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Home , Alosa, American shad, Atlantic herring, Clupea, Curtis Ebbesmeyer, Sardine

Sapidissima (Wilson 1811):

(Also: common shad, Atlantic shad, white shad)

KC Dill 423 – Fall 2011

http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=49

numbering more than 60 on the first arch, before Diagnostic Information the bend (Moyle 1976). The Pacific

Taxonomy: Order – ( sagax) is the fish in this region that most closely resembles A. sapidissima (Figure Family – 2), but it is much smaller (up to 41 cm in length, but usually no more than 30 cm). S. sagax does – Alosa have dark spots similar to those of the American

Species – sapidissima shad, but they have more variation in number and placement. In addition, it has a shallower body and less pronounced scutes than the shad. Finally, the Pacific sardine is a and American shad is an anadromous would not be located in river systems as is the member of the family. It is the largest American shad (Peterson et al 1999). clupeid and the only anadromous herring on the

West Coast. As a clupeid, A. sapidissima is thin- bodied and has a small approximately midway down the back, with pelvic fins positioned abdominally. Herring have no adipose fin or fin spines. Clupeids also possess a deeply forked caudal fin and cycloid scales, which grow by adding concentric layers (Figure 1). The head lacks scales (Peterson et al 1999). As the only member of the genus Alosa present on the West Coast, American shad is relatively easy to identify. It is large, up to 76 cm, and has a deep belly with bony scutes, giving it a saw Figure 1. Diagram of cycloid-type scales tooth appearance. The coloring of live fish tends (reproduced from earthlife.net to be a steel blue on the back with silver sides http://nathistoc.bio.uci.edu/Fish/Sardinops%20sa and belly. A row of dark spots starting just h) behind the is a useful identifying feature for this fish. The rakers tend to be long and numerous, typically al 2003). This usually results in spawning in the main stems of rivers, rather than the more distant

and colder tributaries preferred by .

Males are generally the first to arrive and are three years old on average, while the females follow after and are typically around four years of age. Historically, American shad begin to run in small numbers in March or April, with a peak around June. Shad soon after entering freshwater, with the females releasing between 30,000 and 300,000 eggs, depending on her age Figure 2. Pacific sardine pictured on top, American shad is on bottom. Note differences and size (Moyle 1976). Based on their location in body shape and depth. and the ambient temperature, American shad may be either semelparous or iteroparous. This occurs along a latitudinal cline, with semelparity Life History and Basic Ecology dominant in the more southern, warmer waters Life Cycle and Reproductive Strategies and iteroparity more typical of the northern, colder areas (Leggett and Carscadden 1978). The life history of the American shad is The timing of spawning also varies spatially, complex and spatially variable. Like our native apparently in response to temperature. As shown salmon, A. sapidissima is anadromous, with the in Figure 3, spawning time moves earlier in the exception of one isolated population in Millerton year with decreasing latitude and increasing Lake in , which has been landlocked temperature (Limburg et al 2003). since 1955 (DJ Hasselman University of Once the eggs have been released, they tend to personal communication). Most of remain suspended in the water column and are the research in this area has been focused on the gradually carried downstream by the currents. American shad’s native range, along the eastern The eggs hatch quickly, on the order of three to coast of . In its native area, the six days (Moyle 1976). Larvae then recruit to the shad exhibits a high rate of philopatry, with 97% shorelines to rear before transforming to young- of spawners returning to their natal stream of-the-year juveniles. In the (Melvin et al 1986). Adults swim upriver and basin, this process appears to take approximately can spawn in a wide range of , although two months, with larvae emerging in June and they appear to prefer areas with temperatures July (for 1995 and 1996), recruiting to the between 14°C and 24.5°C and a low water shoreline in July and August, and finally velocity, typically less than 0.7 m/s (Petersen et River systems. Adults spend three to six years in the marine environment before returning to their natal streams to spawn (Petersen et al 2003; Moyle 1976; DJ Hasselman personal communication).

