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2007 Updates
Portage Creek is a small spring fed tributary located on the Sibley Peninsula near the hamlet of Pass Lake (40 km east of Thunder Bay). The stream has long been known for supporting a quality steelhead fishery.
Portage Creek drains 6000 ha of farmland, wooded escarpment and wetlands, all part of the Sibley Peninsula. Numerous tributaries join the main branch as it meanders downstream to Black Bay, Lake Superior. A small waterfall located approximately 1 km from the mouth slows upstream movement of adult steelhead during their spring migration.
Portage Creek's steelhead population is maintained solely by natural reproduction. In the 1980's, anglers noted that adult steelhead were fewer in number and smaller in size. Excessive angler harvest was suspected as the most likely cause of this change in catch. A lake wide steelhead stock assessment study between 1991 and 1994 identified Portage Creek as being excessively harvested and near collapse. In the spring of 1994, the lower reaches of Portage Creek, including the waterfall, was posted as private property. This controlled access to the creek and effectively closed the fishery, creating a unique opportunity to monitor the recovery of this steelhead stock. A partnership with the landowner, the North Shore Steelhead Association and Ontario Ministry of Natural Resources was formed to undertake the project.
The main objectives of the Portage Creek research project are:
- Quantitatively describe adult steelhead population characteristics before and after the reduction of fishing mortality.
- Illustrate the effects of environmental variables (e.g. weather) on wild steelhead.
- Use Portage Creek life history data to demonstrate the ability of a steelhead population to rebound when harvest is restricted.
- Use the Portage Creek data set as a reference population with which to model the sustainability and health of other Lake Superior steelhead populations.
- Demonstrate the value of angler gathered data and partnerships in fisheries management.
Anglers and MNR fisheries specialists work in partnership to collect and to biologically sample adult steelhead during the spring spawning migration. Each day over a six week period (beginning mid April and lasting to the end of May) one or two anglers and an MNR specialist catch (using normal angling practices) and biologically sample (length, sex, scale sample) each captured steelhead. A numbered (colour coded) plastic disc tag is sewn on the anterior end of dorsal fin. To account for any tag losses, a unique fin clip is also applied each year. Water temperatures are recorded daily and annually using automated temperature loggers. Life history information (number of stream and lake years, age at maturity, total age and number of spawning events) is interpreted using scale sample analysis.
Population size is calculated using a Petersen population estimate. Fish are marked (tag and fin clip) in one year, and based on the proportion of tagged fish captured the following spring, population size can be estimated. Tags are also used to determine growth rates of individual fish, validate scale ages, document movement patterns and stray rates.
Adult Population
The adult population of steelhead in Portage Creek has undergone a dramatic shift in population size, age structure and year class strength from 1991 to 2007. This is illustrated in the first three graphs (Figure 1, 2 and 3).
The adult population slowly increased between 1994 and 2001, had a major increase from 2002 to 2004 before declining slightly in 2005 and 2006 (figure 1).
The increase in the years following fishing closure was due to better survival of adult steelhead into older age groups. In turn these large fish were more fucund (higher egg production) and produced the good year classes of 1998 (age 4 in 2002), 2000 (age 4 in 2004) and 2001 (age 4 in 2005) (Figure 3). The decline witnessed in 2005 and 2006 was due to the poor year classes in 2002 and 2003 (age 3 and 4 in 2006) (Figure 2). The good news is 2004 year class that appears to be one of the strongest we have seen in Portage Creek since the program began. The 2007 data indicates that this year class (age 3) represented close to 50% of the spawning population (Figure 2).
Life history strategies
In Portage Creek one year of stream life is a dominant life history strategy. Figure 4 illustrates the number of stream and lake years (by sex) expressed by the adult population. Once in Lake Superior one to three years is required prior to the first spawning event. Males may reach maturity following one year in the lake while females generally require two or three years in the lake before spawning for first time. (Figure 5)
Steelhead growth is slow while in the stream environment and rapid once in Lake Superior. Figure 6 illustrates the average fork length of adult steelhead found in the spawning population. In Portage Creek, a one year old stream steelhead is approximately 8 cm in length. After one year in the lake the same fish will average 35 cm. At maturity, steelhead average 50 cm (2 lake years) and 58 cm (3 lake years). Following the first spawning event growth slows as the spent adults must recover from spawning and replenishing their gonads in order to spawn again the following spring. The largest steelhead in Portage Creek (>70 cm) are often three and four lake years at maturity rather than old individuals.
