Course:CONS200/2020/The White Sturgeon recovery plan in the upper Columbia River

Introduction

White sturgeon (Acipenser transmontanusare) is a unique species of freshwater anadromous fish in the Upper Columbia River. The species plays a vital role in the biodiversity of the Columbia River. They are currently threatened with local extinction within the Upper Columbia River, attaining endangered status criteria of 2,500 by the World Conservation Union. The main factors contributing to the decline of white sturgeon in the Columbia river are the construction of new and naturally formed dams that have affected the natural flow of rivers, the introduction of competitive, invasive species, overfishing, and other anthropogenic impacts of humans.

History

Sturgeon have been around for over a million years making them one of the oldest fish species on the earth . During this time, they have survived through many different climatic conditions such as an ice age and planetary warming. Their ability to adapt and overcome extreme conditions has led to them being one of the most resilient species on earth. However, since the late 1800s their numbers have been in decline. The main cause of the initial drop in Sturgeon inventory during the late 1800s and early 1900s was due to a growing interest in the delicacy of Caviar (Sturgeon eggs). People around the world were paying top dollar for these eggs. One female sturgeon is capable of having anywhere between 700,000 and 4 million eggs . This resulted in female sturgeon being worth a lot of money and therefore contributed to the overfishing of the species.

Figure 1. Sturgeon Caviar

Physical Characteristics

Figure 2. The White Sturgeon at the Vancouver Aquarium

The White Sturgeon's body is elongated with a large cylindrical shape. Adult specimens can grow as large as 3.8 to 6 meters and can weigh as much as 630 kg . The upper and back sides of the White Sturgeon can be different in colour from the Kamloops region with dark to medium grey often with obvious white markings. The lower sides and belly are pale grey to white. There are 11-14 plates in front of the single dorsal fin, It has no scales but five rows of "scutes" along the body attaining 38 to 48 lateral shields and 9-12 from the head to the pelvic fins. Its barbels are nearer to the mouth than the tip of the snout. The mouth is ventral on the sturgeon, it's moderately sized and directed downwards. As for teeth, the white sturgeon has no teeth; it uses its 'vacuum cleaner' like mouth to siphoning up food. This fish is recognized by its short broad snout with four barbels closer to the tip of the snout than the mouth.

Life Cycle

Sturgeons are egg-laying fish. Females lay eggs directly into the river's flowing current. Fertilization will occur and the incubation period will follow. Many eggs will not survive due to poor water conditions, suffocation by the river substrate, or predation. After 7 days, the eggs hatch and enters the first motile stage of life: the larvae stage. The larvas are 1 cm in length and will stay attached to a yolk sac for nourishment. After they completely absorb the yolk sac, the larvae will begin to feed on small aquatic animals or plants. At 20-30 days old, the larvae will transition into the fry stage. At two months old, the fry will grow up to 3-5 cm and develop distinct features such as barbells (whiskers) and scutes (bony plates on dorsal and lateral side). As they become more mobile, the fry can swim longer distances for prey and some may be carried downstream by surface currents. After one year, the fry become juveniles. Juveniles can be anywhere from 15-30 cm in length. With better feeding conditions and more nutritious prey, they can grow up to 7 cm per year, and gradually slow down as they reach maturity. They can migrate great distances within, or outside of the Columbia River to marine areas such as Puget Sound or the Georgia Strait. The last stage is the adult stage. Male sturgeons reach sexual maturity earlier, at 90-120 cm in length at 12-18 years of age. Females reach maturity at 160-170 cm in length, at 25-30 years of age. Unlike the younger sturgeons, adult sturgeons do not feed on insects or shellfish. They feed exclusively on live matters such as adult salmons and even smaller sturgeons. Males can spawn annually, but the frequency is unknown. Females spawn more infrequently, around 3-6 years for younger females and up to 9-12 years for older sturgeons.

Figure 3. White Sturgeon typically grow 4-10 feet long.

The Cost of Human Interaction and Intervention

Overview

Through research done in the last century, human interaction and intervention is the leading cause to the harm of this river fish . Loss of habitat, introduction of exotic species, and over harvesting are some factors that contribute to the devastating decline. Habitat loss caused by dams and flood control dikes claimed countless numbers of adult and juvenile formed species; thus being the greatest factor of the decline in completing the full cycle to sexual maturity .