Feeding Habits

American shad primarily feed on , although the adults will consume and small fish in some areas. Adults typically do not feed at all during spawning or Figure 3. Periods of spawning runs for the American when in freshwater (Facey and Van Den Avyle shad within its native range (Source: Limburg et al. 1986). Juveniles feed on smaller zooplankton 2003) and their diet in the Pacific Northwest consists mainly of Cyclopoid and Calanoid and appearing as young juveniles in late July and various cladocerans, but they will feed September (Petersen et al 2003). Juveniles opportunistically on insect larvae and other exhibit diel migration, tending to stay at the small planktonic organisms (Petersen et al bottom of the river channel or near shore during 2003). Again, the Millerton Lake population the day and move through the water column at presents an exception, as there is anecdotal night (Gadomski and Barfoot 1998). Little is evidence they have become piscivorous, known about the migration patterns of American predating on the threadfin shad. The gill rakers shad once they leave the rivers. Juveniles will have become reduced in both length and number often overwinter in nearshore , but accordingly (DJ Hasselman personal others leave immediately for the open . communication). Mature adults in the Atlantic may migrate to the to feed between spawning Environmental Optima and Tolerances seasons, although this pattern does not hold true American shad have the ability to adapt for the first year of life (Walther and Thorrold to a fairly wide range of environments, as 2010). Even less is known about migration evidenced by their anadromous lifestyle and patterns in the Pacific, but it appears the shad variable life histories and feeding strategies migrate north from spawning sites, as indicated based on temperature and location. However, by higher than usual by-catch of American shad temperature is a very important factor for shad on trawls north of the Columbia and Sacramento as it determines when and where they will migrate (Leggett and Whitney 1972). When only five hours (Facey and Van Den Avyle spawning, A. sapidissima prefers a water 1986). temperature between 14°C and 21°C and their An adequate supply of dissolved oxygen is also outer limits for temperature have been recorded important for American shad. A dissolved as low as 8°C and as high as 26°C (Facey and oxygen content greater than 5.0 mg/l is ideal for Van Den Avyle 1986). However, the highest spawning, with 4.0 mg/l being the minimum survival rates for eggs and larvae are achieved amount necessary for success (Chittenden 1973). between 15.5°C and 26.6°C (Leggett and Larvae exposed to concentrations lower than 2.9 Whitney 1972). Temperatures below 9°C tend to mg/l experience high mortality rates, with 100% be lethal to both eggs and larvae. Juvenile shad mortality below 1.0 mg/l (Facey and Van Den can tolerate colder waters and have been Avyle 1986). A minimum oxygen content of 2.5 recorded in waters as cold as 2°C, but they stop to 3.0 mg/l is necessary during juvenile feeding and begin experiencing negative effects migration, but they may be able to survive at around 6°C (Facey and Van Den Avyle 1986). lower levels for short periods of time When in the , shad have been (Chittenden 1973). noted in temperatures ranging from 3°C to 15°C, The velocity of water movement is also very although most were found between 7°C and important during spawning and early life stages. 13°C (Neves and Depres 1979). No data has High velocities can affect mature adults been collected on American shad’s tolerances or swimming upstream by increasing the amount of preferences in the . energy expended to reach their spawning American shad must be able to acclimatize to a grounds. After spawning, the flow must be wide range of salinities over their lifetime. Eggs strong enough to keep the eggs suspended, but are laid in freshwater systems, but studies have not so strong that they are washed out into the determined some eggs can successfully hatch in sea or into other inhospitable environments mild salinities of 7.5 ppt to 15 ppt. None of the (Facey and Van Den Avyle 1986). The optimal eggs in the study were viable at salinities of 22.5 water velocity for American shad is around 0.7 ppt and above. are capable of m/s (Petersen et al 2003). Turbidity level, depth tolerating both fresh and brackish waters, and of water, and type of substrate do not appear to frequently travel between estuaries and rivers affect shad much, and they are able to (Chittenden 1972). Adult shad must spend two successfully spawn in a wide range of conditions or three days in brackish water before venturing (Facey and Van Den Avyle 1986). into freshwater streams in order to effectively osmoregulate. If they are moved suddenly from seawater to freshwater, they begin to die after Biotic Associations Ichthyophonus spp. are parasitic protists of fish. An epizootic in American shad occurred in the American shad are subject to several Columbia River drainage in 2007, with a 72% parasites, although they tend to be relatively free infection prevalence (Shields et al 2010). from severe infection in most cases. Common Ichthyophonus infections are systemic and parasites include sea lice, flukes and characterized by granulomas in both internal and roundworms. In some areas of their native range, external tissues. Replacement of tissues and sea lamprey (Petromyzon marinus) and organs by the protist generally leads to necrosis freshwater lamprey (Icthyomyzon spp) can also and death of the host within 180 days (Rahimian infest shad (Facey and Van Den Avyle). 1998). However, one parasite in particular has caused concern recently. The nematode Current Geographic Distribution simplex is found in both the native and the American shad are native to the Atlantic introduced ranges of American shad, but has a coast of North America, with a range stretching fairly low prevalence and intensity in the from to Newfoundland. They can be Atlantic fish. Conversely, the Pacific population found in river systems throughout this range appears to be particularly susceptible to A. during larval and juvenile stages, as well as simplex infection, with a possible 100% spawning adults. However, many populations infection rate of varying intensities in the along the eastern coast have been declining since Umpqua and Willamette Rivers. The nematode the early 1900s and conservation efforts are historically has an entirely marine life cycle, underway (Petersen et al 2003). American shad using ( harengus pallasi) were introduced to the Pacific coast in 1871 via and (C. harengus harengus) as the Sacramento River. They have been important intermediate hosts before ultimately documented in the Pacific Northwest since at infesting marine mammals, typically , least 1880, and possibly as early as 1876, with seals, and sea lions. Consumption of A. simplex the earliest reports coming from the Columbia by through raw or undercooked River (Welander 1940). Since that time, shad can result in a condition known as anisakiasis. have increased their range south to Baja The symptoms can range from mild to severe, California and north to coastal Alaska, with but, if left untreated, can lead to ulcerations in sightings as far away as the Anadyr’ River in the gastrointestinal tract and possibly death Russia (Petersen et al 2003). They are very (Shields et al 2002). prevalent in the Columbia River basin, and have Another marine pathogen native to both the been located very far inland, at the Priest Rapids Pacific Northwest and the Atlantic coast, Dam on the Columbia River and the Lower Ichthyophonus spp, infests American shad. Granite Dam on the (Petersen et al surviving 10,000 shad fry into the Sacramento 2003). Very little is known about the shad’s River (Petersen et al 2003). The shad quickly range while outside of rivers and estuaries established a population and began expanding (Walther and Thorrold 2010). their range, spreading from San Diego, The Geological Survey (USGS) California to Kodiak Island, Alaska by 1926 has compiled information on distribution of the (Welander 1940). In recent years, the American American shad from the literature, museum shad run in the Columbia River has been larger collection records, government agencies, and than the runs of all the salmon combined, universities. Those distribution maps are numbering up to 4,000,000 passing through reproduced below (Figures 4 and 5) for both the Bonneville Dam (Petersen et al 2003), and a United States in general, and for the Pacific possible 8,000,000 when spawners below the Northwest. dam are included (DJ Hasselman personal communication).

