Catch & Release Impacts On Wild Steelhead

www.wildsteelheadcoalition.org

WHAT WE KNOW & WHAT WE DON’T KNOW

How do our actions impact the fish?

Recent research on Atlantic salmon has found some very harmful reproductive results from the way many sport-caught fish are handled.

Other laboratory and field studies of rainbow trout and Atlantic salmon found that extended fights, handling, and air exposure can all increase natural steroid hormones in the blood which can decrease fry production.

While studies are not available to draw parallel conclusions for wild steelhead, the studies of Atlantic salmon and rainbow trout (the freshwater form of steelhead) indicate that longer fights, extended handling, and air exposure all may have a more deleterious sublethal impact than is currently understood.

The groundbreaking study of the sublethal impacts from CnR angling on Atlantic salmon (10), an earlier study in Alaska on rainbow trout (14), and laboratory studies of both species that further describe the impacts of stress and fry loss on these fish (11-13) illustrate the potential magnitude and range of unintentional harm caused by anglers practicing CnR. These studies also illuminate the knowledge gap that exists regarding the impact of CnR fisheries on Washington’s wild steelhead populations (10-13).

Given the increasing fishing pressure on diminishing populations of wild steelhead, a comprehensive study that focuses on both the lethal and the delayed reproductive impacts on wild steelhead from both CnR and gill-net fisheries is needed. The CnR study should be conducted on winter wild steelhead in the cold-water temperatures of the Olympic Peninsula and only on sport-caught fish. Moreover, it should cover the effects on all life stages, including fry and smolts.

The good news from available research is that CnR fishing, if done correctly, can be a good management method for reducing mortality as it eliminates harvests. Fish that are caught and released quickly with selective gear (barbless hooks, no bait) and handled only in the water appear to have low mortality and no observed reproductive impacts (10). But the bad news is that longer encounters, difficult and deep hook removals from barbed hooks and/or bait, and the handling of fish in the air for photographs and unhooking seem to be very stressful to wild fish when they are developing eggs and sperm, potentially resulting in much lower egg and fry survival.

CnR Impacts Recent Research Challenges Commonly-Held Beliefs

Those of us who have practiced CnR fishing for wild steelhead have long believed we were treating the fish in the best possible way and had assumed our released fish would spawn and produce viable eggs and fry. However, recent research on other fish reveals that there exists significant nuance within CnR and that small differences in how fish are caught, handled, and released can have a major impact over the long term.

Studies have shown that some types of terminal gear and increased air exposure can cause higher mortality and large reductions in the fry production of caught fish. Combining this new information with what we already know about CnR mortality of wild steelhead, we can think about actions we can take to be more responsible anglers.

Lethal CnR impacts from hooking and releasing steelhead have been studied for many years and have shown that the hooking mortality lies between 3.4% and 23.15% for winter fish caught either for hatchery spawners or for CnR studies (1-9). This mortality is due

mostly to bleeding and tissue damage from hooks that penetrate the gills, esophagus, and heart.

The mortality data for Olympic Peninsula coastal rivers was 23.15% for the Snider Creek broodstock collections, with 11.4% for males and 31.7% for females (4). This rate comes from an area where most of the directed western Washington wild steelhead CnR fishing now occurs. The CnR estimates from these studies are primarily the results from experienced professional guides, so it is reasonable to expect higher rates of mortality from sport fishing.

Previous studies on steelhead put estimates of the direct lethal impact from catch and release (CnR) fishing around 10% (3.4 to 23.15) (1-9). However, one recent study, which examined delayed CnR impacts, found that larger Atlantic salmon held in the air for even short periods of time produced fewer fry (10). Similar concerns have been shown for rainbow trout (13), and laboratory studies (11-13) of both species help us understand the reasons behind these impacts.

An important component of minimizing CnR impacts is understanding the effects of different gear types. Studies directed specifically at steelhead and those focused on other salmonids have shown that bait and barbed hooks produce a higher mortality than other terminal gear (1,2,6). One author (1) reviewed studies of different gear impacts from a variety of North American salmonid species and reported that the impacts from bait were three to nine times higher than from artificial lures. That translates to using the published midranges of mortalities for terminal gear: about 10% for bait, 3% for lures, and 1% for flies.

