness crab ized by higher summer temperatures, shallow density of about 1,300 crabs/ha, compared to depths, extensive intertidal areas, and high the Lower Main Channel habitat (600 crabs/ shell and macroalgae cover. Other habitats ha) and the Upper Estuary habitat (700 crabs/ called Lower Main Channel habitat and the ha)(Figure 6). Although it contains the most Upper Estuary habitat were also described productive (and thus most dense) habitat, the and were characterized as follows: Lower Lower Side Channel makes up only 11% of Main Channel was defined as being adjacent the estuary. Due to its small size this habitat

Crabs in the Coos Estuary 14-15 supports the smallest overall Dungeness crab tive oyster habitat (5 crab/m2) far more than population in the Coos estuary, with a total adjacent eelgrass habitat (0 crab/m2). At the summer abundance around 300,000 juvenile Haynes Inlet site, crab densities were higher crabs. The Lower Main Channel represents in Japanese Oyster habitat (8.5 crab/m2) than 64% of the estuary and thus supports the in adjacent eelgrass habitat (0.57 crab/m2), biggest population with a total summer though crab refuge provided by commercial abundance around 850,000 juvenile crabs, oyster beds is thought to be temporary due while the Upper Bay supports nearly 500,000 to the frequent disturbances in those areas juvenile crabs. (S. Groth, pers. comm., 2014). Ramsay’s study did not discern a significant difference in den- Another study by Ramsay (2012) shows the sity by oyster species. importance of oysters as habitat refuge for juvenile Dungeness crabs. Ramsay deter- Adults also prefer specific habitats. Results mined juvenile Dungeness crab densities in from McMillan et al. (1995) found adult three habitat types: native oysters, non-native densities to be highest in habitats containing oysters, and eelgrass. At the Isthmus Slough mixed sand and gravel along with macroal- study site (Figure 7), juvenile crabs used na- gae or eelgrass, while the lack of complexity in open sand habitats resulted in the fewest crabs. Intertidal zones are also important as they provide crucial foraging habitat for Dungeness crab adult, as seen in studies at Willapa Bay (Holsman et al. 2006).

Brooding female Dungeness crabs appear to require sandy habitat (Rasmuson 2013). Due to the large number of eggs they carry under their abdominal flap, female Dungeness bury themselves in sand up to 10 cm (4 in.) deep to hold the eggs in place, limiting their move- ment (Rasmuson 2013).

Estuaries not only provide excellent habitat for juvenile and adult Dungeness crabs, they also may provide refuge from some parasites Figure 7. Study sites from Ramsay 2012, showing juvenile Dungeness crab density (per m2) in eelgrass, native oyster that may otherwise threaten the health of and commercial oyster habitats. Numbers on bars represent average density in that habitat type adult Dungeness crab populations. Oregon Institute of Marine Biology researcher Paul Dunn (2011) examined the effects of the

14-16 Crabs in the Coos Estuary Dungeness crabs can tolerate salinities rang- ing from 11 to 35, preferring salinities over 20 (Cleaver 1949, Robinson & Potts 1979), and determined that only 50-70% of juvenile parasitic worm parasites survived 2 days at a salinity of 10.

These results suggest that there may be more to the story because reduced estuarine salinity explained some, but not all parasite loading. Dunn indicated that C. errans larvae prefer to settle on crabs already infected with juvenile worms, providing another piece to the puzzle.

ODFW’s Ainsworth and Groth (pers. comm. 2014) report that egg-carrying female Dunge- Figure 8. Study site locations from Dunn 2011, showing per- ness crab have never been found in estuarine centage of Dungeness crabs caught that were infected with the parasitic worm. Locations near the mouth of the estuary show waters (only in the nearshore ocean), which higher infection rates. confounds scientists’ ability to conclusively parasitic worm (Carcinonemertes errans) on decide whether estuarine waters provide ref- adult Dungeness crabs. Dunn documented uge from the parasites for Dungeness crabs. parasitic feeding on the egg masses of female Parasites documented on Dungeness crabs in crabs, which caused potentially significant estuarine waters have been found in relative- brood loss. Dunn investigated the relative ly low numbers on male crabs (in clusters at abundance of this parasitic worm in the the base of their walking legs). They report Dungeness crab population and found that that the presence of these parasites on the crabs living closest to the mouth of the es- male Dungeness crabs decreases in lower tuary were infected with greatest number of salinity waters in the upper estuary. parasites (Figure 8), and that crabs sampled in nearshore ocean waters had more parasites than crabs sampled from estuarine waters. References Ainsworth, J. C., M. Vance, M. V. Hunter, and This difference suggested that the parasite’s E. Schindler. 2012. The Oregon recreational salinity tolerances were different than those dungeness crab fishery, 2007-2011. [Oregon Department of Fish and Wildlife Information of their hosts, which means that estuarine Report 2012-04]. Marine Resources Program. waters may act as a refuge for crabs from C. Newport, OR. errans parasites. In fact, Dunn reported that

