White Sturgeon
Habitat alteration and declining water quality threaten the survival of this species in British Columbia
Ministry of Environment, Lands and Parks geon in both the British Columbia and used by young sturgeon. So far, pollu- United States parts of the Columbia tion levels in the Fraser don’t seem to River watershed. For example, sturgeon have affected the White Sturgeon, in the Kootenai (Kootenay) River, but increasing human populations, Why are White Sturgeon which flows from Idaho into Kootenay agricultural land development and in- at risk? Lake in British Columbia, have failed dustrial effluents are still long-term ver the past century, White Stur- to reproduce and have declined in concerns. Sturgeon are very long-lived geon populations throughout their numbers since flows were first regulated animals, and it may take decades to show range have been adversely affected at the Libby Dam in 1974. Trapping the effects of pollutants concentrating in O by over-fishing, construction of nutrients in Lake Koocanusa, their tissues. of hydroelectric dams, dyking behind Libby Dam, is believed to Mysterious die-offs of sturgeon and drainage projects, and human have caused a serious decline in occurred in the lower Fraser during the competition for food such as Kootenay Lake kok- hot summers of 1993 and 1994. Thirty- salmon and eulachon. Their In the anee populations, an four huge sturgeon were found dead future is also threatened by important food for along the shoreline, mostly old females. declining water quality as human Kootenay sturgeon. Unfortu- How many others died and weren’t populations increase and land drainage, nately, White Stur- found will never be known. This seems uses intensify in the Sacramento, geons don’t appear to to have been a natural die-off, but it may Columbia, and Fraser river basins, sturgeon be maintaining their have been heightened by human effects the main watersheds where White have not numbers anywhere on the environment. Sturgeon occur. in the British Colum- The first major human impact reproduced bia part of the Co- What is their status? on this sensitive species, over-fish- since about lumbia River system n Canada, White Sturgeon are pri ing, began before the end of the and their long-term marily resident in only two water 19th century in all three water- 1974. prospects there are sheds, the Fraser and Columbia, sheds. The lower Columbia River exceedingly poor. I where their populations are much-re- sturgeon fishery in Oregon and Wash- White Sturgeon were also over- duced due to historical over-fishing on ington collapsed in the late 1890s, after fished in the Fraser River from 1880 to both rivers and dam building 2.5 million kilograms of fish were har- 1915, with a peak harvest of half a mil- in the Columbia Basin. Accurate vested in a few years. A multitude of lion kilograms in 1897. Commercial estimates of sturgeon numbers are dams were also constructed on the up- catches after 1915, until closure of the not available, but the number of per Columbia in the United States and fishery in 1994, declined dramatically to large breeding-age individuals may several in British Columbia. These dams between 5000 and 20 000 kilo- be dangerously partitioned most of the remaining stur- grams per year. The population Armoured low in many geon in this system into several land- has never regained its historical areas. As a re- locked populations, many of which are abundance. Fortunately for stur- relics from the sult, the harvest not able to remain viable as stocks. geon and other fish, no dams have past, sturgeons of sturgeon has Hydro dams, particularly those like been built on the mainstem Fraser been illegal in Keenleyside in British Columbia and River. However, sturgeon in one have remained British Colum- Libby in Montana which are used for tributary, the Nechako River, may relatively bia since 1994. storage, may harm sturgeon in several have been harmed by diversion of In the Koot- ways. The dams block access to essential water out of the basin and regula- unchanged for enay drainage, spawning or foraging sites; eliminate tion of the much-reduced flows millions of which straddles spring flooding of traditional spawning that remain. Large commercial the Canada- or rearing habitats; trap nutrients on catches of salmon bound for the years. United States which downstream forage fish like Fraser have undoubtedly reduced border, sturgeon kokanee depend; and reduce down- the supply of this seasonally important have not reproduced since about 1974 stream turbidity, making juvenile sturgeon food. Dyking, drainage and and only 800 to 1000 adults remain. That sturgeon more visible to predators. filling of sloughs and wetlands along the population has been declared endan- The above impacts affect White Stur- lower Fraser have caused loss of habitats gered under the U.S. Endangered Spe- cies Act. In other portions of What do they look like? and more pointed than the lower lobe, the Columbia system in Canada, the re- wo imposing features of the White a shape referred to as heterocercal. maining landlocked populations are Sturgeon – the huge size reached by The White Sturgeon has a broad, flat- also small and may be affected by the oldest adults and the rows tened head and limited spawning success. Based on T of bony shields – set this fish tiny eyes. Its wide trends in the neighbouring Kootenay strikingly apart from other fresh- Reaching toothless mouth, system, their future does not look water species in the province. 