These different mortality rates are quite substantial when you apply them to the total. It was calculated that, for anglers catching 1,000 fish and using an equal number of each gear type, the mortality would be 65 fish for bait, 7 for lures, and 1 for flies (1). CnR studies on various species of trout suggest even greater differences between the lethal effects of fishing bait and artificials. For example, one study on rainbow trout found a 30% mortality rate for fish caught with bait, compared to only 5-10% for fish caught with lures and flies (15). Similar results have been reported for other trout and trout-sized salmonids (a range of 25-58% for bait and 4-24% for lure and fly), indicating that bait has a substantially greater negative effect on trout-size fish than other terminal gear (19-21). Another recent study, in Alaska, looked at resident rainbow trout and found that after CnR, feeding decreased by 5-50% and growth potential decreased by 9-64% (16). A number of studies have found there to be significant

sublethal impacts (impacts that do not kill the fish but do harm their progeny) from long fights and from improper handling techniques prior to release. A recent CnR study on Atlantic salmon examined the difference in lost fry production from handling fish in water and out of water. The findings were as follows:

• Larger (over 31 inches) fish held out of the water for even short periods of time suffered high fry losses. For example, at 12-14°C large fish that were handled totally in the water produced twice as many fry as those held out of the water for less than 10 seconds—the time it may take to lift a fish’s head up and quickly remove a hook.

• The larger fish held in water produced three times as many fry as larger fish held out of the water for more than 10 seconds—the time it might take to remove a deeply embedded hook, handle a fish landed in a net, measure a fish, or take a photograph (10).

While there are genetic and geographical differences between Atlantic salmon and wild steelhead, the results of this study highlight the need to better understand the correlation between fry production in wild steelhead and excess handling and air exposure. Understanding the impacts of excess handling and air exposure on steelhead could empower individual anglers to further minimize their impact on the fish they cherish and could reduce the collective harm caused by the sport fishing community.

Additionally, fishery scientists looked at the blood chemistry of caught and released salmon and trout in several studies and found many changes, including increased levels of cortisol, a steroid hormone (1113). Larger and longer-fought rainbow trout had higher levels of cortisol than smaller, shorter-fought fish (14). Laboratory studies found that increased levels of cortisol in Atlantic salmon and rainbow trout decreased their overall reproductive health and the competitiveness of fry. Impacts found in these studies included reduced egg weight and size in females, lower sperm counts in males, lower fry survival, smaller size and weight of fry during early development, smaller yolk sacks, and a higher rate of body malformation. Cortisol treatment also produced less aggressive fry that were subordinate to non-treated fry, indicating that they would not be as good at competing for food and habitat in their natural setting as non-treated fish (12).

As the research on the impacts of CnR angling becomes more comprehensive, we are in a better position as conservation-minded anglers to think about how we can improve not only the near-term survival of released steelhead, but their reproductive robustness as well. This may be as simple as remembering to pinch a barb, or it may be a more difficult choice, such as omitting bait from your arsenal. Further, it is common practice to handle steelhead with their heads out of water for unhooking, or to show them completely out of water for picture-taking and/or measuring. In recent years, thousands of photos have been posted online and in fishing magazines with the entire body of a wild steelhead held out of the water. Such picture-taking seems the norm today, and it is potentially having large negative impacts on wild steelhead reproductive physiology and their fry production—even in situations where a released fish swims away swiftly in what appears to be good health. This would indicate the importance of always keeping fish submerged and releasing them in 1 to 2 feet of water.

The issues outlined above are particularly relevant considering that the total number of steelhead caught by sport fishermen often comes close to or even exceeds escapement, meaning that some returning steelhead may be caught more than once before they spawn. In the last five winter seasons, sport fishers caught and released an average of 1,756 wild steelhead on the Hoh River—or 73% of the escapement goal (2,400 fish)— between December 1 and April 15. And in 2015 (the first year studied on this river), the sport CnR on the Sol Duc River was 2,929 fish, or 101% of the escapement goal of 2,901 fish (WDFW Annual Management Plans). These

numbers do not include the sport CnR fish for June through November, fish caught and lost before landing, and fish that enter and escape commercial gill nets. But the data available alone sugests that we are putting far too many stressed and reproductively unhealthy fish on the spawning grounds.

