Please read & inwardly digest:
www.asf.ca/live_release.php?type=science"Research carried out both in North America and Europe shows that wild Atlantic salmon angled, and then PROPERLY released will recover successfully in a short time and go on to spawn successfully.
The most critical factor is the expertise anglers develop in releasing Atlantic salmon. Wild salmon angled are exerting themselves to an exhausted state in the same way a marathon runner might.
The fish needs oxygen in order to recover. Keep the fish in the water so it can continue to breathe and recover with the oxygen-bearing water flowing over the gills.
Dr. Bruce Tufts of Queens University, Kingston says it this way:
"...The practices of individual anglers are important in determing the magnitude of the post-angling disturbance. Minimizing air exposure of fish is very important. Under conditions where the likelihood of delayed mortality is increased (eg. elevated temperatures), additional stresses such as air exposure may be critical in determining the fate of angled salmon." - Dr. Bruce Tufts
In Other Words: For the angler, this means that if the angler learns proper Live Release skills and keeps the wild Atlantic salmon in the water, almost every released fish will survive.
Some Samples of the Research
2003 Release of Research Results from the Spey River, in UK
The Catch and Release Tagging Project concluded in 2002 with 386 spring salmon (Feb.-May) and 473 summer salmon and grilse (June-Sept.) tagged and released. Recaptures of spring salmon varied, from 16% in 2000, to 7% in 2001 and 11% in 2002, with an average recapture rate of 10%.
Only two summer salmon were recaptured (0.4%). Recapture rates are highest for February fish, with 30% of fish caught again. However, recapture rates decline as the season progresses, with only 3% of June fish caught a second time. These figures may well reflect the actual exploitation rates of fish entering the river at different times of the year. When analysed in more detail it is evident that among spring salmon, fish caught and released in February-March can be recaptured until May,and fish caught in April-May are vulnerable until July.
Many spring fish can also be recaptured in September when the spawning season approaches. These findings confirm that spring salmon are particularly vulnerable to capture by anglers. Released fish were recaptured in every month except August, and therefore require measures to protect them beyond the spring period. These results underpin the SFB's Salmon Conservation Policy for 2003, which aims to protect spring salmon throuthout the season.
The project also contributed significant numbers of extra eggs laid in the river. Of the 386 spring salmon that were recaptured 368 were re-released to spawn. Approximately 70% of these were female with an average weight 9lbs. Knowing that Spey salmon stripped at the Sandbank Hatchery produce 700 eggs per lb these returned springers contributed 1.6 million additional naturally-spawned eggs in 2000-2002. Assuming a 50:50 sex ratio for summer salmon and grilse and an average weight of 10lbs, the 471 tagged fish re-released provided a further 1.6 million eggs.
The tagging experiment was carried out on ten fishing beats, and partly due to the success of the project and a growing acceptance of catch and release, many other beats also released salmon further boosting the numbers of extra eggs laid in the river.
25 Years of Studies on Live Release
Over the past 25 years research has been conducted on many rivers on both sides of the Atlantic showing that Atlantic salmon survive after release when properly handled by anglers.
In Iceland a three year study in the late 1970s saw 42 angled salmon tagged and released. Fifteen per cent were angled a second time. One hundred per cent survival of caught and released salmon was observed.
Between 1982 and 1984, a study on North Pole Brook, a tributary of the Little Southwest Miramichi in New Brunswick, found in the latter two years no mortality among the caught and released salmon. In the first year a 3 per cent mortality was related to fish being hooked in eyes or gills only.
The Ponoi: As part of a multi-year program of research and management in northwestern Russia on the Ponoi River, ASF's Dr.Fred Whoriskey carried out research in which 62 angled fish were penned for 24 hours, and only a single fish died. They were then released with radio transmitters and most were followed until the end of the fishing season. Two of the fish were caught a second time, and were successfully released.
It is worthwhile noting that only a single mortality occurred even with the increased stresses of having a transmitter inserted into their bodies.
