Initial and long-term consequences of attempts to improve fish-food resources in Lithuanian waters by introducing alien peracaridan species: a retrospective overview

Abstract

Summary In this overview, we consider the rationale and practice of invertebrate introductions into Lithuanian waters, the current distribution of introduced species, test the theoretical expectations of introduction of peracaridan species into lakes, and summarize the large‐scale consequences of these translocations. After some early attempts to transfer locally available species within the country, peracaridan species from the Ponto‐Caspian region were introduced into Lithuanian waters during the 1960s (Pontogammarus robustoides, Obesogammarus crassus, Chaetogammarus warpachowskyi, Paramysis lacustris, Limnomysis benedeni and Hemimysis anomala). After their establishment at the site of first introduction in a newly constructed water reservoir on the Nemunas River, further deliberate introductions into Lithuanian lakes and water reservoirs, as well as into more distant areas, were undertaken. These introduced species soon contributed to fish diet and a subsequent increase in the production of commercially important fish was envisaged. However, our collation of available data does not support the enhancement of fish production in Lithuanian lakes. Although perch (selected as a model fish species) assimilated the introduced species into diet and sometimes in large quantities, there was no subsequent influence on somatic growth rates when compared with perch from lakes devoid of alien peracaridans. Comparisons of littoral fish communities of different lakes, and commercial catches in the lake with the most numerous populations of introduced species also indicate no significant effect on fish production. Negative consequences of introduction are more than obvious in contrast. To date, most of the introduced Ponto‐Caspian amphipod and mysid species occur in different sites of the Baltic Sea basin outside Lithuania, and their further dispersal may be expected. These species, especially amphipods, have proved to be highly ecologically aggressive, inducing change in resident macroinvertebrate communities and causing increase of biological contamination (i.e. detract from naturalness). Thus, the introduction of alien fodder species was ill advised from an economic, and even adverse from an environmental perspective.

Range expansion of Ponto-Caspian mysids (Mysida, Mysidae) in the River Tisza: first record of Paramysis lacustris (Czerniavsky, 1882) for Hungary

“…anómala), especially in the impounded reaches and in stagnant or slow-flowing backwaters, where the species itself can find hospitable environment and the conditions of the formation of an ample Zooplankton stock are provided. It also may become an important food source of certain fish species (Bäcescu, 1954;Rakauskas et al, 2010); however, Arbaciauskas et al (2010) could not demonstrate positive effects on fish stocks in Lithuanian waters.…”

Hemimysis anomala in Lake Ontario food webs: Stable isotope analysis of nearshore communities

“…Borcherding et al (2007) suspect Hemimysis are a higher quality food item (compared to zooplankton), and the reduction in zooplankton as a result of Hemimysis predation provokes a heavier fish reliance on Hemimysis to augment their diet. In contrast, Arbačiauskas et al (2010) concluded no growth or production advantage was evident for European perch when comparing lakes with and without introduced mysids in Lithuanian waters. While both the Borcherding et al (2007) and Arbačiauskas et al (2010) studies reached different conclusions regarding the effect of Hemimysis on fish growth and production, both groups agree that Hemimysis will reduce resident zooplankton density in invaded waters.…”

“…However, previous stable isotope studies in the LGL suggest opportunistic omnivory regardless of size (Marty et al, 2010). Hemimysis, in turn, are consumed by a variety of fish species, including alewife, round goby, yellow perch and rock bass (Borcherding et al, 2007;Arbačiauskas et al, 2010;Lantry et al, 2010;Fitzsimons et al, (2012-this issue)). …”

“…However, some fish species, especially Perca sp., became voracious predators of Hemimysis following their establishment in European lakes (Borcherding et al, 2007;Arbačiauskas et al, 2010). Young-of-year Perca fluviatilis, sampled from a lake recently invaded by Hemimysis, increased their reliance on Hemimysis from 20% to 100% of their diet in just four months (Borcherding et al, 2007).…”

Size matters: predation of fish eggs and larvae by native and invasive amphipods

“…It has been suggested that this invasive amphipod will provide a plentiful food resource for fish that traverse the predatory gauntlet (Luecke et al 1990) to reach adulthood, perhaps boosting survival and fecundity (Kelleher et al 1998;Madgwick and Aldridge 2011;Brandner et al 2013;Czarnecka et al 2014). However, the higher density of D. villosus could just compensate for its lower quality and profitability as prey (Arbaciauskas et al 2010;Błońska et al 2015) and so provide little additional benefit to fish populations.…”