The popularity of CnR on the Olympic Peninsula rivers for wild steelhead has increased significantly in recent years. This has reduced the wild steelhead sport harvest over the last 10+ years, but it has brought with it higher numbers of caught, handled, and released steelhead and has introduced new and poorly understood fry survival and management issues. For the future, state regulations will require the release of all wild steelhead on the Olympic Peninsula, meaning the CnR numbers will increase.

This new situation underscores the importance of tracking the interception and release rates on all the rivers, the type and percent of gear used and their lethal impacts, and, especially, the stress impacts on reproductive success from handling fish and holding them out of the water. With run sizes declining on the Olympic Peninsula (see Figure 1 below) and sport fishing on the rise, our best ―and possibly only ―opportunity to prevent further wild stock depletion and fishery closures is to conduct the needed research now and make changes as needed. Waiting 5 to 10 years may be too late, as the depletions and ESA listings from other areas have shown. With fishing and CnR increasing, putting measures in place as soon as possible to protect spawning fish and their progeny will help minimize sport fishermen’s impacts on declining wild steelhead stocks.

Hoh River Trends in Wild Steelhead

The total run size has declined from a range of 8,00013,000 wild fish (during 1948 to 1961) to 4,850 fish in the late 1980’s (5-year average) to 3,700 fish today (last 5-year average). The red dots are the total run sizes, purple squares are the spawner estimates, green triangles are the tribal harvest (does not include net drop out mortalities) and blue tilted squares are the sport harvest (does not include CnR mortality). The red dashed line is the necessary MSH spawner escapement goal set at 2,400 wild fish to maximize the harvest. The required escapement has been below the minimum goal 50% of the years since 1992.

Figure 1. Hoh River Run Graph [Data from WDFW]

Recommendations

To Reduce CnR Impacts & Improve Fry Production

CnR & Handling Discussion

Understanding the Effects of Fisheries on Populations

Personal Recommendations for Sport-Fishers:

Use heavy line (e.g., 15 pound) to land steelhead and release them as quickly as possible.

Use only barbless hooks to reduce tissue damage and bleeding as well as to decrease the time of unhooking wild steelhead.

Do not use bait in anadromous fish rivers except in hatchery zones, in order to reduce mortality from bleeding and deep hooking of adults, parr, smolts, and resident steelhead.

Do not lift wild steelhead out of the water for any reason (including landing, taking photographs, measuring, or removing hooks). If you must take a picture or otherwise handle the fish, do it quickly in 1 to 2 feet of water and keep the entire fish submerged.

Release all steelhead in 1 to 2 feet of water to avoid air exposure and bruising on rocks.

If you land your steelhead with a net, use only rubber, knotless nets and always keep the steelhead submerged.

7 8 9 10

There are a number of fishing techniques that can be used to reduce hooking mortality and fry losses in order to significantly increase the productivity of wild steelhead. The following techniques may seem restrictive compared to present fishing methods, but they offer continued opportunity to fish the entire season (as opposed to seasonal and total closures) and can make a major difference in the survival and production of wild steelhead. 1 2 3 4 5 6

Cut off the hook if the steelhead is hooked deep, as in the throat or gills, to avoid additional tissue damage and handling time. These remaining hooks are normally lost in a few days.

Fish only from shore, and use boats for transportation only, during March and April in upriver areas where fish hold and are spawning. This action, if taken now, may prevent the need to close fishing in these areas to protect holding and spawning fish.

Reduce daily encounters with wild steelhead A personal limit of two or three daily encounters will significantly reduce the total fishery encounter rate, allowing more non-stressed and healthy fish to spawn and their progeny to survive.

Use selective gear (no bait or barbed hooks) when fishing rainbow trout in anadromous rivers in order to keep impacts low on this resident form of steelhead and help rebuild its populations and provide additional male mates for anadromous female steelhead.

Successful management and conservation ofwild steelhead requires a complete understanding of the effects of fisheries on populations. In particular, there has been increased interest in understanding how catch-and-release influences the health and survival of wild steelhead.

