Portage Creek (A Partnership in Steelhead Research)

             

 

 

 

 

 

2009 Updates

Study Background

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). This stream has long been recognized for its quality steelhead fishery.

The main branch of Portage Creek is 11 km in length and drains a 6000 ha watershed. Numerous tributaries of the creek drain both the Sibley escarpment and adjacent wetland areas. A small waterfall, located approximately 1 km from the mouth, slows upstream movement of adult steelhead during their spring migration.

Portage Creek sustains its steelhead population by natural reproduction. During the 1980's, anglers noted that adult steelhead were smaller in size and number. Over-harvest by recreational fishing was thought to be the most likely cause. From 1991 to 1994, a steelhead assessment study was conducted on the Canadian tributaries of Lake Superior. Portage Creek was found to have an adult steelhead population that showed all the signs of over-fishing. In the spring of 1994, the lower reaches of Portage Creek, including the waterfall, were posted as private property, thereby limiting access to the creek and effectively closing the fishery. This created a unique opportunity to monitor the steelhead population and determine if it could recover. A partnership was formed with the land owner and the North Shore Steelhead Association (NSSA) to conduct a long-term research study.

The main objectives of the Portage Creek research project are:

1. Quantitatively describe adult steelhead population characteristics before and after the reduction of fishing mortality.
2. Illustrate the effects of environmental variables (e.g. weather) on wild steelhead.
3. Use the Portage Creek life history data to demonstrate the ability of a steelhead population to rebound once harvest is reduced.
4. Use the Portage Creek data set as a reference population to describe and compare the sustainability and health of other Lake Superior steelhead populations.
5. Demonstrate the value of angler-gathered data and partnerships in fisheries management.

 

How the Study is carried out

Anglers (from the NSSA) and Ontario Ministry of Natural Resources (OMNR) fisheries specialists work in partnership to collect and biologically sample adult steelhead during the spring spawning migration. Each day, over a six-week period (mid April to the end of May), one or two anglers and an OMNR specialist catch (using normal angling practices) and biologically sample (length, sex, scale specimen) each steelhead. In addition, a numbered colour-coded plastic disc tag is sewn on the front part of the dorsal fin. In order to take into account possible tag loss, a unique fin clip also is applied each year. Water temperatures are recorded throughout the open water season using automated temperature loggers. Life history information (stream and lake years, age at maturity, total age and number of spawning events) is obtained by analyzing scale samples. 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 steelhead growth rates, validate ages, document movement patterns and provide stray rates.

                   

 Results

Adult Population 

The adult steelhead population in Portage Creek increased from an estimated size of 500 in 1992 to over 2000 in 2004. (Figure 1). The increase in the adult population can be attributed to higher production of juveniles (e.g. 2000 year class), and better survival of adults following the end of harvest in 1994. The fluctuation in abundance from 2004 to 2009 is due to variance in production of juveniles which can be tied to environmental variables. The poor recruitment in 2002, 2003, 2005, 2006 and 2007 has left one strong year class (2004) to support the spawning population. (Figure 2 and Figure 3). The 2004 year class has been prominent in the spawning population for three years. Now at age five, numbers are declining due to natural mortality. With limited recruitment from other years, the population size is projected to be less than 1000 adults in 2009.

At three to five years of age, most Portage Creek steelhead have reached maturity and are at the most abundant level in the spawning population. With 30% to 40% natural mortality following each annual spawning event (rigors of migration, nesting, and predation), few adults survive past age eight years. The strong production years, i.e. (2000, 2001 and 2004), can maintain reasonable representation to older ages if harvest is minimized. This is illustrated in Figure 2 where the 2004 year class (age 5 years) still contributes to half the 2009 spawning migration. The 2000 and 2001 year class (age 8 and 9 years) still represent 10% of the spawning migration or 90 large fecund individuals which are now multiple repeat spawners. These are large individuals and very effective spawners (high egg production and nest in prime stream locations).

 

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 the 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 first time spawning adult steelhead with one stream year at smolting. 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 30 cm, 50 cm after two lake years, and 58 cm after three lake years. Following the first spawning event, growth slows as the spent adults must recover from spawning and replenish their gonads in order to reproduce 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 (steelhead nest) 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. Steelhead that migrate into Portage Creek during the fall rains (October and November) appear to over-winter back in the lake rather than in the river. In the fall of 2007, 18 adult steelhead were tagged within the study area of Portage Creek. Half of these were recaptured during the spring 2008 spawning migration. All recaptures occurred two to three weeks after the spring spawning migration began. If they had over-wintered in the river they would have been darkly coloured (an indication of over-wintering behaviour) and vulnerable to capture at ice-out.

 

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. Following the end of harvest in 1994, survival to multiple repeat spawning for both sexes has increased (Figure 8 and Figure 9). In Portage Creek, repeat spawning steelhead over nine consecutive years have been documented using tag recaptures. The 2009 spawning population had 87% repeats which is the highest we have seen since the study began. This is due to poor spawning success since 2004.

