In this post Associate Editor Verena Trenkel discusses a paper she recently handled from Michael Melnychuk and colleagues ‘Informing conservation strategies for the endangered Atlantic sturgeon using acoustic telemetry and multi-state mark–recapture models‘

According to the International Union for Conservation of Nature (ICUN), ten out 17 sturgeon species are currently critically endangered. Among the two species listed as least concern is Atlantic sturgeon which occurs along the east coast of North America (St. Pierre and Parauka, 2006). However, certain populations of Atlantic sturgeon have recently been listed as threatened or endangered in U.S. waters (USOFR, 2012). The continuing poor and in many cases worsening status of sturgeon species world wide is caused by overfishing, illegal catch and illegal caviar trade, as well as coastal habitat degradation and pollution (Rosenthal et al. 2014). Putting into place effective conservation measures depends on better understanding the life cycle requirements of the species, as well as identifying locations and times of bycatch by fisheries (Dunton et al. 2015).

In this recent study Melnychuk and colleagues analyse with multi-state mark-recapture models acoustic telemetry data from 429 Atlantic sturgeon tagged on the southern coast of Long Island (New York State). Application of this model provides for the first time quantitative estimates of both seasonal patterns in survival and migration rates while accounting for detection probabilities of tagged fishes at receiver stations. The exciting novelty of the study lies in being able to simultaneously estimate migration and survival rates over a relatively large area as well as resolving these estimates on a seasonal basis. In previous studies either survival (Hightower et al. 2015) or movements were studied (Breece et al. 2016), but not both. Due to the large number of tagged individuals Melnychuk and colleagues could also investigate body size effects on migration and survival rates. Overall the study found that bycatch fishing mortality might be of the same order as natural mortality (estimated as 5.88% per year), which the authors consider too high for recovery. These are the bad news.

The good news are, as this study demonstrates, that it is possible to carry acoustic telemetry studies at scales relevant for conservation of large anadromous species (~800 km coastline in this study) and use state of the art multi-state mark-recapture models for separating survival, migration and detection rates on a seasonal basis. This might inspire researchers studying the other 16 sturgeon populations to launch similar research programs, or join forces to study Atlantic sturgeon along the entire Atlantic coast.

References
Breece, M. W., Fox, D. A., Dunton, K. J., Frisk, M. G., Jordaan, A., and Oliver, M. J. 2016. Dynamic seascapes predict the marine occurrence of an endangered species: Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus. Methods in Ecology and Evolution, 7: 725-733.

Dunton, K. J., Jordaan, A., Conover, D. O., McKown, K. A., Bonacci, L. A., and Frisk, M. G. 2015. Marine Distribution and Habitat Use of Atlantic Sturgeon in New York Lead to Fisheries Interactions and Bycatch. Marine and Coastal Fisheries, 7: 18-32.

Hightower, J. E., Loeffler, M., Post, W. C., and Peterson, D. L. 2015. Estimated Survival of Subadult and Adult Atlantic Sturgeon in Four River Basins in the Southeastern United States. Marine and Coastal Fisheries, 7: 514-522.

Rosenthal, H., Gessner, J., and Bronzi, P. 2014. Conclusions and recommendations of the 7th International Symposium on Sturgeons: Sturgeons, Science and Society at the cross-roads – Meeting the Challenges of the 21st Century. Journal of Applied Ichthyology, 30: 1105-1108.

St. Pierre, R., and Parauka, F. M. 2006. Acipenser oxyrinchus. The IUCN Red List of Threatened Species 2006: e.T245A13046974. http://dx.doi.org/10.2305/IUCN.UK.2006.RLTS.T245A13046974.en. Downloaded on 07 October 2016.

USOFR 2012. Endangered and threatened wildlife and plants: Threatened and endangered status for distinct population segments of Atlantic Sturgeon in the northeast region. U.S. Office of the Federal Register 77:22 (6 February 2012): 5880–5912.