Catch-and-release surveys conducted on the Hoh River since the 2003-04 season and for one year on the Sol Duc and Bogachiel River indicate that anglers may be catching and releasing wild steelhead numbers close to or even higher than the spawning population. Hence, most of the fish that reach the spawning grounds have been stressed by struggling at the end of a sport line, possibly handled in a stressful manner (often out of water), or exhausted and stressed from escaping a gill net. Such a high encounter rate raises many questions about the effects of CnR on wild steelhead, particularly for wild winter steelhead

that have recently entered freshwater and are actively spawning.

Studies that examine the direct lethal effects of CnR on wild steelhead suggest a range of mortalities from different types of gear, where a portion of the fish caught die within a period of time after being caught and released. For instance, bait is typically more successful in catching steelhead—and therefore produces higher encounter rates than jigs, flies, and other types of gear; bait also produces much higher rates of mortality. Also, hooking location is known to be important, with deeper

hookings (e.g., in the throat, gills, or heart) leading to higher mortalities. On the other hand, while handling practices were not examined during any steelhead CnR studies, inappropriate handling—i.e., handling that is extended and/or leads to air exposure—has been shown to have significant negative effects on the reproductive fitness of Atlantic salmon and rainbow trout.

The Washington Department of Fish and Wildlife assumes a 10% mortality on caught-and-released wild steelhead for the Olympic Peninsula based on the British Columbia studies and management recommendations. Direct lethal impacts—where fish die from CnR—are highly variable with figures of 3.4% to 23.15%. Some of the lower figures were from hatchery collections, where bleeding fish were released and not part of the total mortality number. The only data for winter steelhead on the Olympic Peninsula coastal rivers was 23.15% for the Snider Creek broodstock collections on the Sol Duc River. This is important because the data comes from the area where a substantial part of the Western Washington wild steelhead CnR fishing takes place. Thus, the present use of 10% mortality for management purposes may be low for the conditions on the Olympic Peninsula, and the effects could be magnified because most or all of each river’s population is caught by sport anglers. Additionally, an unknown number escape commercial gill nets each

year. These CnR and gill net impacts occur just before the fish spawn. We should also assume that some fish are caught two or more times, potentially increasing their mortality rate.

There are no studies that looked at sublethal effects of CnR on steelhead, but research suggests that sublethal effects can be very important. A recent study on CnR of Atlantic salmon found that large fish maintained in the water for unhooking produced 2 to 3 times the number of fry compared to fish held out of the water for various short periods of time. Laboratory and field studies of exercised and of air-stressed rainbow trout have found elevated levels of cortisol in the blood system. The same blood that circulates in a fish’s body also circulates in its eggs and spermatozoa.

Cortisol is a steroid hormone found in animals and fish. It aids in fat and sugar metabolism and helps produce energy as it is needed. It can provide for a quick burst of energy to run rapids or to avoid a predator. It also aids anadromous fish by stimulating their olfactory (smell) organs during navigation to their home rivers, and it is present when salmon have spawned and their body cells and nervous system cells deteriorate. At higher stress levels—as from long fights, difficult hook removals, and air exposure—increased cortisol levels may result in deleterious effects on a fish’s eggs and fry. For example, in laboratory studies of air-exercised or cortisol-treated fish including rainbow trout and Atlantic salmon, studies found lower egg condition and sperm counts, higher fry mortality, smaller length and weight of the fry, smaller yolk sacks, and fry that had behavior changes and were not as competitive as normal fish (11,12,13).

This information has direct implications for fish-handling on the Olympic Peninsula. Bait and barbed hooks often increase the time it takes to release an excited steelhead. And there are thousands of photographs online of winter steelhead from the Peninsula with anglers holding the steelhead out of the water. Such angler activities seem to be the norm, and it could be having strong negative

effects on wild steelhead productivity—even if, as we have noted, the fish swims away in apparent good health.

Catch-and-release studies on resident rainbow trout suggest even higher lethal and sublethal effects. For example, one study on rainbow trout found a 30% mortality rate for fish caught with bait, compared to only 5-10% for trout caught with lures and flies (15). A recent study on resident rainbow trout in Alaska found that after CnR, feeding potential decreased by 5-50% and growth potential decreased by 9-64% (16). Further, fish that took longer to land had substantially increased levels of cortisol and lactate in their blood, and these effects were worse in warmer water temperatures (14,16). These shocking results indicate that CnR of rainbow trout, if not lethal, can slow their growth and size. Given that male resident rainbow trout are often important mates with female steelhead, such impacts could have negative effects on steelhead spawning success.

