Genetic Monitoring for Managers


Types of GEM

Category 1b GeM Project Example: Trade in Fish and Wildlife Products

Two distinct applications of genetic sampling exist with regard to monitoring markets in fish and wildlife products. The first uses genetic information obtained directly from markets to explore patterns in natural populations. The second uses genetic information to determine the species or source population of animals found in markets. We provide recent examples of each below.

Baker 2008

Commercial and traditional markets for wildlife and fisheries present important opportunities for genetic monitoring of biodiversity. Whereas the primary objective of past market surveys has been to document illegal trade in species, it is less well appreciated that market surveys, over time, can also provide information on changes in species composition (diversity) and even for inferring population dynamics (abundance and effective population size) of species subject to direct or indirect exploitation (Baker 2008). With the appropriate sampling design for collection of samples from market products and application of standard or modified statistical analyses (e.g., assignment tests, mixed-stock of capture-recapture), market surveys can fulfill many of the primary objectives of genetic monitoring for many natural populations that would otherwise fall outside of conventional monitoring programs.

trade fig 1
A variety of products from whales, dolphins and porpoises, taken as incidental fisheries bycatch, are sold in Korea markets. Without genetic monitoring, it is not possible to identify the species or estimate the number of individuals represented in these butchered products. The latter is important for management purposes by the International Whaling Commission.


Using DNA to track the origin of the largest ivory seizure since the 1989 trade ban.

Wasser et al. 2007

Policing trade in illegal wildlife products is often hindered by the inability of enforcement officers to determine the source species or population. For example, large shipments of ivory destined for Far East markets may contain ivory from elephants in multiple populations spanning many countries. Coordinated smuggling

trade fig 4
Map of Africa showing the sampling sites used for developing model (plus signs) and location of tissue/scat samples (circles) color-coded to reflect region of origin. Key: West Africa (cyan), Central forest (red), and Central (black), South (green), and East (blue) savannah. [from Wasser et al. 2004]

efforts gather tusks from across Africa in single, large shipments. Therefore, even when officials are fortunate enough to intercept a shipment and confiscate their contents, they may not be able to reliably determine the origin. This limits the opportunities to focus enforcement, education, and conservation efforts in affected populations.

Wasser et al. (2004) developed a method to identify the geographic origin of confiscated ivory across the entire range of African elephants, including areas where no samples had been genotyped. Their method uses similarities in allele frequencies across multiple samples (tusks) simulataneously. They found this method to be more accurate than pairwise sample analyses.

Another advantage of their method is that is can estimate how much confidence to place in assigned sample origins by comparing relative support across mutiple putatitve locations. Accuracy of assignment is a function of both sample size and genetic characteristics of the source population (i.e., diversity and degree of separation from other populations). Therefore, as the size of the reference dataset grows, the ability to identify the origin of confiscated will

Contrary to initial expectations, Wasser et al. (2007) found that the ivory was entirely from savanna elephants, likely originating from a narrow east-to-west strip centering on Zambia. Wildlife authorities initially suspected that this ivory came from multiple locations across forest and savanna Africa. However, we show that These findings enabled law enforcement to focus their investigation to a smaller area and fewer trade routes and led to changes within the Zambian government to improve antipoaching efforts. Such outcomes demonstrate the potential of genetic analyses to help combat the expanding wildlife trade by identifying origin(s) of large seizures of contraband ivory.

trade fig 2
Assignment results for 37 tusks from a large seizure in Singapore. Circles represent the estimated origin of the 37 tusks analyzed. Plus signs coincide with the those in the figure above. [from Wasser et al. 2007]