Stray Rate and Movement patterns

Portage Creek steelhead move 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 the Portage Creek tag returns are captured in foreign streams. Some of these returns are native to Portage Creek and were feeding in a foreign stream. Many of these steelhead will return to Portage Creek for spawning.

 

                                    

 

Value of the Portage Creek Study

1.  Year class strength of juvenile steelhead is reasonably consistent over large geographical expanses, e.g. Western Lake Superior. As a result of this, the annual life history data obtained from the Portage Creek research can be used to index the status of steelhead stocks in most western Lake Superior tributaries.

2.   The attractive steelhead fishery that we witnessed between 2002 and 2006 was the result of three excellent years of juvenile production (1998, 2000 and 2001).These year classes are rapidly disappearing from the fishery through natural mortality and harvest (exploitation). We are now left with one good production year (2004) and several poor years to sustain the spawning population. Low numbers of juvenile steelhead were produced in Portage Creek during 2002, 2003, 2005, 2006 and 2007. These years had hot, dry summers and / or severe winter conditions. Larger ground water systems, i.e. Steel River and Wolf River, are more resilient to these adverse climatic conditions.

3.   If the environmental conditions we witnessed between 2002 and 2007 persist (hot dry summers and cold dry winters), we may be relying on the strength of occasional strong recruiting years. In order to allow maximum contribution of these strong years, maintaining suitable habitat and minimizing the harvest will become critical management objectives.

4.   The cool, wet summers of 2008 and 2009 appear favourable for high production of juvenile steelhead. These year classes will enter the spawning population of Portage Creek starting in 2010 to 2012. If these year classes are similar to the bumper crops of 2000, 2001 and 2004, the steelhead fishery on the north shore of Lake Superior will be greatly enhanced.

5.   The research on Portage Creek also allows us to document the susceptibility of wild Lake Superior steelhead populations to over-fishing, plus the ability of a wild population to rebound following a reduction of harvest. Steelhead are a relatively easy fish to catch by angling. This is especially true when they concentrate in spawning tributaries during the spring of the year. The research in Portage Creek shows that two to three anglers over four weeks can angle close to half the spawning population. Forty percent of the steelhead captured initially was caught more than once, some as many as six times within the same spring. In rivers open to the public, a high percent of the annual steelhead migration will potentially be caught several or more times. The vulnerability of steelhead to been angled many times during the spawning migration gives anglers the perception of a much larger run than actually exists.

 6.   In Lake Superior tributaries that are relatively unproductive, adult steelhead stocks may have difficulty maintaining themselves if harvest is high. A major concern among anglers is survival of their released steelhead. The Portage Creek research relies on angling to capture steelhead. Not only are these fish caught by normal angling practices, but they are also biologically sampled and tagged. Angling and handling mortality appears to be extremely low (< than 2%). If handled carefully, a high percent of released steelhead will survive. Healthy steelhead stocks can be maintained in catch and release fisheries.

7.    One of the most important aspects of this research is the partnerships between government, industry and anglers working together collecting valid scientific data that contributes to fisheries management.

Conditions that can generate a strong year class of steelhead

• Adult spawning run with >50 % repeats (a good representation of 3- to 5-time repeats)
• High spring stream flows (distribution of adults to all stream spawning locations)
• Stable stream flows from early June to mid-July when fry are small and fragile
• Summer rains that maintain adequate habitat for fry and yearling steelhead
• Summer stream temperatures 18 to 22 C.
• Fall rains to maintain flows into winter
• Significant winter snows to insulate stream from anchor ice and freezing to the bottom

Steelhead Year Class Strength chart including 2009 results .

 

                                        

 

Resident Brook Trout and Coaster

Resident brook trout and migratory coasters are abundant in Portage Creek during the spring steelhead spawning migration and in the fall of the year when they spawn. Although the production of juvenile brook trout varies, their overall abundance has not appeared to change in spite of the dramatic increase in the steelhead population.

 

Future Activities                                                                         

The Portage Creek steelhead study will continue on an annual basis for at least one more generation (2012). This data will be used to monitor climate change on a cold water fish community, to evaluate of steelhead year class strength, and to utilize Portage Creek as an Index Stream for managing North Shore steelhead populations.

 

Acknowledgements                                                                            

The Portage Creek Research is funded in part by the Northshore Steelhead Association (NSSA) and CFIP (Community Fisheries Involvement Program). Corporate sponsorship was obtained from Yakima Bait Company, Normark Canada and Lindy Little Joe. Their support in scientific research is much appreciated. The NSSA supplies the angling expertise and assistance with biologically sampling of steelhead during the spring spawning migration. Without these individuals the study would not exist. Northshore Environmental Services (Jon Tost) conducts the aging analyses and critical reviews each year. Dr. Michael Bozek , University of Wisconsin-Stevens Point, Wisconsin contributed to the original study design and data presentations.

We would like to thank the Dougall family, Ray Dee and the landowners of Pass Lake for allowing this internationally recognized research to continue. Laurie McMillan, OMNR wildlife biologist proof read and edited this update. Her assistance was much appreciated.

Click below to view the poster

Portage Creek 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@ontario.ca