During the 1990s Dr. Bruce Tufts of Queens University, Kingston, Ontario, along with several associates, undertook a number of research projects.
The many studies showed low or zero mortality in most conditions, when the wild Atlantic salmon were carefully handled and kept in the water. It was very evident, however, that when water temperatures were above 20 C/ 68 F it was vitally important to keep the Atlantic salmon in the water, and to reduce stresses on the fish to the absolute minimum.
Many of the research projects involved wild salmon being equipped with visual or radio tags. In one study 15 angled grilse (1 Sea-winter salmon) on the Upsalquitch River of New Brunswick were visually tagged with Carlin tags. They were released back into the river, and 100% survival in the clear waters of the river was observed. Ten fish were equipped with radio tags, and nine were found several days after being angled on the same river.
Dr. Bruce Tufts' work also included muscle analysis of caught & released wild Atlantic salmon. In late fall he discovered that after angling, muscle pH and lactate levels, signs of the exertions of the wild salmon, returned to normal within 2 to 4 hours - more rapidly than that observed in other species such as wild rainbow trout.
One research project involved the assessment of differences in the egg survival between angled and non-angled wild salmon. This involved the added stress of containment and transport of these Atlantic salmon to a hatchery. Among 20 Atlantic salmon caught and transported to the hatchery for study, there was ZERO mortality.
Even more interestingly, ninety-eight per cent of the angled fish eggs survived, vs. 97 per cent of eggs from non-angled salmon. Thus Live Release did not impact the spawning success of the fish.
Dr. Tufts concludes the following from the experiment on autumn fish, "Our results indicate that the likelihood of delayed mortality is minimal and there are probably no significant consequences on gamete viability following angling and release of Atlantic salmon in the late fall."
Kelts, Atlantic salmon that have already spawned, were studied by Dr. Tufts group in the Margaree River of Nova Scotia for two successive spring seasons. Mortality was ZERO out of 26 in one season, and 1 out of 83 in the other season, the single mortality being due to hooking the gills. That translates into a Live release mortality of less than ONE per cent for the study.
Air Exposure: For wild Atlantic salmon, even brief air exposure of 1 minute after the exertion of being angled increased the changes seen in their physiology. But if air exposure of the gills is kept to a minimum, the Atlantic salmon survived, Tufts notes.
In summer, the research has shown that anglers need to be especially sensitive to the needs of the wild salmon, not angling the fish to exhaustion, nor taking it out of the water for more than a few seconds. But even in summer conditions, properly handled Atlantic salmon will recover.
Overall, Dr. Bruce Tufts concludes:
"Our results indicate that most Atlantic salmon do survive being caught and released. Regardless of the conditions, the majority of the salmon that were exhaustively exercised or angled in each of our studies survived. These findings are probably not surprising since this species is already highly adapted to cope with periods of exhaustive exercise during its arduous spawning migrations."
In Scotland, the Dee has had a large Live Release program for five years. Researcher John Webb, Research Biologist of the Atlantic Salmon Trust, radio tagged salmon, which were subsequently recovered. There was 100 per cent survival more than two months after the tagging.
Conclusion:
If an angler learns proper techniques of Live Release, and keeps the Atlantic salmon in the water, the fish will almost always survive."
Associated File: The Case for Releasing Grilsewww.asf.ca/docs/pages/grilse.pdfgrilse.pdf converted to text:
The Case for Releasing Grilseby Gary Atkinson and Dave Moore
"AFTER AN EXCITING ROUND of spirited give-and-take, punctuated byflashing silver arcs haloed in spray, a fine fresh-run grilse lies docile atyour feet. Resisting the primeval instinct to possess your prize, you remove the hook and hold the head into the current until it recovers the strength to pull away and continue its perilous odyssey - an offering to appease the salmon spirits. You watch his nebulous form melt into the depths, and resume your fishing, content.