Crabs in the Coos Estuary 14-17 Armstrong, D. A., C. Rooper, and D. Gunder- Miller, D. R., R. L. Emmett, and S. A. Hinton. son. 2003. Estuarine Production of Juvenile 1990. A preliminary survey of benthic inverte- Dungeness Crab (Cancer magister) and Con- brates in the vicinity of the Coos Bay, Oregon, tribution to the Oregon-Washington Coastal navigation channel. Northwest and Alaska Fishery. Estuaries 26(4): 1174-1188. Fisheries Center, Coastal Zone and Estuarine Studies Division. Seattle, WA. Cleaver, F. C. 1949. Preliminary results of the coastal crab (Cancer magister) investigation. National Aeronautics and Space Administra- Biological Report 49A: 47-82. tion Jet Propulsion Laboratory (JPL). 2000. La Niña’s persistence may be part of larger cli- Dean Runyan Associates. 2009. Fishing, Hunt- mate pattern. Available online http://sealevel. ing, Wildlife Viewing, and Shellfishing in jpl.nasa.gov/newsroom/pressreleases/index. Oregon: 2008 State and County Expenditure cfm?FuseAction=ShowNews&NewsID=211 Estimates. [Prepared for Oregon Department of Fish and Wildlife and Travel Oregon]. Dean Oregon Department of Fish and Wildlife Runyan Associates. Portland, OR. Available (ODFW). 2001. Oregon marine fisheries 2000 online http://www.dfw.state.or.us/agency/ status report. Oregon Department of Fish and docs/Report_5_6_09--Final%20%282%29.pdf Wildlife Marine Resources Program. Newport, OR. deRivera, C. E., G. M. Ruiz, J. Crooks, K. Was- son, S. Lonhart, P. Fofonoff, B. Steves, S. Rum- Ramsay, J. 2012. Ecosystem services provid- rill, M. S. Brancato, S. Pegau, D. Bulthuis, R. K. ed by Olympia oyster () habitat Preisler, C. Schoch, E. Bolwby, A. DeVogelaere, and Crassostrea( gigas) habitat; M. Crawford, S. Gittings, A. Hines, L. Takata, K. Dungeness crab (Metacarcinus magister) Larson, T. Huber, A. M. Leyman, E. Collinetti, T. production in Willapa Bay, WA. [MS Thesis]. Pascot, S. Shull, M. Anderson, and S. Powell. Oregon State University. 2005. Broad-scale nonindigenous species Rasmuson, L. K. 2013. The biology, ecology monitoring along the West Coast in National and fishery of the Dungeness crab, Cancer Marine Sanctuaries and National Estuarine magister. Advances in Marine Biology 65: Research Reserves. [Report to National Fish & 95-148. Wildlife Foundation]. 126 pp. Ricketts, E. F., J. Calvin, J. W. Hedgpeth, and Dunn, P. H. 2011. Larval biology and estuarine D. W. Phillips. 1985. Between Pacific tides. ecology of the nemertean egg predator Car- Stanford, CA: Stanford University Press. cinonemertes errans on the Dungeness crab, Cancer magister. [PhD Dissertation]. Universi- Robinson G. D., and W. T. W. Potts. 1979. Ion ty of Oregon, Department of Biology. fluxes and diffusion potentials in the Dunge- ness crab, Cancer magister. Journal of Com- Holsman, K. K., P. S. McDonald, and D. A. Arm- parative Physiology B 131: 285-292. strong. 2006. Intertidal migration and habitat use by subadult Dungeness crab Cancer ma- Shanks A. L. and G. C. Roegner. 2007. Recruit- gister in a NE Pacific estuary. Marine Ecology ment Limitation In Dungeness Crab Popula- Progress Series 308: 183-195. tions Is Driven By Variation In Atmospheric Forcing. Ecology 88(7): 1726–1737. McMillan, R., D. Armstrong, and P. Dinnel. 1995. Comparison of intertidal habitat use Shanks A. L. 2013. Atmospheric forcing drives and growth rates of two northern Puget recruitment variation in the Dungeness crab Sound cohorts of 0+ age Dungeness crab, (Cancer magister), revisited. Fisheries Ocean- Cancer magister. Estuaries and Coasts 18(2): ography 22(4): 263-272. 390-398.

