As I see it, there are three reasons that can explain the apparent lack of effort that agencies are devoting to the problem of illegal stocking of aquatic organisms:

1. They don’t see illegal stocking as a serious problem compared to other environmental issues of our time.

   It is surprising to me that the penalty for illegally stocking fish in many jurisdictions (<$100; Johnson et al. 2009) is less than the fine can be for littering.

   This suggests that regulatory agencies are not as concerned about deterring an action that can wreak havoc on entire ecosystems as others are about the appearance of our highways. Or, agencies simply refuse to acknowledge that illegal stocking is a very widespread phenomenon.

   For example, Kerr et al. (2005) evaluated eight pathways of invasion by aquatic species into Ontario. They minimized the importance of illegal stocking, stating:

   “In some cases, private individuals have illegally moved fishes from one water to another to create a new fishery or enhance the forage base. These are usually isolated occurrences which are difficult to prevent.”

   Unfortunately, this does not appear to be the case as Vander Zanden et al. (2004) reported:

   “The ranges of many game fishes such as smallmouth bass, rock bass (Ambloplites rupestris), northern pike (Esox lucius), and largemouth bass (Micropterus salmoides) have expanded dramatically during the past century, and their expansion continues at a rapid pace. While stocking of nonnative game fishes by resource management agencies is no longer a common practice, littoral (inshore) predators continue to expand their range as a result of unauthorized introduction by anglers, (and) accidental bait bucket transfers…”

2. They believe illegal stocking is an intractable problem that is impossible to interdict with rules that are difficult to enforce.

   Because illegal stocking can be such a cryptic activity that can occur over an enormous geographic area, it may seem almost pointless to attempt to catch a culprit “in the act”.  However, there are strategies to overcome the challenges. As Johnson et al. (2009) describe, agencies should put more effort into deterrents and encourage angler peers to notify agencies when they have knowledge that illegal stocking has occurred. Severe penalties for violators and substantial rewards for turning in stockers send the message that the behavior is not tolerable.

3. They are unwilling to take the necessary steps for fear of disenfranchising license buyers.

   It has been widely known that allowing the use of live bait has greatly contributed to the illegal fish stocking problem (Litvak and Mandrak 1993; Ludwig and Leitch 1996), but it is also responsible for widespread illicit introductions of crayfish (Lodge et al. 2000; DiStephano et al. 2009).  Despite the fact that North America harbors 75% of the world’s crayfish diversity, only 4% of states and provinces responding to a recent survey prohibit the use of live crayfish as bait (DiStephano et al. 2009).

   Prohibiting the use of live aquatic organisms as bait would eliminate “bait bucket introductions” when anglers release bait remaining at the end of a fishing outing. Prohibiting the possession of live fish (in boat livewells for instance) could greatly reduce the opportunity for anglers to translocate fish. But these regulatory actions would require anglers to forfeit traditional fishing activities and eliminate popular live weigh-in events at fishing tournaments. Because fishing license sales have been in steady decline since 1996 (USFWS 2007), agencies may simply be afraid to take actions that could drive down fishing participation and lead to further loss of license revenue.

Literature cited

DiStephano, R.J., M. E. Litvan, and P. T. Horner.  2009.  The bait industry as a potential vector for alien crayfish introductions: problem recognition by fisheries agencies and a Missouri Evaluation.  Fisheries 34(12): 586-597.

Johnson, B.M., R. Arlinghaus, and P.J. Martinez. 2009. Are we doing all we can to stem the tide of illegal fish stocking? Fisheries 34(8): 389-394.

Litvak, M. K., and N. E. Mandrak. 1993. Ecology of freshwater baitfish use in Canada and the United States. Fisheries 18(12):6–13.

Lodge, D. M., C. A. Taylor, D. M. Holdich, and J. Skurdal. 2000. Reducing impacts of exotic crayfish introductions: new policies needed. Fisheries 25(8):21–23.

Ludwig, H.R. Jr., and J.A. Leitch. 1996. Interbasin transfer of aquatic biota via anglers’ bait buckets. Fisheries 21(7):14–18.

USFWS (United States Fish and Wildlife Service). 2007. The 2006 National Survey of Fishing, Hunting, and Wildlife-Associated Recreation. U.S. Department of the Interior, Fish and Wildlife Service, and U.S. Department of Commerce, U.S. Census Bureau. Washington, D.C.

Vander Zanden, M. J., J. D. Olden, J. H. Thorne and N. E. Mandrak.  2004.  Predicting occurrences and impacts of smallmouth bass introductions in north temperate lakes. Ecological Applications 14:132–148.