Damaging Dams: Loss of Habitat

Specific sections of the Columbia river are highly regulated by hydroelectric generation and storage dams. This control flows and current in the river (Figure 10.). Dam construction has blocked movements and restricted sturgeon to river fragments that may no longer provide the full spectrum of habitats necessary to complete the life cycle . The presence of dams alters the natural movement patterns in the river. As migration occurs, overwintering, feeding and spawning activities come into play. Movement affects the food type availability generously, without a strong food supply, numbers begin to dwindle . Flow fluctuation (altered seasonal and annual fluctuations that provide behaviour cues and suitable spawning or reassuring conditions) caused by dams and dykes and pollution make breeding grounds far from safe for mature fish in the river.

Competition with Exotic Species

Food and shelter remained sparse after the alteration of the sturgeon's natural habitat. Exotic species pose a threat to the white sturgeon by competing with food, breeding grounds and even through the consumption of eggs and juvenile offspring.

Figure 4. The Walleye, also called the Yellow Pike or Yellow Pickere

The Walleye (Figure 4.) was introduced in the 1940s and 1960s throughout the upper Mississippi and Columbia River basins, Over the past few decades the Walleye have migrated up river into the Canadian portion of the river . They are known to be introduced solely for the reason of sport fishing.

Figure 5. Northern Pike pose a risk to juvenile sturgeon due to their carnivorous nature

The Northern Pike (Figure 5.) is a species of carnivorous fish that are typical of brackish and fresh waters of the Northern Hemisphere . The species was first detected in 2010 In the Canadian portion of the Columbia River . The Northern Pike are believed to have been illegally introduced into the Columbia River Basin through the Flathead Lake system in Montana in the 1980s .

Figure 6. Non-native Freshwater shrimp found in the Columbia river

The Siberian Freshwater Shrimp (Figure 6.) were first detected in the lower Columbia River in 1995, the shrimp was very likely introduced by ship ballast water . Although there have been no detrimental impacts to date, this nonnative shrimp may prey on native amphipods, such as Corophium salmonis . This directly competes with juvenile endangered sturgeon and salmon for important food resources .

Overfishing

White Sturgeon were overfished during the late 1800s, with a peak harvest of half a million kilograms in 1897 . The population was severely diminished, enough to warrant restoration actions. Commercial catches after 1915 stretched out until the closure of fisheries in 1994 still noticed the decline in population dramatically to between 5000 and 20 000 kilograms per year. By the mid 1900s populations of sturgeon recovered to support commercial and recreational fisheries though the population has never regained its historical abundance.

Recruitment Failure

One of the key problems with the establishment of White Sturgeon is recruitment failure . Recruitment failure is characterized by the limitation or failure of a species offspring to attain sexual maturity and reproduce . Since it takes around 10 years for White Sturgeon to attain sexual maturity, there is a large gap between when they are born to when they can reproduce. During this time the larvae and juvenile sturgeon are very prone to predators. A study conducted by Charles Coutant investigates the effects of water levels and submerged riparian areas on the recruitment of White Sturgeon . What he found was that in times of high river flows, the White Sturgeon had higher levels of recruitment . This can be attributed to the increase in food supply (primarily through insects) and a safer habitat.

The intrinsic biological factors most limiting to White Sturgeon population growth are very low early life stage survival and delayed maturation . Without intervention, the Upper Columbia White Sturgeon population will continue to decline, eventually reaching critical thresholds from which recovery may be difficult even with intervention.

Current remedial actions

Fishing Regulations

Humans have had a negative influence on the sturgeon population for many years but it wasn't until the early 1990’s that any action was taken to protect them. In 1993, Environment Canada added new fishing regulations making it illegal to catch and keep sturgeon in the Upper Columbia River. 3 years later in 1996 it became illegal to fish for these creatures at all in the Canadian portion of the Upper Columbia River . These regulations were passed in Canada however the United States had their own regulations. It wasn't until 1995 that the US Environmental Protection Agency and the Washington Department of Ecology changed the regulation to catch and release. Furthermore. it took 7 more years to ban fishing on the Upper Columbia River outright.

Water Monitoring and Sturgeon Tracking

Figure 7. Upper Columbia River, Revelstoke, BC Canada.

It was in this same era that Environment Canada and the Washington Department of Ecology implemented the Columbia River Integrated Environmental Monitoring Program (CRIEMP). This program was tasked with monitoring the quality of the water along the Upper Columbia River to ensure the survivability of the sturgeon . This was important in determining whether the quality of the water was affecting the survival rate of the sturgeon and if so, determining what was causing the reduced water quality. Many studies have been conducted by many different parties (Environment Canada, BC Hydro, Hatcheries) that look into the movement, habitat use, spawning migration patterns, and inventory of White Sturgeon. These parties was then able to use this data to track problem areas and make conservation decisions. One of the findings of these studies were that the inventory of White Sturgeon in the Upper Columbia River is significantly lower than that of the Fraser River which helped create the current fishing regulations.