Two years later, under similar circumstances and after a fight that will remain indelibly stamped in your mental log of such events, you are reviving a trophy fish that you judge to be about a grilse-worth heavier than the typical large salmon. Elated, you wipe the tailwash off your polaroids as the large spawner torpedoes upriver and perhaps utter the hope that it will reproduce and return again.
'Thus, a single perfect scale from a particularly large salmon may encodea fascinating story - one that any angler would be fascinated to know, especially if he or she had caught it.
But in fact, it has already. Your released and long-forgotten "offering to the spirits" has returned.
What are the odds? Scale samples tell us they're pretty good.
Many dedicated salmon anglers are also keen amateur biologists (vice-versa for some of us) who have done considerable background reading on matters only incidentally relevant to fish capture; such as behaviour and life history. With respect to the latter, they know that a salmon's scales record certain significant aspects of its past. These are periods or events that impact growth rate, since, in effect, a scale is an indicator of relative growth in a salmon. The major events apparent on scales are:
• The juvenile years in fresh water, from hatching to smoltification(usually two or three at our latitude);
• The number of years subsequently spent at sea, and;
•The sea age(s) at which the salmon returned to its natal river to spawn.
Essentially, these periods are delineated by circuli, or ridges, which are laid down on the scale as it grows with the fish. They are more widely spaced during periods of relatively rapid growth in summer, and more closely packed into "bands" as growth slows in colder winter water.
Evidence that a fish has spawned appears as an area where circuli have been eroded, indicative of the physiological stress related to cessation of feeding in fresh water. Atlantic salmon, unlike their Pacific relatives, are not genetically programmed to die after spawning the first time and may, depending on the many vicissitudes of survival in river, estuary and ocean, return a number of times. Thus, a single perfect scale from a particularly large salmon may encode a fascinating story - one that any angler would be fascinated to know, especially if he or she had caught it.
However, this is but one story, garnered from one fish at one moment in time: how much more could we learn from many thousand scales, collected over the better part of a decade?
Having recently completed the aging and verification of data from just such a scale collection from the Miramichi River in New Brunswick, we felt there was much of interest to the latent biologist in every keenangler/conservationist. The samples were obtained at various salmon monitoring facilities operated in both the Northwest and Southwest branches by the Department of Fisheries and Oceans, and Eel Ground and Red Bank First Nations. This comprises a total of 11,486 fish sampled throughout the season between 1992 and 1998. Since most anglers relate to fish in terms of "inches" and "pounds", we have used traditional measure throughout.
The majority of salmon comprising a run are returning for the first time, and thus have not previously spawned. They form two distinct groups, designated by the number of winters spent at sea: one-sea-winter (1SW) and two-sea-winter (2SW) fish. (Some rivers such as the Restigouche have a significant component of maiden 3SW fish as well, but these are very rare in the Miramichi and elsewhere.) The term multi-sea-winter (MSW) is often used and includes all salmon of two sea winters or more, regardlessof spawning history.
To anglers generally, 1SW fish are called "grilse" and all others, "salmon". These two designations correspond respectively to the terms "small" (shorter than 63 cm, or about 24 inches), and "large" (63 cm or more) used in fisheries management. While not all "small" salmon are only 1SW,
nor all "large" salmon 2SW or more, the dichotomy is remarkably consistent.
Late-run fish (after August 31) are generally longer at a given age than their early-run counterparts, having been at sea an extra few months. This effect decreases with age. For example, a late grilse will be about 6per cent longer than his early counterpart, whereas a late-run 2SW fish will only be about 3 per cent longer. (Smaller fish grow at a faster rate.)
On average, Miramichi grilse are 22 inches in fork length and weigh 4.4lb., and maiden 2SW fish 29.5 inches and 10.5 lb., with early and late run averages being respectively slightly smaller and larger.