6 m in length, located on the bright. Fraser River sturgeon, though Reaching 6 m in length, 635 kg in underside of the much reduced from historical levels, weight and over 100 years in age, 635 kg in head well back appear to be holding their own and this is the largest freshwater fish in weight, and from the snout, is might increase now that harvests have Canada. Armoured relics from the protrusible, an ad- been curtailed. The Nechako River past, sturgeon have remained rela- over 100 years aptation for suck- population, however, is thought to be tively unchanged in structure for in age, this is ing up food from endangered. millions of years. the lake or river Because of its restricted distribution The torpedo-shaped White the largest bottom. Its four in Canada, its reduced populations, Sturgeon has no scales. Its protec- freshwater whiskers or bar- and concerns for future habitat quality, tive bony plates, or scutes, are bels, located be- the Committee on the Status of Endan- arranged in five rows – one along fish in tween the mouth gered Wildlife in Canada () the back, one along the middle of Canada. and snout, aid in has classified the White Sturgeon as each side, and one along each side finding food in Vulnerable. Provincially, it has been of the belly. The plates of young stur- the murky or darker waters where given Red List (species being considered geon have very sharp points which sturgeons prefer to lurk. for legal designation as Endangered or become blunted with age. Its tail has a The back and upper sides of the Threatened) status. shark-like upper lobe which is longer “White” Sturgeon vary in colour from dark to medium grey often with obvious more than once, but only every 4 Distribution of White Sturgeon in British white markings. The lower sides and to 10 years. Nothing is known Columbia belly are pale grey to white. about the spawning interval of In British Columbia waters the males. Sturgeon make up for this White Sturgeon could only be confused pattern of delayed maturity and with its more marine relative the Green infrequent spawning by produc- Sturgeon. The Green Sturgeon has 25 to ing prodigious numbers of eggs – 30 lateral shields (compared to 38 to 48 from about 700 000 in medium in the White Sturgeon), barbels that are sized females to 3 or 4 million in nearer to the mouth than the tip of the largest, whose ovaries may Kamloops the snout (nearer the snout in White weight over 100 kg! Sturgeon), and has generally greenish to Based on research in the Co- olive-coloured upper body parts. Both lumbia River, White Sturgeon species can be found in the mouths of usually migrate upstream in large rivers such as the Fraser. spring to spawning sites that have faster detect food are on the underside of its currents and rockier bottoms than their flattened head, an adaptation for bot- What makes them unique? normal foraging habitats. Spawning fe- tom feeding. And it is wonderfully he White Sturgeon is certainly males release their small brown, sticky adapted indeed for this mode of life. unique. Its physical appearance, eggs over large areas of river bed, where Sensory nerve endings on the bottom particularly the plates of armour, they readily adhere to the rocky bottom. of the snout, which function much like T give it a bizarre, prehistoric look. Strong currents ensure that the female the lateral line of other fish, allow it to Indeed, the fossil record tells us that eggs and male sperm are well mixed and detect movements of potential prey. Its sturgeon have changed relatively little that the developing eggs are bathed in four dangling barbels serve to pick up for millions of years. Despite this they well-oxygenated water. The incubation odours in the water and to identify suit- are survivors, having successfully per- period lasts for 5 to 25 days, being long- able food by touch and taste. These fea- sisted through eons of climatic change, est where temperatures are lowest. The tures, rather than eyesight, are crucial including ice ages. They have found a larvae, with yolk sacs attached, drift for finding food in the sturgeon’s usu- niche today as scavenger/predators in a downstream with the current for many ally murky environment. Food items few large, productive lakes and rivers. kilometres, then remain largely hidden may be located by following a water- Among fish, its reproductive habits for their first two weeks. After about 18 borne odour upstream to its source, or are also quite unusual. Adults require 15 days, sturgeon transform into fry by simply lounging in a spot where to 30 years to reach sexual maturity, (young-of-the-year), complete with the drifting materials tend to collect. Once spawn at intervals of up to 10 years and elongated snout, flattened under-sur- the barbels contact acceptable food, the can deposit a million or more eggs at a face, and plates that characterize the huge mouth is extruded and used to single spawning. Sturgeon are also re- species. During their larval and fry suck it in. Indigestible debris, often nowned for the delicacy of their eggs, stages, many sturgeon are undoubtedly found in sturgeon stomachs, is fre- or caviar, for human consumption. eaten by other, larger fish. In the Fraser, quently ingested with the food. Although present in rivers and lakes the fortunate survivors reach a length of Sturgeon diet varies somewhat from close to large cities, the White Sturgeon about 50 cm by age 5, and then grow system to system, depending on the remains a beast of much mystery and about 5 cm per year to about age 25 and food species that are present. However, awe due to its reclusive habits and at slower rates beyond that age. Stur- invertebrates such as larval insects, cray- choice of dark or muddy waters where geon in the upper Columbia River don’t fish, freshwater clams and snails tend to observation and study are difficult. grow as quickly or as large as those in the be important for young sturgeon, while lower Fraser. fish of one kind or another predominate How do they reproduce? in the diets of older sturgeon. n the Fraser River, the age of sexual What do they eat? In the lower Fraser River, small maturity of White Sturgeon is esti he White Sturgeon lives entirely on sturgeon eat larval chironomids (blood- mated to be 11 to 22 years for males animal matter, some of which is worms), stoneflies, caddisflies and I and up to 