4 Interactions of Wild and Reared Fish and Invertebrates
147
9. Genetically Modified (transgenic) animals should be prohibited from “open”
culture until further experiments are conducted.
10. Movement of animals for rearing between documented major population
groupings should be prohibited, e.g., eastern North America, western Europe
and rivers around the Baltic Sea for Atlantic salmon; western and eastern North
Atlantic and Baltic for cod; and Mediterranean and east Atlantic for sea bass.
11. Most experimental investigations of interactions to date have involved Atlantic
salmon. This species appears to be very different both in life history and
genetics from all of the other species cultured in Europe, so studies are needed
with some of these other species to investigate whether general principles can
be developed.
4.10 Conclusions
As noted at the beginning of this chapter it is anticipated that aquaculture will
continue to grow both for closed-cycle farming and for stocking/ranching. This
expanded production will mean that there is the potential for greater numbers of
reared fish and invertebrates to be inadvertently or deliberately introduced to the
wild, with the latter being potentially as detrimental as the former. Thus, the
problem of genetic interactions may increase, unless (i) measures are taken to avoid
escapes or ameliorate their effects, and (ii) more research is undertaken to quantify
and reduce the effect of deliberately released reared species. Another incompletely
researched area is whether it is possible to extrapolate from previous results, mostly
with Atlantic salmon, to other marine fish and invertebrate species. Most previous
studies have concentrated on direct genetic effects and used relative survival as a
surrogate for reproductive fitness. It is now clear from some of the case studies
reported here that indirect effects, mediated either pathologically (by diseases) or
ecologically, may have severe detrimental influence on wild conspecifics or other
native species in the natural environment. Since these indirect effects may be
masked by direct effects, it is important to devise experiments to unravel these
influences. Advances in molecular genetics, particularly in the area of genomics
and the study of adaptive genes, e.g., associated with disease resistance, should
greatly assist future investigations.
References
Agnalt A-L, Jørstad KE, Kristiansen T, Nøstvold E, Farestveit E, Næss H, Paulsen OI, Svåsand T
(2004) Enhancing the European lobster (Homarus gammarus) stock at Kvitsøy Islands:
Perspectives of rebuilding Norwegian stocks. In: Leber KM, Kitada S, Blankenship HL,
Svåsand T (eds.), Stock enhancement and sea ranching: developments, pitfalls and opportunities. Blackwell, Oxford, pp. 415–426
Agnalt AL, van der Meeren GI, Jorstad KE, Naess H, Farestveit E, Nostvold E, Svasand T,
Korsoen E, Ydstebo L (1999) Stock enhancement of European lobster (Homarus gammarus):
147
9. Genetically Modified (transgenic) animals should be prohibited from “open”
culture until further experiments are conducted.
10. Movement of animals for rearing between documented major population
groupings should be prohibited, e.g., eastern North America, western Europe
and rivers around the Baltic Sea for Atlantic salmon; western and eastern North
Atlantic and Baltic for cod; and Mediterranean and east Atlantic for sea bass.
11. Most experimental investigations of interactions to date have involved Atlantic
salmon. This species appears to be very different both in life history and
genetics from all of the other species cultured in Europe, so studies are needed
with some of these other species to investigate whether general principles can
be developed.
4.10 Conclusions
As noted at the beginning of this chapter it is anticipated that aquaculture will
continue to grow both for closed-cycle farming and for stocking/ranching. This
expanded production will mean that there is the potential for greater numbers of
reared fish and invertebrates to be inadvertently or deliberately introduced to the
wild, with the latter being potentially as detrimental as the former. Thus, the
problem of genetic interactions may increase, unless (i) measures are taken to avoid
escapes or ameliorate their effects, and (ii) more research is undertaken to quantify
and reduce the effect of deliberately released reared species. Another incompletely
researched area is whether it is possible to extrapolate from previous results, mostly
with Atlantic salmon, to other marine fish and invertebrate species. Most previous
studies have concentrated on direct genetic effects and used relative survival as a
surrogate for reproductive fitness. It is now clear from some of the case studies
reported here that indirect effects, mediated either pathologically (by diseases) or
ecologically, may have severe detrimental influence on wild conspecifics or other
native species in the natural environment. Since these indirect effects may be
masked by direct effects, it is important to devise experiments to unravel these
influences. Advances in molecular genetics, particularly in the area of genomics
and the study of adaptive genes, e.g., associated with disease resistance, should
greatly assist future investigations.
References
Agnalt A-L, Jørstad KE, Kristiansen T, Nøstvold E, Farestveit E, Næss H, Paulsen OI, Svåsand T
(2004) Enhancing the European lobster (Homarus gammarus) stock at Kvitsøy Islands:
Perspectives of rebuilding Norwegian stocks. In: Leber KM, Kitada S, Blankenship HL,
Svåsand T (eds.), Stock enhancement and sea ranching: developments, pitfalls and opportunities. Blackwell, Oxford, pp. 415–426
Agnalt AL, van der Meeren GI, Jorstad KE, Naess H, Farestveit E, Nostvold E, Svasand T,
Korsoen E, Ydstebo L (1999) Stock enhancement of European lobster (Homarus gammarus):