There are no studies that looked at the effects of CnR on steelhead parr or smolts, but studies on other salmonids, such as brook and cutthroat trout, suggest that such small-sized fish can experience mortality rates of 25 to 58% when bait and/or large hooks are used (19,20,21). It is not clear how many steelhead parr and smolts are caught by anglers each year, but it is common to see steelhead and salmon anglers hooking and landing these fish on Olympic Peninsula rivers. These fish are often removed entirely from the water, held in-hand until the large hook is removed—often while being squeezed quite hard (if only because a small fish is hard to handle)—and then tossed back into the water. It would be of value to study the mortality and sublethal effects of such handling practices, which could be drastically reducing the survival of steelhead smolts during a life stage in which managers and anglers often assume a minimal impact.

Given the increasing fishing pressure on diminishing populations of wild steelhead, a comprehensive study

is needed that focuses on both the lethal and sublethal impacts on wild steelhead from CnR and gill net fisheries. For CnR mortality information, the study should include the direct losses that result from differences in terminal gear (as bait, lures, and flies), type of hook (barbed vs. non-barbed), location in the river (recent entry vs. upriver holding/spawning areas), and number and impacts on fish caught and lost before landing and fish caught more than once. Of the highest importance, as none have been conducted on steelhead, are studies of the non-lethal impacts of CnR fishing from extended fights, difficult (as deep hooking) releases, and fish held out of water for various reasons. This would include the reduced quality of eggs and sperm and the loss of egg and fry production from spawners handled out of water for various times (such as 5, 10, or 20 seconds or longer). These studies should be conducted on sport-caught winter wild steelhead on the Olympic Peninsula.

Additional studies should determine the gill net dropout rate and mortality (fish that escape gill nets and die) and the sublethal impacts of wild fish that survive net entanglement. Research on other species, such as sockeye salmon, have shown high entanglement and dropout rates, high mortality, and negative impacts on spawning fish that escaped gill nets. Researchers

should also look at the blood chemistry of caughtand-released and air-exposed fish and determine what changes and what differences occurred. Further, studies should determine if caught-and-released, airhandled, and net-drop-out steelhead have the ability to spawn normally in their native habitat, including time, area, and red-gravel depth; to kelt and return again to spawn. Moreover, the study should cover the CnR effects on all life stages, including smolts and rainbow trout. Because the Olympic Peninsula rivers are the only rivers remaining in Washington that are considered healthy enough to support normal seasons and harvests of wild winter steelhead, and these runs are all in decline, these studies are of high importance to be completed as soon as possible. The information on steelhead CnR lethal mortalities, the unknown net-drop-out impacts, the handling stress and fry losses from other fish studied, and the large numbers of fish that are caught and released each year in Olympic Peninsula rivers tell us that that these spawning populations are highly impacted and may not be reproductively healthy. If Olympic Peninsula

Research Snapshot

Lethal Effects of CnR on Steelhead

3.8%

Overall mortality in the Keogh RIver, with 5.6% for bait and 9.1% for bait and barbed hooks. Other Vancouver Island collections: 3.4% mortality. However, bleeding fish were released and were not part of this measure.

10%/3%/1%

caught-and-released wild steelhead spawners are producing fry that that have a high mortality rate or are otherwise not in good health, we must know. It is highly possible that the combination of the sport and tribal fishing practices are partly or wholly responsible for the declining productivity and run sizes that we see in these rivers.

9-23%

Expected median CnR mortality rates of bait, lures, and flies respectively.

Mortality from collections for the Green River and Snider Creek hatchery programs. Female mortality was 31.7% for Snider Creek

Lethal and Reproductive Loss from Air Exposure

25-58%

Mortality from bait; 4-24% for lure and fly; 38% mortality in rainbow trout exposed for 30 seconds to air; 72% mortality from 60-second exposure.rainbow trout exposed for 30 seconds to air increases to 72% mortality from 60-second exposure.

50-60%

Loss in production in Atlantic Salmon fry from handling and air exposure in 1 to 9 seconds and in more than 10 seconds, respectively.

