Sander lucioperca
(pike-perch)

As S. lucioperca is an obligate piscivore as an adult, this species will predate on native and non-native fish species where introduced. Following its importation to the England in the mid-1800s, S. lucioperca was introduced into the wild during the mid-twentieth century, most notably to the lower part of the River Great Ouse system (East Anglia) and then to canals of the Midlands. A summary of the extensive research on the species that followed (Smith et al., 1998) could not lend support to the numerous claims of adverse impacts, reporting that evidence of negative impacts was equivocal, with only one study suggesting lower numbers of native forage fishes in a stretch of (man-made) canal with S. lucioperca than in a nearby stretch of canal where the species was absent. Predation on native fishes was subsequently reported elsewhere, including on ruffe (Gymnocephalus cernuus) as well as seaward migrating smolts of sea trout (Salmo trutta) and Atlantic salmon (Salmo salar), with potentially adverse population impacts (Jepsen et al., 2000; Koed, 2001; Koed et al., 2002). Crivelli (1995) also shows how the introduction of a non-native piscivorous species into inland waters can lead to the extinction and decimation of populations of native species in the Mediterranean region and how the removal of these native species, leads to major changes in the ecosystem. Schulze et al. (2006) noted that when S. lucioperca was introduced into a German lake, there was a shift in perch (Perca fluviatilis) habitat usage from the pelagic zones of the lake towards the littoral zone in response to the competition from the pikeperch. They also stated there was an increase in predation on juvenile perch by both pikeperch and pike (Esox Lucius) leading to a decrease in the abundance of large perch. As S. lucioperca is an open water predator and well adapted to feeding in turbid water or low-light conditions (Karas and Sandström, 2002), it can also potentially cause the collapse of a fishery by removing many of the young fish not allowing them to grow and spawn. S. lucioperca is a vector of fish diseases and parasites which can be transmitted to native and farmed fish and it has also been found to be capable of hybridizing with Eurasian perch (Perca fluviatilis) (Kahilainen et al., 2011) and Volga perch Sander volgensis (Specziar et al., 2009; Müller et al., 2010).

Historically, S. lucioperca has been mostly introduced into lakes, and from these lakes, the fish have migrated into larger rivers (e.g. River Gudenaa in Denmark; Koed, 2001), and in some cases have, through migration, established themselves into neighbouring lakes (Larsen and Berg, 2006). In Sweden and other countries, S. lucioperca is still stocked to support fisheries, both within and outside the area of its natural range (Laikre and Palmé, 2005), including as illegal releases by anglers (Copp et al., 2003). Illegal stockings by anglers have also been reported from Denmark (Berg, 2012).

S. lucioperca inhabits rivers, lakes, reservoirs, moderately running waters and brackish coastal waters with salinities of ca. 12 ppt (Larsen and Berg, 2006) or more. It thrives in turbid, moderately eutrophic waters with high oxygen content (http://www.briancoad.com). This species can be found in small schools near sandy and stony bottoms in deeper areas of rivers, preferably in areas with cover. They are also found in clear waters if the depth is sufficient to enable it to seek refuge during daytime (Sonesten, 1991). Habitat preferences vary over the year and according to age and environmental conditions (Lappalainen et al., 1995). During the autumn, S. lucioperca inhabits areas of 1.2–1.8 m in depth, until the winter months when they move to much deeper waters. Once winter is over, they migrate to shallower waters with a gravel/pebble substratum for spawning. Habitat usage during the summer months is varied. Diel variations in adults indicate elevated activity levels at dusk (Poulet et al., 2005).

Genetics

S. lucioperca has a chromosone number of 24 haploid/gametic (n) and 48 diploid/zygotic (2n) (Klinkhardt et al., 1995). It is known to hybridize with Sander volgensis (Specziar et al., 2009; Müller et al., 2010) and also perch (Perca fluviatilis) (Kahilainen et al., 2011). DNA analyses of this species have been conducted by Säisä et al. (2010) and April et al. (2011).

Reproductive Biology

S. lucioperca begin migrating about a month prior to spawning into shallow areas, usually around April-May, or when temperatures reach 10–14°C in the spawning grounds. Brackish water fish will migrate to freshwater habitats. The males are territorial and construct a shallow nest, usually about 5–10 cm deep and 50 cm in diameter in sand or gravel, or among exposed plant roots on which eggs are deposited, usually in turbid water and at 1–3 m depth (Sokolov and Berdicheskii, 1989). Breeding usually takes place at dawn or during the night. Fecundity is dependant on the size of the female, but ranges between 150–400 eggs/g and range in size from 0.9–1.5 mm. After spawning, the female departs and the male guards the nest, fanning the eggs with his pectoral fins.