Tell Others

Certainly, not all fish introductions have catastrophic consequences, but many do. Knowledge about problems that may arise from biological invasions into aquatic systems is growing rapidly, but invasion biology is still a new science. However, we can expect to understand older impacts and to detect new ones in the near future. Still, aside from the potential ecological problems (and the many that have already been demonstrated) that occur in the short-term, we may be causing changes that will be perceived only in the longterm (for instance, in evolutionary time), at a global scale (see Rahel 2000). As these consequences are still largely unpredictable, a precautionary approach is the best option.

One relevant aspect of this complex issue is that introducing fish species usually rewards a relatively small group of individuals or corporations, while society as a whole ultimately pays the costs. This fact results in pressure to downplay news about possible ecological impacts. Even more importantly, if the precautionary approach is abandoned and concern about introductions is unpublicized, potentially devastating consequences of indiscriminate introduction of freshwater fishes around the globe, especially in megadiverse tropical underdeveloped countries, will simply happen. An introduction that goes astray usually cannot simply be called back. Introduction rates are increasing, and the pressure for introductions by individuals or corporations involved in aquaculture for food or ornamental species is very powerful, rapidly outstripping any attempt to understand potential or real impacts.

Introduction of species in general is one of the greatest global threats to the conservation of biological diversity and is generating one of the main forms of global change: biotic homogenization (see Simberloff 2003; 2004; 2005; 2006a; b; 2007; Rahel 2000; Rahel & Olden 2008). For aquatic species, perception of the problem is often delayed, limiting the opportunity for control or eradication; aquatic introductions are usually irreversible, particularly in regions with many endemic species. Fish in particular can easily become serious threats due to their mobility. We do not deny the benefits of some non-native species introductions. Such benefits can accrue quickly, but they are generally restricted, as in control of aquatic weeds and improvement of fish production and/or sport fisheries (Pullin et al. 1997; Bartley & Casal 1998; Vitule 2006; Alves et al. 2007). After these immediate rewards, costs begin to appear. These include changes in natural competition and predation rates, changes in the behavior of native species (fish and other species), limnological perturbations, introduction of diseases and parasites, hybridization with native species, changes in natural assemblages with consequences for fisheries and local economy, and finally local or global native species extinction (and there are many real cases, vide e.g. Pullin et al., 1997; Bartley and Casal, 1998; Pompeu & Goldinho, 2001; Pompeu & Alves, 2003; Townsend, 2003; Begon et al., 2006; Vitule, 2006; Alves et al., 2007). A simple literature search yields many other real-world examples of disastrous freshwater fish introductions.

Aquaculture is often a highly profitable activity in underdeveloped countries, but it is usually inadequately planned. This is the major cause of global fish introductions (Casal 2006). In addition to aquaculture practices, sport fishing, biological control, pet trade and agriculture are among the main reasons for introducing fish. Construction of canals and irrigation channels has frequently connected formerly separate hydrographic basins, leading to species migration among distinct ichthyofaunal provinces that often results in harmful consequences (Cambray 2003; Agostinho et al. 2005, Vitule et al. 2006). It is also essential to understand that a species of fish can be non-native when moved to a new water body even within the same basin or sub-basin (Cambray 2003; Vitule et al. 2006). There are also many problems associated to illegal handling of animals through the web (WWW). This deleterious activity should be controlled or verified the same way pornographic and other illegal sites are controlled. Currently, through a simple internet search anyone can purchase and illegally introduce exotic aquatic organisms, to many places of the world.

Even worse, in tropical underdeveloped countries (in general with many hotspots, see Abell et al. 2008), laws and law enforcement are minuscule in comparison to the size of the problem. Legal and regulatory control are almost non-existent in nations such as Brazil (see Alves et al. 2007; Vitule et al. 2009). As noted by Alves et al. (2007): “In summary, although laws governing non-native fish species exist, in practice, fish introductions are of little concern. In fact, any citizen can buy cultured fish from any Brazilian river basin or from another country and release them into privately owned water bodies. The owners and managers of many privately operated hatcheries state in magazine advertisements that their fishes can be delivered to anywhere in Brazil.” This is not a local problem, nor is it restricted to Brazil (e.g. Fuller et al. 1999; Welcomme 1988; Rahel 2000).

If there is scientific uncertainty with respect to the impact of introducing an exotic species into a new habitat, it should not be introduced there until there has been careful consideration of potential costs and benefits. Once established, an introduced species is usually impossible to eradicate. The notion that economic and social development can be considered independently of the maintenance of biological biodiversity is irrational and unacceptable. The United Nations Conference on Environment and Development that occurred in Rio de Janeiro in 1992 advocated the precautionary principle (United Nations Environmental Programme – UNEP, 1992). Principle 15 reads: “In order to protect the environment, the precautionary approach shall be widely applied by States according to their capabilities. Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation”. Further, Article 8h of the Convention arising from that conference calls on all parties to “as far as possible and as appropriate…prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species.”