Vancouver Island

BC to California

Washington State

Rainbow Trout

Atlantic Salmon

References Recent CnR Research and Related Papers

What follows are some of the more valuable study results from wild steelhead caught for hatchery use and held for 24 hours, fish held in the hatchery for longer periods before spawning, and fish tagged for CnR evaluations.

Lethal Effects of CnR on Steelhead

1. British Columbia Rivers. (Hooton, 2002) This paper published by The Osprey reviewed the mortalities from many CnR reports and studies. This is a good review of the impacts of different gear types (bait, lures, and flies). Find it online at: www.ospreysteelhead.org/archives/TheOspreyIssue43

2. Keogh River, BC, Canada (Hooton, 1987) Reported on the use of various terminal gear types for steelhead hatchery collections and found 3.8% mortality overall, 5.6% for bait, and 9.1% for bait and barbed hooks.

3. Vancouver Island, BC, Canada (Hooton, 2011) Reported on the steelhead hatchery collections on the island (other than the Keogh) where 3,715 fish were collected with a mortality rate of 3.4%. These BC hatchery collection mortalities all occurred during the first 24 hours. These results did not include many of the fish that were bleeding badly and released, and all fish were angled by professional collectors (Hooton, 2001). This data, and the regular use of bait in BC, led Hooton to suggest that 10% mortality be used for management purposes.

4. Snider Creek, WA. Hatchery collections (Michael Gross, WDFW, 2012, provided the hatchery mortality data) had a 23.15% overall mortality, with 11.4% for males and 31.7% for females.

5. Green River, WA. Hatchery collections (Brodie Antipa, 2014, provided the hatchery data) produced an 8.8% mortality from 2002 to 2011, 10.5% in 2012, and 22% in 2013. These fish may have been compromised by fungal and bacterial infections and the collections were made by WDFW employees who are more experienced than the angling public; collectors used heavy lines and quick retrievals to minimize stress.

6. Washington State, multiple streams (Bruesewitz, WDFW, 1995) Looked at hooking locations (in the fish) for three years

and found single hook and bait combinations resulted in a 2.33 times higher incidence of hooking in critical locations that led to higher mortality (14.9% vs. 6.4%) compared to single hooks and lures.

7. Trinity and Mad Rivers, CA. (Taylor and Barnhart, 1997) For angled summer steelhead, the authors found a 9.5% mortality among lure-only caught fish. The authors also found that mortality increased with higher temperatures.

8. Vedder River, BC, Canada. (Nelson, 2005) This study reported an average mortality of 3.56% (1.4% mortality in 1999 and 5.8% in 2000) using radio telemetry.

9. Samish River, WA. This study examined early and late mortality for winter steelhead in 2008 and 2009. Ashbrook (in prep.) studied CnR impacts on naturally spawning fish (assumed to be winter wild based on an adipose fin, although DNA testing has revealed that some fish had hatchery ancestry and summer return timing ancestry). She found that although there was no difference between the control fish (collected at a hatchery trap) and CnR fish in initial survival, there was a biological cost: 14.7% fewer CnR fish that kelted as compared to the control group.

Sublethal Effects on Reproductive Success and Fitness

Although unstudied in steelhead, there appear to be major sublethal effects (impacts other than death) associated with CnR—such as physiological stress due to fighting, excessive handling of the fish out of water for removing hooks or for photography, and measuring fish—that negatively affect the fish’s reproductive success.

Sublethal impacts have been addressed in some salmonids and in direct response to concerns about CnR and handling impacts on populations of Atlantic salmon and rainbow trout.

10. Atlantic Salmon (Richard et al., 2013) This study examined CnR impacts on the reproductive success of Atlantic salmon, a species similar to steelhead in diversity and behavior. Some results include:

> Large CnR salmon (with fork length greater than 30 inches) produced fewer fry than controls and also fewer than smaller fish. Controls, on the other hand, produced more fry with increasing number of fry positively related to spawner size.

> At lower temperatures (12-14°C) reproductive success can be two to three times higher for salmon kept in the water during CnR compared to those exposed to air. Fish exposed to air for less than 9 seconds produced 50% fewer fry while fish exposed to air for over 9 seconds produced 67% less.