Figure 8. Submerged River Bank - representing ideal habitat for newly hatched sturgeon.

Fisheries

One way the government has been attempting to mitigate the loss of population is through the addition of larvae and juvenile sturgeon raised in hatcheries. Between 2001 and 2011, it is estimated that hatcheries have released 160,000 juvenile sturgeon and 1.5 million sturgeon larvae . Additionally, Roosevelt Reach hatchery has attempted to catch wild sturgeon larvae and raise them within the safety of the hatchery until they reach juvenile age to improve the likelihood of survival .

Options for future remedial action(s)

Ecosystem Recovery

To their full life cycle, white sturgeons require sufficient suitable habitat, an abundant food base, and appropriate water conditions. In the Columbia River, the white sturgeon’s present habitat is inadequate to support sufficient survival through early life stages (egg, yolk sac larvae, larvae). Dams have dramatically altered the landscape and ecosystem of the river. In order to sustain the growth of current and future white sturgeon populations, alterations to flows are recommended in dam-affected systems. Slowing down the construction of new dams or the removal of older dams are some other viable methods. This could potentially reverse the effects of habitat fragmentation and loss, allowing sturgeons to access previously used habitats once again. Improvement to existing dams or construction of more environmentally friendly, sturgeon safe infrastructures will further help with the recovery of white sturgeons. Installation of infrastructures such as fish ladders will not only benefit white sturgeons, but many other species such as salmon. Aquaculture of species such as salmon, eulachon, and smelt along the Columbia River may be an option for solving the sturgeon’s reduced prey supply and overfishing. Breeding and stocking of these species from hatcheries into the river will be beneficial to the growth of sturgeons and the long term health of their habitat.

Figure 9. Juvenile white sturgeons reared in a hatchery to supplement existing wild populations.

Regulations

Figure 10. Revelstoke Dam in Revelstoke, BC, Canada. One of BC's 17 dams on the Columbia River.

Under SARA (Species at Risk Act), human activities that lead to the destruction of critical habitat is prohibited. However, activities that impact but not destroy critical habitats are not prohibited. River regulation, extensive harvest of prey, intentional or unintentional introduction of invasive non-native species, release of pollutants, and floodplain development are all primary activities that threaten the white sturgeon's habitat. In many cases in the past, the knowledge of the species and its habitat may be lacking. It is important that federal, provincial, and regional governments increase awareness, education, and enforcement of regulations in local communities to protect these fish. Groups can seek local and traditional (First Nations) knowledge to support the recovery strategy and its development. It is necessary to understand the underlying mechanisms that control sturgeon abundance and distributions across populations, and use the information to develop acceptable strategies for protecting and recovering sturgeon populations.

Water Level Adjustment

As discussed in the previous sections, recruitment failure is one of the leading problems associated with the falling Sturgeon population. One way to increase the levels of recruitment is through submerging riparian areas downstream of spawning grounds. Sturgeon lose the largest amount of their offspring in the first few stages of their life. When the water levels rise, and more of the riverbank is submerged, it creates new habitat and new food sources for the larvae. There are currently 17 dams set up along the Columbia River. These dams have negative effects on the sturgeon populations however, they may be used to help raise the water levels. Through studies conducted by Environment Canada, BC Hydro, and various hatcheries, we now know where common White Sturgeon spawning grounds are. If the dams were to release more water into the rivers downstream of the spawning grounds, more riparian area would be submerged and the recruitment rates of sturgeon would increase.

Conclusion

The unique habitat of white Sturgeon population in the upper Columbia river has undergone a dramatic shift in decline during the Anthropocene epoch. The local first nations have long relied on the predictable yield of these fish and valued their nutrient and protein content. White sturgeon prey has been significantly affected by commercial and recreational fishing. Smelt, eulachon, and salmon are important species in the white sturgeon’s food base.

The current distribution of white sturgeon in the upper Columbia River extends from Revelstoke Dam to Grand Coulee Dam in Washington, and the lower Kootenay River from its confluence with the Columbia River to the Brilliant Dam. In addition to human made physical barriers, the unpredictability of weather has shaped rivers and streams which may be inaccessible to the white surgeon.

Fortunately, through relatively recent habitat restoration efforts, the White Sturgeon population is starting to make a resurgence. This can be attributed to both local egg hatchery programs and local awareness through Canada Fisheries and Oceans selective fishing regulations and enforcement actions. Ecosystem rehabilitation efforts can be attributed to the tracking of spawning and migration patterns. Future work includes selective dredging of dams that obstructs or hinders the white sturgeon's natural migratory routes.