14-18 Crabs in the Coos Estuary Red Rock Crab in the Coos Estuary

Summary: „„ The population of red rock crab appears stable in the Coos estuary but more data are needed to understand the population dynamics of this Adult species. Red Rock Crab

Juvenile Red Rock Crab

per day. Despite this, scientists think red rock crab populations may be relatively stable in the Coos estuary. Preliminary results from a crab tagging study by Groth et al. (2013)

Location of red rock show relative stability in Coos Bay’s red rock crab study sites. crab’s size distributions compared with those What’s happening? of Dungeness crab, though Groth urges caution on this point because the results may Oregon Department of Fish and Wildlife simply be highlighting red rock crab’s high (ODFW) regulates the harvest of red rock site fidelity (S. Groth, pers. comm., 2014). He crab (Cancer productus) less rigorously than also found that all red rock crab age classes Dungeness crab, allowing any size or sex to are found year round within the estuary, be taken and a limit of 24 crabs per person

Crabs in the Coos Estuary 14-19 which differs from Dungeness crabs (larger Distribution in the Coos Estuary crabs are found inside the estuary in the fall Red rock crab adults are found among rocks and smaller crabs in the spring and summer) and hard bottom substrates. They’re found (Figure 1). This work suggests, at minimum, mostly in estuarine habits and infrequently the importance of the estuary as a year-round outside estuaries (e.g., nearshore ocean bot- habitat for red rock crabs. tom, where Dungeness crabs are abundant) (S. Groth, pers. comm., 2013).

Figure 1. Density of different size classes of female red rock crab compared to Dungeness crab, shown across three seasons. Red rock crab population struc- ture is similar spring, fall and summer, while Dungeness crab sizes shift seasonally. Graph (preliminary data): Groth et al. 2013.

14-20 Crabs in the Coos Estuary Red rock crabs do not burrow and tend to avoid sandy substrates as they lack any straining apparatus for sand removal (Rudy et al. 2013). They have been found at Crown and Collver Points in South Slough (deRivera et al. 2005) as well as the inner boat basin in Charleston (S. Groth, pers. comm., 2013). deRivera et al. (2005) found the highest num- bers of red rock crabs closest to the mouth of the South Slough and found them conspicu- ously absent at their Winchester Creek and Sengstacken Arm study sites in the upper South Slough estuary, possibly due to lack of suitable habitat (Figure 2).

Red rock crabs are often found at the rocky dredge spoils areas north of Pigeon Point, in the greater Coos bay (Daly 1981) and have Figure 2. deRivera et al. (2005) study locations. Size of red circles represent relative abundance of red rock crab found. been found as far up the Coos estuary as Numbers in symbols represent total number of red rock crabs McCullough Bridge in North Bend, even in caught at each site during a single trapping event. wintertime when they prefer to stay in the deeper, more saline water (S. Groth, pers. An inventory of the abundance and spatial comm., 2013). Because red rock crabs are distribution of red rock crabs in the Coos osmoconformers whose body fluids match estuary would be very useful to better under- surrounding sea water salinity, they cannot stand this ecologically important species. tolerate brackish or fresh water for any length of time (Carroll and Winn 1989). Consequent- References ly, red rock crab distribution is influenced Carroll, J. C. and R. N. Winn. 1989. Species by tidally-driven salt water concentrations profiles: life histories and environmental requirements of coastal and inverte- and are thus more commonly found in lower brates (Pacific Southwest)—brown rock crab, regions of the bay in times of large fresh- red rock crab, and yellow crab. [United States water input (i.e., winter) and further up the Fish and Wildlife Service Biological Report 82(11.117) and United States Army Corps of bay during dryer periods (Daly 1981). During Engineers, TR EL-82-4]. 16 pp. periods of high salinity in the upper estuary, red rock crabs outcompete both Hemigrapsus Daly, G. P. 1981. Competitive interactions shore crab species for prime intertidal habitat among three crab species in the intertidal zone. [PhD Thesis]. University of Oregon. (Daly 1981).