There is little difference between males and females in terms of length at age, although males usually average slightly longer than females, the tendency being more noticeable in grilse, and somewhat stronger in the Southwest Miramichi system. Otherwise, the two major divisions of the Miramichi, the Northwest and Southwest branches, are almost identical inrelation to the characteristics just mentioned. Where they do show a significant difference, though, is the proportion of females in the various time and size components of the runs. In the Southwest, females account for about 18 per cent of early and 12 per cent of late-run grilse and 90 per cent of 2SW salmon in both runs. The Northwest is more variable; 28 per cent of early and 12 per cent of late grilse runs are female, while 74 per cent of early, rising to 90 per cent of late 2SW fish, are female.
So far we have discussed the maiden component of salmon runs, the fish that are returning to spawn for the first time. What about those repeat spawners that so captivate our imagination with their incredible journeys, and become the trophy size fish so coveted by anglers?
In the Miramichi system from 1982 to 1998 the proportion of the large or MSW salmon that were repeat spawners was variable, ranging between 14 and 57 per cent, with a mean of 27 per cent. There has been a slight tendency for the proportion to increase in the past few years, with a significant rise to its highest level in 1998 due to decreased returns of 2SW fish. On average, early runs have a higher proportion (40 per cent) of repeat spawners than late runs (29 per cent). Females make up about 72 per cent of both early and late MSW runs in both major branches, which is much lower than the proportion in 2SW runs, with the exception of the early Northwest run, as stated above. To a considerable extent, this is due to relatively large numbers of returning fish having previously spawned as grilse, which are predominantly males.
Repeat spawners exhibit three basic types of returning pattern:
•Fish that spawn in alternate years;
•Fish that return in consecutive years; and
•Fish that combine these two patterns.
Most salmon returning to spawn for the second time do so two years after their first run. Oddly, this includes about two thirds of the fish that returned the first time as grilse, having then spent only one year at sea. After the second spawning, things really start to get interesting, and confusing! There are no hard and fast rules here, but the evidence from thousands of scales supports the following broad generalities:
Fish returning a number of times tend to do so at the same time during the season - that is, they are either early or late run and generally maintain that pattern all their lives. The earlier a fish enters the river, the more likely it is to spawn in alternate years, and the later, the more likely to return consecutively. Up to mid July, the vast majority of repeat spawners are alternates, and after this time there is an increasing proportion of consecutives, which constitute about two thirds of the repeats in the late run.
This makes sense because kelts from the early run leaving the river the following April and May probably don't have time to recondition themselves and return in just a month or two; they therefore stay out a full year.
Kelts from fall run fish, on the other hand, can mend in the estuary or coastal waters during the three to five months before they are due to return (the short-migration Bay of Fundy fish being a prime example). This, of course, doesn't mean they are in any way obliged to spawn in consecutive years, but it certainly provides an opportunity to avoid a long and hazardous trek to Greenland and back. Given adequate food close to home, the advantages seem obvious.
Salmon which commence their careers as consecutive spawners stay that way for as long as their luck holds; the odd one goes alternate, but this is very rare. Alternates, however, are another kettle of fish. To turn an old expression around, these would rather switch than fight, and after spawning once or perhaps twice at two-year intervals, most seem to tire of extended vacations from nuptial responsibilities and go consecutive.
Having done this, they very rarely switch back, although we have seen a few examples of this, too. To put this in better perspective, of all repeat spawners in the sample, 42 per cent were alternates, 40 per cent were consecutives, 18 per cent had switched from alternate to consecutive, and fewer than 1 per cent had changed from consecutive to alternate.
How many times can a salmon spawn, and how old can they get?
In our sample, 98 per cent of all previous spawners showed from one to three spawning marks on their scales (the year in which they were sampled would presumably have added one more). The remaining 2 per cent had from four, to a maximum of six, previous marks. Intriguingly, the three fish with six marks were all lifelong consecutive spawners.
