Friday, May 11, 2018

What Limits Recovery of Atlantic Sturgeon, Austin Beaudet

One hundred years ago, a fisherman could fish in any river on the east coast and have a chance to catch a colossal, prehistoric looking monster, Acipenser oxyrinchus, or better known as the Atlantic Sturgeon. This bony plated monster could grow up to 14 feet in length a weigh a whopping 800 pounds (NOAA). This creature’s huge size and bizarre features made it a target to fisherman all along the east coast. They began to catch these fish at an at a frantic pace to get in on the short lived goldmine that sturgeon provided. Then it all just stopped. Humans kept hunting them until they had completely decimated their numbers. In areas like the Chesapeake Bay which had an estimated 20,000 sturgeon at one point were brought down to roughly 300 alive in the present that are able to reproduce (Dietrich 2017). Since the inclusion of the sturgeon under the endangered species act, many groups and agencies have been desperately trying to bring this population back to a much more stable and healthy size. Certain methods of recovery today include a ban on all capture of Atlantic Sturgeon, hatcheries attempting to provide a boost to the sturgeon population, and other research projects and studies which are trying to learn more about the habitat, life history, and migration patterns of the sturgeon. However, recovery efforts are not going nearly as well as we have hoped and the sturgeon population has failed to comeback in the numbers we wished and many people want to figure out why. According to the research and data that scientists currently have, the main problems limiting the recovery efforts are bycatch mortality, water quality, and dredging activities which all seem to be hugely detrimental in regions inhabited by sturgeon.
           
Young Atlantic Salmon captured from the Altamaha basin in Georgia.  Photo by Brett Albanese, Georgia DNR.  Creative Commons Flickr
Water quality plays a major role in the development, reproduction, and overall health of the Atlantic Sturgeon. Although there has been multiple laws protecting our waters from pollution, mankind still finds a way to dump harmful chemicals into our river system. One chemical that is particularly damaging to the recovery of sturgeon is polychlorinated biphenyls (PCB). PCB was a very popular form of coolant within many electrical systems in the 1900’s but usage has since declined due to the discovery of it's harmful properties to both humans and wildlife. However, the damage has already been done and will continue to haunt our environment long into the foreseeable future. One estimate has stated that the United States has produced 600,000 tonnes of PCB and a good portion of it has entered our riverways (Cooper 1989, Sinderman 1994). To make things worse, according to the Atlantic Sturgeon Status Review, “Atlantic sturgeon may be particularly susceptible to impacts from environmental contamination due to their benthic foraging behavior and long-life span” (Cooper 1989, Sinderman 1994). Today, PCB sits at the bottom of local rivers and continues to poison the sturgeon population and it seems as though there is very little we can do about it. Studies have now been conducted and have concluded that, “exposure to PCBs reportedly causes a higher incidence of fin erosion, epidermal lesions, blood anemia, and an altered immune response” (Kennish et al. 1992). Until a proper method of removal of PCB from our waterways can be figured out then sturgeon will never stop dealing with the consequences the pollutant causes.
           
Another major factor that continues to hinder Atlantic Sturgeon recovery efforts is the freshwater dredging that occurs up and down the east coast river systems. This dredging still goes on today and it needs to be run in a much more environmentally conscious manner or be shut down all together. The consequences that sturgeon face due to dredging include, “direct removal/burial of organisms; turbidity/siltation effects; contaminant resuspension; noise/disturbance; alterations to hydrodynamic regime and physical habitat and actual loss of riparian habitat...destruction of benthic feeding areas, disruption of spawning migrations, deposition of resuspended fine sediments in spawning habitat…, and the lethal entrainment of fish up through the dredge drag-arms and impeller pumps” (Chytalo 1996, Winger et al. 2000). To make matters worse, this form of dredging is not nearly regulated enough especially considering the damage is currently is causing. Changes need to start happening as soon as possible if there is still hope to save the Atlantic Sturgeon population from extinction.
A five-foot Atlantic Sturgeon killed by ship strike in the James River, Virginia.  Photo by James River Association. creative commons Flickr
The last major factor preventing the Atlantic Sturgeon from having a stable population size is the damages done through ship strikes and by-catch of the sturgeon (Melnychuk et al. 2016; ASMFC 2017). By-catch is when a certain fish is caught by commercial fisheries that is not the intended target fish. Although intentional hunting of Atlantic Sturgeon is strictly banned, bycatch still remains to be a huge problem. Records show that Atlantic Sturgeon become victims of by-catch through trawls, pound nets, and gill nets. Pound nets seem to be the least damaging to the sturgeon population and don’t have any recorded cases of directly causing death to sturgeon. Trawls have caused some deaths in the sturgeon population but most trawling systems on the southern half of the east coast have mechanisms in place to help prevent the capture of unwanted fish species. Gill nets are the main source of death and accountable for doing the most harm to the sturgeon population. Certain surveys have shown that sturgeon caught in these nets have up to a 70% chance of mortality depending on length of time before the sturgeon are freed (NMFS Observer Database). These nets continue to cause incidents that result in the death of sturgeon every year and if environmental groups and protection/conservation agencies continue to work on the recovery of this species without figuring out a solution to by-catch problems then their fight will most likely be doomed.
           
