ROUNDTABLE SESSION 3 REINTRODUCTION OF NATIVE CRAYFISH AND HABITAT RESTORATION

The aim of this roundtable session was to discuss reintroduction of native crayfish and habitat restoration providing practical recommendations of value to environmental authorities, decision makers and local managers. A (re)introduction may be appropriate: a) to reintroduce a population recently lost, b) to extend the distribution of an ICS into historic range and c) to create new or isolated populations to conserve genetic diversity or the species. Before (re)introduction it is imperative to demonstrate the probability that the receptor locality is empty of crayfish, to know the reason for crayfish extinction, and that the reason is removed before restocking. Before restocking, the receptor locality should also be assessed for crayfish suitability, including: water type and chemistry, physical conditions (shelter), presence of crayfish plague, risk of NICS, predatory fish. In general, major constraints in a restocking project is money and availability of stocking material. General recommendations: a) if have abundant/readily available and acceptable donor population use adults and young/juveniles as available, b) if short of stock boost with hatchery rearing, and c) if want population quickly, stock as many as can afford and several times. Trade offs: time vs. cost. Genetic distinctiveness/possible spread of diseases must be considered. In general, the preferential ranking is donor from: 1) same watercourse, 2) same catchment, 3) adjacent catchment or one nearby in the same biogeographic region for crayfish, and 4) any other catchment. Habitat restoration can be a valuable action, and should be prioritised to: 1) give greatest overall benefit to the ecosystem, 2) benefit ICS and 3) be achievable and cost effective. Natural characteristics of waterbodies in local area should be considered. A key factor in the protection of ICS populations is the knowledge and attitude of local people. Objectives and actions should be agreed with local stakeholders to improve chances of success

Regionfelt Østlandet. Konsekvensutredning for temaet: Vann og grunn, inklusive dyreliv i vann

Årsliste 2001Rapporten omhandler en statusbeskrivelse for vannkvalitet og vannlevende dyr i Regionfelt Østlandet. Dette inkluderer generell vannkjemi, tungmetaller i vann, moser, løsmasser, tålegrenser for surt vann, bunndyr, krepsdyrplankton og fisk. Det er utført en konsekvensanalyse på bakgrunn av foreslåtte lokaliseringer av målområder, standplasser, kjøretraseer, baneanlegg, ingeniørøvningsfelt, broskole og oversettningsområde samt bruken av disse, inklusive ammunisjons-regnskap. Tiltak for å begrense skadeeffekter er diskutert og konklusjonen er at de mest effektive tiltakene ligger i en god plan for lokaliseringer av målområdene og de ulike manøvrerings-områdene. Vi har foreslått en basisundersøkelse for områdene som berøres av Ingeniørvåpenets aktiviteter. Årsaken til dette er at de foreslåtte områdene ikke ble nevneverdig berørt i den opprinnelige planen og derfor ikke er nødvendig undersøkt. På bakgrunn av befaringer er det imidlertid gjennomført konsekvensvurderinger til bruk i planarbeidet. Overvåkningsundersøkelsene som allerede er startet opp foreslås videreført og modifisert etter at Ingeniørvåpenets bruksområder er fastlagt. Hensikten er å avdekke endringer i forurensningsituasjonen i vannforekomstene inklusive effekter på vannlevende organismer tidligst mulig slik at tiltak kan iverksettes.Forsvarets bygningstjeneste (FBT

Biosecurity and Vector Behaviour: Evaluating the Potential Threat Posed by Anglers and Canoeists as Pathways for the Spread of Invasive Non-Native Species and Pathogens

Invasive non-native species (INNS) endanger native biodiversity and are a major economic problem. The management of pathways to prevent their introduction and establishment is a key target in the Convention on Biological Diversity's Aichi biodiversity targets for 2020. Freshwater environments are particularly susceptible to invasions as they are exposed to multiple introduction pathways, including non-native fish stocking and the release of boat ballast water. Since many freshwater INNS and aquatic pathogens can survive for several days in damp environments, there is potential for transport between water catchments on the equipment used by recreational anglers and canoeists. To quantify this biosecurity risk, we conducted an online questionnaire with 960 anglers and 599 canoeists to investigate their locations of activity, equipment used, and how frequently equipment was cleaned and/or dried after use. Anglers were also asked about their use and disposal of live bait. Our results indicate that 64% of anglers and 78.5% of canoeists use their equipment/boat in more than one catchment within a fortnight, the survival time of many of the INNS and pathogens considered in this study and that 12% of anglers and 50% of canoeists do so without either cleaning or drying their kit between uses. Furthermore, 8% of anglers and 28% of canoeists had used their equipment overseas without cleaning or drying it after each use which could facilitate both the introduction and secondary spread of INNS in the UK. Our results provide a baseline against which to evaluate the effectiveness of future biosecurity awareness campaigns, and identify groups to target with biosecurity awareness information. Our results also indicate that the biosecurity practices of these groups must improve to reduce the likelihood of inadvertently spreading INNS and pathogens through these activities