That the number of freshwater fish introductions will increase is almost certain. If something can be very bad, and its occurrence will grow in the future, what can we consider to be a realistic attitude? Simply to ignore the problem? It seems that some authors (e.g. Gozlan, 2008) are trying to downplay widely acknowledged huge problems associated with introducing freshwater fishes. But it is our duty to warn that, if we do so, and if we minimize the real danger of species introductions based on insufficient and unreliable data, we are aiding people or organizations who think only about immediate profit without considering longer-term losses. The losses will be borne by everyone and will be experienced for many generations.

Despite the recent increase in publicity on this subject, and the many problems that have been documented worldwide, in fact the number of introductions is trending upward (e.g. Rahel 2000; Simberloff 2005; 2007; Wilson, 2006; Rahel & Olden 2008). These factors may generate a feeling of pessimism: there is nothing you can do, so why bother, and after all….this is not so bad. No, definitely, no! This is an unacceptable attitude. We should be aware that, if we do nothing about this situation, we are sure to have problems in the future. Introduced species can be restricted and avoided, and, if they reach a new environment where they can cause harm to local species or cause other undesirable effects, they must be detected quickly and, if possible, eradicated. If this is not possible, they must be studied, controlled, and an attempt must be made to keep them at acceptable levels.

We expect that this site can help clarify issues and promote debates on this subject, in order to protect the world’s biodiversity.

If you are interested in reading more on our point of view, see the references cited or Vitule, J.R.S.; Freire C.A. & Simberloff, D. (2009). Introduction of non-native freshwater fish can certainly be bad. Fish and Fisheries, DOI: 10.1111/j.1467- 2979.2008.00312.x, (Early View): http://www3.interscience.wiley.com/journal/120125848/issue

References

• Abell, R, Thieme ML, Revenga C, Bryer M, Kottelat M, Bogutskaya N, Coad B, Mandrak N, Balderas SC, Bussing W, Stiassny MLJ, Skelton P, Allen GR, Unmack P, Naseka A, Rebecca NG, Sindorf N, Robertson J, Armijo E, Higgins JV, Heibel TJ, Wikramanayake E, Olson D, López HL, Reis RE, Lundberg JG, Sabaj Pérez MH, Petry P. 2008. Freshwater ecoregions of the World: a new map of biogeographic units for freshwater biodiversity conservation. BioScience 58(5):403-414. doi: 10.1641/B580507
• Agostinho, A.A.; Thomaz, M.S. and Gomes, C.L. 2005. Conservation of the biodiversity of Brazil’s inland waters. Conservation Biology, 19:646-652.
• Alves, C.B.M.; Vieira, F.; Magalhães, A.L.B. and Brito, M.F.G. 2007. Impacts of nonnative fish species in Minas Gerais, Brazil: present situation and prospects. In: T. M.
• Bert (ed.), Ecological and Genetic Implications of Aquaculture Activities. (eds T.M. Bert). Springer Verlag, Berlin, pp. 291-314.
• Bartley D. 2007. An ecosystems approach to risk assessment of alien species and genotypes in aquaculture. In: Ecological and Genetic Implications of Aquaculture Activities. (eds T.M. Bert). Springer Verlag, Berlin, pp. 35-52.
• Bartley, D., and Casal C.V. 1998. Impacts of introductions on the conservation and sustainable use of aquatic biodiversity. FAO Aquaculture Newsletter 20: 15–19.
• Begon M, Harper J.L. and Townsend C.R. 2006. Ecology: individual, populations and communities. Blackwell, Oxford, 759 p.
• Fuller P.L., Nico L.G. and Williams, J.D. 1999. Nonindigenous fishes introduced into inland waters of the United States. American Fisheries Society, Bethesda, 613 p.
• Cambray, J.A. 2003. The need for research and monitoring on the impacts of translocated sharptooth catfish, Clarias gariepinus, in South Africa. African Journal of Aquatic Science, 28: 191-195.
• García-Berthou, E. 2007. The characteristics of invasive fishes: what has been learned so far? Journal of Fish Biology 71 (Suppl. D), 33-55.
• Gozlan, R.E. 2008. Introduction of non native freshwater fish: is it all bad? Fish and Fisheries 9, 106-115.
• Magalhães, A.L.B. and Jacobi, C.M. 2008. Ornamental exotic fish introduced into Atlantic Forest water bodies, Brazil. Neotropical Biology and Conservation, 2:73-77.
• Pompeu, P.S., and C.B.M. Alves. 2003. Local fish extinction in a small tropical lake in Brazil. Neotropical Ichthyology 1(2): 133–135.
• Pompeu, P.S., and A.L. Godinho. 2001. Mudanc¸a na dieta da traira Hoplias malabaricus (Bloch) (Erythrinidae, Characiformes) em lagoas da bacia do rio Doce devido a` introducão de peixes piscívoros. Revista Brasileira de Zoologia 18(4): 1219–1225.
• Pullin, R.S.V., M.L. Palomares, C.V. Casal, M.M. Dey, and D. Pauly. 1997. Environmental impacts of tilapias. International Council for Living Aquatic Resource Management Contribution 1350: 554–570.
• Simberloff, D. 2004. Community ecology: is it time to move on? American Naturalist 163: 787–799.
• Simberloff, D. 2005. The politics of assessing risk for biological invasions: the USA as a case study. Trends in Ecology and Evolution 20: 216-222.
• Simberloff, D. 2006a. Invasional meltdown 6 years later: important phenomenon, unfortunate metaphor, or both? Ecology Letters 9: 912–919.
• Simberloff, D. 2006b. Book review of Black Carp. Biological Synopsis and Risk Assessment of an Introduced Fish. Biological Invasions 8: 1433-1434.
• Simberloff, D. 2007. Given the stakes, our modus operandi in dealing with invasive species should be ‘‘guilty until proven innocent.’’ Conservation Magazine 8: 18–19.
• Vitule, J.R.S.; Umbria, S.C. and Aranha, J. M. R. 2006b. Introdução de espécies, com ênfase em peixes de ecossistemas continentais. In: E.L.A. Monteiro-Filho, and Aranha,
• J.M.R. (eds.). Revisões em Zoologia – I: Volume Comemorativo dos 30 Anos do Curso de Pós-Graduação em Zoologia da Universidade Federal do Paraná. Secretaria do Meio Ambiente do Estado do Paraná, Curitiba, 217- 229 p.
• United Nations Environmental Programme (UNEP) (1992). Rio declaration on environment and development. Made at the United Nations Conference on Environment and Development, Rio de Janeiro, Brazil. Available at: http://www.unep.org/Documents/Default.asp?DocumentID=78andArticleID=1163.
• United States Geological Survey. 2000. Zebra mussels Cause Economic and Ecological Problems in the Great Lakes. GLSC Fact Sheet 2000-6. Great Lakes Science Center, Michigan.
• Rahel, J. F. 2000. Homogenization of fish faunas across the United States. Science, 288:854-856.
• Rahel, F.J. and Olden, J.D. 2008. Assessing the effects of climate change on aquatic invasive species. Conservation Biology 22, 521-533.
• Ricciardi, A. 2003. Predicting the impacts of an introduced species from its invasion history: an empirical approach applied to zebra mussel invasions. Freshwater Biology 48, 972–981.
• Townsend C.R. 2003. Individual, Population, Community, and Ecosystem Consequences of a Fish Invader in New Zealand Streams. Conservation Biology, 6: 273-282.
• Welcomme, R.L. 1988. International introductions of inland aquatic species. FAO - Fisheries Technical Papers n 294, Rome, 318 p.
• Wilson, E.O. 2006. The Creation: An Appeal to Save Life on Earth. W. W. Norton and Company, Inc.