History of Invasiveness After the successful transport of live American shad fry by Green, numerous attempts to stock Historically, American shad was an the fish were made throughout the nation, and important food fish in the eastern United States, even into other countries. Shad introductions supporting one of the largest and most were attempted in 40 states during the last part economically valuable commercial by of the 19th century, all of which were ultimately the late 1800s (Limburg et al 2003). As such, it unsuccessful. Efforts were also made to was thought that introductions into the rapidly introduce American shad to Germany and growing area would provide in 1874 and 1900, respectively. The a valuable food source (DJ Hasselman personal introductions failed in Germany, while the communication). To that end, the California Fish outcome of the Irish population remains unclear Commission worked with fish culturist Seth (DJ Hasselman personal communication). Green to transport shad fry to the Sacramento River (Petersen 2003). Along the way, Green Invasion Process introduced some of the fry into Lake Erie at Cleveland, Lake Michigan at Chicago, and the Ogden River in Utah, although those populations Pathways, Vectors, and Routes of Introduction failed to establish (DJ Hasselman personal The pathway for the invasion of communication). These appear to be the first American shad into the Pacific Northwest, and introductions of American shad outside its to the West Coast in general, was intentional native range. In June of 1871, Green released the stocking as a food fish for the rapidly growing population, particularly around the San propagule pressure, with both large propagule Francisco Bay (DJ Hasselman personal sizes and numbers increasing likelihood of communication). In 1871, the transcontinental survival and establishment. Fry were introduced railroad had only recently been completed, and into the Sacramento River basin on several Seth Green used this railroad to transport the fry instances for a total release of 619,000 (DJ to the Sacramento River. As there were no Hasselman personal communication). In cars at this time, the fry were initially addition, fry were also planted in the Columbia carried in 8-gallon milk jugs, with stops along River drainage twice for a total of 910,000 fry, the way for water exchanges and ice to cool the albeit after the shad had already appeared there containers (Petersen 2003). Shad fry were (Chapman 1942). introduced to the Sacramento River on several In addition to increasing propagule pressure, occasions between 1871 and 1880, with no humans also assisted in establishment of shad introductions into California after that point (DJ through a lack of consistent harvesting. Demand Hasselman personal communication). Shad were for American shad on the Pacific coast was subsequently transported to the Columbia River never as high as along the Atlantic (Petersen et watershed in 1885 and 1886, although these al 2003). The presence of the more valuable and plantings occurred only after mature shad had prized salmon kept the shad small for already invaded the Columbia River basin most of its history (Chapman 1942). Although (Welander 1940). Since these introductions there were shad and canneries for a while covered only a short time span, and there is no early on, and some locals consumed the fish evidence of later stocking, railroad cars while others were shipped back to the East remained the only vector for the invasion of Coast, demand was never sufficient to maintain American shad. a robust commercial fishery (Petersen et al 2003).