11.Atlantic salmon. (Eriksen, Bakken, Espmark, Braastaad, and Salate, 2006) These authors augmented the natural level of cortisol by injection and found increased fry mortality, reduced fry fork length and mass, diminished yolk-sac volume, decelerated yolk sac utilization, and some fish with body malformations.

12.Brown trout. (Burton, Hoogenloom, Armstrong, Groothuis, and Metcalfe, 2011). Using dilute hormone baths at fertilization, scientists studied the effect of increased cortisol on behavior. Juveniles from cortisol-treated eggs were smaller at the development stage and less aggressive and subordinate to fish from untreated eggs in socially competitive conditions such as feeding.

13.Rainbow trout. (Campbell, Pottinger, and Sumpter, 1992) Repeated air stress to rainbow trout during reproductive development resulted in higher cortisol levels, delay in ovulation (spawning), reduced egg size and egg weight in females, lower sperm counts in males, and significantly lower fry survival rates.

14.Rainbow trout. (Meka and McCormick, 2004). This study evaluated the immediate physiological responses of wild rainbow trout to CnR fishing. Levels of plasma cortisol and lactate in extended-capture fish (more than 2 minutes) were significantly higher than levels in rapid-capture fish (less than 2 minutes). Rapid-caught fish were smaller. These study results indicate the importance of minimizing the duration of angling and handling to reduce stress/cortisol/reproductive impacts.

Lethal & Sublethal Effects on Resident Rainbow Trout and Other Salmonids

15. Rainbow trout. (Mongillo, 1984) Found immediate mortalities of 30% for bait but only 5-10% for lure and fly.

16.Rainbow trout (Meka and Margraf, 2007) Rainbow trout taken via CnR ceased feeding for 24 hours after being caught, and 1-2 such episodes during the summer decreased maximum feeding potential by 5-50% and growth potential by 9-64%.

17.Rainbow Trout. (Ferguson and Tufts, 1991) Stated that a brief period of air exposure from CnR is a significant additional stress, which may ultimately influence whether a released fish survives. Some results include:

• Survival after 12 hours was 88% in exercised fish, 62% in fish exposed for 30 seconds to air, and 28% for fish exposed to air for 60 seconds.

• During exposure, there was retention of carbon dioxide in the blood; oxygen tension and hemoglobin, and oxygen carriage fell by more than 80%.

18. Sockeye salmon. (Gale, Hinch, Eliason, Cooke, and Patterson, 2011) Fish exposed to air at higher temperatures (21°C) lost equilibrium on return to water, but less than half of the air-exposed fish in cold temperature (13°C) demonstrated this impairment.

19. Trout and small salmonids. (Wydoski, 1977) Reported 25% mortality for bait fishing and 5% for artificial lures and flies in a multi-species investigation of trout and small salmon.

20.Small resident Atlantic salmon. (Warner and Johnson, 1978) Found 35% mortality among bait-caught, landlocked Atlantic salmon and 4% among those caught with flies.

21.Cutthroat trout. (Pauley and Thomas, 1993) Found 39.558.1% mortality among anadromous coastal cutthroat trout that were bait-caught and 10.5-23.8% for those caught on lures.

22. Chinook salmon. Studies report 8.6% (Schroeder, 2000); 7.6% (Bendock, 1993); and 12.2% (Lindsey, 2004) for hooking mortalities in Oregon and the Kenai River, AK. Higher mortalities for Chinook hooked in the gills or esophagus (81.6% and 67.3%, respectively) were reported by Lindsay (2004).

If you are interested in reading any of the above papers, most can be found on the internet by searching for authors and subjects. If you find they are unavailable, you can email Dick Burge at fskibum@olypen.com for electronic copies.

www.wildsteelheadcoalition.org n info@wildsteelheadcoalition.org

Publication Credits

Author

Richard Burge, Fisheries Biologist

Design

Natasha Dworkin, Matterhorn Creative www.matterhorncreative.com

Editing

Ryan Petzold

Jonathan Fine

Photography

Luke Kelly

Dave McCoy, Emerald Water Anglers

Todd Ripley, Rvrfshr Products

Flickr user four12

Funding

Contact

www.wildsteelheadcoalition.org

info@wildsteelheadcoalition.org