REINTRODUCTION OF NOBLE CRAYFISH ASTACUS ASTACUS AFTER CRAYFISH PLAGUE IN NORWAY

The Glomma and Halden watercourses in Norway were hit by crayfish plague in 1987 and 1989. Reintroduction of the noble crayfish started in 1989 in the Glomma and in 1995 in the Halden watercourse. Norway has especially good conditions for reintroduction of the native crayfish after crayfish plague, as there is no alien plague-carrying crayfish species in the country. In the Glomma watercourse, approx. 15 000 adult crayfish and 10 000 juveniles have been stocked while in the Halden watercourse the figures are 19 000 adults and 26 500 juveniles. All stocking sites were previously regarded as very good crayfish localities. Four years after stocking, natural recruitment was recorded at all adult crayfish stocking sites in the Glomma watercourse and at most sites in the Halden watercourse. Current crayfish density is, however, much lower than pre-plague densities even at the sites where population development has been in progress for more than 10 years. Extensive post-stocking movements were recorded among adult crayfish. Some sites seemed more suitable for settling, resulting in a great variation in CPUE between the different test-fishing sites. Juveniles seem more appropriate as stocking material if the goal is to re-establish a population in a particular area, due to their stationary behaviour, which seems to remain as they grow larger

EXPLOITATION IS A PREREQUISITE FOR CONSERVATION OF ASTACUS ASTACUS

The noble crayfish, Astacus astacus, is highly valued from a recreational and economical point of view. In most noble crayfish areas, there are long traditions of crayfish catching. The noble crayfish is also included in national and international Red Lists as a vulnerable or threatened species. Intuitively, the first thought is that such a species should be protected from exploitation. However, in many cases the possibility for exploitation and local economic benefits may be important for the conservation of the species. For the noble crayfish this is especially true. The greatest threat against noble crayfish is the man-facilitated spread of plague-carrying alien crayfish species. If local people are allowed and encouraged to catch and make a benefit from noble crayfish, this is also the best protection against illegal stocking of alien crayfish. The possibility to exploit the crayfish is of major importance for the will to protect. Examples from Norway showing different ways of getting an economical and recreational outcome from the noble crayfish are presented

ROUNDTABLE SESSION 3 REINTRODUCTION OF NATIVE CRAYFISH AND HABITAT RESTORATION

The aim of this roundtable session was to discuss reintroduction of native crayfish and habitat restoration providing practical recommendations of value to environmental authorities, decision makers and local managers. A (re)introduction may be appropriate: a) to reintroduce a population recently lost, b) to extend the distribution of an ICS into historic range and c) to create new or isolated populations to conserve genetic diversity or the species. Before (re)introduction it is imperative to demonstrate the probability that the receptor locality is empty of crayfish, to know the reason for crayfish extinction, and that the reason is removed before restocking. Before restocking, the receptor locality should also be assessed for crayfish suitability, including: water type and chemistry, physical conditions (shelter), presence of crayfish plague, risk of NICS, predatory fish. In general, major constraints in a restocking project is money and availability of stocking material. General recommendations: a) if have abundant/readily available and acceptable donor population use adults and young/juveniles as available, b) if short of stock boost with hatchery rearing, and c) if want population quickly, stock as many as can afford and several times. Trade offs: time vs. cost. Genetic distinctiveness/possible spread of diseases must be considered. In general, the preferential ranking is donor from: 1) same watercourse, 2) same catchment, 3) adjacent catchment or one nearby in the same biogeographic region for crayfish, and 4) any other catchment. Habitat restoration can be a valuable action, and should be prioritised to: 1) give greatest overall benefit to the ecosystem, 2) benefit ICS and 3) be achievable and cost effective. Natural characteristics of waterbodies in local area should be considered. A key factor in the protection of ICS populations is the knowledge and attitude of local people. Objectives and actions should be agreed with local stakeholders to improve chances of success