             When thinking of limiting factors to the recovery of the Atlantic Sturgeon, things like hunting, global warming, and fecundity come to mind. However, after extensive research it can clearly be seen that the obstacles limiting the Atlantic Sturgeon are quite different. Problems dealing with water quality, by-catch, ship strikcs, and dredging all have become major contributors in the continued decline of this species. Although these threats may not cause as much mortality to sturgeon as ship strikes or dams that block migration routes, they are currently problems that have gone under the radar and need to be fixed just as badly as other, more commonly discussed problems. The good news is that in some rivers, such as the Hudson and Savannah,  biologists are beginning to see an increase in the numbers (Bahr and Peterson 2016; New York State Conservationist 2016).  If protective measures continue, the Atlantic Sturgeon may show signs of recovery in more rivers.

References

ASMFC. 2017. Atlantic Sturgeon Benchmark Stock Assessment and Peer Review Report, Arlington, VA. 456p.  Available from
http://www.asmfc.org/files/Meetings/AtlMenhadenBoardNov2017/AtlSturgonBenchmarkStockAssmt_PeerReviewReport_2017.pdf

Bahr, D.L., and D.L. Peterson. 2016.  Recruitment of Atlantic Sturgeon in the Savannah River, Georgia.  Transactions of the American Fisheries Society 145:1171-1178.
Chytalo, K. 1996. Summary of Long Island Sound dredging windows strategy workshop. In:    Management of Atlantic Coastal Marine Fish Habitat: Proceedings of a Workshop for Habitat Managers. ASMFC Habitat Management Series #2.
Cooper, K. 1989. Effects of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans on aquatic organisms. Reviews innAquatic Sciences 1(2): 227-242.
Dietrich, Tamara. “Sturgeon Get a Double Boost in the Chesapeake Bay.”Dailypress.com, Daily  Press, 17 Aug. 2017, www.dailypress.com/news/science/dp-nws-sturgeon-virginia-20170816-story.html.
Kennish, M. J., T. J. Belton, P. Hauge, K. Lockwood, and B. E. Ruppert. 1992. Polychlorinated biphenyls in estuarine and coastal marine waters of New Jersey: a review of contamination problems. Reviews in Aquatic Sciences 6: 275-293.
Melnychuk, M.C., K.J. Dunton, A. Jordaan, K. McKown, and M.G. Frisk. 2016.  Informing conservation strategies for the endangered Atlantic sturgeon using acoustic telemetry and multi-state mark-recapture models.  Journal of Applied Ecology 54:914-925.
New York State Conservationist. 2016.  "Atlantic sturgeon show signs of population recovery." ,  p. 36. Student Resources In Context
http://link.galegroup.com/apps/doc/A457106794/SUIC?u=viva_vpi&sid=SUIC&xid=73bd1561. Accessed 10 May 2018.
Sindermann, C. J. 1994. Quantitative effects of pollution on marine and anadromous fish populations. NOAA Technical Memorandum NMFS-F/NEC-104, National Marine Fisheries Service, Woods Hole, Massachusetts.
Smith, T., and J. Clugston. “Atlantic Sturgeon Recovery Program.” Greater Atlantic Regional Fisheries Office, NOAA Fisheries, 29 Jan. 2014, www.greateratlantic.fisheries.noaa.gov/protected/atlsturgeon/.

Winger, P. V., P. J. Lasier, D. H. White, J. T. Seginak. 2000. Effects of contaminants in dredge material from the lower Savannah River. Archives of Environmental Contamination and Toxicology 38: 128-136.

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