Table 1.
Round goby interactions with Eurasian perch (Perca fluviatilis) are context dependent (n.a. = not available, TL = total length, SL = standard length)
| Species | Eurasian perch (Perca fluviatilis) | ||
|---|---|---|---|
| Water body | Baltic Sea | Middle Danube | |
| Sampling site | Bay of Gdansk, Poland | Curonian Lagoon, Lithuania | Near Bratislava, Slovakia |
| Abiotic factors | |||
| Salinity | Brackish water | Brackish water | Fresh water |
| Depth (m) | n.a. | n.a. | 0.5–2.5 |
| Min./max./mean temp. (°C) | n.a. | n.a. | n.a. |
| Year(s) of study | 2004 | 2007–2012 | 2004 |
| Season of study | May–August | n.a. | 30 Aug. and 1 Sept. |
| First record round goby | Late 1980s | 2002 | 2003 |
| Age of round goby population | Approx. 15 years | 5–7 years | 1 year |
| Round goby population density | n.a. (“one of the dominant species”) | 1–251 ind./1000 m3 | n.a. |
| Life stage or length of round goby | n.a. | n.a. | 1–4 years |
| Life stage or length of native species | 113–293 mm TL | Small: 8.9 ± 0.3 cm TL Medium: 13.1 ± 1.0 cm TL Large: 27.2 ± 1.4 cm TL |
Age 1: 56.8–63.7 mm SL Age 2: 89.2–109 mm SL Age 3: 78.5–138.3 mm SL Age 4: 104.1–178.1 mm SL |
| Primary data acquisition method | Stomach content and stable isotopes from field samples; comparison between invaded and uninvaded area (around island of Öland) | Stomach content and stable isotopes from field samples | Stomach content and stable isotopes from field samples |
| Sample size of perch | 100 | 9 | 56 |
| Predation on round goby | Competition with round goby | ||
|---|---|---|---|
| Primary interaction | Perch almost exclusively feed on round goby; importance as food organism increases with increasing perch size | Round goby constitutes 17.4 ± 14.3% of large perch diet (estimated from stable isotopes); no isotopic niche overlap with benthivorous perch (small and medium length classes), thus no competition suspected | High diet overlap (except for age 2 or 3 perch [unclear]), due to preference for gammarids |
| Resulting impact on native species | Changes in trophic links; round goby is an energy pathway from mussels to top predators | Change in top predator diets | Potential for competition with small perch |
| Anticipated future effects | Bioaccumulation of toxins via mussels and round goby possible; may contribute to a new link in the energy pathway from bivalves to higher human exploited trophic levels (i.e., fish) | Stabilization of round goby population density due to predation | n.a. |
| Authors | Almqvist et al. (2010) | Rakauskas et al. (2013) | Copp et al. (2008) |