As to age, since most fish spend two to three years in the river and return as either 1SW or 2SW virgins, the majority are between three and five years old. The oldest fish in this sample was 11 years of age. This was a late run female from the Southwest Miramichi that had spent the first two years in the river and nine at sea. She was 41.3 inches long, weighed about 29 lb., and had spawned five previous times, having started as an alternate and switched to a consecutive spawner after the third time back.
These are the extremes, of course; the more captivating pages in the book.
The largest group of previous spawners is comprised of fish with only one former mark, accounting for 63 per cent of all repeats. Of these, 61 per cent spawned first as maiden 2SW salmon. Slightly fewer than half these fish were returning as consecutives, with a mean length of 32.3 inches and weighing about 13.7 lb. The balance were alternates measuring 35.8 inches and weighing a hefty 18.8 lb. These two groups showed length gains over their maiden condition of 9 per cent and 21 percent, respectively. As a useful rule of thumb, it can be said that a typical growth increment for a fish that spawned first as a 2SW is about 2.3 inches for each additional year at sea.
It is worth bearing in mind that this growth increment is in the middle of the body, not at the ends! The probability of a 2SW fish returning to spawn again is around 11 per cent, and the chances improve to about 41 per cent with increasing age and size.
Females generally show higher return rates than males, particularly the largest ones, which are nearly twice as likely to spawn again as similar size males. There is obviously a limit to this, and for the Miramichi it occurs at about 8 total years of age and a length of around 37 inches. Females this size typically produce one third more eggs than 2SW fish, and make a significant contribution to overall egg deposition. Salmon larger than this are quite rare in the Miramichi, and are likely back for the final time.
Of the balance of repeat spawners with one previous mark, 38 per cent came back for the first time as grilse. This is equivalent to 24 per cent of all the repeats, and 7 per cent of all large, or MSW salmon. These fish are rather interesting, not the least because anglers have the most significant impact on this component by virtue of their option to kill or release them as grilse. In the Maritime Provinces, anglers are obligated to release all large salmon, and therefore have little influence on their chance of returning (except to exercise great care in handling).
For a grilse, on the other hand, releasing improves the odds immeasurably!
During the 1997 bright angling season on the Miramichi, 72 per cent of all grilse caught by anglers were retained, amounting to more than 8,000 fish. Had they been returned to the water, a reasonable expectation would see 4.5 per cent or 360 come back to spawn again. Catching any Atlantic salmon is a thrilling experience, but to most anglers the larger the fish, the better it gets, and this is where our repeat spawning grilse really shine. As salmon go, grilse are small, and small fish grow at a more rapid rate than large ones.
Two thirds of the grilse that make it back a second time will be alternate spawners; that is, they will have spent an additional two winters at sea, during which time their growth is truly impressive. From an average of 22inches and 4.4 lb., they will return as 32.6 inches and 14.2 lb., a whopping 48 per cent increase in length and a tripling in weight. This is, in fact, the trophy fish that face-washed you at the beginning of this discussion, and there could obviously be more of them to improve the quality of angling if more grilse were released. While the majority of grilse are males, some runs, as noted earlier, have an important female component. These females (which are more than twice as likely to return than are the males) could significantly improve egg deposition, especially in the Northwest Miramichi. The alternate spawners will individually make an even greater spawning contribution than the maiden 2SW females,
which are normally considered the mainstay of the run.
The egg contribution of all repeat spawners is thus quite considerable, and its importance could increase dramatically in the wake of apparently dwindling 2SW returns. Although this article has dealt only with the Miramichi River, similar patterns, varying only in detail, are found in other rivers with a similar run composition.
By releasing salmon, anglers are contributing to (essential) continued genetic diversity, increased egg deposition, and ultimately to their own chances of future success. The species and the sport need all the help they can get; and, who knows?, the investment may spawn better returns than your other mutual funds.
Gary Atkinson and Dave Moore are salmon assessment technicians with the Canadian Department of Fisheries & Oceans, Diadromous Division, Moncton, N.B. office. This is their first contribution to the Atlantic Salmon Journal.