26 or more years for fe- scavenged from the river bottom. mayflies, as well as adult crustaceans males. Once mature, the females spawn T Its mouth and sense organs which such as crayfish and freshwater shrimp. Large sturgeon there from river to river also consume inverte- through the ocean. brates, particularly cray- Since the entire Fraser fish, but the bulk of their Basin was ice-covered diet is made up of fish. during the Pleistocene In May, spawning Ice Age, the White eulachons are devoured Sturgeon probably in great quantities, reached it via coastal while spawning salmon waters during the past are important in sum- 10 000 years. mer and fall. Some of Based on historical these fish are probably catch records, the spawned-out carcasses lower Fraser between scavenged from the bot- its delta and the Fraser tom. Sculpins, stickle- Canyon once had a back, lamprey and small . Mark White photo sizeable White Stur- sturgeon have also been geon population and, found in sturgeon stomachs. tributaries like the Stuart, McGregor, under natural conditions, was probably Bowron, Harrison and Pitt rivers. the most productive unit of habitat in Where do they live? White Sturgeon also occur in the British the province. Recent studies there indi- ore than twenty species of sturgeon Columbia portion of the Columbia cate that sturgeon spend most time are distributed across the cooler River drainage. Within this drainage, in large pools in the main channels, parts of Asia, Europe and North Columbia River and Kootenay River but young individuals in particular M America; almost all are threatened sturgeon, originally isolated from one frequently move between the main to some degree. Of five species found in another by Bonnington Falls, are now, channel and adjacent sloughs over the Canada, only the White and Green since the last Ice Age, further isolated summer months. Tagging studies on the Sturgeon occur in between several dams. They have lower Fraser have so far not shown any British Columbia. In British also been reported from several long distance movements within the The White Stur- lakes in those drainages including river or any migrations to the sea. geon, Acipenser Columbia, Fraser, Takla, Trembleur, Stuart transmontanus the most and Williams lakes in the Fraser What can we do? (“the sturgeon system, and Kootenay, Arrow, everal measures have recently been across the moun- widespread Slocan and Duncan lakes in the taken to improve the White Stur- tains”) occurs population Columbia watershed. geon’s prospects for survival. along the Pacific White Sturgeon have also been S In 1994, commercial and sport har- Coast from Cali- occurs in the found in a few rivers on Vancou- vest of sturgeon became illegal in the fornia to British Fraser River ver Island. Sturgeon have been province, and First Nations people Columbia and reported occasionally in northern voluntarily stopped their sustenance possibly southern mainstem. British Columbia rivers, includ- harvests. This should allow more fish Alaska. However, ing the Skeena and Nass, al- to reach reproductive age, and may significant populations are confined to though these are mostly believed to be help to rebuild some stocks. Designa- just three large river systems – the Green rather than White Sturgeon. Any tion of the White Sturgeon by Sacramento, Columbia, and Fraser. In a White Sturgeon populations north of as a Vulnerable species in Canada has global perspective, this is quite a re- the Fraser, if they exist, are very small. focused attention on its plight stricted distribution. In British Columbia this species appears and stimulated some long-needed re- In British Columbia the most wide- to be mostly freshwater in distribution; search. But this unique and valuable spread population occurs in the Fraser specimens have rarely been taken in species deserves considerably more River mainstem inland to upstream of marine waters. Nevertheless, tagging research effort. Prince George, high into the Nechako, studies in the United States have shown A major need is for more informa- and in the lower reaches of other large that White Sturgeon are able to disperse tion on the distribution, abundance, . . Mark White photo Marvin Rosenau photo more difficult than in the Fraser, and present ban on stur geon harvest, and will require increased international report any illegal sturgeon fishing that cooperation. Releases of reservoir comes to their attention. water during the spring spawning With the increased pressures of season, lake fertilization to replace human settlement, White Sturgeon depleted nutrients, and conservation populations have been decimated hatchery programs may have potential and its habitats degraded. Today, for helping sturgeon in that area. the plight of the White Sturgeon is Much more research is needed widely recognized and the species to determine if those measures will is getting increasing attention. Hope- really do the job. Those studies will only fully, this will ensure its continued be done if there is strong public support existence as a unique and valued for them. It is important that the public member of our provincial and national encourage more research, support the fauna.
: Fisheries Branch BC Environment ’ . Ministry of Environment, Lands and Parks Mark White photo Parliament Buildings Victoria, British Columbia V8V 1X4 population dynamics and seasonal habitat needs of White Sturgeon in brochure funding provided by British Columbia. Without that infor- mation it is very difficult to design meaningful conservation plans. In the Fraser watershed it is crucial that water quality not be allowed to deteriorate further. The public can be of great assistance by supporting exist- ing pollution control and clean-up pro- --- . grams, and by reporting any habitat . , degradation they observe. Improving the lot of sturgeon in the Columbia watershed will be much
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