Environmental Engineering Reference
In-Depth Information
Non-migratory marine species generally spread by entrainment of pelagic larval
stages in coastal and oceanic currents, although some larvae have considerable abil-
ity to disperse by active swimming. Larvae of marine species may be transported
in ballast water and adults in sea chests. One of the most common teleost families
to spread in this manner is the gobies (Gobiidae). Migratory marine species either
follow highly prescribed migration routes, such as diadromous eels (Anguillidae)
and salmonids, or range widely over great oceanic distances (tuna, billfi shes and
pelagic sharks). In many cases it may be impossible to determine whether new
records of marine fi sh are naturally dispersed vagrants or have been introduced by
shipping or aquarium releases. Marine fi sh may also spread to new regions by the
construction of canals. Since the construction of the Suez Canal in 1869, more
than 60 Indo-Pacifi c marine fi shes have invaded the Levantine Basin of the Eastern
Mediterranean Sea and now dominate both the biomass and community structure
of shallow sublittoral and littoral habitats (Goren and Galil 2005).
Constructed physical barriers such as dams, weirs, and culverts on streams and
rivers are typically regarded as problems for fi sh passage and much research and
expense has been invested in designing suitable structures to assist upstream fi sh
passage, and in enacting legislation to prohibit the construction of impassable bar-
riers (Roni
et al
. 2002). However, physical barriers may help to prevent the spread
of nuisance fi shes, while fi sh passes may assist such spread. Preventing the spread of
invasive species in rivers where the upstream or downstream passage of migratory
indigenous species is required therefore presents special problems. Some research
has been undertaken to design structures that provide passage for native species but
prohibit or trap invasive exotics (Stuart
et al
. 2006).
Recent technological applications in preventing the spread of invasive fi sh are
electrical and bubble barriers, although these technologies are not new. Electrical
barriers were extensively employed in the Great Lakes sea lamprey control pro-
gramme in the 1950s (Smith and Tibbles 1980). An electrical barrier has recently
been constructed on the Des Plaines River, Illinois, to prevent the spread of species
such as round goby and ruff e from the Great lakes into the Mississippi drain-
age, and the spread of bighead, black, and silver carps in the opposite direction.
Unfortunately the round goby had already invaded downstream of the barrier
prior to its construction in 2002 (Corkum
et al
. 2004) and the ultimate success
of this venture in preventing the spread of other invasive fi sh is uncertain because
recent studies show that such barriers are only partially eff ective for some species
(Dawson
et al
. 2006).
13.8.2.2 Chemical control
The chemical renovation of freshwaters is the most common and historically
effective method in controlling or eradicating nuisance fi sh species. However,
options for chemical eradication are limited to relatively small enclosed water bod-
ies or small streams and rivers because of the quantity of chemical required and the
potential for signifi cant collateral ecosystem damage. Not only is cost an import-
ant consideration in treating a large water body but also the availability of suffi cient
