Tench (Tinca Tinca) Modelled for Capture Probability
Due to its particular meat flavour and interest among sport anglers, tench (Tinca tinca) is an attractive pond fish species with a growing aquaculture potential in Europe. It also has unique features that distinguish it from other members of the genus Cyprinidae.
The aim of the present study was to develop within/cross-species microsatellite markers for tench with high conversion and validation rates for non-model organisms. Seven tench populations were genotyped with the newly developed markers.
Characteristics
In models predicting capture probability, carp and tench were modelled separately. In the final models for both species, TL, lipid percentage, time in the sublittoral and activity space were included, whereas the number of switches among feeding sites was not (Tables 5 and 6). The 95% confidence intervals for all model averaged parameters overlapped one, showing that no behavioural trait consistently distinguished between vulnerable and invulnerable carp or tench.
Both fish shifted their core home range locations to the feeding site locations once corn was introduced, and strongly reacted to groundbait presence as expected [55,56]. However, catchability quickly declined for both species from the onset of the angling experiment, in agreement with previous reports of rapid hook avoidance by carp in lake recreational fisheries and tanks in Europe.
Habitat
Tench inhabit rivers and lakes, especially those with a lot of vegetation, spending the winter buried in the mud. They feed on a variety of aquatic insects, snails, detritus, and plants by extending short sensory organs, called barbels, from their mouths to search the bottom for their prey.
In Europe, tench was first introduced outside its native range in 1877 (Baird 1879), and it was later introduced to the United States in 1936 (Nico and Fuller 2010) and to Canada in 1986 (Dumont et al. 2002). These invasive populations contain both Western and Eastern phylogroups, with high congruence between mtDNA and nuclear DNA loci.
Similarly, six putative non-native tench populations in Turkey carry only haplotypes from the Eastern phylogroup and were placed in the same SAMOVA group as eastern European sites (Figs 2A-D). This suggests that the tench was recently introduced into these river drainages from Europe or perhaps even further east, from the Ponto-Caspian refugium.
Breeding
Tench (Tinca tinca) is the only member of its subfamily, Tincinae, within the carp family, Cyprinidae. It is a freshwater fish that thrives in eutrophic lakes. It eats aquatic plants, small snails and bivalves, and crustaceans. It can also live in brackish water.
Its unique morphological and genetic characteristics set it apart from other members of the genus Cyprinus. Among these are its unequivocal body colour (green to brown-green, although golden and albinotic phenotypes exist), specific reproductive biology, and monophyletic origin.
Genome-wide linkage disequilibrium studies show that tench are genetically distinct from other cyprinid species. The tench genome contains fewer polymorphic sites than the carp genome, but it is still a large and complex sequence. It has been used to develop genome-wide SNP arrays that can distinguish between Eastern and Western tench breeds. These SNPs were validated in a sample of two tench breeds that had been grown under cultured conditions for six generations. These SNPs did not have any negative effects on the main growth-related traits of tench.
Feeding
Tench prefer lakes and ponds with muddy bottoms and dense vegetation, where they can hide from predators. They eat a variety of small insects and aquatic plants, including some of the same baits used by carp anglers. This behaviour increases water turbidity, and can affect native benthic invertebrates, snails and fish eggs.
Tench may also compete with native species for spawning sites and gill function. They can scavenge algae and other phytoplankton, and consume the seeds of some vascular plants.
The number of seed items retrieved from the feces of Roach, Rudd and Tench progressively increased with increasing water temperature (Table S1). These data suggest that tench consume and disperse plant seeds in a seasonal manner. This is consistent with observations that tench become more herbivorous during the summer and autumn, when they egested vegetative parts of vascular plants. Seeds of Juncus effusus, Betula pendula and grasses were the most common genus-specific species retrieved from tench feces.
