FEATURES - SUMMER 1996
[ BURROWING OWLS ]
by Frank Bishop
How many times is this expression applied to a a fish? When it comes to the sturgeon, it's no exaggeration. The lake sturgeon (Acipenser fulvescens) is the largest fish in Alberta. Sturgeon look much the same as they did 100 million years ago. Instead of scales, they have five rows of bony plates called scutes. The skeleton, made of cartilage, not bone, and the shark-like tail remind us these fish are true survivors of prehistoric times.
"Many people are unaware that sturgeon even exist in Alberta. Yet these primitive fish are long-time residents in drainages of the North and South Saskatchewan rivers. Lake sturgeon are most plentiful in the South Saskatchewan River where the Alberta record of 47.7 kg was caught. Lake sturgeon are one of five species of the sturgeon families that are found in Canada. The other four species are the white sturgeon, the green sturgeon, the shortnose sturgeon and the Atlantic sturgeon.
Lake sturgeon are slow-growing fish but they live a long time. Generally sturgeon from the cooler, northern waters grow slower than those found in southern rivers. In Alberta a sturgeon that is 100 cm long (the minimum size limit) is from 11 to 15 years old, depending on its sex. The oldest sturgeon aged in Alberta was a 63-year-old from the North Saskatchewan River but some sturgeon in Canada have been known to live more than 150 years.
Sturgeon spawn in the spring, usually in May and June when water temperatures are about 13 C. It takes many years before a sturgeon reaches sexual maturity. The average age for a male is 19 years and for a female it is 22 to 26 years before they spawn for the first time. A female sturgeon will produce 50,000 to 700,000 eggs when she is ripe but another peculiarity of the sturgeon is that it doesn't spawn every year. Females spawn only every four to six years and the males spawn every one to three years.
During spawning the eggs are broadcast along rocky shorelines near strong currents and the attending males fertilize the eggs as they are released. The water current keeps the eggs from clumping and helps disperse them. The fertilized eggs hatch in about five to eight days and the larvae depend on their yolk sac for nourishment for the first 18 days. Then they start foraging for themselves. Sturgeon are bottom feeders and they use the four barbels or feelers that hang down the underside of the snout to find their food. once something edible is detected they extend their tube like mouths and suck up the prey. food items consist of insect larvas, clams and fish but sturgeon have also been known to ingest coins, tin cans and other debris. most anglers in the south saskatchewan river believe that fish are the best bait to attract sturgeon. Another study indicates that lake sturgeon prefer river minnows to store bought smelts so fish are probably a natural food item for the sturgeon.
Lake sturgeon are classified as a "unique species" by the Natural Resources Service, requiring regulations and a management strategy that is tailored for them. While not on the endangered species list, this fish is very susceptible to extirpation. Alberta is most western extension of the sturgeon's habitat, concentrated mainly in Central North America. The sturgeon's unusual biological characteristics make it a species that is vulnerable to any significant habitat changes.
The lake sturgeon's slow rate of growth and its longevity results in a time lag of 10 to 20 years before any effects of regulation changes can be measured. In fact, only now are we probably seeing the benefits of changes that we enacted about 50 years ago.
In the 1940s the sturgeon fishery was closed completely, presumably because of low population numbers and limited distribution. When the fishing was re-opened in 1968 it was tightly constrained. Anglers had to purchase a special sturgeon licence and could keep only two sturgeon per year with a minimum size limit of 36 inches (now one metre). Current regulations have not changed much since then.
Because of increasing angling pressures there is some thought that the sturgeon regulations should be tightened up even further to better protect this unique species.
One of the management methods initiated in 1968 was a yearly mail-out questionnaire to each licencee to record the annual harvest and demographics of the anglers who utilize this resource. After 27 years of questionnaires a number of things are quite apparent. The sturgeon angler is very loyal and concerned about this species - an average of 79 per cent of licencees have returned completed questionnaires. Almost 40 per cent of the anglers who fish for sturgeon catch at least one and lately only 8 per cent of the sturgeon are kept. Sturgeon angling licence sales have varied from a low of 24 to a high of 552 but over the past seven years the average is 320.
Lake sturgeon can be caught in the Bow River, the Oldman River and the Red Deer River as well as the North and South Saskatchewan rivers. Success rates are generally best in the South Saskatchewan River where 95 per cent of Alberta's sturgeon are caught each year. Evidence that the angling regulations instituted in 1968 are working, can been seen in the increasing catch success in the South Saskatchewan River. The catch rate now is 2.5 times better than it was 10 years ago.
Because angling pressures and catches are increasing, fisheries biologists are considering updating the sturgeon angling regulations to better protect this important species. Biologists and enforcement staff from Saskatchewan and Alberta have met to trade reviews on each province's regulations and management strategies. Under consideration is a common strategy to protect transboundary lake sturgeon populations.
A study carried out in 1985 and 1986 by R.L.&L. Environmental Services Ltd. showed that sturgeon in the South Saskatchewan River moved back and forth across the boundaries. Some fish move as much as 185 km in a relatively short time. Other regulation changes being considered are a further reduction in the bag limit to one per year, an increase in the minimum size limit to 130 cm., closure of known spawning areas in the spring and separate management of the North and South Saskatchewan River populations. Whatever regulation changes are finally decided upon, the best interests of the lake sturgeon populations will be paramount. This important species of fish has suffered declines in many other parts of North America but in Alberta we plan to keep and hopefully increase the numbers of this unique fish.