Factors Influencing Establishment and Spread The plasticity apparent in the life histories and environmental requirements for American shad The reasons behind the success of also likely played a role in establishment. Shad American shad in California and the Pacific experience and thrive in a wide range of Northwest are not well studied and, therefore, conditions in their native range, including remain unclear. It is likely that multiple factors exposure to the variable salinities, temperatures influenced their successful establishment and and ecological communities present in their spread here, even while failing in so many other native range, which extends over approximately locations. During the initial introduction stage 21° of latitude (Welander 1940). In addition, government agencies ensured very high shad appear to be generalists when it comes to substrate and turbidity requirements, allowing were an abnormally large number of El Niño for a wider range of suitable habitats and events occurring around the time of the shad’s spawning grounds (Facey and Van Den Avyle introduction (1864-1891). The warm surface 1986). Perhaps the most dramatic example of the currents brought up the West coast during these ability of this fish to adapt to new environments events could have raised the temperature into the is the landlocked population of Millerton Lake preferred range, allowing more fish to migrate in California. These fish have somehow out of the bay and into the Davidson Current. managed to evolve quickly enough to maintain This current runs along the Pacific coast to their ability to osmoregulate in freshwater into Vancouver Island from October to April. The adulthood and possibly change the structure of combination of these events could explain the their to accommodate a more piscivorous rapid dispersal throughout the Pacific Northwest lifestyle. Some of this plasticity may be a result experienced by the American shad (personal of increased genetic variation due to two communication, unpublished data). separate source stocks: one from the Hudson