Associations

Most of the work completed on this species has been undertaken in Iran, with Eslami and Mokhayer (1977) finding some of the S. lucioperca to be infested with larvae of the nematode Anisakis. Eslami et al. (2011) reported Anisakis from the gastro-intestinal tract. This parasite can infest man if fish is eaten smoked, salted or fried at temperatures below 50°C. Mokhayer (1976) records the acanthocephalan Corynosoma caspicum. Jalali and Molnár (1990) record the monogenean Ancyrocephalus paradoxus. Masoumian et al. (2005) recorded the protozoan parasite Trichodina perforata. Pazooki et al. (2007) recorded various parasites, including Diplostomum spathaceum and Argulus foliaceus. Barzegar et al. (2008) recorded the digenean eye parasite Diplostomum spathaceum from this fish. Barzegar and Jalali (2009) reviewed crustacean parasites in Iran and found Achtheres percarum on this species. Azadikhah et al. (2009) found 6 parasite species including two Trichodina spp. from the gills and Vorticella sp. on the skin; other parasites included Gyrodactylus sp. and Argulus foliaceus from the gills, and Diplostomum spathaceum from the lens of the eyes. Rolbiecki (1993) noted the parasitic metazoa of pikeperch in Poland to include Achteres percarum, Ancyrocephalus paradoxus, Argulus foliaceus, Azygia lucii, Bothriocephalus sp., pleroceroid, Brachyphallus crenatus, Bucephalus polymorphus, Bunodera luciopercae, Camallanus lacustris, Camallanus truncates, Corynosoma semerme, Diplostomum spathaceum, Ichthyocotylurus playcephalus, Neoechinorhynchus rutile, Piscicola geometra, Pomphorhynchus laevis and Tylodelphys clavata.

Nutrition

The diet of pikeperch in Estonia included smelt (Osmerus eperlanus), ruffe (Gymnocephalus cernuus), perch (Perca fluviatilis), vendace (Coregonus albula), pikeperch itself and roach (Rutilus rutilus; Kangur and Kangur, 1998). In Finland, smelt were the most numerous prey species for every size-class of pikeperch, but the diet also included perch and roach (Keskinen, 2008). Pikeperch has also been reported to feed on smolts of migrating sea trout (Salmo trutta) and Atlantic salmon (Salmo trutta; Jepson et al., 2000; Koed, 2001, Koed et al., 2002).  

Environmental Requirements

S. luciperca occurs in large, turbid rivers and eutrophic/mesotrophic lakes, brackish coastal lakes and estuaries (Lelek, 1987); however, it requires a high oxygen concentration. It also occurs in oligotrophic clearwater lakes if they are deep enough to provide dark environments during the daytime (Sonesten, 1991). Salinity levels of up to 20 psu are tolerated, with preferred levels of <5 ppt (Winkler et al. 1988; Saisa et al., 2010). Spawning is restricted to salinity levels below 5 ppt (Lappalainen, 2003).

Animal feed, fodder, forage

• Forage

Environmental

• Biological control

General

• Sport (hunting, shooting, fishing, racing)

Human food and beverage

• Meat/fat/offal/blood/bone (whole, cut, fresh, frozen, canned, cured, processed or smoked)

Dorsal fins almost touching; no black spot on the base of the backward end of the 1^st dorsal fin; large canine teeth; 80-95 lateral ctenoid scales; no spine pointing backwards on the operculum bone.

Generally easy to distinguish from other percids except the other Sander species.

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Prevention

SPS measures

In the UK, S. lucioperca requires a licence under the Import of Live Fish Act (1980) to keep or release (i.e. fisheries).

Early warning systems

The list server Aliens-L provides an international forum for announcing recent discoveries of non-native species. A similar, but peer-reviewed function for non-native aquatic organisms is provided by the international journal, Aquatic Invasions (www.aquaticinvasions.net), which was set up as part of the EC Integrated Project No. 506675 ‘Assessing LArge scale environmental Risks for biodiversity with tested Methods (ALARM)’.

Rapid response

This is established at the national level.

Public awareness

Not much awareness on species invasiveness; however, introductions are well published through the angling media.

Eradication

In the UK there have been local attempts to remove S. lucioperca (e.g. Smith et al., 1996), however, Britton et al. (2010) states that eradication would be virtually impossible when the species has a wide geographical distribution (e.g. England).

Containment/zoning

In the UK, the current policy for consents to keep and release is based on a presumption against licenses for drainage basins where the species is currently absent. Similar policies may exist in other countries where the species is not native.

Control

As established populations are difficult and costly to control, further introductions or stocking should be avoided.

Physical/mechanical control

Includes electrofishing and gill and seine netting.

Movement control

Under current EU legislation on the use of alien species in aquaculture, movements and releases of non-native species within the EU are regulated, requiring an appropriate risk assessment and consideration of management options for parts of the EU where a species is ‘locally absent’.

Chemical control

The only effective method of fish eradication is the application of rotenone, a piscicide that is also toxic to non-target species.

Monitoring and Surveillance

General survey methods include gill nets (including multi mesh gill nets designed for monitoring fish in lakes), seine nets, fyke nets etc. and electrofishing. Both radio and acoustic telemetry can also be used.

Ecosystem Restoration

S. lucioperca is used in the top-down biomanipulation of ecosystems for restoration purposes (e.g. Mehner et al., 2004; Dörner et al., 2007).

07/12/11 Original text by:

Michael Godard, CEFAS, Salmon and Freshwater Team, Pakefield Road, Lowestoft, Suffolk, NR33 0HT, UK

Gordon Copp, CEFAS, Salmon and Freshwater Team, Pakefield Road, Lowestoft, Suffolk, NR33 0HT, UK

Reviewers' names are available on request.