Spawning
The spawning migration of Portage Creek steelhead begins in mid to late April, peaks during early May and is usually completed by mid June. Timing of the migration and upstream movement is influenced by flow regimes and water temperature. Redd construction occurs in the lower river from late April to late May and in the upper river (above the falls) from mid May to late June. There is little evidence of fall migrations or over wintering of steelhead in Portage Creek. The fall migrants observed were mainly one lake year immature steelhead that likely return to the lake prior to freeze-up.
Repeat Spawning
The number of adult steelhead spawning in consecutive years has increased from less than 100 individuals in the early 1990's to over 1000 in 2004 and 2005 (Figure 7).There is generally a higher natural mortality in male fish resulting in lower repeat spawning numbers (Figure 8). Following the reduction in fishing mortality in 1994, survival to multiple repeat spawning for both sexes has greatly increased (Figure 9). It would appear that improved spawning success (juvenile recruitment) is related to the increased abundance of three to five time repeat spawners (Figure 8). In Portage Creek we have documented nine times repeat spawning in females and seven times in males.
Stray Rate and Movement Patterns
Portage Creek steelhead wander throughout Lake Superior but generally return to spawn in their home stream. Tag returns from the south shore of Lake Superior, Nipigon Bay, and the Sault Ste Marie area illustrate the nomadic nature of this species. Approximately 2% of steelhead tagged in Portage Creek are captured in other Lake Superior tributaries the following year. If released some of these eventually spawn in Portage Creek. In the spring of 2006 an adult steelhead was tagged in Portage Creek and then captured six weeks later in a Wisconsin stream.
Year class strength of juvenile steelhead is generally similar over large geographical expanses ie. 2000 year class. Because of this, Portage Creek's adult steelhead population can be used to index the fluctuations in steelhead juvenile production over much of western Lake Superior.
Research on Portage Creek also allows us to document not only the susceptibility of wild Lake Superior steelhead populations to over fishing, but also the ability of a wild population to rebound in number following the restriction of harvest.
In Portage Creek there was a sharp increase in the adult population size between 2000 and 2004. This was a direct result of the 1998, 2000 and 2001 year classes recruiting into the spawning population. These three year classes were produced by adult migrations with a high proportion of multiple repeat spawners. The hot dry summers of 2002 and 2003 along with the severe winter of 2002/03(rivers froze to the bottom with the lack of snow cover) produced back to back poor year classes. The 2006 year class may also suffer the same fate following the cold dry winter of 2006/07. The strong 2004 year class may be a critical buffer in maintaining healthy adult populations in Portage Creek and other north shore tributaries over the next few years.
In the Portage Creek research, fully half the estimated population size is angled and biologically sampled each year. Approximately 40% of these tagged steelhead are caught more than once (some as many as six times) during any given spawning migration. In spite of this handling the adult population has seen an increase of more than three fold. This illustrates the value of catch and release in the management of wild steelhead stocks.
One of the most important aspects of this research is the partnership between government and anglers working together collecting valid scientific data that contributes to fisheries management.
The Portage Creek steelhead study will continue yearly until at least 2010. The data will be used as an ongoing monitoring tool in evaluation of climate change on coldwater salmonid communities.
The Portage Creek Research is funded through grants from Bob Izumi and the Fishing Forever fund, CFIP (Community Fisheries Involvement Program) the NSSA (North Shore Steelhead Association and NOSA (Northern Ontario Sport Alliance). Their ongoing partnership in research is much appreciated.
We would also like to thank the Dougal family, Ray Dee and the landowners of Pass Lake for allowing this Internationally recognized research on steelhead to be continued.
Portage Creek Steelhead Poster
If you have any additional questions regarding the Portage Creek Study, please contact Jon George at the Ministry of Natural Resources, Thunder Bay.
Phone: (807) 939-3113
E-mail: jon.george@mnr.gov.on.ca |