Crabs in the Coos Estuary 14-21 deRivera, C. E., G. M. Ruiz, J. Crooks, K. Was- son, S. Lonhart, P. Fofonoff, B. Steves, S. Rum- rill, M. S. Brancato, S. Pegau, D. Bulthuis, R. K. Preisler, C. Schoch, E. Bolwby, A. DeVogelaere, M. Crawford, S. Gittings, A. Hines, L. Takata, K. Larson, T. Huber, A. M. Leyman, E. Collinetti, T. Pascot, S. Shull, M. Anderson, and S. Powell. 2005. Broad-scale nonindigenous species monitoring along the West Coast in National Marine Sanctuaries and National Estuarine Research Reserves. [Report to National Fish & Wildlife Foundation]. 126 pp.

Groth, S., S. Yamada, E. Post, and J. Heinrich. 2013. Mark recapture of red rock crab, Cancer productus, in Coos Bay, OR. [Poster session presented at Towards an Estuarine Ethic: inte- grating science and stewardship]. 36th Annual Meeting of the Pacific Estuarine.

Rudy, P. Jr, L. H. Rudy, A. Shanks, and B. Butler. 2015. Oregon Estuarine Invertebrates, Third Edition. University of Oregon. Available online https://library.uoregon.edu/scilib/oimb/oei

14-22 Crabs in the Coos Estuary Other Crabs in the Coos Estuary Summary: • As of 1981, the yellow shore

crab and the purple shore crab Yellow were relatively abundant in shore crab rocky intertidal invertebrate communities in the Coos estuary Purple Kelp crab (Daly 1981). shore crab • More research is needed to evaluate status and trends for

the numerous non-Dungeness Striped shore crab crab species in the Coos estuary. Graceful kelp crab

What’s happening?

In addition to Dungeness Cancer( magister) and red rock (Cancer productus) crabs, there are at least 30 known crab species historically Figure 1. Location of other crabs study sites. found in the Coos estuary. Surprisingly little is known about the status of these crab species The most comprehensive study of other or how they’re using the estuary. Studies of crabs is nearly 85 years old – a thesis from these “other” crab species are either dated 1930 completed by John Queen. Queen (e.g., Daly 1981) or included incidentally exhaustively surveyed 12 stations throughout in other studies (e.g., deRivera et al. 2005) the Coos estuary, finding 30 species of crab (Figure 1). regularly using various habitats in the estu-

Crabs in the Coos Estuary 14-23 ary (Figure 2). While Queen’s study provides Yellow Shore Crab: The yellow shore crab an excellent historic baseline for other crabs (Hemigrapsus oregonensis) is a native crab in the Coos estuary, the data are obviously which, along with the purple shore crab (see of limited use for understanding the sta- following summary), dominates the inverte- tus of current crab populations. It’s worth brate populations in the rocky intertidal areas noting that the Coos estuary has changed of the Coos estuary (Daly 1981). Yellow shore considerably since that study was complet- crabs have been found in salinities as low as 3 ed, including major changes in bathymetry, in the Coos estuary, which overlaps with the hydrology and geography (e.g., in 1930 Pony salinity range of the non-native Atlantic mud Slough drained to the west, where the airport crab (Rhithropanopeus harrisi). Anywhere runway now is; there is now a jetty creating their habitat ranges overlap, yellow shore the Charleston inner boat basin; the main crabs push juvenile Atlantic mud crabs into shipping channel has been dredged wider and more freshwater habitats, effectively limiting deeper). As a result, crab habitats have also the non-native crab’s populations in the Coos understandably changed dramatically, with estuary (Jordan 1989). some being augmented and some diminished. A more recent study in 2002 by Puls on the Two introduced crabs (the Atlantic mud crab, larval migration of the yellow shore crab Rhithropanopeus harrisi and the green crab, provides some insights into the life history Carcinus maenas) were not documented in of this small crab. Puls captured over 43,000 the 1930 study, but are relatively common yellow shore crab larvae in four plankton now. Non-native and invasive crabs are dis- sampling sessions in South Slough and went cussed in Chapter 17: Non-Indigenous and on to describe how, over a four to five week Invasive Species. period, newly spawned larvae are exported from the estuary to the ocean where they Several species (see below) have been stud- develop. They are then most likely imported ied since 1930, although none in the past few back into the estuary as more mature crab decades. We found no record of the remain- “megalopae” before finally settling out in the ing species having been studied since Queen’s estuary’s rocky intertidal areas as adult crabs. effort. However, little is known about returning The following information summarizes our megalopae numbers or abundance of adults current understanding of how different in the estuary. species of non-Dungeness crabs are using Purple shore crab: The purple shore crab the Coos estuary. To fill the considerable data (Hemigrapsus nudus), along with the yellow gaps about the status and trends of “other” shore crab, represent a dominant portion crab populations in the Coos estuary, further of the macrofauna found in rocky intertidal research and monitoring of these species areas in the Coos estuary, with densities ex- should be considered. ceeding 100/m2 (Daly 1981). The purple

14-24 Crabs in the Coos Estuary Figure 2. Location of Queen’s 1930 study sites. Size of symbol over each station shows the proportional number of crab species found at that station. Also shown is a complete list of species and where they were found.

