Survival, behaviour and welfare of Atlantic salmon after catch and release

Reduced salmon populations has led to more stringent regulations in many Norwegian rivers, and catch and release (C&R) has become more common due to introduction of daily and seasonal bag-limits or size limits. In 2014, 79 tonnes of salmon were released in Norwegian rivers, which is equivalent to 22% of the total catch (Statistics Norway). The proportion of fish that was released in 2014 was more than twice as high as when the registration of the incidence of catch and release was initiated in 2009 (9%). Effects of C&R on salmon has been examined in the project "Survival, behaviour and welfare of Atlantic salmon after catch and release (SalCaRe)" in the period from 2012 to 2014. The project has involved tagging of released fish with external spaghetti tags in rivers Gaula, Orkla, Verdalselva, Otra, Lakselva, Ranaelva and Osen Vestre Hyen, as well as by tagging released salmon with radio transmitters in Otra, Gaula, Orkla and Lakselva. The purpose has been to investigate how variation in water temperatures, handling, playing and various fishing methods affects survival and behaviour after release, and to determine how many times individual salmon is caught and released in different rivers. A total of 650 salmon were tagged before being released during the project period, 147 with radio tags and 503 with spaghetti tags. The tagging was carried out in close cooperation with anglers and river owner organizations. Survival rates after C&R were estimated in three rivers. In Otra (2012 and 2013, N = 75) the overall survival rate was 91%, with 93% and 86% survival at water temperatures below and above 18 ° C, respectively. In Gaula (2013, N = 27) survival was 89%, at the same time as the survival of a control group caught with bag nets in the ocean (N = 33) was 100%. In Lakselva (2014, N = 39) survival after C&R was 97%. The vast majority of the fish that died had either minor injuries or were played/handled disproportionately long under adverse conditions. The mortality rate was in other words minimal for uninjured and properly handled fish at normal water temperatures. Analysis of the behavior and movements for C&R salmon showed that a varying proportion of the fish moved downstream after release (Otra 72%, Gaula: 28% and Lakselva: 26%), which indicated a certain migration delay. Most of these fish were, however, located in spawning areas during the spawning season. In Gaula, downstream movements were also observed for a significant proportion of the fish in the control group. It was furthermore no difference in the capacity to overcome a large waterfall in Gaula between the C&R fish and the control group. Recapture rate of C&R fish varied significantly between the rivers (0-37%), and was on average 12.9% for all rivers and years as a whole. The variation in recapture rates between years and rivers can be caused by many factors, but differences in exploitation pattern and environmental conditions probably explains a large part. The probability of recapture was, among other factors, related to how much of the fishing season that remained after release, and fish caught early in the season had the highest probability of being recaptured. The results also suggest that the recapture of C&R fish may be many times higher than what is previously recorded in Norway, which could have an impact both for local and national management of salmon. There was also a clear tendency that the recaptured fish were caught on other types of gear than that they were captured on the first time. The SalCaRe project has thus shown that C&R will result in some mortality, but also that the majority of the mortality can be associated with injuries, treatment or high water temperatures. This finding underlines, in line with the existing recommendations for C&R, that it is important not to release injured fish and that the fish should landed as quickly as possible in order to avoid exhaustion, and that caution should be shown at high water temperatures. The results also show that the behavior of the fish will be affected because of C&R, but probably not to an extent that will involve that the fish will be unable to reach the spawning areas in time, as long as they are released during the regular fishing season. The project has also shown that recapture rates of C&R fish varies considerably among rivers and years, and that it in some cases could be much higher than previously thought. The main conclusion is thus that C&R will involve some mortality and changed behavior, but also that the mortality is likely to be minimal if recommendations with regard to not releasing injured fish and optimal handling are followed.

Many populations of wild salmonids have decreased significantly during the last decades due to anthropogenic impacts acting both in freshwater and in the sea. As the menaces these fish species experience will likely continue to increase, salmonid populati ons are expected to further decline in the future, unless effective mitigative actions are imposed. Catch and release (C&R) of adult fish is a frequently used, but also controversial, management tool aimed at maintaining sustainable spawning stocks. C&R i s practiced worldwide and it is in most countries regarded as an adequate management tool. In Norway, C&R has so far not been widely used or accepted, mainly due to ethical and welfare concerns. Although some studies have been performed on effects of C&R in Atlantic salmon, a range of questions remains unanswered. The proposed project aims to obtain new knowledge regarding the effects of catch and release of salmon in recreational fisheries that 1) will improve the way this management tool is used, and 2) implicitly will contribute to maintenance of sustainable spawning stocks. More specifically the proposed study will investigate effects of C&R at high water temperatures and performance after C&R in relation to angling method, playing time and migration stage. In addition, risk of repeated recapture and effects on reproduction will be determined. The project will also focus on efficient and targeted dissemination. As recreational angling for Atlantic salmon is a significant source of income and employmen t in many rural societies, the project will provide knowledge that will support development and management of local industry, including tourism.