River and one from the Susquehanna River (DJ Potential Ecological and Economic Impacts Hasselman personal communication). At the Very little research has been conducted same time, impoundment of the Columbia River on the impacts of American shad in the Pacific system created a series of reservoirs and altered Northwest. This is likely due to being the flow and temperature regime of the rivers intentionally introduced over a century ago, until they more closely resembled the calmer before the field of invasion ecology was formed. waters of their native range (Petersen et al Interest in studying the impacts associated with 2003). shad has only recently taken hold, as the The factors involved in how the American shad population of shad continues to increase, and has increased its range so dramatically are this interest is mainly focused on potential particularly difficult to ascertain. However, one adverse effects on the native salmon (Sanderson plausible theory will be presented in an et al 2009). The Columbia River is home to upcoming, as yet unpublished, article by Daniel both endangered salmon and the largest Hasselman, Richard Hinrichsen, Barbara American shad population in the world. The Shields, and Curtis Ebbesmeyer. They suggest sheer numbers of shad involved caused concern that a combination of the Davidson current and that they were crowding the fish ladders of some El Niño conditions facilitated the initial dams and essentially blocking the salmon from expansion of the shad’s range. The waters of San continuing upriver. Some of these ladders have Francisco Bay are generally colder than outmigrating young shad prefer. However, there since been modified to allow easier passage for salmon as well. There is evidence this may be both fish (Petersen 2003). true, at least in the northern pikeminnow, and Other concerns with shad impacts on salmon may also be true of other fish predators such as relate to trophic relationships. This is a very and walleye (Petersen et al complicated interaction that certainly requires 2003). more study. We do know that larval and juvenile In addition to the impacts on salmon, American shad occur in high densities in the Columbia shad have become important vectors for two River, particularly in the John Day Reservoir, marine parasites, A. simplex and Ichthyophonus, where larvae number around 150 fish/1000 m3 as discussed earlier in this paper. Historically, A. (Petersen et al 2003). At these densities, shad simplex has not occurred in freshwater systems, may be outcompeting salmon and other fish for while Ichthyophonus generally does not, and food resources, since they typically although isolated freshwater populations have inhabit similar environments and consume a developed in other parts of the world. In both of similar diet of zooplankton (Sanderson et al these cases, the parasites have experienced a 2009). However, subyearling much greater influx into the freshwater systems are known to prey on small American shad, of the Columbia River, via the increased although the extent to which this might offset prevalence of infection in American shad. This potential negatives due to competition are has raised concern that these rapidly evolving unknown (Petersen et al 2003). species may develop a freshwater population It has been hypothesized that American shad and become epizootic. Furthermore, increased may also affect salmon indirectly through their parasitism of American shad could result in predators. Many predators of salmon also exploit spillback, whereby the prevalence of infection in shad, or even replace a significant portion of the nonnative host causes the parasites to re- their diet with shad. This interaction could be of infect the native populations (Shields et al 2002; potential benefit to the salmon by reducing Hershberger et al 2010). pressure. However, the opposite may The major monetary impact of American shad is actually be true. American shad are excellent probably on the very important cultural and sources of energy, better than most other fish economically valuable salmon fishery in the and crustaceans in that ecosystem. As a result Pacific Northwest. Any of the potential negative some predators may experience a faster growth impacts discussed above could also adversely rate and possibly a larger size at maturation affect the regional economy by decreasing when replacing other organisms in their diet salmon stocks. It is not possible to determine with shad. This may lead to higher consumption how much the economy would suffer, if at all, rates and, therefore, higher predation rates on due to the lack of research and general knowledge about how salmon and American solution for now would be to encourage further shad interact with each other and with the exploitation of this resource to try and moderate environment. However, American shad is also a some of the numbers. This strategy is in effect in potential source of revenue in the form of some locations now; the Washington recreational and commercial Department of Fish and Wildlife is attempting to opportunities. Yet the average harvest during the do this now by promote in the state early 1990s was only 4.2% and 4.8% for via their website, the link to which is provided in commercial and recreational fisheries, a later section of this paper. respectively (Petersen et al 2003).

Literature Cited Management Strategies and Control Methods

American shad are widespread and Chapman WM (1942) Alien in the waters numerous throughout the Pacific Northwest, of the Pacific Northwest. CA Fish Game even outnumbering those in their native range 28(1): 9-15 (Petersen et al 2003). At this late stage in the invasion process, it is unlikely A. sapidissima Chittenden ME, Jr (1972) Responses of young could ever be extirpated from the region. American shad, Alosa sapidissima, to low Moreover, there has never been much of a push temperatures. Trans Am Fish Soc 101: 680- to remove or even control the shad, and they 685 have, in effect, become “naturalized.” The recent increase in scientific interest regarding the shad Chittenden ME, Jr (1973) Effects of handling on and the consequences of its introduction will oxygen requirements of American shad hopefully reveal more information about where (Alosa sapidissima). J Fish Res Board Can to focus our attentions as far as management and 30: 105-110 control (DJ Hasselman personal communication). It seems somewhat premature Facey DE, Van Den Avyle MJ (1986) Species to make any judgments about appropriate profiles: life histories and environmental methods of response before the scientific data is requirements of coastal fishes and gathered. invertebrates (South Atlantic) – American Commercial and recreational shad fisheries are shad. US Fish Wildl Serv Biol Rep currently exploited throughout the Pacific 82(11.45): 1-18 Northwest, but the harvest rates remain low (Petersen et al 2003). Perhaps a moderate Gadomski DM, Barfoot CA (1998) Diel and Neves RJ, Depres L (1979) The oceanic distributional abundance patterns of of American shad, Alosa embryos and larvae in the lower Columbia sapidissima, along the Atlantic coast. Fish and Deschutes rivers. Environ Biol Fish 51: Bull 77(1): 199-212 353-368