(Frank Bishop is Head of Regional Fisheries Management, Prairie Region)
Census not just a numbers game
By Ed Hofman
An open letter to landholders in the mixed grass prairie region of Alberta.
It has become increasingly evident that many landholders and others in the Hanna area and elsewhere are concerned about the fate of burrowing owls here. This is very good news, except that some of the concerns are fueled by misconceptions and incorrect information. I would like to clarify the goals and objectives of the Burrowing Owl Program in Alberta.
Recently, burrowing owls were uplisted from "Threatened" status to "Endangered" by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC)in their recently published "Canadian Species at Risk" brochure (April 1995). That means burrowing owls are in even more trouble than they were in 1979 and 1991 when they were first recognized as being a threatened species by researchers and field biologists.
Burrowing owls are now classed as an "endangered" species. Photo courtesy of Earth Images Foundation.
Ever since, concerted efforts have been made by government agencies, universities and non-government organizations to discover the cause or causes of the declining owl populations and hopefully reverse the trend. Some of these efforts involve locating the burrowing owl's wintering area thousands of miles from the prairies.
Here in central Alberta the efforts have been primarily directed toward identifying and protecting key breeding areas. This requires that biologists, technicians, researchers, students and anyone else involved in the recovery of the burrowing owl search the prime habitat areas used by this species in order to discover how many owls there are and exactly where they establish nest sites. Without this information, we cannot be successful in our efforts to restore owl populations. I speak for my colleagues as well as myself when I say that none of us would willingly or knowingly jeopardize the fate of the owls themselves by needlessly disturbing or harassing them on their nesting burrows.
1995 is the second year of an intensive census using the technique of searching randomly-selected four-square-mile "blocks" of habitat. Two people(two only, to reduce disturbance) systematically search the blocks a quarter section at a time. Upon locating a pair of owls and the subsequent nest site, a visit is made to the site to collect owl "pellets" as these tell us what the owls have been feeding on (primarily small rodents and grasshoppers).
This brief visit (five minutes is average)is only a minor annoyance to the birds and is not a factor in causing birds to abandon their nests. No owls are caught or similarly handled during a census. A more likely cause of nest abandonment is predator activity. Badgers have been known to dig up nest burrows and coyotes and foxes searching for ground squirrels are also culprits. Another cause is nearby industrial activity.
The exact location of the site is also recorded on GPS (Global Positioning System)units so it can be visited later if necessary (and only by authorized people). By counting owls on the census blocks, the data is later statistically manipulated to give us a realistic estimate of total owl numbers in a given area of similar habitat. As I already mentioned, owls are counted and nest sites are located and recorded during these censuses. However this information is treated confidentially and no one without a vested interest in burrowing owls is given the locations of nest sites.
Owls are counted and nest sites recorded during the census. That information is treated confidentially and no one without a vested interest in burrowing owls is given the locations of nest sites.
Unfortunately, we cannot protect nest sites from such permanent disturbance as occurs during oil and gas exploration and seismic activity if we don't know where they are. In the last few years, major petroleum companies routinely ask Alberta Fish and Wildlife staff for assistance in avoiding potential and/or historical nesting areas (of not only burrowing owls but other endangered birds as well). We are supplied with the route of the pipeline or the location of the wellsite, and it is up to us to work with the company to realign or relocate the disturbance.
This is impossible if we are not able to conduct censuses or if we are intentionally not told of nest sites due to the misconception that our activities have a negative impact on burrowing owl populations. We too have a genuine concern for the welfare of these creatures and it simply is not in anyone's best interest to gamble with the few remaining birds left. It is true that mistakes have been made in the past but techniques have been refined and modified to reduce unnecessary disturbance to the birds while looking for them.
If any researchers felt they were having a negative impact on the birds the program would be discontinued and other methods of determining their status would be developed.
Another common misconception is that burrowing owls always return to the same nesting burrows that they have used in the past. Though this is true in many cases it is by no means consistent. These birds are not averse to setting up house-keeping elsewhere in the general area of their former nest sites. They may actually nest several miles from where they once nested, and this may lead one to believe that they perished or met some other fate since it appears that they have abandoned the old site. Locating another suitable burrow (made by ground squirrels, which they do not feed on - another myth) may not be easy, but they do so willingly and readily.
So why are they disappearing? The answer to that appears to be that their habitat of unbroken, native mixed and short grass prairie is disappearing and their food supply, primarily insects and small rodents, has dwindled because of widespread use of pesticides along roadsides and canals and sometimes near burrows. Chemicals such as Furadan, used to control grasshoppers, are extremely toxic to birds which may ingest the chemical either by direct means or from the food they eat.
Each year, the prairies lose thousands of acres of uncultivated land to industrial and urban development (i.e., pipelines, wellsites, city expansion, etc.) and the plow, primarily for the planting of cereal and hay crops. Burrowing owls do not normally inhabit these areas as ground squirrels and badgers normally do not use these areas either. Factor in the use of fertilizers, insecticides and herbicides on cultivated land, and there is less nesting area for the birds.
In order to protect a species we must determine their population status, breeding biology and life history. We can only do so if allowed access to the burrowing owls' breeding range, here in the open prairies of central and southern Alberta.
If you have any questions or concerns, please contact Ed Hofman, Area Wildlife Biologist in Hanna at 854-5540, or Dave Scobie, Operation Grassland Community in Brooks at 362-4122. Both offices may be accessed on the Alberta Government RITE line at 310-0000.