Crabs in the Coos Estuary 14-25 Slough at Collver Point or Metcalf Preserve, often under algae or eelgrass (Rudy et al. shore crab frequently out-competes the 2015). The pea crab (Pinnixa faba) is a para- yellow shore crab for their preferred refuge sitic crab that primarily lives inside live gaper of large rocks in the estuary’s intertidal zone clams (Tresus capax), but can also be found (Daly 1981). Rocks provide protection from in soft-shelled or bent-nosed clams (Rudy et predators and from desiccation and high al. 2015). Limited sampling by deRivera et al. temperatures during low tides. Large rocks (2005) did not find pygmy rock crab at any of are more stable from wave action and thus a four sampling sites in South Slough. Without highly valued resource for crabs. additional research, the status of this species Striped shore crab: Also known as green in the South Slough and other parts of the shore crab, the striped shore crab (Pachy- Coos estuary remains uncertain. grapsus crassipes) dominates the rocky high intertidal zone in the Coos estuary and can of- References ten be found crawling among jetty rocks (Daly Daly, G. P. 1981. Competitive interactions 1981, Rudy et al. 2015). The northernmost among three crab species in the intertidal range for this crab is near Newport, OR, prob- zone. [PhD Thesis]. University of Oregon. ably determined by low winter temperatures deRivera, C. E., G. M. Ruiz, J. Crooks, K. Was- (Hiatt 1948 as cited in Rudy et al. 2015). Puls son, S. Lonhart, P. Fofonoff, B. Steves, S. Rum- (2002) investigated larval abundance of the rill, M. S. Brancato, S. Pegau, D. Bulthuis, R. K. striped shore crab and found low numbers Preisler, C. Schoch, E. Bolwby, A. DeVogelaere, M. Crawford, S. Gittings, A. Hines, L. Takata, K. present in South Slough (over 1,500 larvae Larson, T. Huber, A. M. Leyman, E. Collinetti, T. counted over 3 sampling periods). This study Pascot, S. Shull, M. Anderson, and S. Powell. speculated that the lack of suitable habitat for 2005. Broad-scale nonindigenous species adult shore crabs in South Slough could ac- monitoring along the West Coast in National Marine Sanctuaries and National Estuarine count for the low crab larvae numbers there. Research Reserves. [Report to National Fish & Wildlife Foundation]. 126 pp. Other crabs: Numerous other crabs can be found in the lower estuary in higher salinity Hiatt, R. W. 1948. The biology of the lined shore crab, Pachygrapsus crassipes Randall. waters including the pygmy rock crab (Cancer Pacific Science 2: 135-213. oregonensis), found at Fossil Point and Pigeon Jordan, J. R. 1989. Interspecific interactions Point in the rocky lower intertidal and rarely between the introduced Atlantic crab Rhithro- found south of Oregon (Rickets et al. 1985); panopeus harrisii and the native estuarine the kelp crab (Pugettia producta), found in crab Hemigrapsus oregonensis in Coos Bay, the South Slough hanging onto kelp, eelgrass Oregon. [MS Thesis]. University of Oregon. Available online https://scholarsbank.uore- or pilings; the porcelain crab (Petrolisthes gon.edu/xmlui/bitstream/handle/1794/9809/ cinctipes), found at Pigeon Point under rocks jordan009.pdf?sequence=1 or in mussel beds; and the hairy hermit crab Puls, A. L. 2002. Transport of zooplankton in (Pagurus hirsutiusculus), found in the South South Slough, Oregon. [MS Thesis]. University

14-26 Crabs in the Coos Estuary of Oregon. Queen, J. C. 1930. Marine decapod crustacea of the Coos Bay, Oregon district. [MS Thesis]. University of Oregon, Department of Biology. Ricketts, E. F., J. Calvin, J. W. Hedgpeth, and D. W. Phillips. 1985. Between Pacific tides. Stanford: Stanford University Press. Rudy, P. Jr, L. H. Rudy, A. Shanks, and B. Butler. 2015. Oregon Estuarine Invertebrates, Third Edition. University of Oregon. Available online https://library.uoregon.edu/scilib/oimb/oei

Crabs in the Coos Estuary 14-27