Petersen JH, Hinrichsen RA, Gadomski DM, Leggett WC, Carscadden JE (1978) Latitudinal Feil DH, Rondorf DW (2003) American variation in reproductive characteristics of shad in the Columbia River. Am Fish Soc American shad: evidence for population Symp 35: 141-155 specific life history strategies in fish. J Fish

Res Board Can 35 (11): 1469-1478 Peterson RT, Herald ES, Eschmeyer WN (1999) A field guide to Pacific coast fishes of Leggett WC, Whitney RR (1972) Water North America. Houghton Mifflin temperatures and the migrations of Harcourt, New York, pp. 70-73 American shad. US Natl Mar Fish Serv

Fish Bull 70: 659-670 Rahimian H (1998) Pathology and morphology of Ichthyophonus hoferi in naturally Limburg KE, Hattala KA, Kahnle A (2003) infected fishes off the Swedish west coast. American shad in its native range. Am Fish Dis Aquat Org 34: 109-123 Soc Symp 35: 125-140

Sanderson BL, Barnas KA, Wargo Rub MA Melvin GD, Dadswell MJ, Martin JD (1986) (2009). Nonindigenous species of the Fidelity of American shad, Alosa Pacific Northwest: an overlooked risk to sapidissima (Clupeidae), to its river of endangered salmon? Bio Sci 59: 245-256 previous spawning. Can J Fish Aquat Sci

43: 640-646 Shields BA, Bird P, Liss WJ, Groves KL, Olson R, Rossignol PA (2002) The nematode Moyle, P (1976) Inland fishes of California. in American shad (Alosa University of California Press, Berkeley sapidissima) in two rivers. J and , pp. 104-107 Parasitol 88(5): 1033-1035 Walther BD, Thorrold SR (2010) Limited Seattle, Washington 98195-5020 diversity in natal origins of immature Ph: (206) 397-2255 anadromous fish during ocean residency. Fax: (206) 221-6931 Can J Fish Aquat Sci 67: 1699-1707 [email protected]

Welander AD (1940) Notes on the dissemination Richard A. Hinrichsen of shad, Alosa sapidissima (Wilson), along Hinrichsen Environmental Services th the Pacific coast on North America. Copeia 9034 45 Ave NE 4:221-223 Seattle, Washington 98115 Ph: (206) 715-2859 [email protected]

Other Key Sources of Information Current Research and Management Efforts

Fish Base fact sheet There are no current management efforts http://www.fishbase.org/summary/Alosa- in place to control the spread or proliferation of sapidissima.html American shad. Several papers have been The Shad Foundation: an international non- written in the last decade calling for further profit organization for the study, protection, and research on the impacts of shad on salmon, in celebration of shad around the world particular. It is likely that more of the necessary http://www.cbr.washington.edu/shadfoundation/ research will be completed as the scientific Washington Department of Fish and Wildlife: community becomes more aware of the issue. shad fishing in Washington Upcoming research may also focus on the http://wdfw.wa.gov/fishing/shad/ and of an anadromous fish USGS: Nonindigenous Aquatic Species in a novel environment, which could lead to http://nas.er.usgs.gov/ many insights as they do not generally make

successful invaders. The American shad in Expert Contact Information in the Pacific particular has been relatively free from Northwest anthropogenic manipulation since its

introduction due to low harvest rates and a lack Daniel J. Hasselman of stocking that may introduce new genetic School of Aquatic and Fishery Sciences variables. This provides a rare opportunity to examine the changes that have taken place in the Box 355020 population since introduction with a minimum of distortion from human activities. Such research could also help with responsibly rebuilding the depleted stocks on the East Coast (DJ Hasselman personal communication). With further study, we will hopefully answer some of these lingering questions and develop a more effective management strategy if necessary.