Tell Others

By Dr Jim Cambray (March 23, 2009)

When most people see the phrase “Polluter Pays” we think of industries pumping toxic chemicals into aquatic ecosystems. We must revisit this impression. Many toxic spills (but not all) are once off leaks caused by poor management or equipment failure. If the toxic waste gets into a river system it may be flushed along the system killing aquatic organisms until it is diluted enough to not be lethal to living organisms. This is quite easy to comprehend and yes the polluter must pay and due to the nature of the spill its chemical makeup can be traced back to a specific source.

However what about biological pollution? What happens when an angler (what I call an ecovandal) selfishly thinks that adding another species to his special angling river will “improve” the angling for him and his friends. After the bucket of fish is emptied into the river the angler may have changed the aquatic ecosystem and the intricate interactions and evolutionary pathways of the native organisms forever.

Now we may ask what are the differences between a chemical spill event and a biological “spill” event? In many cases the chemical spill is once off and the polluter can be traced and fined. The chemicals do not move upstream or into tributaries therefore there are refugia for native aquatic organisms that can recolonize the main channel after the polluting chemicals have been diluted below lethal levels.

In comparison the biological pollution is potentially long term. If the stocked fish breed successfully and become invasive we have the makings of an ecological disaster. The fish move upstream, downstream, into the tributaries. Each year they increase in numbers and out‐compete the native fauna. It can be very difficult to find the polluter who should pay.

Both chemical and biological pollution events are disasters. But from the above we can see that the biological pollution event is a long‐term and invasive one compared to a more short term and localized (in most cases) chemical pollution event. We are therefore left with the fact that an ecovandal should be fined more and pay for the clean‐up costs, which with breeding fish, could cost millions. One well publicized case could drastically reduce the number of eco‐vandal cases and leave our rivers free of these alien invasive species.

I strongly support Brett Johnson’s initiative with this website. If we can even reduce 50% of the illegal stockings we have come a long way. It is up to you to make this work.

Tell Others