STATUS OF FRESHWATER CRAYFISH IN LATVIA

There are three crayfish species present in Latvia: the European noble crayfish (Astacus astacus), the narrow-clawed crayfish (Astacus leptodactylus), and the North-American signal crayfish (Pacifastacus leniusculus) species. Probably only noble crayfish are native and migrated into the country after the last glaciation. Narrow-clawed crayfish has also been present at least since the beginning of the 20th century. In total there are current information on crayfish from 258 localities in Latvia. Most of these localities are lakes (175), but many crayfish populations are also found in river and streams (66). A few populations are found in reservoirs, ponds and gravel-pits. The noble crayfish (Astacus astacus) is the dominant crayfish species and widely distributed in all regions of Latvia. 220 out of 258 crayfish localities contain only noble crayfish. The situation is much the same as in the 1960s, the most obvious change being that more noble crayfish populations are established in the area south of Riga. The narrowclawed crayfish has expanded its distribution since the 1960s when it was reported in 13 localities. Current records include 34 populations and eight of these are coexisting with noble crayfish. Previously, the narrow-clawed crayfish was confined to the southern part of the country. The present distribution includes several populations around Riga and in other parts of the Vidzeme region. The signal crayfish was introduced to one small lake in 1983. In 2004 it is found in another three localities (two rivers and one gravel-pit) quite a distance from the first locality. This indicates stocking by man and not a natural dispersal. Probably the signal crayfish is more widespread than the current data show. Further in this paper, we present information on crayfish legislation, harvest and farming. The threats to the noble crayfish and the main objectives for crayfish conservation and use are also discussed

MANAGEMENT STRATEGIES, YIELD AND POPULATION DEVELOPMENT OF THE NOBLE CRAYFISH ASTACUS ASTACUS IN LAKE STEINSFJORDEN

Lake Steinsfjorden is the most important noble crayfish locality in Norway. The crayfish population has been monitored annually since 1979 including data on total trapping effort, yield and population composition before and after the catching season. The harvest has ranged from 0.7-4.7 kg.ha-1. The catch per trap night decreased prior to 1991 and the yield was reduced by some 50% over the years 1987-1992 as compared to 1979-1986. This was due to removal of small crayfish, high exploitation and the establishment of dense stands of Canadian pondweed (Elodea canadensis). Baited traps catch a large fraction of crayfish < 95 mm total length minimum size. These should according to the regulations immediately be released into the lake. However, it is apparent from the size composition that release of these small crayfish was rather incomplete. In 1983, trap mesh size was increased from 17.5 mm to 21 mm to reduce the fraction of undersized crayfish in the trap catches, yet no effects of this increased mesh size on crayfish size distribution were observed. The legal season has been reduced three times during the study period. In 1983, the closing date was changed from 31 December to 15 September. In 1989 the legal season was further reduced to two weeks and finally in 1995 to 10 days. This reduced total trap effort by 45%. The shorter season allow many crayfish to moult twice instead of once between seasons and the fraction of large crayfish has thus increased and so has the catch per trap night. Canadian pondweed has established dense annual stands and thus has made large parts of the shallow areas unsuitable for crayfish, causing an overall decrease in crayfish population size and production

MANAGEMENT STRATEGIES, YIELD AND POPULATION DEVELOPMENT OF THE NOBLE CRAYFISH ASTACUS ASTACUS IN LAKE STEINSFJORDEN

Lake Steinsfjorden is the most important noble crayfish locality in Norway. The crayfish population has been monitored annually since 1979 including data on total trapping effort, yield and population composition before and after the catching season. The harvest has ranged from 0.7-4.7 kg.ha-1. The catch per trap night decreased prior to 1991 and the yield was reduced by some 50% over the years 1987-1992 as compared to 1979-1986. This was due to removal of small crayfish, high exploitation and the establishment of dense stands of Canadian pondweed (Elodea canadensis). Baited traps catch a large fraction of crayfish < 95 mm total length minimum size. These should according to the regulations immediately be released into the lake. However, it is apparent from the size composition that release of these small crayfish was rather incomplete. In 1983, trap mesh size was increased from 17.5 mm to 21 mm to reduce the fraction of undersized crayfish in the trap catches, yet no effects of this increased mesh size on crayfish size distribution were observed. The legal season has been reduced three times during the study period. In 1983, the closing date was changed from 31 December to 15 September. In 1989 the legal season was further reduced to two weeks and finally in 1995 to 10 days. This reduced total trap effort by 45%. The shorter season allow many crayfish to moult twice instead of once between seasons and the fraction of large crayfish has thus increased and so has the catch per trap night. Canadian pondweed has established dense annual stands and thus has made large parts of the shallow areas unsuitable for crayfish, causing an overall decrease in crayfish population size and production